Search for low mass vector resonances decaying into quark-antiquark pairs in proton-proton collisions at $$ \sqrt{s}=13 $$ TeV

Journal of High Energy Physics, Jan 2018

The CMS collaboration, A. M. Sirunyan, A. Tumasyan, W. Adam, F. Ambrogi, E. Asilar, T. Bergauer, J. Brandstetter, E. Brondolin, M. Dragicevic, et al.

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Search for low mass vector resonances decaying into quark-antiquark pairs in proton-proton collisions at $$ \sqrt{s}=13 $$ TeV

HJE 13 TeV Search for low mass vector resonances decaying into quark-antiquark pairs in proton-proton collisions at A search for narrow vector resonances decaying into quark-antiquark pairs is presented. The analysis is based on data collected in proton-proton collisions at p Jet substructure; Hadron-Hadron scattering (experiments); Dark matter; Jets - The CMS collaboration s = 13 TeV with the CMS detector at the LHC, corresponding to an integrated luminosity of 35.9 fb 1. The hypothetical resonance is produced with su ciently high transverse momentum that its decay products are merged into a single jet with two-prong substructure. A signal would be identi ed as a peak over a smoothly falling background in the distribution of the invariant mass of the jet, using novel jet substructure techniques. No evidence for such a resonance is observed within the mass range of 50{300 GeV. Upper limits at 95% con dence level are set on the production cross section, and presented in a mass-coupling parameter space. The limits further constrain simpli ed models of dark matter production involving a mediator interacting between quarks and dark matter particles through a vector or axial-vector current. In the framework of these models, the results are the most sensitive to date, extending for the rst time the search region to masses below 100 GeV. 1 Introduction 2 CMS detector 3 Event simulation and selection 3.1 3.2 Simulated samples Event reconstruction and selection 4 Background estimate 5 Systematic uncertainties 6 Results 7 Summary A Supplementary materials The CMS collaboration D0 [20] experiments using p Many extensions of the standard model (SM) predict the existence of new resonances that couple to quarks (q) [1{11]. The rst searches for such particles were reported by the UA1 [12] and UA2 [13, 14] experiments using p s = 630 GeV collisions at the CERN SppS, and were extended to larger values of resonance masses by the CDF [15{19] and the CERN LHC, the searches in proton-proton (pp) collisions at p s = 7, 8 and 13 TeV performed by the ATLAS [21{27] and CMS [28{35] Collaborations have mostly focused on the production of heavy particles. For resonance masses below 1 TeV, the sensitivity is limited by high trigger thresholds and by the large expected backgrounds, notably from SM events consisting of jets produced through the strong interaction, referred to here as s = 1:8 and 1:96 TeV collisions at the Fermilab Tevatron. At QCD multijet events. These di culties can be avoided by an approach focused on the events where at least one high transverse momentum (pT) jet from initial-state radiation (ISR) is produced in association with a light resonance decaying into a qq pair. The ISR requirement provides enough energy in the event to satisfy the trigger, either by the ISR jet or by the resonance itself. The minimum pT of the resonance considered in this search is su ciently high that the hadronization products of the daughter quarks merge and are reconstructed as a { 1 { single, large-radius jet. The only previous search in this topology to place constraints on resonance masses below 300 GeV was by the CMS Collaboration, applying this technique to data collected at the LHC in 2015 [36]. In the current paper, the results of a search for leptophobic vector resonances (Z0) decaying to quark-antiquark pairs in pp collisions at p s = 13 TeV are reported, using data collected by the CMS detector in 2016, corresponding to an integrated luminosity of 35:9 fb 1 . The search is performed by looking for a narrow resonance peak in the continuous jet mass distribution. The analysis exploits a new substructure variable that is decorrelated from the jet mass and pT and preserves the shape of the jet mass distribution used in the search. The jet is required to have the two-prong substructure expected from the signal. The dominant background from SM QCD multijet production is estimated from a signal-depleted control region created by inverting the substructure requirement. The signal yield is extracted by simultaneously tting the signal and control regions, while requiring that the ratio of QCD components in each region is described by a smooth twodimensional function of jet mass and pT. The W+jets and Z+jets background components are estimated from simulation and the top quark background contribution is obtained from simulation corrected with scale factors derived from a tt-enriched control sample. Results are interpreted within the framework of a leptophobic vector resonance model, and are also used to set limits on the existence of generic vector-like resonances decaying into quarks [37]. Limits are also set in the context of a simpli ed model of dark matter (DM) production at the LHC, in which the mediators couple only to quarks and DM particles [38]. 2 CMS detector The central feature of the CMS apparatus is a superconducting solenoid of 6 m internal diameter, providing a magnetic eld of 3.8 T. Within the solenoid volume are a silicon pixel and strip tracker, a lead tungstate crystal electromagnetic calorimeter (ECAL), and a brass and scintillator hadron calorimeter (HCAL), each composed of a barrel and two endcap sections. Forward calorimeters extend the pseudorapidity ( ) coverage provided by the barrel and endcap detectors. Muons are detected in gas-ionization chambers embedded in the steel ux-return yoke outside the solenoid. Events are selected using a two-tiered trigger system [39]. The rst level, composed of custom hardware processors, uses information from the calorimeters and muon detectors to select events of interest in a time interval of less than 4 s. The second level, known as the high-level trigger (HLT), consists of a farm of processors running a version of the full event reconstruction software optimized for fast processing, and further reduces the event rate from around 100 kHz to less than 1 kHz, before data storage. A more detailed description of the CMS detector, together with a de nition of the coordinate system used and the relevant kinematic variables, can be found in ref. [40]. { 2 { HJEP01(28)97 3.1 Event simulation and selection Simulated samples Simulated samples of the Z0 resonance decaying into a quark-antiquark pair are generated at leading order (LO) with the MadGraph5 amc@nlo 2.2.3 generator [41] with up to 3 extra jets in matrix element calculations. The dominant SM backgrounds arise from multijet and W/Z + jets processes. These backgrounds are simulated at LO using the MadGraph5 amc@nlo generator with the MLM matching [42] between jets from matrix element calculations and from parton showers, while the powheg 2.0 [43] generator at nextto-leading order (NLO) precision is used to model the subdominant contribution from pair pythia 8.212 [44], with the CUETP8M1 underlying event tune [45], to simulate parton showering and hadronization e ects. The generated events are further processed through a Geant4 [46] simulation of the CMS detector. The parton distribution function (PDF) set NNPDF3.0 [47] is used to produce all simulated samples, with the accuracy (LO or NLO) determined by the generator used. For events containing W and Z bosons, we apply higher-order QCD and electroweak (EW) pT dependent corrections to improve the modeling of the pT distribution of W and Z events, following refs. [48{52]. The same NLO QCD corrections that are applied to the W and Z simulation are also applied to the signal simulation. However, since the coupling of the Z0 mediator di ers from that of the Z boson, the equivalent Z NLO EW corrections are not applied to the signal model. 3.2 Event reconstruction and selection The CMS particle- ow (PF) event algorithm [53] reconstructs and identi es individual particles with an optimized combination of information from the various elements of the CMS detector. Each particle candidate is classi ed as either an electron, a muon, a photon, or a charged or neutral hadron. The energy of photons is obtained directly from the ECAL measurement, corrected for zero-suppression e ects. The energy of electrons is determined from a combination of the electron momentum at the primary interaction vertex as determined by the tracker, the energy of the corresponding ECAL cluster, and the energy sum of all bremsstrahlung photons spatially compatible with originating from the electron track. The energy of muons is obtained from the curvature of the corresponding track. The energy of charged hadrons is determined from a combination of their momentum measured in the tracker and the matching ECAL and HCAL energy deposits, corrected for zerosuppression e ects and for the response function of the calorimeters to hadronic showers. Finally, the energy of neutral hadrons is obtained from the corresponding corrected ECAL and HCAL energy. The missing transverse momentum vector is de ned as the negative vectorial sum of the transverse momenta of all the particles identi ed in the event, and its magnitude is referred to as pTmiss. The PF candidates are clustered into jets using the anti-kT algorithm [54, 55]. Jets are clustered with distance parameters of 0.4 and 0.8, and are referred to as AK4 and AK8 interactions within the same or adjacent bunch crossings (pileup), weights calculated with the pileup-per-particle identi cation algorithm [56] are applied to each PF candidate prior to jet clustering, based on the likelihood of it coming from the hard-scattering vertex. Further corrections are applied to simulated jet energies as a function of jet and pT to match the observed detector response [57, 58]. This search focuses on events in which a high-pT jet from a merged Z0 ! qq recoils against another high-pT ISR jet. A combination of several online signatures is required for the trigger selection, all requiring the total hadronic transverse energy in the event (HT) or the jet pT to exceed a certain threshold. In addition, soft radiation remnants are removed with the jet trimming technique [59] before the mass selection, allowing the HT and jet pT trigger thresholds to be reduced, and improving the signal acceptance. To be fully e cient with respect to the trigger requirement, we require at least one AK8 jet with pT > 500 GeV and j j < 2:5. Additional quality criteria are applied to the jets in order to remove spurious jet-like features originating from isolated noise patterns in the calorimeters or the tracker. The e ciency of these jet quality requirements for signal events is above 99%. In order to reduce backgrounds from SM EW processes, events are removed if they contain identi ed and isolated electrons, muons, or taus with pT > 10 GeV and j j < 2:5, 2:4, or 2:3, respectively, according to the isolation criteria in [48]. In the subsequent o ine analysis, the most energetic jet in the event is assumed to correspond to the Z0 ! qq system, and is reconstructed as a single AK8 jet. The search is performed using the distribution of the jet mass groomed with the soft-drop algorithm (mSD), which is an extension of the modi ed mass drop tagger [60, 61] that removes soft and wide-angle radiation produced by parton shower activity, pileup interactions, and the underlying event from the jet. Jets are groomed using the parameters zcut = 0:1 and = 0. Here, zcut speci es subleading the energy fraction relative to the whole jet at which jet declustering into subjet pairs is stopped. The parameter adds additional angular requirements on the jet declustering. For = 0, these requirements are neglected, and approximately the same fraction of energy is groomed away regardless of the initial jet energy [61]. The soft-drop grooming reduces the jet mass for QCD background jets when large masses arise from soft gluon radiation. In contrast, the jet mass for merged Z0 ! qq and W=Z ! qq jets comes from the kinematic distributions of the decay, and is largely unchanged by grooming. Figure 1 shows the distributions of mSD for data and simulation, after the jet kinematic selection. In this paper, the dimensionless scaling variable [60, 62], de ned as is used in the characterization of the correlation of jet substructure variables with the jet mass and pT. For QCD jets, the distribution of is approximately invariant under a change of jet pT, in the region where perturbative contributions dominate and scale as (mSD=pT). This property does not hold in two regimes: in the low mass region below 6, where non-perturbative e ects are large and scale as (1=mSD) instead, and in the high mass region above 2. The departure from invariance in the latter case arises because the cone size of the AK8 jets is insu cient to provide complete containment at high masses. Consequently, only events in the range 5:5 < < 2:0 are considered. This requirement is fully e cient for the Z0 boson signal and roughly translates to a mSD range from 25 GeV to 185 GeV at pT = 500 GeV. = ln(m2SD=p2T), { 4 { V e 9G107 / tsn106 e v E105 104 103 1 jet soft-drop mass after the jet kinematic selection. Dashed lines illustrate the signal contribution for di erent Z0 boson masses. The multijet processes (QCD) dominate the background component, with subdominant contributions from inclusive SM W, Z, and tt and single top quark processes. The QCD simulation is corrected by an overall factor of 0.74 to match the data yield. In addition to the jet mass, the observable N21 [63] is used to discriminate the two-prong structure of the jets from the Z0 ! qq decay from the hadronization products of single light quarks or gluons, which are overwhelmingly one-prong. This jet substructure variable is de ned from a combination of generalized energy correlation functions ven, sensitive to correlations of v pairwise angles among n-jet constituents [63]. In particular, the 2-point (1e2) and 3-point (2e3) correlation functions are de ned as: 1e2 = 2e3 = X 1 i<j n X 1 i<j<k n zizj Rij ; zizj zk minf Rij Rik; Rij Rjk; Rik Rjkg ; where zi represents the energy fraction of the constituent i in the jet and Rij is the angular separation between constituents i and j. For a two-prong structure, signal jets have a stronger 2-point correlation than a 3-point correlation. The discriminant variable N21 is then constructed via the ratio: The energy correlation functions are computed from the jet constituents after the softdrop grooming has been applied, thereby reducing their dependence on the jet mass and pT [63]. N21 = 2e3 (1e2)2 : { 5 { (3.1) (3.2) (3.3) HJEP01(28)97 5% quantile of the N21 distribution in simulated multijet events. The distribution is shown as a function of the jet and pT and smoothed using a kNN approach [64]. The N21 distribution is mostly insensitive to the jet and pT in the kinematic phase space considered for this analysis ( 5:5 < < 2:0). Residual correlations in simulation are corrected by applying a decorrelation procedure that yields the N21;DDT variable. The N21 observable has excellent performance in discriminating two-prong signal jets from multijet QCD background jets [63]. However, N21 and similar variables are correlated with the jet mass and pT. A selection based on N21 would distort the jet mass distribution, with the amount of distortion depending on the pT of the jet. This would make the search for a resonant peak in the jet mass distribution, over a large range of pT, particularly challenging. The key feature of our approach is that the application of the substructure requirement preserves the shape of the soft-drop jet mass distribution. Improving on the decorrelation procedure proposed in ref. [62], we apply a DDT (designed decorrelated tagger) transformation of N21 to N 1;DDT. It is de ned as N 1;DDT( ; pT) 2 2 N21( ; pT) X(5%)( ; pT), require events to pass the N 1;DDT( ; pT) < 0 selection, such that we select a 2 where X(5%) is derived from the simulated N21 distribution and illustrated in gure 2. We xed 5% of QCD multijet events independent of and pT. The distribution of X(5%) is smoothed using a distance weighted k-nearest neighbor (kNN) approach [64]. The chosen percentile maximizes the sensitivity to the Z0 boson signal. 2 The distributions of N 1;DDT for data and simulation are shown in gure 3 after the jet pT > 500 GeV requirement. Since there is a visible disagreement between simulation and data, the multijet background is estimated from data, as described in the next section. Additional distributions of kinematic observables for data and simulation are available in appendix A. { 6 { ts108 n variable for the leading pT jet after the kinematic selection. Dashed lines illustrate the signal contribution for di erent Z0 boson masses. The multijet processes (QCD) dominate the background component, with subdominant contributions from inclusive SM W, Z, and tt and single top quark processes. The QCD simulation is corrected by an overall factor of 0.74 to match the data yield. 4 Background estimate The search is performed by looking for a resonance in the soft-drop mass distribution over background contributions dominated by QCD multijet events and smaller contributions from W(q0q)+jets, Z(qq)+jets, and top quark background processes. To model the background contribution from pair and single top quark production we utilize simulation with data-driven corrections based on a dedicated control region. This region has the same kinematic requirements as the signal region but with the muon veto inverted. The muon is selected using dedicated muon triggers and is required to have pT > 100 GeV and j j < 2:1 and to be in the opposite hemisphere to the selected AK8 jet. To enrich the tt contribution and reduce the multijet contamination, at least one AK4 jet with pT > 50 GeV is required to pass the b-tagging medium selection based on the combined secondary vertices version-2 algorithm [ 65 ], which identi es AK4 jets that originate from the hadronization of b quarks. Separate scale factors correct the overall top quark background normalization and the N 1,DDT e ciency for mistagging jets from top quark decays. These scale factors are SFtntorm = 0:75 0:10 and SFtmistag = 0:83 0:03, 2 respectively. Subdominant backgrounds arising from resonant SM processes (W/Z+ jets) are estimated from simulations that include corrections to the shape and normalization from higher order NLO QCD and EW calculations. Additional data-to-simulation corrections { 7 { HJEP01(28)97 A schematic of the background estimation method. The pass-to-fail ratio, Rp=f ( (mSD; pT)), is de ned from the events passing and failing the N21,DDT selection. The variable N21,DDT is constructed so that, for simulated multijet events, Rp=f is constant (left). To account for residual di erences between data and simulation, Rp=f is extracted by performing a two-dimensional t to data in ( ; pT) space (right). 2 for the jet mass shapes and N 1,DDT tagging e ciencies are applied to the simulation. These corrections are evaluated from a tt control region rich in merged hadronic W bosons, as further explained below. We estimate the main QCD multijet event background by taking advantage of the decorrelation of N 1,DDT from 2 and pT. The fraction of events passing the N 1,DDT selection 2 is, by construction, a constant 5% in simulated multijet events. The decorrelation ensures that the events passing and failing the selection have the same shape of the QCD jet mass distribution, and their ratio, the \pass-to-fail ratio" Rp=f , is constant for simulated multijet events. The prediction of events passing the selection can then be expressed as: npQaCssD(mSD; pT) = Rp=f ( (mSD; pT); pT) nfQaCil D(mSD; pT) ; where npQaCssD and nfail QCD are the number of passing and failing events in a given mSD, pT bin. This procedure is illustrated schematically in gure 4. Since the distribution of is expected to be invariant under a change of pT, Rp=f is parametrized as a function of , which is in turn expressed as a function of mSD and pT. Owing to residual di erences between data and simulation, the correction Rp=f ( ; pT) is allowed to deviate from a constant. The deviation is modeled by expanding Rp=f ( ; pT) into a polynomial series in orders of and pT: Rp=f ( ; pT) = QCD(1 + a01pT + a02p2T + + (a10 + a11pT + a12p2T + + (a20 + a21pT + a22p2T + ) ) 2 + ): (4.1) (4.2) The coe cients QCD and ak` have no external constraints but are determined from a simultaneous t to the data events passing and failing the substructure requirement, together with the signal yield. The number of required coe cients in the t is determined with a Fisher F -test on data [66] by iteratively adding polynomial orders. The optimum { 8 { choice is found to be of fourth order in and third order in pT. The fact that Rp=f varies slowly across the mSD{pT domain is essential, since it allows one to estimate the background under a narrow signal resonance based on the events across the whole jet mass range. 5 Systematic uncertainties 2 Uncertainties in the multijet background arise from the t parameter uncertainties in the pass-to-fail ratio t described in eq. (4.2). The uncertainties in the top quark background normalization (10%) and N 1,DDT mistag (2%) scale factors are propagated to the signal extraction through the t. The systematic e ects for the shapes and normalization of the W, Z backgrounds, and signal components are strongly correlated since they are a ected by similar systematic mismeasurements. We constrain the jet mass scale, the jet mass resolution, and the N 1,DDT selection e ciency using a sample of merged W boson jets in semileptonic tt events in data. In this region, events are required to have an energetic muon with pT > 100 GeV, pmiss > 80 GeV, a high-pT AK8 jet with pT > 200 GeV, and a b-tagged AK4 jet separated T from the AK8 jet by R > 0:8. Using the same N 1,DDT requirement described above, we de ne samples with events that pass and fail the selection for merged W boson jets in data and simulation, shown in gure 5. A simultaneous t to the two samples is performed in order to extract the selection e ciency of a merged W jet in simulation and in data. We measure the data-to-simulation scale factor for the N 1,DDT selection to be 0:88 0:10. The mass scale between data and simulation is found to be 1:10 0:05. The jet mass resolution data-to-simulation scale factor is measured to be 1:14 0:06. These 2 2 scale factors determine the initial distributions of the jet mass for the W, Z boson, and signal and they are further constrained in the t to data because of the presence of the W and Z resonances in the jet mass distribution. To account for potential deviations due to missing higher-order corrections to the simulated boson pT distributions, uncertainties are assumed in the W and Z boson yields that are pT-dependent. An additional systematic uncertainty is included to account for potential di erences between the W and Z boson higher-order corrections. Finally, uncertainties associated to the jet energy resolution [57], trigger e ciency, lepton veto e ciency, and the integrated luminosity determination [ 67 ] are also applied to the W, Z boson, and Z0 boson signal yields. A quantitative summary 2 of the systematic e ects considered is listed in table 1. To validate the robustness of the t, we perform a goodness-of- t test and bias tests using pseudo-experiments and injecting a simulated signal, for di erent values of Z0 boson 2 mass. No signi cant bias is observed. As a further test of t robustness, we split the region failing the N 1;DDT selection into two smaller regions mimicking the passing and failing regions in the signal extraction t. The mimicked passing-like region corresponds to a background e ciency of 60{65% and the mimicked failing-like region corresponds to an e ciency of 65{100%. We repeat our background estimation procedure on this selection as if the 60{65% e ciency region were the passing region. We nd negligible biases in the tted signal strength. { 9 { 5eG900 /ts800 n veE700 600 500 400 300 200 100 0 40 CMS Systematic source Lepton veto e ciency Jet mass scaley Jet mass scale (pT dependence) y4 Trigger e ciency Top quark mistag rate Integrated luminosity 2 Multijet t parameters N 1,DDT selection e ciency Top quark background normalization Jet energy resolutiony NLO QCD corrections NLO EW corrections4 NLO EW W/Z decorrelation Data Total MC Simult. data fit Simult. MC fit Data (peak) MC (peak) Data (continuum) MC (continuum) 120 mSD(GeV) Data Total MC Simult. data fit Simult. MC fit Data (peak) MC (peak) Data (continuum) MC (continuum) HJEP01(28)97 CMS Multijet 1{3% 0.5{2% 0.5{2% Z0 the semileptonic tt sample. Results of ts to data and simulation are shown. relative size. The symbol 4 denotes uncertainties decorrelated per pT bin in the 500{1000 GeV range. The symbol y denotes a shape uncertainty in the peaking SM W and Z boson backgrounds and Z0 boson signal shape. A long dash (|) indicates that the uncertainty does not apply. 6 Results We combine the estimates of the various SM background processes and search for a potential signal from a Z0 resonance in the mass range from 50 to 300 GeV. A binned maximum likelihood t to the observed shape of the soft-drop jet mass distribution is performed simultaneously in the passing and failing regions of ve pT ranges whose boundaries are: 500, 600, 700, 800, 900 and 1000 GeV. The number of observed events is consistent with the predicted background from SM processes. Figure 6 shows the soft-drop jet mass distribution for data and measured background contributions in the di erent pT ranges for a Z0 mass of 135 GeV; the W and Z boson contributions are clearly visible in the data. The mSD distribution for data in the combined pT ranges is available in appendix A. The results are interpreted in terms of 95% con dence level (CL) upper limits on the production cross section. Upper limits are computed using the modi ed frequentist approach for con dence levels (CLs); taking the pro le likelihood as the test statistic [68, 69] in the asymptotic approximation [70]. They are shown as a function of the resonance mass in gure 7 (left), where they are compared to cross sections for a model of a leptophobic Z0 resonance with quark coupling gq0 value of either 0:17 or 0:08 that are close to our current sensitivity. Systematic uncertainties are treated as nuisance parameters, which are modeled with log-normal priors and pro led over in the limit calculations. The maximum local observed p-value corresponds to 2:9 standard deviations from the background-only expectation at a Z0 boson mass of 115 GeV, and the global signi cance, calculated over the probed mass range [71], corresponds to approximately 2:2 standard deviations. Upper limits on the signal cross section are translated into the coupling gq0 as a function of Z0 boson mass, related to the Z0 coupling convention of ref. [37] by gq0 = gB=6. Coupling values above the solid curves are excluded. In gure 7 (right), we show previous results from UA2, CDF, ATLAS and CMS experiments. Indirect constraints from the hadronic Z boson partial width measurement and limits from the UA2 and CDF experiments are interpreted from [37]. The results of this analysis can be used to constrain simpli ed models of DM. Figure 8 shows the excluded values at 95% CL of mediator mass (mMed) as a function of the dark matter particle mass (mDM) for vector mediators, in simpli ed models that assume a leptophobic mediator that couples only to quarks and DM particles [38, 73]. Limits are shown for a choice of universal quark coupling gq = 0:25 and a DM coupling gDM = 1:0. The di erence in limits between axial-vector and vector mediator couplings is small and thus only constraints for the latter coupling scenario are shown. The excluded range of mediator mass (red) is between 50 and 300 GeV. The upper bound decreases to 240 GeV when mMed > 2mDM, because the branching fraction (BR) to qq decreases as the BR to DM becomes kinematically favorable. If mMed < 2mDM, the mediator cannot decay to DM particles and the dijet cross section from the mediator model becomes identical to that in the leptophobic Z0 model, meaning that the limits on the mediator mass in gure 8 are identical to the limits on the Z0 mass with a coupling gq0 = gq = 0:25. For axialvector mediators, the excluded values of mediator mass are expected to be identical to the excluded values in gure 8 when mDM > mMed=2 or mDM = 0, with di erences only expected in the transition region mMed ' 2mDM. Additional limits (blue) in gure 8 come from traditional dijet searches [35]. 7 Summary A search for a vector resonance (Z0) decaying into a quark-antiquark pair and reconstructed p as a single jet has been presented, using a data set comprising proton-proton collisions at s = 13 TeV, corresponding to an integrated luminosity of 35.9 fb 1 . Novel substructure techniques are employed to identify a jet containing a Z0 boson candidate over a smoothly Data Data are shown as black points. The multijet background prediction, including uncertainties, is shown by the shaded bands. Contributions from the W and Z boson, and top quark background processes are shown, scaled up by a factor of 3 for clarity. A hypothetical Z0 boson signal at a mass of 135 GeV is also indicated. In the bottom panel, the ratio of the data to the background prediction, including uncertainties, is shown. The scale on the x-axis di ers for each pT range due to the kinematic selection on . 15%05 9 σ 104 103 CMS 95% CL upper limits Observed Expected ± 1 std. deviation ± 2 std. deviation Theory, g Theory, g , g n lip0.4 uo0.3 c0.2 UA2 [13] CDF Run 1 [18] CDF Run 2 [19] ATLAS 8 TeV, 20.3 fb-1[24] CMS 8 TeV, 18.8 fb-1[34] CMS 13 TeV, 12.9 fb-1[35] Z Width (indirect) [71] 50 100 150 200 250 300 The 95% CL upper limits on the Z0 boson production cross section compared to theoretical cross sections (left) and on the quark coupling gq0 as a function of resonance mass for a leptophobic Z0 resonance that only couples to quarks (right). The observed limits (solid), expected limits (dashed) and their variation at the 1 and 2 standard deviation levels (shaded bands) are shown. Limits from other relevant searches and an indirect constraint on a potential Z0 signal from the SM Z boson width [72] are also shown. The 95% CL observed (solid red) and expected (dashed red) excluded regions in the plane of dark matter particle mass (mDM) vs. mediator mass (mMed), for vector mediators. A branching fraction of 100% is assumed for a leptophobic vector mediator decaying to dijets. The exclusion is computed for a quark coupling choice gq = 0:25 and for a dark matter coupling gDM = 1. The excluded regions from the dijet resolved analysis (blue dot dashed lines) using early 2016 data [35] are also shown. Results are compared to constraints from the cosmological relic density of DM (light gray) determined from astrophysical measurements [ 74, 75 ] and MadDM version 2.0.6 [ 76, 77 ] as described in ref. [ 78 ]. falling soft-drop jet mass distribution in data. No signi cant excess above the SM prediction is observed, and 95% con dence level upper limits are set on the Z0 boson coupling to quarks, gq0, as a function of the Z0 boson mass. Coupling values of gq0 > 0:25 are excluded over the Z0 mass range from 50 to 300 GeV, with strong constraints for masses less than 200 GeV. The results obtained for masses from 50 to 100 GeV represent the rst direct limits to be published in this range. Limits are set on a simpli ed model of dark matter mediators that only couple to quarks and dark matter particles, excluding vector mediators with masses between 50 and 300 GeV, and using a universal quark coupling gq = 0:25 and a dark matter coupling gDM = 1:0. Acknowledgments We congratulate our colleagues in the CERN accelerator departments for the excellent performance of the LHC and thank the technical and administrative sta s at CERN and at other CMS institutes for their contributions to the success of the CMS e ort. In addition, we gratefully acknowledge the computing centres and personnel of the Worldwide LHC Computing Grid for delivering so e ectively the computing infrastructure essential to our analyses. Finally, we acknowledge the enduring support for the construction and operation of the LHC and the CMS detector provided by the following funding agencies: BMWFW and FWF (Austria); FNRS and FWO (Belgium); CNPq, CAPES, FAPERJ, and FAPESP (Brazil); MES (Bulgaria); CERN; CAS, MoST, and NSFC (China); COLCIENCIAS (Colombia); MSES and CSF (Croatia); RPF (Cyprus); SENESCYT (Ecuador); MoER, ERC IUT, and ERDF (Estonia); Academy of Finland, MEC, and HIP (Finland); CEA and CNRS/IN2P3 (France); BMBF, DFG, and HGF (Germany); GSRT (Greece); OTKA and NIH (Hungary); DAE and DST (India); IPM (Iran); SFI (Ireland); INFN (Italy); MSIP and NRF (Republic of Korea); LAS (Lithuania); MOE and UM (Malaysia); BUAP, CINVESTAV, CONACYT, LNS, SEP, and UASLP-FAI (Mexico); MBIE (New Zealand); PAEC (Pakistan); MSHE and NSC (Poland); FCT (Portugal); JINR (Dubna); MON, RosAtom, RAS, RFBR and RAEP (Russia); MESTD (Serbia); SEIDI, CPAN, PCTI and FEDER (Spain); Swiss Funding Agencies (Switzerland); MST (Taipei); ThEPCenter, IPST, STAR, and NSTDA (Thailand); TUBITAK and TAEK (Turkey); NASU and SFFR (Ukraine); STFC (United Kingdom); DOE and NSF (U.S.A.). Individuals have received support from the Marie-Curie programme and the European Research Council and Horizon 2020 Grant, contract No. 675440 (European Union); the Leventis Foundation; the A. P. Sloan Foundation; the Alexander von Humboldt Foundation; the Belgian Federal Science Policy O ce; the Fonds pour la Formation a la Recherche dans l'Industrie et dans l'Agriculture (FRIA-Belgium); the Agentschap voor Innovatie door Wetenschap en Technologie (IWT-Belgium); the Ministry of Education, Youth and Sports (MEYS) of the Czech Republic; the Council of Science and Industrial Research, India; the HOMING PLUS programme of the Foundation for Polish Science, co nanced from European Union, Regional Development Fund, the Mobility Plus programme of the Ministry of Science and Higher Education, the National Science Center (Poland), contracts Harmonia 2014/14/M/ST2/00428, Opus 2014/13/B/ST2/02543, 2014/15/B/ST2/03998, search Program by Qatar National Research Fund; the Programa Severo Ochoa del Principado de Asturias; the Thalis and Aristeia programmes co nanced by EU-ESF and the Greek NSRF; the Rachadapisek Sompot Fund for Postdoctoral Fellowship, Chulalongkorn University and the Chulalongkorn Academic into Its 2nd Century Project Advancement Project (Thailand); the Welch Foundation, contract C-1845; and the Weston Havens Foundation (U.S.A.). A Supplementary materials HJEP01(28)97 CMS /.00 106 s ten 105 v E 104 103 102 10 a ilum 1 D D QCD (k-factor 0.74) Distributions of data (points) and simulated backgrounds (histograms) of the leading pT jet N21 (top left) and (top right) observables, after the kinematic selection. The soft-drop jet mass distributions for the passing (bottom left) and failing (bottom right) region, de ned by the N21;DDT selection, are also shown. The decorrelation ensures that the shape of the multijet mass distribution in both regions is una ected by the N21;DDT selection for di erent pT ranges. Dashed lines illustrate the signal contribution for di erent Z0 boson masses. The multijet processes (QCD) dominate the background component, with subdominant contributions from inclusive SM W, Z, and tt and single top quark processes. The QCD simulation is scaled by an overall factor of 0.74 to match the data yield. Residual di erences between data and simulation demonstrate the need for a background estimation method based on control samples in data. CMS Data multijet background prediction in the passing region is obtained using the failing region and the pass-fail ratio Rp=f (mSD; pT). Data are shown as black points. The multijet background prediction, including uncertainties, is shown by the shaded bands. Contributions from the W and Z boson, and top quark background processes are shown, scaled up by a factor of 3 for clarity. A hypothetical Z0 boson signal at a mass of 135 GeV is also indicated. The features at 45, 185, 220 and 255 GeV in the mSD distribution are due to the kinematic selection on , which a ects each pT category di erently. In the bottom panel, the ratio of the data to the background prediction, including uncertainties, is shown. 35.9 fb-1 (13 TeV) Observed 100 150 200 250 300 Z' mass (GeV) mass. The maximum local observed p-value, at 115 GeV, is 1:72 10 3 and corresponds to 2:9 standard deviations from the background-only expectation, and the global p-value, calculated over the probed mass range, corresponds to 0:0138 and 2:2 standard deviations. Open Access. This article is distributed under the terms of the Creative Commons Attribution License (CC-BY 4.0), which permits any use, distribution and reproduction in any medium, provided the original author(s) and source are credited. (2008) 241803 [arXiv:0808.0497] [INSPIRE]. HJEP01(28)97 Phys. Rept. 183 (1989) 193 [INSPIRE]. Mod. Phys. A 2 (1987) 1285 [INSPIRE]. Phys. Rev. D 42 (1990) 815 [INSPIRE]. Lett. B 190 (1987) 157 [INSPIRE]. topology, JHEP 12 (2010) 085 [arXiv:1010.4309] [INSPIRE]. (1984) 579 [INSPIRE]. 4690 [hep-th/9906064] [INSPIRE]. [12] UA1 collaboration, C. Albajar et al., Two jet mass distributions at the CERN proton-anti-proton collider, Phys. Lett. B 209 (1988) 127 [INSPIRE]. [13] UA2 collaboration, J. 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Yerevan Physics Institute, Yerevan, Armenia A.M. Sirunyan, A. Tumasyan Institut fur Hochenergiephysik, Wien, Austria W. Adam, F. Ambrogi, E. Asilar, T. Bergauer, J. Brandstetter, E. Brondolin, M. Dragicevic, J. Ero, M. Flechl, M. Friedl, R. Fruhwirth1, V.M. Ghete, J. Grossmann, J. Hrubec, M. Jeitler1, A. Konig, N. Krammer, I. Kratschmer, D. Liko, T. Madlener, I. Mikulec, E. Pree, N. Rad, H. Rohringer, J. Schieck1, R. Schofbeck, M. Spanring, D. Spitzbart, W. Waltenberger, J. Wittmann, C.-E. Wulz1, M. Zarucki HJEP01(28)97 Institute for Nuclear Problems, Minsk, Belarus V. Chekhovsky, V. Mossolov, J. Suarez Gonzalez Universiteit Antwerpen, Antwerpen, Belgium Haevermaet, P. Van Mechelen, N. Van Remortel Vrije Universiteit Brussel, Brussel, Belgium E.A. De Wolf, D. Di Croce, X. Janssen, J. Lauwers, M. Van De Klundert, H. Van S. Abu Zeid, F. Blekman, J. D'Hondt, I. De Bruyn, J. De Clercq, K. Deroover, G. Flouris, D. Lontkovskyi, S. Lowette, I. Marchesini, S. Moortgat, L. Moreels, Q. Python, K. Skovpen, S. Tavernier, W. Van Doninck, P. Van Mulders, I. Van Parijs Universite Libre de Bruxelles, Bruxelles, Belgium D. Beghin, H. Brun, B. Clerbaux, G. De Lentdecker, H. Delannoy, B. Dorney, G. Fasanella, L. Favart, R. Goldouzian, A. Grebenyuk, T. Lenzi, J. Luetic, T. Maerschalk, A. Marinov, T. Seva, E. Starling, C. Vander Velde, P. Vanlaer, D. Vannerom, R. Yonamine, F. Zenoni, F. Zhang2 Ghent University, Ghent, Belgium A. Cimmino, T. Cornelis, D. Dobur, A. Fagot, M. Gul, I. Khvastunov3, D. Poyraz, C. Roskas, S. Salva, M. Tytgat, W. Verbeke, N. Zaganidis Universite Catholique de Louvain, Louvain-la-Neuve, Belgium H. Bakhshiansohi, O. Bondu, S. Brochet, G. Bruno, C. Caputo, A. Caudron, P. David, S. De Visscher, C. Delaere, M. Delcourt, B. Francois, A. Giammanco, M. Komm, G. Krintiras, V. Lemaitre, A. Magitteri, A. Mertens, M. Musich, K. Piotrzkowski, L. Quertenmont, A. Saggio, M. Vidal Marono, S. Wertz, J. Zobec Centro Brasileiro de Pesquisas Fisicas, Rio de Janeiro, Brazil W.L. Alda Junior, F.L. Alves, G.A. Alves, L. Brito, M. Correa Martins Junior, C. Hensel, A. Moraes, M.E. Pol, P. Rebello Teles Universidade do Estado do Rio de Janeiro, Rio de Janeiro, Brazil E. Belchior Batista Das Chagas, W. Carvalho, J. Chinellato4, E. Coelho, E.M. Da Costa, G.G. Da Silveira5, D. De Jesus Damiao, S. Fonseca De Souza, L.M. Huertas Guativa, H. Malbouisson, M. Melo De Almeida, C. Mora Herrera, L. Mundim, H. Nogima, Brazil S. Ahujaa, Sciences tanov L.J. Sanchez Rosas, A. Santoro, A. Sznajder, M. Thiel, E.J. Tonelli Manganote4, F. Torres Da Silva De Araujo, A. Vilela Pereira Universidade Estadual Paulista a, Universidade Federal do ABC b, S~ao Paulo, C.A. Bernardesa, T.R. Fernandez Perez Tomeia, E.M. Gregoresb, P.G. Mercadanteb, S.F. Novaesa, Sandra S. Padulaa, D. Romero Abadb, J.C. Ruiz Vargasa Institute for Nuclear Research and Nuclear Energy of Bulgaria Academy of A. Aleksandrov, R. Hadjiiska, P. Iaydjiev, M. Misheva, M. Rodozov, M. Shopova, G. SulUniversity of So a, So a, Bulgaria A. Dimitrov, L. Litov, B. Pavlov, P. Petkov Beihang University, Beijing, China W. Fang6, X. Gao6, L. Yuan Institute of High Energy Physics, Beijing, China M. Ahmad, J.G. Bian, G.M. Chen, H.S. Chen, M. Chen, Y. Chen, C.H. Jiang, D. Leggat, H. Liao, Z. Liu, F. Romeo, S.M. Shaheen, A. Spiezia, J. Tao, C. Wang, Z. Wang, E. Yazgan, H. Zhang, S. Zhang, J. Zhao Beijing, China State Key Laboratory of Nuclear Physics and Technology, Peking University, Y. Ban, G. Chen, J. Li, Q. Li, S. Liu, Y. Mao, S.J. Qian, D. Wang, Z. Xu Universidad de Los Andes, Bogota, Colombia C. Avila, A. Cabrera, L.F. Chaparro Sierra, C. Florez, C.F. Gonzalez Hernandez, J.D. Ruiz Alvarez, M.A. Segura Delgado University of Split, Faculty of Electrical Engineering, Mechanical Engineering and Naval Architecture, Split, Croatia B. Courbon, N. Godinovic, D. Lelas, I. Puljak, P.M. Ribeiro Cipriano, T. Sculac University of Split, Faculty of Science, Split, Croatia Z. Antunovic, M. Kovac Institute Rudjer Boskovic, Zagreb, Croatia V. Brigljevic, D. Ferencek, K. Kadija, B. Mesic, A. Starodumov7, T. Susa University of Cyprus, Nicosia, Cyprus M.W. Ather, A. Attikis, G. Mavromanolakis, J. Mousa, C. Nicolaou, F. Ptochos, P.A. Razis, H. Rykaczewski Charles University, Prague, Czech Republic M. Finger8, M. Finger Jr.8 Universidad San Francisco de Quito, Quito, Ecuador E. Carrera Jarrin Academy of Scienti c Research and Technology of the Arab Republic of Egypt, Egyptian Network of High Energy Physics, Cairo, Egypt E. El-khateeb9, S. Elgammal10, A. Ellithi Kamel11 National Institute of Chemical Physics and Biophysics, Tallinn, Estonia R.K. Dewanjee, M. Kadastik, L. Perrini, M. Raidal, A. Tiko, C. Veelken Department of Physics, University of Helsinki, Helsinki, Finland P. Eerola, H. Kirschenmann, J. Pekkanen, M. Voutilainen Helsinki Institute of Physics, Helsinki, Finland J. Havukainen, J.K. 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Zghiche Universite de Strasbourg, CNRS, IPHC UMR 7178, F-67000 Strasbourg, France S. Gadrat J.-L. Agram12, J. Andrea, D. Bloch, J.-M. Brom, M. Buttignol, E.C. Chabert, N. Chanon, C. Collard, E. Conte12, X. Coubez, J.-C. Fontaine12, D. Gele, U. Goerlach, M. Jansova, A.-C. Le Bihan, N. Tonon, P. Van Hove Centre de Calcul de l'Institut National de Physique Nucleaire et de Physique des Particules, CNRS/IN2P3, Villeurbanne, France Universite de Lyon, Universite Claude Bernard Lyon 1, CNRS-IN2P3, Institut de Physique Nucleaire de Lyon, Villeurbanne, France S. Beauceron, C. Bernet, G. Boudoul, R. Chierici, D. Contardo, P. Depasse, H. El Mamouni, J. Fay, L. Finco, S. Gascon, M. Gouzevitch, G. Grenier, B. Ille, F. Lagarde, I.B. Laktineh, M. Lethuillier, L. Mirabito, A.L. Pequegnot, S. Perries, A. Popov13, V. Sordini, M. Vander Donckt, S. Viret T. Toriashvili14 Georgian Technical University, Tbilisi, Georgia Tbilisi State University, Tbilisi, Georgia Z. Tsamalaidze8 RWTH Aachen University, I. Physikalisches Institut, Aachen, Germany C. Autermann, L. Feld, M.K. Kiesel, K. Klein, M. Lipinski, M. Preuten, C. Schomakers, J. Schulz, V. Zhukov13 RWTH Aachen University, III. Physikalisches Institut A, Aachen, Germany A. Albert, E. Dietz-Laursonn, D. Duchardt, M. Endres, M. Erdmann, S. Erdweg, T. Esch, R. Fischer, A. Guth, M. Hamer, T. Hebbeker, C. Heidemann, K. Hoepfner, S. Knutzen, M. Merschmeyer, A. Meyer, P. Millet, S. Mukherjee, T. Pook, M. Radziej, H. Reithler, M. Rieger, F. Scheuch, D. Teyssier, S. Thuer RWTH Aachen University, III. Physikalisches Institut B, Aachen, Germany G. Flugge, B. Kargoll, T. Kress, A. Kunsken, T. Muller, A. Nehrkorn, A. Nowack, C. Pistone, O. Pooth, A. Stahl15 Deutsches Elektronen-Synchrotron, Hamburg, Germany M. Aldaya Martin, T. Arndt, C. Asawatangtrakuldee, K. Beernaert, O. Behnke, U. Behrens, A. Bermudez Mart nez, A.A. Bin Anuar, K. Borras16, V. Botta, A. Campbell, P. Connor, C. Contreras-Campana, F. Costanza, C. Diez Pardos, G. Eckerlin, D. Eckstein, T. Eichhorn, E. Eren, E. Gallo17, J. Garay Garcia, A. Geiser, J.M. Grados Luyando, A. Grohsjean, P. Gunnellini, M. Gutho , A. Harb, J. Hauk, M. Hempel18, H. Jung, M. Kasemann, J. Keaveney, C. Kleinwort, I. Korol, D. Krucker, W. Lange, A. Lelek, T. Lenz, J. Leonard, K. Lipka, W. Lohmann18, R. Mankel, I.-A. Melzer-Pellmann, A.B. Meyer, G. Mittag, J. Mnich, A. Mussgiller, E. Ntomari, D. Pitzl, A. Raspereza, M. Savitskyi, P. Saxena, R. Shevchenko, S. Spannagel, N. Stefaniuk, G.P. Van Onsem, R. Walsh, Y. Wen, K. Wichmann, C. Wissing, O. Zenaiev University of Hamburg, Hamburg, Germany R. Aggleton, S. Bein, V. Blobel, M. Centis Vignali, T. Dreyer, E. Garutti, D. Gonzalez, J. Haller, A. Hinzmann, M. Ho mann, A. Karavdina, R. Klanner, R. Kogler, N. Kovalchuk, S. Kurz, T. Lapsien, D. Marconi, M. Meyer, M. Niedziela, D. Nowatschin, F. Pantaleo15, T. Pei er, A. Perieanu, C. Scharf, P. Schleper, A. Schmidt, S. Schumann, J. Schwandt, J. Sonneveld, H. Stadie, G. Steinbruck, F.M. Stober, M. Stover, H. Tholen, D. Troendle, E. Usai, A. Vanhoefer, B. Vormwald Institut fur Experimentelle Kernphysik, Karlsruhe, Germany M. Akbiyik, C. Barth, M. Baselga, S. Baur, E. Butz, R. Caspart, T. Chwalek, F. Colombo, W. De Boer, A. Dierlamm, N. Faltermann, B. Freund, R. Friese, M. Gi els, M.A. Harrendorf, F. Hartmann15, S.M. Heindl, U. Husemann, F. Kassel15, S. Kudella, H. Mildner, M.U. Mozer, Th. Muller, M. Plagge, G. Quast, K. Rabbertz, M. Schroder, I. Shvetsov, G. Sieber, H.J. Simonis, R. Ulrich, S. Wayand, M. Weber, T. Weiler, S. Williamson, C. Wohrmann, R. Wolf Institute of Nuclear and Particle Physics (INPP), NCSR Demokritos, Aghia Paraskevi, Greece G. Anagnostou, G. Daskalakis, T. Geralis, A. Kyriakis, D. Loukas, I. Topsis-Giotis National and Kapodistrian University of Athens, Athens, Greece G. Karathanasis, S. Kesisoglou, A. Panagiotou, N. Saoulidou National Technical University of Athens, Athens, Greece K. Kousouris University of Ioannina, Ioannina, Greece I. Evangelou, C. Foudas, P. Gianneios, P. Katsoulis, P. Kokkas, S. Mallios, N. Manthos, I. Papadopoulos, E. Paradas, J. Strologas, F.A. Triantis, D. Tsitsonis MTA-ELTE Lendulet CMS Particle and Nuclear Physics Group, Eotvos Lorand University, Budapest, Hungary M. Csanad, N. Filipovic, G. Pasztor, O. Suranyi, G.I. Veres19 Wigner Research Centre for Physics, Budapest, Hungary G. Bencze, C. Hajdu, D. Horvath20, A. Hunyadi, F. Sikler, V. Veszpremi Institute of Nuclear Research ATOMKI, Debrecen, Hungary N. Beni, S. Czellar, J. Karancsi21, A. Makovec, J. Molnar, Z. Szillasi Institute of Physics, University of Debrecen, Debrecen, Hungary M. Bartok19, P. Raics, Z.L. Trocsanyi, B. Ujvari Indian Institute of Science (IISc), Bangalore, India S. Choudhury, J.R. Komaragiri National Institute of Science Education and Research, Bhubaneswar, India S. Bahinipati22, S. Bhowmik, P. Mal, K. Mandal, A. Nayak23, D.K. Sahoo22, N. Sahoo, S.K. Swain Panjab University, Chandigarh, India S. Bansal, S.B. Beri, V. Bhatnagar, R. Chawla, N. Dhingra, A.K. Kalsi, A. Kaur, M. Kaur, S. Kaur, R. Kumar, P. Kumari, A. Mehta, J.B. Singh, G. Walia University of Delhi, Delhi, India Ashok Kumar, Aashaq Shah, A. Bhardwaj, S. Chauhan, B.C. Choudhary, R.B. Garg, S. Keshri, A. Kumar, S. Malhotra, M. Naimuddin, K. Ranjan, R. Sharma Saha Institute of Nuclear Physics, HBNI, Kolkata, India R. Bhardwaj, R. Bhattacharya, S. Bhattacharya, U. Bhawandeep, S. Dey, S. Dutt, S. Dutta, S. Ghosh, N. Majumdar, A. Modak, K. Mondal, S. Mukhopadhyay, S. Nandan, A. Purohit, A. Roy, S. Roy Chowdhury, S. Sarkar, M. Sharan, S. Thakur Indian Institute of Technology Madras, Madras, India P.K. Behera Bhabha Atomic Research Centre, Mumbai, India R. Chudasama, D. Dutta, V. Jha, V. Kumar, A.K. Mohanty15, P.K. Netrakanti, L.M. Pant, P. Shukla, A. Topkar Tata Institute of Fundamental Research-A, Mumbai, India T. Aziz, S. Dugad, B. Mahakud, S. Mitra, G.B. Mohanty, N. Sur, B. Sutar Tata Institute of Fundamental Research-B, Mumbai, India S. Banerjee, S. Bhattacharya, S. Chatterjee, P. Das, M. Guchait, Sa. Jain, S. Kumar, M. Maity24, G. Majumder, K. Mazumdar, T. Sarkar24, N. Wickramage25 HJEP01(28)97 Indian Institute of Science Education and Research (IISER), Pune, India S. Chauhan, S. Dube, V. Hegde, A. Kapoor, K. Kothekar, S. Pandey, A. Rane, S. Sharma Institute for Research in Fundamental Sciences (IPM), Tehran, Iran S. Chenarani26, E. Eskandari Tadavani, S.M. Etesami26, M. Khakzad, M. Mohammadi Najafabadi, M. Naseri, S. Paktinat Mehdiabadi27, F. Rezaei Hosseinabadi, B. Safarzadeh28, M. Zeinali University College Dublin, Dublin, Ireland M. Felcini, M. Grunewald INFN Sezione di Bari a, Universita di Bari b, Politecnico di Bari c, Bari, Italy M. Abbresciaa;b, C. Calabriaa;b, A. Colaleoa, D. Creanzaa;c, L. Cristellaa;b, N. De Filippisa;c, M. De Palmaa;b, F. Erricoa;b, L. Fiorea, G. Iasellia;c, S. Lezkia;b, G. Maggia;c, M. Maggia, G. Minielloa;b, S. Mya;b, S. Nuzzoa;b, A. Pompilia;b, G. Pugliesea;c, R. Radognaa, A. Ranieria, G. 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Stroma, INFN Laboratori Nazionali di Frascati, Frascati, Italy L. Benussi, S. Bianco, F. Fabbri, D. Piccolo, F. Primavera15 INFN Sezione di Genova a, Universita di Genova b, Genova, Italy V. Calvellia;b, F. Ferroa, E. Robuttia, S. Tosia;b INFN Sezione di Milano-Bicocca a, Universita di Milano-Bicocca b, Milano, Italy A. Benagliaa, A. Beschib, L. Brianzaa;b, F. Brivioa;b, V. Cirioloa;b;15, M.E. Dinardoa;b, S. Fiorendia;b, S. Gennaia, A. Ghezzia;b, P. Govonia;b, M. Malbertia;b, S. Malvezzia, R.A. Manzonia;b, D. Menascea, L. Moronia, M. Paganonia;b, K. Pauwelsa;b, D. Pedrinia, S. Pigazzinia;b;30, S. Ragazzia;b, T. Tabarelli de Fatisa;b INFN Sezione di Napoli a, Universita di Napoli 'Federico II' b, Napoli, Italy, Universita della Basilicata c, Potenza, Italy, Universita G. Marconi d, Roma, F. Thyssena INFN Sezione di Padova a, Universita di Padova b, Padova, Italy, Universita di Trento c, Trento, Italy P. Azzia, N. Bacchettaa, L. Benatoa;b, D. Biselloa;b, A. Bolettia;b, A. Carvalho Antunes De Oliveiraa;b, P. Checchiaa, M. Dall'Ossoa;b, P. De Castro Manzanoa, T. Dorigoa, U. Dossellia, F. Gasparinia;b, A. Gozzelinoa, S. Lacapraraa, P. Lujan, M. Margonia;b, A.T. Meneguzzoa;b, D. Pantanoa, N. Pozzobona;b, P. Ronchesea;b, R. Rossina;b, E. Torassaa, S. Venturaa, M. Zanettia;b, P. Zottoa;b, G. Zumerlea;b INFN Sezione di Pavia a, Universita di Pavia b, Pavia, Italy A. Braghieria, A. Magnania, P. Montagnaa;b, S.P. Rattia;b, V. Rea, M. Ressegottia;b, C. Riccardia;b, P. Salvinia, I. Vaia;b, P. Vituloa;b INFN Sezione di Perugia a, Universita di Perugia b, Perugia, Italy L. Alunni Solestizia;b, M. Biasinia;b, G.M. Bileia, C. Cecchia;b, D. Ciangottinia;b, L. Fanoa;b, R. Leonardia;b, E. Manonia, G. Mantovania;b, V. Mariania;b, M. Menichellia, A. Rossia;b, A. Santocchiaa;b, D. Spigaa Pisa c, Pisa, Italy INFN Sezione di Pisa a, Universita di Pisa b, Scuola Normale Superiore di K. Androsova, P. Azzurria;15, G. Bagliesia, T. Boccalia, L. Borrello, R. Castaldia, M.A. Cioccia;b, R. Dell'Orsoa, G. Fedia, L. Gianninia;c, A. Giassia, M.T. Grippoa;29, F. Ligabuea;c, T. Lomtadzea, E. Mancaa;c, G. Mandorlia;c, A. Messineoa;b, F. Pallaa, A. Rizzia;b, A. Savoy-Navarroa;31, P. Spagnoloa, R. Tenchinia, G. Tonellia;b, A. Venturia, P.G. Verdinia INFN Sezione di Roma a, Sapienza Universita di Roma b, Rome, Italy L. Baronea;b, F. Cavallaria, M. Cipriania;b, N. Dacia, D. Del Rea;b;15, E. Di Marcoa;b, M. Diemoza, S. Gellia;b, E. Longoa;b, F. Margarolia;b, B. Marzocchia;b, P. Meridiania, G. Organtinia;b, R. Paramattia;b, F. Preiatoa;b, S. Rahatloua;b, C. Rovellia, F. Santanastasioa;b INFN Sezione di Torino a, Universita di Torino b, Torino, Italy, Universita del Piemonte Orientale c, Novara, Italy N. Amapanea;b, R. Arcidiaconoa;c, S. Argiroa;b, M. Arneodoa;c, N. Bartosika, R. Bellana;b, C. Biinoa, N. Cartigliaa, F. Cennaa;b, M. Costaa;b, R. Covarellia;b, A. Deganoa;b, N. Demariaa, B. Kiania;b, C. Mariottia, S. Masellia, E. Migliorea;b, V. Monacoa;b, E. Monteila;b, M. Montenoa, M.M. Obertinoa;b, L. Pachera;b, N. Pastronea, M. Pelliccionia, G.L. Pinna Angionia;b, F. Raveraa;b, A. Romeroa;b, M. Ruspaa;c, R. Sacchia;b, K. Shchelinaa;b, V. Solaa, A. Solanoa;b, A. Staianoa, P. Traczyka;b INFN Sezione di Trieste a, Universita di Trieste b, Trieste, Italy S. Belfortea, M. Casarsaa, F. Cossuttia, G. Della Riccaa;b, A. Zanettia Kyungpook National University, Daegu, Korea D.H. Kim, G.N. Kim, M.S. Kim, J. Lee, S. Lee, S.W. Lee, C.S. Moon, Y.D. Oh, S. Sekmen, D.C. Son, Y.C. Yang Chonbuk National University, Jeonju, Korea A. Lee Chonnam National University, Institute for Universe and Elementary Particles, H. Kim, D.H. Moon, G. Oh Hanyang University, Seoul, Korea J.A. Brochero Cifuentes, J. Goh, T.J. Kim Korea University, Seoul, Korea J. Lim, S.K. Park, Y. Roh Seoul National University, Seoul, Korea S.h. Seo, U.K. Yang, H.D. Yoo, G.B. Yu University of Seoul, Seoul, Korea H. Kim, J.H. Kim, J.S.H. Lee, I.C. Park Sungkyunkwan University, Suwon, Korea Y. Choi, C. Hwang, J. Lee, I. Yu Vilnius University, Vilnius, Lithuania V. Dudenas, A. Juodagalvis, J. Vaitkus S. Cho, S. Choi, Y. Go, D. Gyun, S. Ha, B. Hong, Y. Jo, Y. Kim, K. Lee, K.S. Lee, S. Lee, J. Almond, J. Kim, J.S. Kim, H. Lee, K. Lee, K. Nam, S.B. Oh, B.C. Radburn-Smith, National Centre for Particle Physics, Universiti Malaya, Kuala Lumpur, Malaysia M.N. Yusli, Z. Zolkapli I. Ahmed, Z.A. Ibrahim, M.A.B. Md Ali32, F. Mohamad Idris33, W.A.T. Wan Abdullah, Centro de Investigacion y de Estudios Avanzados del IPN, Mexico City, Mexico Reyes-Almanza, R, Ramirez-Sanchez, G., Duran-Osuna, M. C., H. Castilla-Valdez, E. De La Cruz-Burelo, I. Heredia-De La Cruz34, Rabadan-Trejo, R. I., R. Lopez-Fernandez, J. Mejia Guisao, A. Sanchez-Hernandez Universidad Iberoamericana, Mexico City, Mexico S. Carrillo Moreno, C. Oropeza Barrera, F. Vazquez Valencia Benemerita Universidad Autonoma de Puebla, Puebla, Mexico J. Eysermans, I. Pedraza, H.A. Salazar Ibarguen, C. Uribe Estrada Universidad Autonoma de San Luis Potos , San Luis Potos , Mexico A. Morelos Pineda University of Auckland, Auckland, New Zealand University of Canterbury, Christchurch, New Zealand National Centre for Physics, Quaid-I-Azam University, Islamabad, Pakistan A. Ahmad, M. Ahmad, Q. Hassan, H.R. Hoorani, A. Saddique, M.A. Shah, M. Shoaib, National Centre for Nuclear Research, Swierk, Poland H. Bialkowska, M. Bluj, B. Boimska, T. Frueboes, M. Gorski, M. Kazana, K. Nawrocki, M. Szleper, P. Zalewski Warsaw, Poland Institute of Experimental Physics, Faculty of Physics, University of Warsaw, K. Bunkowski, A. Byszuk35, K. Doroba, A. Kalinowski, M. Konecki, J. Krolikowski, M. Misiura, M. Olszewski, A. Pyskir, M. Walczak Laboratorio de Instrumentac~ao e F sica Experimental de Part culas, Lisboa, Portugal P. Bargassa, C. Beir~ao Da Cruz E Silva, A. Di Francesco, P. Faccioli, B. Galinhas, M. Gallinaro, J. Hollar, N. Leonardo, L. Lloret Iglesias, M.V. Nemallapudi, J. Seixas, G. Strong, O. Toldaiev, D. Vadruccio, J. Varela Joint Institute for Nuclear Research, Dubna, Russia S. Afanasiev, P. Bunin, M. Gavrilenko, I. Golutvin, I. Gorbunov, A. Kamenev, V. Karjavin, A. Lanev, A. Malakhov, V. Matveev36;37, V. Palichik, V. Perelygin, S. Shmatov, S. Shulha, N. Skatchkov, V. Smirnov, N. Voytishin, A. Zarubin Petersburg Nuclear Physics Institute, Gatchina (St. Petersburg), Russia Y. Ivanov, V. Kim38, E. Kuznetsova39, P. Levchenko, V. Murzin, V. Oreshkin, I. Smirnov, D. Sosnov, V. Sulimov, L. Uvarov, S. Vavilov, A. Vorobyev Institute for Nuclear Research, Moscow, Russia Yu. Andreev, A. Dermenev, S. Gninenko, N. Golubev, A. Karneyeu, M. Kirsanov, N. Krasnikov, A. Pashenkov, D. Tlisov, A. Toropin Institute for Theoretical and Experimental Physics, Moscow, Russia V. Epshteyn, V. Gavrilov, N. Lychkovskaya, V. Popov, I. Pozdnyakov, G. Safronov, A. Spiridonov, A. Stepennov, M. Toms, E. Vlasov, A. Zhokin Moscow Institute of Physics and Technology, Moscow, Russia T. Aushev, A. Bylinkin37 National Research Nuclear University 'Moscow Engineering Physics Institute' (MEPhI), Moscow, Russia M. Chadeeva40, O. Markin, P. Parygin, D. Philippov, S. Polikarpov, V. Rusinov P.N. Lebedev Physical Institute, Moscow, Russia V. Andreev, M. Azarkin37, I. Dremin37, M. Kirakosyan37, A. Terkulov Skobeltsyn Institute of Nuclear Physics, Lomonosov Moscow State University, Moscow, Russia A. Snigirev A. Baskakov, A. Belyaev, E. Boos, V. Bunichev, M. Dubinin41, L. Dudko, A. Gribushin, V. Klyukhin, O. Kodolova, I. Lokhtin, I. Miagkov, S. Obraztsov, S. Petrushanko, V. Savrin, Novosibirsk State University (NSU), Novosibirsk, Russia V. Blinov42, Y.Skovpen42, D. Shtol42 State Research Center of Russian Federation, Institute for High Energy Physics, Protvino, Russia I. Azhgirey, I. Bayshev, S. Bitioukov, D. Elumakhov, A. Godizov, V. Kachanov, A. Kalinin, D. Konstantinov, P. Mandrik, V. Petrov, R. Ryutin, A. Sobol, S. Troshin, N. Tyurin, A. Uzunian, A. Volkov University of Belgrade, Faculty of Physics and Vinca Institute of Nuclear Sciences, Belgrade, Serbia P. Adzic43, P. Cirkovic, D. Devetak, M. Dordevic, J. Milosevic, V. Rekovic Centro de Investigaciones Energeticas Medioambientales y Tecnologicas (CIEMAT), Madrid, Spain J. Alcaraz Maestre, I. Bachiller, M. Barrio Luna, M. Cerrada, N. Colino, B. De La Cruz, A. Delgado Peris, A. Escalante Del Valle, C. Fernandez Bedoya, J.P. Fernandez Ramos, J. Flix, M.C. Fouz, O. Gonzalez Lopez, S. Goy Lopez, J.M. Hernandez, M.I. Josa, D. Moran, A. Perez-Calero Yzquierdo, J. Puerta Pelayo, A. Quintario Olmeda, I. Redondo, L. Romero, M.S. Soares, A. Alvarez Fernandez Universidad Autonoma de Madrid, Madrid, Spain C. Albajar, J.F. de Troconiz, M. Missiroli J. Cuevas, C. Erice, J. Fernandez Menendez, I. Gonzalez Caballero, J.R. Gonzalez Fernandez, E. Palencia Cortezon, S. Sanchez Cruz, P. Vischia, J.M. Vizan Garcia Instituto de F sica de Cantabria (IFCA), CSIC-Universidad de Cantabria, Santander, Spain I.J. Cabrillo, A. Calderon, B. Chazin Quero, E. Curras, J. Duarte Campderros, M. Fernandez, J. Garcia-Ferrero, G. Gomez, A. Lopez Virto, J. Marco, C. Martinez Rivero, P. Martinez Ruiz del Arbol, F. Matorras, J. Piedra Gomez, T. Rodrigo, A. Ruiz-Jimeno, L. Scodellaro, N. Trevisani, I. Vila, R. Vilar Cortabitarte HJEP01(28)97 CERN, European Organization for Nuclear Research, Geneva, Switzerland D. Abbaneo, B. Akgun, E. Au ray, P. Baillon, A.H. Ball, D. Barney, J. Bendavid, M. Bianco, P. Bloch, A. Bocci, C. Botta, T. Camporesi, R. Castello, M. Cepeda, G. Cerminara, E. Chapon, Y. Chen, D. d'Enterria, A. Dabrowski, V. Daponte, A. David, M. De Gruttola, A. De Roeck, N. Deelen, M. Dobson, T. du Pree, M. Dunser, N. Dupont, A. Elliott-Peisert, P. Everaerts, F. Fallavollita, G. Franzoni, J. Fulcher, W. Funk, D. Gigi, A. Gilbert, K. Gill, F. Glege, D. Gulhan, P. Harris, J. Hegeman, V. Innocente, A. Jafari, P. Janot, O. Karacheban18, J. Kieseler, V. Knunz, A. Kornmayer, M.J. Kortelainen, M. Krammer1, C. Lange, P. Lecoq, C. Lourenco, M.T. Lucchini, L. Malgeri, M. Mannelli, A. Martelli, F. Meijers, J.A. Merlin, S. Mersi, E. Meschi, P. Milenovic44, F. Moortgat, M. Mulders, H. Neugebauer, J. Ngadiuba, S. Orfanelli, L. Orsini, L. Pape, E. Perez, M. Peruzzi, A. Petrilli, G. Petrucciani, A. Pfei er, M. Pierini, D. Rabady, A. Racz, T. Reis, G. Rolandi45, M. Rovere, H. Sakulin, C. Schafer, C. Schwick, M. Seidel, M. Selvaggi, A. Sharma, P. Silva, P. Sphicas46, A. Stakia, J. Steggemann, M. Stoye, M. Tosi, D. Treille, A. Triossi, A. Tsirou, V. Veckalns47, M. Verweij, W.D. Zeuner Paul Scherrer Institut, Villigen, Switzerland W. Bertly, L. Caminada48, K. Deiters, W. Erdmann, R. Horisberger, Q. Ingram, H.C. Kaestli, D. Kotlinski, U. Langenegger, T. Rohe, S.A. Wiederkehr Institute for Particle Physics and Astrophysics (IPA), Zurich, Switzerland M. Backhaus, L. Bani, P. Berger, L. Bianchini, B. Casal, G. Dissertori, M. Dittmar, M. Donega, C. Dorfer, C. Grab, C. Heidegger, D. Hits, J. Hoss, G. Kasieczka, T. Klijnsma, W. Lustermann, B. Mangano, M. Marionneau, M.T. Meinhard, D. Meister, F. Micheli, P. Musella, F. Nessi-Tedaldi, F. Pandol , J. Pata, F. Pauss, G. Perrin, L. Perrozzi, M. Quittnat, M. Reichmann, D.A. Sanz Becerra, M. Schonenberger, L. Shchutska, V.R. Tavolaro, K. Theo latos, M.L. Vesterbacka Olsson, R. Wallny, D.H. Zhu Universitat Zurich, Zurich, Switzerland T.K. Aarrestad, C. Amsler49, M.F. Canelli, A. De Cosa, R. Del Burgo, S. Donato, C. Galloni, T. Hreus, B. Kilminster, D. Pinna, G. Rauco, P. Robmann, D. Salerno, K. Schweiger, C. Seitz, Y. Takahashi, A. Zucchetta National Central University, Chung-Li, Taiwan V. Candelise, Y.H. Chang, K.y. Cheng, T.H. Doan, Sh. Jain, R. Khurana, C.M. Kuo, W. Lin, A. Pozdnyakov, S.S. Yu National Taiwan University (NTU), Taipei, Taiwan Arun Kumar, P. Chang, Y. Chao, K.F. Chen, P.H. Chen, F. Fiori, W.-S. Hou, Y. Hsiung, Y.F. Liu, R.-S. Lu, E. Paganis, A. Psallidas, A. Steen, J.f. Tsai Chulalongkorn University, Faculty of Science, Department of Physics, Bangkok, Thailand Turkey B. Asavapibhop, K. Kovitanggoon, G. Singh, N. Srimanobhas Cukurova University, Physics Department, Science and Art Faculty, Adana, M.N. Bakirci50, A. Bat, F. Boran, S. Damarseckin, Z.S. Demiroglu, C. Dozen, E. Eskut, S. Girgis, G. Gokbulut, Y. Guler, I. Hos51, E.E. Kangal52, O. Kara, A. Kayis Topaksu, U. Kiminsu, M. Oglakci, G. Onengut53, K. Ozdemir54, A. Polatoz, U.G. Tok, H. Topakli50, S. Turkcapar, I.S. Zorbakir, C. Zorbilmez Middle East Technical University, Physics Department, Ankara, Turkey B. Bilin, G. Karapinar55, K. Ocalan56, M. Yalvac, M. Zeyrek Bogazici University, Istanbul, Turkey E. Gulmez, M. Kaya57, O. Kaya58, S. Tekten, E.A. Yetkin59 Istanbul Technical University, Istanbul, Turkey M.N. Agaras, S. Atay, A. Cakir, K. Cankocak, I. Koseoglu Institute for Scintillation Materials of National Academy of Science of Ukraine, Kharkov, Ukraine B. Grynyov Kharkov, Ukraine L. Levchuk National Scienti c Center, Kharkov Institute of Physics and Technology, University of Bristol, Bristol, United Kingdom F. Ball, L. Beck, J.J. Brooke, D. Burns, E. Clement, D. Cussans, O. Davignon, H. Flacher, J. Goldstein, G.P. Heath, H.F. Heath, L. Kreczko, D.M. Newbold60, S. Paramesvaran, T. Sakuma, S. Seif El Nasr-storey, D. Smith, V.J. Smith Rutherford Appleton Laboratory, Didcot, United Kingdom K.W. Bell, A. Belyaev61, C. Brew, R.M. Brown, L. Calligaris, D. Cieri, D.J.A. Cockerill, J.A. Coughlan, K. Harder, S. Harper, J. Linacre, E. Olaiya, D. Petyt, C.H. ShepherdThemistocleous, A. Thea, I.R. Tomalin, T. Williams Imperial College, London, United Kingdom G. Auzinger, R. Bainbridge, J. Borg, S. Breeze, O. Buchmuller, A. Bundock, S. Casasso, M. Citron, D. Colling, L. Corpe, P. Dauncey, G. Davies, A. De Wit, M. Della Negra, R. Di Maria, A. 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Hadley, J. Hakala, U. Heintz, J.M. Hogan, K.H.M. Kwok, E. Laird, G. Landsberg, J. Lee, Z. Mao, M. Narain, J. Pazzini, S. Piperov, S. Sagir, R. Syarif, D. Yu University of California, Davis, Davis, U.S.A. R. Band, C. Brainerd, D. Burns, M. Calderon De La Barca Sanchez, M. Chertok, J. Conway, R. Conway, P.T. Cox, R. Erbacher, C. Flores, G. Funk, W. Ko, R. Lander, C. Mclean, M. Mulhearn, D. Pellett, J. Pilot, S. Shalhout, M. Shi, J. Smith, D. Stolp, K. Tos, M. Tripathi, Z. Wang University of California, Los Angeles, U.S.A. M. Bachtis, C. Bravo, R. Cousins, A. Dasgupta, A. Florent, J. Hauser, M. Ignatenko, N. Mccoll, S. Regnard, D. Saltzberg, C. Schnaible, V. Valuev University of California, Riverside, Riverside, U.S.A. E. Bouvier, K. Burt, R. Clare, J. Ellison, J.W. Gary, S.M.A. Ghiasi Shirazi, G. Hanson, J. Heilman, G. Karapostoli, E. Kennedy, F. Lacroix, O.R. Long, M. Olmedo Negrete, M.I. Paneva, W. Si, L. Wang, H. Wei, S. Wimpenny, B. R. Yates University of California, San Diego, La Jolla, U.S.A. J.G. Branson, S. Cittolin, M. Derdzinski, R. Gerosa, D. Gilbert, B. Hashemi, A. Holzner, D. Klein, G. Kole, V. Krutelyov, J. Letts, I. Macneill, M. Masciovecchio, D. Olivito, S. Padhi, M. Pieri, M. Sani, V. Sharma, S. Simon, M. Tadel, A. Vartak, S. Wasserbaech63, J. Wood, F. Wurthwein, A. Yagil, G. Zevi Della Porta bara, U.S.A. N. Amin, R. Bhandari, J. Bradmiller-Feld, C. Campagnari, A. Dishaw, V. Dutta, M. Franco Sevilla, F. Golf, L. Gouskos, R. Heller, J. Incandela, A. Ovcharova, H. Qu, J. Richman, D. Stuart, I. Suarez, J. Yoo California Institute of Technology, Pasadena, U.S.A. D. Anderson, A. Bornheim, J.M. Lawhorn, H.B. Newman, T. Nguyen, C. Pena, M. Spiropulu, J.R. Vlimant, S. Xie, Z. Zhang, R.Y. Zhu Carnegie Mellon University, Pittsburgh, U.S.A. I. Vorobiev, M. Weinberg University of Colorado Boulder, Boulder, U.S.A. M.B. Andrews, T. Ferguson, T. Mudholkar, M. Paulini, J. Russ, M. Sun, H. Vogel, J.P. Cumalat, W.T. Ford, F. Jensen, A. Johnson, M. Krohn, S. Leontsinis, T. Mulholland, K. Stenson, S.R. Wagner Cornell University, Ithaca, U.S.A. J. Alexander, J. Chaves, J. Chu, S. Dittmer, K. Mcdermott, N. Mirman, J.R. Patterson, D. Quach, A. Rinkevicius, A. Ryd, L. Skinnari, L. So , S.M. Tan, Z. Tao, J. Thom, J. Tucker, P. Wittich, M. Zientek Fermi National Accelerator Laboratory, Batavia, U.S.A. S. Abdullin, M. Albrow, M. Alyari, G. Apollinari, A. Apresyan, A. Apyan, S. Banerjee, L.A.T. Bauerdick, A. Beretvas, J. Berryhill, P.C. Bhat, G. Bollay, K. Burkett, J.N. Butler, A. Canepa, G.B. Cerati, H.W.K. Cheung, F. Chlebana, M. Cremonesi, J. Duarte, V.D. Elvira, J. Freeman, Z. Gecse, E. Gottschalk, L. Gray, D. Green, S. Grunendahl, O. Gutsche, R.M. Harris, S. Hasegawa, J. Hirschauer, Z. Hu, B. Jayatilaka, S. Jindariani, M. Johnson, U. Joshi, B. Klima, B. Kreis, S. Lammel, D. Lincoln, R. Lipton, M. Liu, T. Liu, R. Lopes De Sa, J. Lykken, K. Maeshima, N. Magini, J.M. Marra no, D. Mason, P. McBride, P. Merkel, S. Mrenna, S. Nahn, V. O'Dell, K. Pedro, O. Prokofyev, G. Rakness, L. Ristori, B. Schneider, E. Sexton-Kennedy, A. Soha, W.J. Spalding, L. Spiegel, S. Stoynev, J. Strait, N. Strobbe, L. Taylor, S. Tkaczyk, N.V. Tran, L. Uplegger, E.W. Vaandering, C. Vernieri, M. Verzocchi, R. Vidal, M. Wang, H.A. Weber, A. Whitbeck University of Florida, Gainesville, U.S.A. D. Acosta, P. Avery, P. Bortignon, D. Bourilkov, A. Brinkerho , A. Carnes, M. Carver, D. Curry, R.D. Field, I.K. Furic, S.V. Gleyzer, B.M. Joshi, J. Konigsberg, A. Korytov, K. Kotov, P. Ma, K. Matchev, H. Mei, G. Mitselmakher, K. Shi, D. Sperka, N. Terentyev, L. Thomas, J. Wang, S. Wang, J. Yelton Florida International University, Miami, U.S.A. Y.R. Joshi, S. Linn, P. Markowitz, J.L. Rodriguez Florida State University, Tallahassee, U.S.A. A. Ackert, T. Adams, A. Askew, S. Hagopian, V. Hagopian, K.F. Johnson, T. Kolberg, G. Martinez, T. Perry, H. Prosper, A. Saha, A. Santra, V. Sharma, R. Yohay M.M. Baarmand, V. Bhopatkar, S. Colafranceschi, M. Hohlmann, D. Noonan, T. Roy, F. Yumiceva University of Illinois at Chicago (UIC), Chicago, U.S.A. M.R. Adams, L. Apanasevich, D. Berry, R.R. Betts, R. Cavanaugh, X. Chen, O. Evdokimov, C.E. Gerber, D.A. Hangal, D.J. Hofman, K. Jung, J. Kamin, I.D. Sandoval Gonzalez, M.B. Tonjes, H. Trauger, N. Varelas, H. Wang, Z. Wu, J. Zhang The University of Iowa, Iowa City, U.S.A. B. Bilki64, W. Clarida, K. Dilsiz65, S. Durgut, R.P. Gandrajula, M. Haytmyradov, V. Khristenko, J.-P. Merlo, H. Mermerkaya66, A. Mestvirishvili, A. Moeller, J. Nachtman, H. Ogul67, Y. Onel, F. Ozok68, A. Penzo, C. Snyder, E. Tiras, J. Wetzel, K. Yi Johns Hopkins University, Baltimore, U.S.A. B. Blumenfeld, A. Cocoros, N. Eminizer, D. Fehling, L. Feng, A.V. Gritsan, P. Maksimovic, C. Mantilla, J. Roskes, U. Sarica, M. Swartz, M. Xiao, C. You The University of Kansas, Lawrence, U.S.A. A. Al-bataineh, P. Baringer, A. Bean, S. Boren, J. Bowen, J. Castle, S. Khalil, A. Kropivnitskaya, D. Majumder, W. Mcbrayer, M. Murray, C. Royon, S. Sanders, E. Schmitz, J.D. Tapia Takaki, Q. Wang Kansas State University, Manhattan, U.S.A. A. Ivanov, K. Kaadze, Y. Maravin, A. Mohammadi, L.K. Saini, N. Skhirtladze, S. Toda Lawrence Livermore National Laboratory, Livermore, U.S.A. F. Rebassoo, D. Wright University of Maryland, College Park, U.S.A. C. Anelli, A. Baden, O. Baron, A. Belloni, S.C. Eno, Y. Feng, C. Ferraioli, N.J. Hadley, S. Jabeen, G.Y. Jeng, R.G. Kellogg, J. Kunkle, A.C. Mignerey, F. Ricci-Tam, Y.H. Shin, A. Skuja, S.C. Tonwar Massachusetts Institute of Technology, Cambridge, U.S.A. D. Abercrombie, B. Allen, V. Azzolini, R. Barbieri, A. Baty, R. Bi, S. Brandt, W. Busza, I.A. Cali, M. D'Alfonso, Z. Demiragli, G. Gomez Ceballos, M. Goncharov, D. Hsu, M. Hu, Y. Iiyama, G.M. Innocenti, M. Klute, D. Kovalskyi, Y.S. Lai, Y.-J. Lee, A. Levin, P.D. Luckey, B. Maier, A.C. Marini, C. Mcginn, C. Mironov, S. Narayanan, X. Niu, C. Paus, C. Roland, G. Roland, J. Salfeld-Nebgen, G.S.F. Stephans, K. Tatar, D. Velicanu, J. Wang, T.W. Wang, B. Wyslouch University of Minnesota, Minneapolis, U.S.A. A.C. Benvenuti, R.M. Chatterjee, A. Evans, P. Hansen, J. Hiltbrand, S. Kalafut, Y. Kubota, Z. Lesko, J. Mans, S. Nourbakhsh, N. Ruckstuhl, R. Rusack, J. Turkewitz, M.A. Wadud University of Mississippi, Oxford, U.S.A. J.G. Acosta, S. Oliveros E. Avdeeva, K. Bloom, D.R. Claes, C. Fangmeier, R. Gonzalez Suarez, R. Kamalieddin, I. Kravchenko, J. Monroy, J.E. Siado, G.R. Snow, B. Stieger State University of New York at Bu alo, Bu alo, U.S.A. J. Dolen, A. Godshalk, C. Harrington, I. Iashvili, D. Nguyen, A. Parker, S. Rappoccio, B. Roozbahani Northeastern University, Boston, U.S.A. G. Alverson, E. Barberis, C. Freer, A. Hortiangtham, A. Massironi, D.M. Morse, T. Orimoto, R. Teixeira De Lima, D. Trocino, T. Wamorkar, B. Wang, A. Wisecarver, D. Wood Northwestern University, Evanston, U.S.A. S. Bhattacharya, O. Charaf, K.A. Hahn, N. Mucia, N. Odell, M.H. Schmitt, K. Sung, M. Trovato, M. Velasco University of Notre Dame, Notre Dame, U.S.A. R. Bucci, N. Dev, M. Hildreth, K. Hurtado Anampa, C. Jessop, D.J. Karmgard, N. Kellams, K. Lannon, W. Li, N. Loukas, N. Marinelli, F. Meng, C. Mueller, Y. Musienko36, M. Planer, A. Reinsvold, R. Ruchti, P. Siddireddy, G. Smith, S. Taroni, M. Wayne, A. Wightman, M. Wolf, A. Woodard The Ohio State University, Columbus, U.S.A. J. Alimena, L. Antonelli, B. Bylsma, L.S. Durkin, S. Flowers, B. Francis, A. Hart, C. Hill, W. Ji, B. Liu, W. Luo, B.L. Winer, H.W. Wulsin Princeton University, Princeton, U.S.A. S. Cooperstein, O. Driga, P. Elmer, J. Hardenbrook, P. Hebda, S. Higginbotham, A. Kalogeropoulos, D. Lange, J. Luo, D. Marlow, K. Mei, I. Ojalvo, J. Olsen, C. Palmer, P. Piroue, D. Stickland, C. Tully University of Puerto Rico, Mayaguez, U.S.A. S. Malik, S. Norberg Purdue University, West Lafayette, U.S.A. F. Wang, R. Xiao, W. Xie Purdue University Northwest, Hammond, U.S.A. T. Cheng, N. Parashar, J. Stupak Rice University, Houston, U.S.A. A. Barker, V.E. Barnes, S. Das, S. Folgueras, L. Gutay, M.K. Jha, M. Jones, A.W. Jung, A. Khatiwada, D.H. Miller, N. Neumeister, C.C. Peng, H. Qiu, J.F. Schulte, J. Sun, Z. Chen, K.M. Ecklund, S. Freed, F.J.M. Geurts, M. Guilbaud, M. Kilpatrick, W. Li, B. Michlin, B.P. Padley, J. Roberts, J. Rorie, W. Shi, Z. Tu, J. Zabel, A. Zhang University of Rochester, Rochester, U.S.A. A. Bodek, P. de Barbaro, R. Demina, Y.t. Duh, T. Ferbel, M. Galanti, A. Garcia-Bellido, J. Han, O. Hindrichs, A. Khukhunaishvili, K.H. Lo, P. Tan, M. Verzetti The Rockefeller University, New York, U.S.A. R. Ciesielski, K. Goulianos, C. Mesropian Rutgers, The State University of New Jersey, Piscataway, U.S.A. A. Agapitos, J.P. Chou, Y. Gershtein, T.A. Gomez Espinosa, E. Halkiadakis, M. Heindl, E. Hughes, S. Kaplan, R. Kunnawalkam Elayavalli, S. Kyriacou, A. Lath, R. Montalvo, K. Nash, M. Osherson, H. Saka, S. Salur, S. Schnetzer, D. She eld, S. Somalwar, R. Stone, S. Thomas, P. Thomassen, M. Walker University of Tennessee, Knoxville, U.S.A. A.G. Delannoy, M. Foerster, J. Heideman, G. Riley, K. Rose, S. Spanier, K. Thapa Texas A&M University, College Station, U.S.A. O. Bouhali69, A. Castaneda Hernandez69, A. Celik, M. Dalchenko, M. De Mattia, A. Delgado, S. Dildick, R. Eusebi, J. Gilmore, T. Huang, T. Kamon70, R. Mueller, Y. Pakhotin, R. Patel, A. Perlo , L. Pernie, D. Rathjens, A. Safonov, A. Tatarinov, K.A. Ulmer Texas Tech University, Lubbock, U.S.A. N. Akchurin, J. Damgov, F. De Guio, P.R. Dudero, J. Faulkner, E. Gurpinar, S. Kunori, K. Lamichhane, S.W. Lee, T. Libeiro, T. Mengke, S. Muthumuni, T. Peltola, S. Undleeb, I. Volobouev, Z. Wang Vanderbilt University, Nashville, U.S.A. S. Greene, A. Gurrola, R. Janjam, W. Johns, C. Maguire, A. Melo, H. Ni, K. Padeken, P. Sheldon, S. Tuo, J. Velkovska, Q. Xu University of Virginia, Charlottesville, U.S.A. M.W. Arenton, P. Barria, B. Cox, R. Hirosky, M. Joyce, A. Ledovskoy, H. Li, C. Neu, T. Sinthuprasith, Y. Wang, E. Wolfe, F. Xia Wayne State University, Detroit, U.S.A. R. Harr, P.E. Karchin, N. Poudyal, J. Sturdy, P. Thapa, S. Zaleski University of Wisconsin - Madison, Madison, WI, U.S.A. M. Brodski, J. Buchanan, C. Caillol, S. Dasu, L. Dodd, S. Duric, B. Gomber, M. Grothe, M. Herndon, A. Herve, U. Hussain, P. Klabbers, A. Lanaro, A. Levine, K. Long, R. Loveless, T. Ruggles, A. Savin, N. Smith, W.H. Smith, D. Taylor, N. Woods y: Deceased China 1: Also at Vienna University of Technology, Vienna, Austria 2: Also at State Key Laboratory of Nuclear Physics and Technology, Peking University, Beijing, 3: Also at IRFU, CEA, Universite Paris-Saclay, Gif-sur-Yvette, France 4: Also at Universidade Estadual de Campinas, Campinas, Brazil 5: Also at Universidade Federal de Pelotas, Pelotas, Brazil 6: Also at Universite Libre de Bruxelles, Bruxelles, Belgium 7: Also at Institute for Theoretical and Experimental Physics, Moscow, Russia 8: Also at Joint Institute for Nuclear Research, Dubna, Russia 10: Now at British University in Egypt, Cairo, Egypt 11: Now at Cairo University, Cairo, Egypt 12: Also at Universite de Haute Alsace, Mulhouse, France Moscow, Russia 13: Also at Skobeltsyn Institute of Nuclear Physics, Lomonosov Moscow State University, 14: Also at Tbilisi State University, Tbilisi, Georgia 15: Also at CERN, European Organization for Nuclear Research, Geneva, Switzerland 16: Also at RWTH Aachen University, III. Physikalisches Institut A, Aachen, Germany 17: Also at University of Hamburg, Hamburg, Germany 18: Also at Brandenburg University of Technology, Cottbus, Germany 19: Also at MTA-ELTE Lendulet CMS Particle and Nuclear Physics Group, Eotvos Lorand University, Budapest, Hungary 20: Also at Institute of Nuclear Research ATOMKI, Debrecen, Hungary 21: Also at Institute of Physics, University of Debrecen, Debrecen, Hungary 22: Also at Indian Institute of Technology Bhubaneswar, Bhubaneswar, India 23: Also at Institute of Physics, Bhubaneswar, India 24: Also at University of Visva-Bharati, Santiniketan, India 25: Also at University of Ruhuna, Matara, Sri Lanka 26: Also at Isfahan University of Technology, Isfahan, Iran 27: Also at Yazd University, Yazd, Iran 28: Also at Plasma Physics Research Center, Science and Research Branch, Islamic Azad University, Tehran, Iran 29: Also at Universita degli Studi di Siena, Siena, Italy 30: Also at INFN Sezione di Milano-Bicocca; Universita di Milano-Bicocca, Milano, Italy 31: Also at Purdue University, West Lafayette, U.S.A. 32: Also at International Islamic University of Malaysia, Kuala Lumpur, Malaysia 33: Also at Malaysian Nuclear Agency, MOSTI, Kajang, Malaysia 34: Also at Consejo Nacional de Ciencia y Tecnolog a, Mexico city, Mexico 35: Also at Warsaw University of Technology, Institute of Electronic Systems, Warsaw, Poland 36: Also at Institute for Nuclear Research, Moscow, Russia 37: Now at National Research Nuclear University 'Moscow 38: Also at St. Petersburg State Polytechnical University, St. Petersburg, Russia 39: Also at University of Florida, Gainesville, U.S.A. 40: Also at P.N. Lebedev Physical Institute, Moscow, Russia 41: Also at California Institute of Technology, Pasadena, U.S.A. 42: Also at Budker Institute of Nuclear Physics, Novosibirsk, Russia 43: Also at Faculty of Physics, University of Belgrade, Belgrade, Serbia Belgrade, Serbia 45: Also at Scuola Normale e Sezione dell'INFN, Pisa, Italy 46: Also at National and Kapodistrian University of Athens, Athens, Greece 47: Also at Riga Technical University, Riga, Latvia 48: Also at Universitat Zurich, Zurich, Switzerland 49: Also at Stefan Meyer Institute for Subatomic Physics (SMI), Vienna, Austria 50: Also at Gaziosmanpasa University, Tokat, Turkey 51: Also at Istanbul Aydin University, Istanbul, Turkey 44: Also at University of Belgrade, Faculty of Physics and Vinca Institute of Nuclear Sciences, 53: Also at Cag University, Mersin, Turkey 54: Also at Piri Reis University, Istanbul, Turkey 55: Also at Izmir Institute of Technology, Izmir, Turkey 56: Also at Necmettin Erbakan University, Konya, Turkey 57: Also at Marmara University, Istanbul, Turkey 58: Also at Kafkas University, Kars, Turkey 59: Also at Istanbul Bilgi University, Istanbul, Turkey 60: Also at Rutherford Appleton Laboratory, Didcot, United Kingdom 61: Also at School of Physics and Astronomy, University of Southampton, Southampton, United Kingdom 62: Also at Instituto de Astrof sica de Canarias, La Laguna, Spain 63: Also at Utah Valley University, Orem, U.S.A. 64: Also at Beykent University, Istanbul, Turkey 65: Also at Bingol University, Bingol, Turkey 66: Also at Erzincan University, Erzincan, Turkey 67: Also at Sinop University, Sinop, Turkey 68: Also at Mimar Sinan University, Istanbul, Istanbul, Turkey 69: Also at Texas A&M University at Qatar, Doha, Qatar 70: Also at Kyungpook National University, Daegu, Korea [1] L.A. 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Pook, M. Radziej. Search for low mass vector resonances decaying into quark-antiquark pairs in proton-proton collisions at $$ \sqrt{s}=13 $$ TeV, Journal of High Energy Physics, 2018, 97, DOI: 10.1007/JHEP01(2018)097