The European Physical Journal C

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

List of Papers (Total 4,085)

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

A search for pair-produced massive coloured scalar particles decaying to a four-jet final state is performed by the ATLAS experiment at the LHC in proton–proton collisions at \(\sqrt{s} = 7\ \mbox{TeV}\). The analysed data sample corresponds to an integrated luminosity of 4.6 fb−1. No deviation from the Standard Model is observed in the invariant mass spectrum of the two-jet...

On the potentiality of the ZnWO4 anisotropic detectors to measure the directionality of Dark Matter

In the anisotropic scintillators the light output and the pulse shape for heavy particles (p, α, nuclear recoils) depend on the direction with respect to the crystal axes; the response to γ/β radiation is isotropic instead. This feature offers the possibility to study the directionality approach, which is applicable in the particular case of those Dark Matter candidate particles...

Measurements of top quark pair relative differential cross-sections with ATLAS in pp collisions at \(\sqrt{s} = 7\ \mbox{TeV}\)

Measurements are presented of differential cross-sections for top quark pair production in pp collisions at \(\sqrt{s} = 7\ \mbox{TeV}\) relative to the total inclusive top quark pair production cross-section. A data sample of 2.05 fb−1 recorded by the ATLAS detector at the Large Hadron Collider is used. Relative differential cross-sections are derived as a function of the...

D ∗ and D meson production in muon nucleon interactions at 160 GeV/c

The production of D ∗ and D mesons in inelastic scattering of 160 GeV/c muons off a 6LiD target has been investigated with the COMPASS spectrometer at CERN for 0.003 (GeV/c)2<Q 2<10 (GeV/c)2 and 3×10−5<x Bj <0.1. The study is based on 8100 events where a D 0 or \(\bar{D}^{0}\) is detected subsequently to a D ∗+ or D ∗− decay, and on 34000 events, where only a D 0 or \(\bar{D}^{0...

Supersymmetry and generic BSM models in Pythia 8

We describe the implementation of supersymmetric models in Pythia 8 including production and decay of superparticles and allowing for violation of flavour, CP, and R-parity. We also present a framework for importing generic new-physics matrix elements into Pythia 8, in a way suitable for use with automated tools. We emphasize that this possibility should not be viewed as the only...

Measurement of the relative prompt production rate of χ c2 and χ c1 in pp collisions at \(\sqrt{s} = 7\ \mathrm{TeV}\)

A measurement is presented of the relative prompt production rate of χ c2 and χ c1 with 4.6 fb−1 of data collected by the CMS experiment at the LHC in pp collisions at \(\sqrt{s}= 7~\mathrm{TeV}\). The two states are measured via their radiative decays χ c→J/ψ+γ, with the photon converting into an e+e− pair for J/ψ rapidity |y(J/ψ)|<1.0 and photon transverse momentum p T(γ)>0.5...

Development of a magnetometer-based search strategy for stopped monopoles at the Large Hadron Collider

If produced in high energy particle collisions at the LHC, magnetic monopoles could stop in material surrounding the interaction points. Obsolete parts of the beam pipe near the CMS interaction region, which were exposed to the products of pp and heavy ion collisions, were analysed using a SQUID-based magnetometer. The purpose of this work is to quantify the performance of the...

Collinearity approximations and kinematic shifts in partonic shower algorithms

We study kinematic effects due to the approximation of on-shell, collinear partons in shower Monte Carlo event generators. We observe that the collinearity approximation, combined with the requirements of energy-momentum conservation, gives rise to a kinematic shift, event by event, in longitudinal momentum distributions. We present numerical results in the case of jet and heavy...

ATLAS search for a heavy gauge boson decaying to a charged lepton and a neutrino in pp collisions at \(\sqrt{s} = 7\ \mathrm{TeV}\)

The ATLAS detector at the LHC is used to search for high-mass states, such as heavy charged gauge bosons (W′), decaying to a charged lepton (electron or muon) and a neutrino. Results are presented based on the analysis of pp collisions at a center-of-mass energy of 7  TeV corresponding to an integrated luminosity of 4.7 fb−1. No excess beyond Standard Model expectations is...

Search for doubly charged Higgs bosons in like-sign dilepton final states at \(\sqrt{s} = 7\ \mathrm{TeV}\) with the ATLAS detector

A search for doubly charged Higgs bosons decaying to pairs of electrons and/or muons is presented. The search is performed using a data sample corresponding to an integrated luminosity of 4.7 fb−1 of pp collisions at \(\sqrt{s}\) = 7 TeV collected by the ATLAS detector at the LHC. Pairs of prompt, isolated, high-p T leptons with the same electric charge (e ± e ±, e...

Curvature oscillations in modified gravity and high energy cosmic rays

It is shown that F(R)-modified gravitational theories lead to curvature oscillations in astrophysical systems with rising energy density. The frequency and the amplitude of such oscillations could be very high and would lead to noticeable production of energetic cosmic ray particles.

A search for a doubly-charged Higgs boson in pp collisions at \(\sqrt{s} = 7 \ \mbox{TeV}\)

A search for a doubly-charged Higgs boson in pp collisions at \(\sqrt{s} = 7 \ \mbox{TeV}\) is presented. The data correspond to an integrated luminosity of 4.9 fb−1, collected by the CMS experiment at the LHC. The search is performed using events with three or more isolated charged leptons of any flavor, giving sensitivity to the decays of pair-produced triplet components...

Search for light scalar top-quark pair production in final states with two leptons with the ATLAS detector in \(\sqrt{s}=7\ \mathrm{TeV}\) proton–proton collisions

A search is presented for the pair production of light scalar top quarks in \(\sqrt{s}=7~\mathrm{TeV}\) proton–proton collisions recorded with the ATLAS detector at the Large Hadron Collider. This analysis uses the full data sample collected during 2011 running that corresponds to a total integrated luminosity of 4.7 fb−1. Light scalar top quarks are searched for in events with...

Search for supersymmetry in events with large missing transverse momentum, jets, and at least one tau lepton in 7 TeV proton-proton collision data with the ATLAS detector

A search for supersymmetry (SUSY) in events with large missing transverse momentum, jets, and at least one hadronically decaying τ lepton, with zero or one additional light lepton (e/μ), has been performed using 4.7 fb−1 of proton-proton collision data at \(\sqrt{s} = 7\mbox{~TeV}\) recorded with the ATLAS detector at the Large Hadron Collider. No excess above the Standard Model...

Measurement of event shapes at large momentum transfer with the ATLAS detector in pp collisions at \(\sqrt{\mathbf{s}}=7\ \mathrm{TeV}\)

A measurement of event shape variables is presented for large momentum transfer proton-proton collisions using the ATLAS detector at the Large Hadron Collider. Six event shape variables calculated using hadronic jets are studied in inclusive multi-jet events in 35 pb−1 of integrated luminosity at a center-of-mass energy of \(\sqrt{s} = 7~\mathrm{TeV}\). These measurements are...

A non-perturbative contribution to jet quenching

It has been argued by Caron-Huot that infrared contributions to the jet quenching parameter in hot QCD, denoted by \(\hat{q}\), can be extracted from an analysis of a certain static-potential related observable within the dimensionally reduced effective field theory. Following this philosophy, the order of magnitude of a non-perturbative contribution to \(\hat{q}\) from the...

Precise QCD predictions on top quark pair production mediated by massive color-octet vector boson at hadron colliders

We present a theoretical framework for systematically calculating next-to-leading order (NLO) QCD effects to various experimental observables in models with massive COVB in a model independent way at hadron colliders. Specifically, we show the numerical results for the NLO QCD corrections to total cross sections, invariant mass distribution and A FB of top quark pairs production...

Ratios of dijet production cross sections as a function of the absolute difference in rapidity between jets in proton–proton collisions at \(\sqrt{s} = 7\ \mathrm{TeV}\)

A study of dijet production in proton–proton collisions was performed at \(\sqrt{s}=7\mbox{~TeV}\) for jets with p T>35 GeV and |y|<4.7 using data collected with the CMS detector at the LHC in 2010. Events with at least one pair of jets are denoted as “inclusive”. Events with exactly one pair of jets are called “exclusive”. The ratio of the cross section of all pairwise...

MEtop—a generator for single top production via FCNC interactions

We present a generator for single top-quark production via flavour-changing neutral currents. The MEtop event generator allows for Next-to-Leading-Order direct top production pp→t and Leading-Order production of several other single top processes. A few packages with definite sets of dimension six operators are available. We discuss how to improve the bounds on the effective...

Dipole showers and automated NLO matching in Herwig++

We report on the implementation of a coherent dipole shower algorithm along with an automated implementation for dipole subtraction and for performing powheg- and mc@nlo-type matching to next-to-leading order (NLO) calculations. Both programs are implemented as add-on modules to the event generator Herwig++. A preliminary tune of parameters to data acquired at LEP, HERA and Drell...

Colour reconnections in Herwig++

We describe the implementation details of the colour reconnection model in the event generator Herwig++. We study the impact on final-state observables in detail and confirm the model idea from colour preconfinement on the basis of studies within the cluster hadronization model. Moreover, we show that the description of minimum bias and underlying event data at the LHC is...

A Monte-Carlo generator for statistical hadronization in high energy e+e− collisions

We present a Monte-Carlo implementation of the Statistical Hadronization Model in e+e− collisions. The physical scheme is based on the statistical hadronization of massive clusters produced by the event generator Herwig within the microcanonical ensemble. We present a preliminary comparison of several observables with measurements in e+e− collisions at the Z peak. Although a fine...