The European Physical Journal C

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

List of Papers (Total 3,036)

Inclusive production of protons, anti-protons and neutrons in p+p collisions at 158 GeV/c beam momentum

New data on the production of protons, anti-protons and neutrons in p+p interactions are presented. The data come from a sample of 4.8 million inelastic events obtained with the NA49 detector at the CERN SPS at 158 GeV/c beam momentum. The charged baryons are identified by energy loss measurement in a large TPC tracking system. Neutrons are detected in a forward hadronic ...

Measurement of charm and beauty production in deep inelastic ep scattering from decays into muons at HERA

The production of charm and beauty quarks in ep interactions has been measured with the ZEUS detector at HERA for squared four-momentum exchange Q 2>20 GeV2, using an integrated luminosity of 126 pb−1. Charm and beauty quarks were identified through their decays into muons. Differential cross sections were measured for muon transverse momenta \(p_{T}^{\mu}>1.5\ \mbox{GeV}\) and ...

Systematic event generator tuning for the LHC

In this article we describe Professor, a new program for tuning model parameters of Monte Carlo event generators to experimental data by parameterising the per-bin generator response to parameter variations and numerically optimising the parameterised behaviour. Simulated experimental analysis data is obtained using the Rivet analysis toolkit. This paper presents the Professor ...

Measurement of the charm and beauty structure functions using the H1 vertex detector at HERA

Inclusive charm and beauty cross sections are measured in e − p and e + p neutral current collisions at HERA in the kinematic region of photon virtuality 5≤Q 2≤2000 GeV2 and Bjorken scaling variable 0.0002≤x≤0.05. The data were collected with the H1 detector in the years 2006 and 2007 corresponding to an integrated luminosity of 189 pb−1. The numbers of charm and beauty events are ...

Cerenkov emission as a positive tag of double beta decays in bolometric experiments

Active background reduction in high resolution calorimeters is a promising approach to achieve ultimate sensitivity in neutrinoless double beta decay experiments. We propose Cerenkov emission from beta rays in bolometric crystals as a viable alternative to scintillation. This novel approach could broaden the range of materials of interest for calorimetric searches of the double ...

Resonant antineutrino induced electron capture with low energy bound-beta beams

Antineutrino induced electron capture is a resonant process that can have a large cross-section for beams of monochromatic antineutrinos. We calculate the cross-section of this process and investigate an experimental setup where monochromatic antineutrinos are produced from the bound-beta decay of fully ionized radioactive atoms in a storage ring. If the energy between the source ...

A new numerical method for obtaining gluon distribution functions G(x,Q 2)=xg(x,Q 2), from the proton structure function \(F_{2}^{\gamma p}(x,Q^{2})\)

An exact expression for the leading-order (LO) gluon distribution function G(x,Q 2)=xg(x,Q 2) from the DGLAP evolution equation for the proton structure function \(F_{2}^{\gamma p}(x,Q^{2})\) for deep inelastic γ * p scattering has recently been obtained (Block et al., Phys. Rev. D 79:014031, 2009) for massless quarks, using Laplace transformation techniques. Here, we develop a ...

Events with isolated leptons and missing transverse momentum and measurement of W production at HERA

Events with high energy isolated electrons, muons or tau leptons and missing transverse momentum are studied using the full e ± p data sample collected by the H1 experiment at HERA, corresponding to an integrated luminosity of 474 pb−1. Within the Standard Model, events with isolated leptons and missing transverse momentum mainly originate from the production of single W bosons. ...

Measurement of the longitudinal spin transfer to Λ and \(\bar{\varLambda}\) hyperons in polarised muon DIS

The longitudinal polarisation transfer from muons to Λ and \(\bar{\varLambda}\) hyperons, \(D_{LL}^{\varLambda(\bar{\varLambda})}\) , has been studied in deep-inelastic scattering off an unpolarised isoscalar target at the COMPASS experiment at CERN. The spin transfers to Λ and \(\bar{\varLambda}\) produced in the current fragmentation region exhibit different behaviours as a ...

A study of quasi-elastic muon neutrino and antineutrino scattering in the NOMAD experiment

We have studied the muon neutrino and antineutrino quasi-elastic (QEL) scattering reactions (ν μ n→μ − p and \(\bar{\nu }_{\mu}p\to\mu^{+}n\) ) using a set of experimental data collected by the NOMAD Collaboration. We have performed measurements of the cross-section of these processes on a nuclear target (mainly carbon) normalizing it to the total ν μ ( \(\bar{\nu}_{\mu}\) ) ...

Observational constraint on generalized Chaplygin gas model

We investigate observational constraints on the generalized Chaplygin gas (GCG) model as the unification of dark matter and dark energy from the latest observational data: the Union SNe Ia data, the observational Hubble data, the SDSS baryon acoustic peak and the five-year WMAP shift parameter. The result is obtained that the best-fit values of the GCG model parameters with their ...

Cross-sections of large-angle hadron production in proton– and pion–nucleus interactions IV: copper 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 abs thick stationary copper 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°. The inclusive pion production cross-sections ...

φ production in In–In collisions at 158 A GeV

The NA60 experiment has measured muon pair production in In–In collisions at 158 AGeV at the CERN SPS. This paper presents a high statistics measurement of φ→μ μ meson production. Differential spectra, yields, mass and width are measured as a function of centrality and compared to previous measurements in other colliding systems at the same energy. The width of the rapidity ...

Quartic gauge couplings and the radiation zero in pp→l±νγγ events at the LHC

We report a study of the process pp→l±νγγ at CERN’s Large Hadron Collider, using a leading order partonic-level event generator interfaced to the Pythia program for showering and hadronisation and a with a generic detector simulation. The process is sensitive to possible anomalous quartic gauge boson couplings of the form WWγγ. It is shown how unitarity-safe limits may be placed on ...

Experimental studies of e + e −→ some charmless processes containing K S 0 at \(\sqrt{s}=3.773\) and 3.65 GeV

We measure the observed cross sections for the charmless processes e + e −→K S 0 K − K − K + π ++ c.c., K S 0 K − π + η+c.c., K S 0 K − π + π + π − η+c.c., K S 0 K − K − K + π + η+c.c., K S 0 K − K − K + π + π 0+c.c., K S 0 K − ρ ++c.c. and K S 0 K − π + ρ 0+c.c. We also extract upper limits on the branching fractions for ψ(3770) decays into these final states at 90% C.L. Analyzed ...

Limits on a nucleon–nucleon monopole–dipole coupling from spin relaxation of polarized ultra-cold neutrons in traps

A new limit is presented on the axion-like monopole–dipole P, T-non-invariant interaction in a range (10−4–1) cm. The spin-dependent nucleon–nucleon potential between neutrons and nucleons of the walls of the cavity containing ultra-cold neutrons should affect the neutron depolarization probability at their reflection from the walls. The limit is obtained from existing data on the ...

Correlations between polarisation states of W particles in the reaction e − e +→W − W + at LEP2 energies 189–209 GeV

In a study of the reaction e − e +→W − W + with the DELPHI detector, the probabilities of the two W particles occurring in the joint polarisation states transverse–transverse (TT), longitudinal–transverse plus transverse–longitudinal (LT) and longitudinal–longitudinal (LL) have been determined using the final states \(WW{\rightarrow}l\nu q\bar{q}\) (l=e,μ). The two-particle joint ...

Q-PYTHIA: a medium-modified implementation of final state radiation

We present a Monte Carlo implementation, within PYTHIA, of medium-induced gluon radiation in the final state branching process. Medium effects are introduced through an additive term in the splitting functions computed in the multiple-soft scattering approximation. The observable effects of this modification are studied for different quantities as fragmentation functions and the ...

Measurement of the inclusive ep scattering cross section at low Q 2 and x at HERA

A measurement of the inclusive ep scattering cross section is presented in the region of low momentum transfers, 0.2 GeV2 ≤Q 2≤12 GeV2, and low Bjorken x, 5⋅10−6≤x≤0.02. The result is based on two data sets collected in dedicated runs by the H1 Collaboration at HERA at beam energies of 27.6 GeV and 920 GeV for positrons and protons, respectively. A combination with data previously ...

Measurement of D ± and D 0 production in deep inelastic scattering using a lifetime tag at HERA

The production of D ±- and D 0-mesons has been measured with the ZEUS detector at HERA using an integrated luminosity of 133.6 pb−1. The measurements cover the kinematic range 5<Q 2<1000 GeV2, 0.02<y<0.7, 1.5<p T D <15 GeV and |η D |<1.6. Combinatorial background to the D-meson signals is reduced by using the ZEUS microvertex detector to reconstruct displaced secondary vertices. ...

A hadronization model for few-GeV neutrino interactions

We present a detailed description of a new hadronic multiparticle production model for use in neutrino interaction simulations. Its validity spans a wide invariant mass range starting from the pion production threshold. This model focuses on the low invariant mass region which is probed in few-GeV neutrino interactions and is of particular importance to neutrino oscillation ...

Cross sections of large-angle hadron production in proton– and pion–nucleus interactions III: tantalum 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 abs thick stationary tantalum 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°. They are of particular relevance for the ...

Subjet distributions in deep inelastic scattering at HERA

Subjet distributions were measured in neutral current deep inelastic ep scattering with the ZEUS detector at HERA using an integrated luminosity of 81.7 pb−1. Jets were identified using the k T cluster algorithm in the laboratory frame. Subjets were defined as jet-like substructures identified by a reapplication of the cluster algorithm at a smaller value of the resolution ...

Tri-bimaximal mixing from twisted Friedberg–Lee symmetry

We investigate the Friedberg–Lee (FL) symmetry and its promotion to include the μ–τ symmetry, and call this the twisted FL symmetry. Based on the twisted FL symmetry, two possible schemes are presented toward the realistic neutrino mass spectrum and the tri-bimaximal mixing. In the first scheme, we suggest the semi-uniform translation of the FL symmetry. The second one is based on ...