The European Physical Journal C

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

List of Papers (Total 3,080)

A search for \(t\bar{t}\) resonances with the ATLAS detector in 2.05 fb−1 of proton-proton collisions at \(\sqrt{s} = 7~\mathrm{TeV}\)

A search for top quark pair resonances in final states containing at least one electron or muon has been performed with the ATLAS experiment at the CERN Large Hadron Collider. The search uses a data sample corresponding to an integrated luminosity of 2.05 fb−1, which was recorded in 2011 at a proton-proton centre-of-mass energy of 7 TeV. No evidence for a resonance is found and ...

A minimal dark matter interpretation for the CRESST-II signal

We report on the possible interpretation of the two proposed dark matter mass values m χ =11.6 GeV and m χ =25.3 GeV from CRESST-II within the framework of the Higgs portal minimal dark matter model. We find that the higher mass value yields a suitable fit with a dark matter-Higgs coupling η/2=0.157 and a recoil cross section which is compatible with contemporary estimates of the ...

Hierarchically acting sterile neutrinos

We propose that a hierarchical spectrum of sterile neutrinos (eV, keV, 1013–15 GeV) is considered as the explanation for MiniBooNE and LSND oscillation anomalies, dark matter, and baryon asymmetry of the universe (BAU), respectively. The scenario can also realize the smallness of active neutrino masses by the seesaw mechanism.

Search for charged Higgs bosons in e+e− collisions at \(\sqrt{s}=189\mbox{--}209\ \mbox{GeV}\)

A search is made for charged Higgs bosons predicted by Two-Higgs-Doublet extensions of the Standard Model (2HDM) using electron-positron collision data collected by the OPAL experiment at \(\sqrt{s}=189\mbox{--}209\ \mbox{GeV}\), corresponding to an integrated luminosity of approximately 600 pb−1. Charged Higgs bosons are assumed to be pair-produced and to decay into \(\mathrm{q} ...

Inclusive measurement of diffractive deep-inelastic scattering at HERA

The diffractive process ep→eXY, where Y denotes a proton or its low mass excitation with M Y <1.6 GeV, is studied with the H1 experiment at HERA. The analysis is restricted to the phase space region of the photon virtuality 3 ≤ Q 2 ≤ 1600 GeV2, the square of the four-momentum transfer at the proton vertex |t|< 1.0 GeV2 and the longitudinal momentum fraction of the incident proton ...

Cross sections for leptophobic topcolor Z′ decaying to top–antitop

We present numerical calculations of the production cross section of a heavy Z′ resonance in hadron–hadron collisions with subsequent decay into top–antitop pairs. In particular, we consider the leptophobic topcolor Z′ discussed under Model IV of hep-ph/​9911288, which has predicted cross sections large enough to be experimentally accessible at the Fermilab Tevatron and the Large ...

A numerical test of differential equations for one- and two-loop sunrise diagrams using configuration space techniques

We use configuration space methods to write down one-dimensional integral representations for one- and two-loop sunrise diagrams (also called Bessel moments) which we use to numerically check on the correctness of the second order differential equations for one- and two-loop sunrise diagrams that have recently been discussed in the literature.

Measurement of beauty and charm photoproduction using semi-muonic decays in dijet events at HERA

Measurements of cross sections for beauty and charm events with dijets and a muon in the photoproduction regime at HERA are presented. The data were collected with the H1 detector and correspond to an integrated luminosity of 179 pb−1. Events with dijets of transverse momentum \(P_{T}^{\mathrm{jet}1}> 7\ \mbox{GeV}\) and \(P_{T}^{\mathrm{jet}2}> 6\ \mbox{GeV}\) in the ...

No role for muons in the DAMA annual modulation results

This paper gathers arguments and reasons why muons surviving the Gran Sasso mountain cannot mimic the Dark Matter annual modulation signature exploited by the DAMA/NaI and DAMA/LIBRA experiments. A number of these items have already been presented in individual papers. Further arguments have been addressed here in order to present a comprehensive collection and to enable a wider ...

Search for heavy neutrinos and right-handed W bosons in events with two leptons and jets in pp collisions at \(\sqrt{s} = 7~\mathrm{TeV}\) with the ATLAS detector

This letter reports on a search for hypothetical heavy neutrinos, N, and right-handed gauge bosons, W R, in events with high transverse momentum objects which include two reconstructed leptons and at least one hadronic jet. The results were obtained from data corresponding to an integrated luminosity of 2.1 fb−1 collected in proton–proton collisions at \(\sqrt{s}=7~\mathrm{TeV}\) ...

Measurement of τ polarization in W→τν decays with the ATLAS detector in pp collisions at \(\sqrt{s} =7~\mathrm{TeV}\)

In this paper, a measurement of τ polarization in W→τν decays is presented. It is measured from the energies of the decay products in hadronic τ decays with a single final state charged particle. The data, corresponding to an integrated luminosity of 24 pb−1, were collected by the ATLAS experiment at the Large Hadron Collider in 2010. The measured value of the τ polarization is ...

Low temperature light yield measurements in NaI and NaI(Tl)

The scintillation light output of a pure and a Thallium doped Sodium Iodide (NaI) crystal under irradiation with 5.486 MeV α particles has been measured over a temperature range from 1.7 K to 300 K. Estimates of the decay time constant at three selected temperatures are given. For pure NaI an increase in light yield towards low temperatures could be confirmed and measured at higher ...

Measurement of the top quark mass with the template method in the \(t\bar{t} \to\mathrm{lepton}+\mathrm{jets}\) channel using ATLAS data

The top quark mass has been measured using the template method in the \(t\bar{t}\to\mathrm{lepton}+\mathrm{jets}\) channel based on data recorded in 2011 with the ATLAS detector at the LHC. The data were taken at a proton-proton centre-of-mass energy of \(\sqrt{s}=7\ \mbox{TeV}\) and correspond to an integrated luminosity of 1.04 fb−1. The analyses in the e+jets and μ+jets decay ...

Measurement of \(t\bar{t}\) production with a veto on additional central jet activity in pp collisions at \(\sqrt{s}=7\) TeV using the ATLAS detector

A measurement of the jet activity in \(t\bar{t}\) events produced in proton–proton collisions at a centre-of-mass energy of 7 TeV is presented, using 2.05 fb−1 of integrated luminosity collected by the ATLAS detector at the Large Hadron Collider. The \(t\bar{t}\) events are selected in the dilepton decay channel with two identified b-jets from the top quark decays. Events are ...

Measurement of the charge asymmetry in top quark pair production in pp collisions at \(\sqrt{s}=7\ \mathrm{TeV}\) using the ATLAS detector

A measurement of the top-antitop production charge asymmetry A C is presented using data corresponding to an integrated luminosity of 1.04 fb−1 of pp collisions at \(\sqrt{s} = 7\) TeV collected by the ATLAS detector at the LHC. Events are selected with a single lepton (electron or muon), missing transverse momentum and at least four jets of which at least one jet is identified as ...

Search for lepton flavour violation in the eμ continuum with the ATLAS detector in \(\sqrt{s} = 7~\mbox{TeV}\) pp collisions at the LHC

This paper presents a search for the t-channel exchange of an R-parity violating scalar top quark (\(\tilde{t}\)) in the e ± μ ∓ continuum using 2.1 fb−1 of data collected by the ATLAS detector in \(\sqrt{s}=7~\mbox{TeV}\) pp collisions at the Large Hadron Collider. Data are found to be consistent with the expectation from the Standard Model backgrounds. Limits on ...

Opposite-side flavour tagging of B mesons at the LHCb experiment

The calibration and performance of the opposite-side flavour tagging algorithms used for the measurements of time-dependent asymmetries at the LHCb experiment are described. The algorithms have been developed using simulated events and optimized and calibrated with B +→J/ψK +, B 0→J/ψK ∗0 and B 0→D ∗− μ + ν μ decay modes with 0.37 fb−1 of data collected in pp collisions at ...

Measurement of ϒ production in pp collisions at \(\sqrt{\boldsymbol{s}}=\boldsymbol{7}~\mathrm{TeV}\)

The production of ϒ(1S), ϒ(2S) and ϒ(3S) mesons in proton-proton collisions at the centre-of-mass energy of \(\sqrt{s}=7~\mbox{TeV}\) is studied with the LHCb detector. The analysis is based on a data sample of 25 pb−1 collected at the Large Hadron Collider. The ϒ mesons are reconstructed in the decay mode ϒ→μ + μ − and the signal yields are extracted from a fit to the μ + μ − ...

Centrality dependence of dihadron correlations and azimuthal anisotropy harmonics in PbPb collisions at \(\sqrt{s_{NN}}= 2.76\ \mbox{TeV}\)

Measurements from the CMS experiment at the LHC of dihadron correlations for charged particles produced in PbPb collisions at a nucleon–nucleon centre-of-mass energy of 2.76 TeV are presented. The results are reported as a function of the particle transverse momenta (p T) and collision centrality over a broad range in relative pseudorapidity (Δη) and the full range of relative ...

Measurement of the polarisation of W bosons produced with large transverse momentum in pp collisions at \(\sqrt{s} = 7\ \mbox{TeV}\) with the ATLAS experiment

This paper describes an analysis of the angular distribution of W→eν and W→μν decays, using data from pp collisions at \(\sqrt{s} = 7\ \mbox{TeV}\) recorded with the ATLAS detector at the LHC in 2010, corresponding to an integrated luminosity of about 35 pb−1. Using the decay lepton transverse momentum and the missing transverse momentum, the W decay angular distribution projected ...

Measurement of inclusive and dijet D ∗ meson cross sections in photoproduction at HERA

The inclusive photoproduction of D ∗ mesons and of D ∗-tagged dijets is investigated with the H1 detector at the ep collider HERA. The kinematic region covers small photon virtualities Q 2<2 GeV2 and photon–proton centre-of-mass energies of 100<W γp <285 GeV. Inclusive D ∗ meson differential cross sections are measured for central rapidities |η(D ∗)|<1.5 and transverse momenta p T ...

Observation of X(3872) production in pp collisions at \(\sqrt{s}=7\mbox{~TeV}\)

Using 34.7 pb−1 of data collected with the LHCb detector, the inclusive production of the X(3872) meson in pp collisions at \(\sqrt{s}=7\mbox{~TeV}\) is observed for the first time. Candidates are selected in the X(3872)→J/ψπ + π − decay mode, and used to measure where σ(pp→X(3872)+anything) is the inclusive production cross section of X(3872) mesons with rapidity in the range ...

Introducing an interface between FeynRules and WHIZARD

While Monte Carlo event generators like Whizard have become indispensable tools in studying the impact of new physics on collider observables over the last decades, the implementation of new models in such packages has remained a rather awkward and error-prone process. Recently, the FeynRules package was introduced which greatly simplifies this process by providing a single unified ...

Search for anomaly-mediated supersymmetry breaking with the ATLAS detector based on a disappearing-track signature in pp collisions at \(\sqrt{s} = 7~\mathrm{TeV}\)

In models of anomaly-mediated supersymmetry breaking (AMSB), the lightest chargino is predicted to have a lifetime long enough to be detected in collider experiments. This letter explores AMSB scenarios in pp collisions at \(\sqrt {s}=7\ \mathrm{TeV}\) by attempting to identify decaying charginos which result in tracks that appear to have few associated hits in the outer region of ...

Sensitivity of LHC experiments to exotic highly ionising particles

The experiments at the Large Hadron Collider (LHC) are able to discover or set limits on the production of exotic particles with TeV-scale masses possessing values of electric and/or magnetic charge such that they behave as highly ionising particles (HIPs). In this paper the sensitivity of the LHC experiments to HIP production is discussed in detail. It is shown that a number of ...