The European Physical Journal C

http://link.springer.com/journal/10052

List of Papers (Total 3,246)

Superluminal neutrinos from Lorentz-violating dimension-5 operators

We consider Lorentz- and CPT-violating dimension-5 operators to address the issue of superluminal neutrinos recently pointed out in OPERA experiments. We assume these operators in the photon and neutrino sectors to be coupled to Lorentz-violating backgrounds in a preferred frame defined by a time-like direction. We show that such operators can produce a curve with OPERA’s slope ...

Measurement of the diffractive longitudinal structure function \(F_{L}^{D}\) at HERA

First measurements are presented of the diffractive cross section σ ep→eXY at centre-of-mass energies \(\sqrt{s}\) of 225 and \(252\mathrm {\;GeV}\), together with a precise new measurement at \(\sqrt{s}\) of \(319\mathrm {\;GeV}\), using data taken with the H1 detector in the years 2006 and 2007. Together with previous H1 data at \(\sqrt{s}\) of \(301\mathrm {\;GeV}\), the ...

Measurement of the inclusive and dijet cross-sections of b-jets in pp collisions at \(\sqrt{s}=7\mbox{~TeV}\) with the ATLAS detector

The inclusive and dijet production cross-sections have been measured for jets containing b-hadrons (b-jets) in proton–proton collisions at a centre-of-mass energy of \(\sqrt{s} = 7\mbox{~TeV}\), using the ATLAS detector at the LHC. The measurements use data corresponding to an integrated luminosity of 34 pb−1. The b-jets are identified using either a lifetime-based method, where ...

Benchmark models, planes, lines and points for future SUSY searches at the LHC

We define benchmark models for SUSY searches at the LHC, including the CMSSM, NUHM, mGMSB, mAMSB, MM-AMSB and p19MSSM, as well as models with R-parity violation and the NMSSM. Within the parameter spaces of these models, we propose benchmark subspaces, including planes, lines and points along them. The planes may be useful for presenting results of the experimental searches in ...

Search for massive colored scalars in four-jet final states in \(\sqrt{s}=7~\mbox{TeV}\) proton–proton collisions with the ATLAS detector

A search for pair-produced scalar particles decaying to a four-jet final state is presented. The analysis is performed using an integrated luminosity of 34 pb−1 recorded by the ATLAS detector in 2010. No deviation from the Standard Model is observed. For a scalar mass of 100 GeV (190 GeV) the limit on the scalar gluon pair production cross section at 95% confidence level is 1 nb ...

Search for a heavy neutral particle decaying into an electron and a muon using 1 fb−1 of ATLAS data

A search is presented for a high mass neutral particle that decays directly to the e ± μ ∓ final state. The data sample was recorded by the ATLAS detector in \(\sqrt{s}=7\mbox{~TeV}\) pp collisions at the LHC from March to June 2011 and corresponds to an integrated luminosity of 1.07 fb−1. The data are found to be consistent with the Standard Model background. The high e ± μ ∓ mass ...

Measurement of the jet fragmentation function and transverse profile in proton–proton collisions at a center-of-mass energy of 7 TeV with the ATLAS detector

The jet fragmentation function and transverse profile for jets with 25 GeV<p T jet<500 GeV and |η jet|<1.2 produced in proton–proton collisions with a center-of-mass energy of 7 TeV are presented. The measurement is performed using data with an integrated luminosity of 36 pb−1. Jets are reconstructed and their momentum measured using calorimetric information. The momenta of the ...

Radon-induced surface contaminations in low background experiments

In low background experiments the reduction of all possible radioactive contaminants is a crucial point for detector construction. This is also true for the surface contaminants, either those introduced during the production of detector components or those introduced during handling, treatment or storage. One of the most critical issue in this field is the control of the ...

Could dynamical Lorentz symmetry breaking induce the superluminal neutrinos?

A toy fermion model coupled to the Lagrange multiplier constraint field is proposed. The possibility of superluminal neutrino propagation as a result of dynamical Lorentz symmetry breaking is studied.

Measurement of multi-jet cross sections in proton–proton collisions at a 7 TeV center-of-mass energy

Inclusive multi-jet production is studied in proton–proton collisions at a center-of-mass energy of 7 TeV, using the ATLAS detector. The data sample corresponds to an integrated luminosity of 2.4 pb−1. Results on multi-jet cross sections are presented and compared to both leading-order plus parton-shower Monte Carlo predictions and to next-to-leading-order QCD calculations.

Measurement of photon production in the very forward direction in deep-inelastic scattering at HERA

The production of photons at very small angles with respect to the proton beam direction is studied in deep-inelastic positron–proton scattering at HERA. The data are taken with the H1 detector in the years 2006 and 2007 and correspond to an integrated luminosity of 126 pb−1. The analysis covers the range of negative four momentum transfer squared at the positron vertex 6<Q 2<100 ...

Measurement of D ∗± meson production and determination of \(F_{2}^{c\bar{c}}\) at low Q 2 in deep-inelastic scattering at HERA

Inclusive production of D ∗ mesons in deep-inelastic ep scattering at HERA is studied in the range 5<Q 2<100 GeV2 of the photon virtuality and 0.02<y<0.7 of the inelasticity of the scattering process. The observed phase space for the D ∗ meson is p T (D ∗)>1.25 GeV and |η(D ∗)|<1.8. The data sample corresponds to an integrated luminosity of 348 pb−1 collected with the H1 detector. ...

Search for diphoton events with large missing transverse energy with 36 pb−1 of 7 TeV proton–proton collision data with the ATLAS detector

Making use of 36 pb−1 of proton–proton collision data at \(\sqrt{s} =7\) TeV, the ATLAS Collaboration has performed a search for diphoton events with large missing transverse energy. Observing no excess of events above the Standard Model prediction, a 95% Confidence Level (CL) upper limit is set on the cross section for new physics of σ<0.38−0.65 pb in the context of a generalised ...

Determination of α S using OPAL hadronic event shapes at \(\sqrt{s} = 91\mbox{--}209~\mathrm{GeV}\) and resummed NNLO calculations

Hadronic event shape distributions from e+e− annihilation measured by the OPAL experiment at centre-of-mass energies between 91 GeV and 209 GeV are used to determine the strong coupling α S. The results are based on QCD predictions complete to the next-to-next-to-leading order (NNLO), and on NNLO calculations matched to the resummed next-to-leading-log-approximation terms (NNLO + ...

Limits on the production of the standard model Higgs boson in pp collisions at \(\sqrt{s} = 7\) TeV with the ATLAS detector

A search for the Standard Model Higgs boson at the Large Hadron Collider (LHC) running at a centre-of-mass energy of 7 TeV is reported, based on a total integrated luminosity of up to 40 pb−1 collected by the ATLAS detector in 2010. Several Higgs boson decay channels: H→γγ, H→ZZ (∗)→ℓℓℓℓ, H→ZZ→ℓℓνν, H→ZZ→ℓℓqq, H→WW (∗)→ℓνℓν and H→WW→ℓνqq (ℓ is e, μ) are combined in a mass range ...

Measurement of the \(\mathrm{{t\bar{t}}}\) production cross section in pp collisions at \(\sqrt{s}=7\) TeV using the kinematic properties of events with leptons and jets

A measurement of the \(\mathrm{t{\bar{t}}}\) production cross section in proton-proton collisions at a centre-of-mass energy of 7 TeV has been performed at the LHC with the CMS detector. The analysis uses a data sample corresponding to an integrated luminosity of 36 pb−1 and is based on the reconstruction of the final state with one isolated, high transverse-momentum electron or ...

A 2D fit with background measurement constraints to boost the Higgs →ZZ(∗)→4ℓ discovery potential at the LHC

A data-driven method for simultaneously extracting a potential Higgs → ZZ(∗) → 4e, 4μ, 2e2μ signal and its dominant backgrounds, is presented. The method relies on a combined fit of the 2-lepton, Z(∗), and 4-lepton invariant masses. The fit is assisted by normalization of the Z+X backgrounds in data control regions. The Higgs discovery potential for the next few years of LHC ...

Improved sensitivity to charged Higgs searches in top quark decays t→bH +→b(τ + ν τ ) at the LHC using τ polarisation and multivariate techniques

We present an analysis with improved sensitivity to the light charged Higgs (\(m_{H^{+}} < m_{t}-m_{b}\)) searches in the top quark decays t→bH +→b(τ + ν τ )+c.c. in the \(t\bar{t}\) and single \(t/\bar{t}\) production processes at the LHC. In the Minimal Supersymmetric Standard Model (MSSM), one anticipates the branching ratio \({\mathcal{B}} (H^{+} \to\tau^{+}\nu_{\tau})\simeq1\) ...

Factorisation breaking in diffractive dijet photoproduction at HERA?

Recent experimental data on dijet cross sections in diffractive photoproduction at HERA collider are analysed with an emphasis on QCD factorisation breaking effects. The possible sources of the different conclusions of H1 and ZEUS collaborations are studied.

Neutrino quasielastic scattering on nuclear targets

We present a parametrization of the observed enhancement in the transverse electron quasielastic (QE) response function for nucleons bound in carbon as a function of the square of the four momentum transfer (Q 2) in terms of a correction to the magnetic form factors of bound nucleons. The parametrization should also be applicable to the transverse cross section in neutrino ...

CMS ridge effect at LHC as a manifestation of bremsstrahlung of gluons off quarks accelerated in a strong color field

The recently reported effect of long-range near-side angular correlations at LHC occurs for large multiplicities of particles with 1 GeV<p T <3 GeV. To understand the effect several possibilities have been discussed. In the letter we propose a simple qualitative mechanism which corresponds to gluon bremsstrahlung of quarks moving with acceleration defined by the string tension. The ...

Cross-sections of large-angle hadron production in proton– and pion–nucleus interactions VII: tin nuclei and beam momenta from ±3 GeV/c to ±15 GeV/c

We report on double-differential inclusive cross-sections of the production of secondary protons, charged pions, and deuterons, in the interactions with a 5% λ int thick stationary tin target, of proton and pion beams with momentum from ±3 GeV/c to ±15 GeV/c. Results are given for secondary particles with production angles 20○<θ<125○. Cross-sections on tin nuclei are compared with ...