The European Physical Journal C

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

List of Papers (Total 2,845)

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 ...

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 ( \(\bar{\nu}_{\mu}\) ) ...

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 ...

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 ...

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 II: beryllium 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 and charged pions, in the interactions with a 5% λ abs thick stationary beryllium 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°.

Spin density matrix elements in exclusive ρ 0 electroproduction on 1H and 2H targets at 27.5 GeV beam energy

Spin Density Matrix Elements (SDMEs) describing the angular distribution of exclusive ρ 0 electroproduction and decay are determined in the HERMES experiment with 27.6 GeV beam energy and unpolarized hydrogen and deuterium targets. Eight (fifteen) SDMEs that are related (unrelated) to the longitudinal polarization of the beam are extracted in the kinematic region 1Q 22, 3.0Wt2. ...

Probing for new physics and detecting non-linear vacuum QED effects using gravitational wave interferometer antennas

Low energy non-linear QED effects in vacuum have been predicted since 1936 and have been subject of research for many decades. Two main schemes have been proposed for such a ‘first’ detection: measurements of ellipticity acquired by a linearly polarized beam of light passing through a magnetic field and direct light–light scattering. The study of the propagation of light through an ...

Mass bounds on a very light neutralino

Within the Minimal Supersymmetric Standard Model (MSSM) we systematically investigate the bounds on the mass of the lightest neutralino. We allow for non-universal gaugino masses and thus even consider massless neutralinos, while assuming in general that R-parity is conserved. Our main focus is on laboratory constraints. We consider collider data, precision observables, and also ...

Measurement of high-Q 2 neutral current deep inelastic e − p scattering cross sections with a longitudinally polarised electron beam at HERA

Measurements of the neutral current cross sections for deep inelastic scattering in e − p collisions at HERA with a longitudinally polarised electron beam are presented. The single-differential cross-sections d σ/dQ 2, d σ/dx and d σ/dy and the double-differential cross sections in Q 2 and x are measured in the kinematic region y<0.9 and Q 2>185 GeV 2 for both positively and ...

Fine structure in the azimuthal transverse momentum correlations at \(\sqrt{s_{NN}}=200\) GeV using the event shape analysis

The experimental results on transverse momentum azimuthal hadron correlations at RHIC have opened a rich field for parton energy loss analysis in heavy-ion collisions. Recently, a considerable amount of work has been devoted to study the shapes of the “away-side” jet which exhibit an interesting and unexpected “double hump” structure not observed in the analogous treatment of the ...

Gravitational anomaly and Hawking radiation of apparent horizon in FRW universe

Motivated by the successful applications of the anomaly cancellation method to derive Hawking radiation from various types of black hole spacetimes, we further extend the gravitational anomaly method to investigate the Hawking radiation from the apparent horizon of a FRW universe by assuming that the gravitational anomaly also exists near the apparent horizon of the FRW universe. ...

Search for resonant absorption of solar axions emitted in M1 transition in 57Fe nuclei

A search for resonant absorption of 14.4 keV solar axions by a 57Fe target was performed. The Si(Li) detector placed inside the low-background setup was used to detect the γ-quanta appearing in the deexcitation of the 14.4 keV nuclear level: A+57Fe→57Fe*→57Fe+γ. The new upper limit for the hadronic axion mass has been obtained of m A ≤159 eV (95% c.l.) (S=0.5, z=0.56).

Search for narrow resonances lighter than ϒ mesons

We report a search for narrow resonances, produced in \(p\bar{p}\) collisions at \(\sqrt{s}=1.96\) TeV, that decay into muon pairs with invariant mass between 6.3 and 9.0 GeV/c 2. The data, collected with the CDF II detector at the Fermilab Tevatron collider, correspond to an integrated luminosity of 630 pb−1. We use the dimuon invariant mass distribution to set 90% upper credible ...

Cross-sections of large-angle hadron production in proton- and pion-nucleus interactions I: beryllium nuclei and beam momenta of +8.9 GeV/c and −8.0 GeV/c

We report on double-differential inclusive cross-sections of the production of secondary protons, deuterons, and charged pions and kaons, in the interactions with a 5% λ abs thick stationary beryllium target, of a +8.9 GeV/c proton and pion beam, and a −8.0 GeV/c pion beam. Results are given for secondary particles with production angles 20○<θ<125○.

Trigger and reconstruction for heavy long-lived charged particles with the ATLAS detector

Long lived charged particles are predicted by many models of physics beyond the standard model (SM). The common signature of such models is a heavy long-lived charged particle with velocity smaller than the speed of light, β<1. This unique signature makes the search for it model independent. This paper presents methods we developed as part of the ATLAS trigger and reconstruction ...

Deuteron and antideuteron measurements in Au + Au collisions at \(\sqrt{s_{NN}}=200~\mbox{GeV}\) at RHIC-PHENIX

In Run-7 of RHIC operations PHENIX has recorded over 5.4 billion minimum bias events, facilitating a detailed study of deuteron and antideuteron production as a function of centrality and up to transverse momentum of p T =5 GeV/c. We present transverse momentum p T and transverse mass m T spectra, mean transverse momentum 〈p T 〉, source parameters, particle ratios, and nuclear ...

Strange particle production at RHIC

We report STAR measurements of mid-rapidity yields for the Λ , \(\bar{\varLambda}\) , K S 0 , Ξ −, \(\bar{\varXi}^{+}\) , Ω −, \(\bar{\varOmega}^{+}\) particles in Cu + Cu and Au + Au \(\sqrt {s_{NN}}=200\) GeV collisions. We show that at a given number of participating nucleons, bulk strangeness production is higher in Cu + Cu collisions compared to Au + Au collisions at the same ...

ALICE-PHOS: acceptance and efficiency correction factors p−p→π 0+X at 10 TeV

In ultra-relativistic Heavy-Ion Collisions (HIC), the properties of the quark gluon plasma (QGP) can be explored, in particular, via measurements of neutral pions. The π 0 is an important probe for both proton and heavy ion physics. In the former case, π 0 production provides an important mean of testing pQCD as well as useful data to constrain current and future theoretical ...

Measurement of low-mass e + e − pair production in 1 and 2 A GeV C–C collision with HADES

HADES is a secondary generation experiment operated at GSI Darmstadt with the main goal to study dielectron production in proton, pion and heavy ion induced reactions. The first part of the HADES mission is to reinvestigate the puzzling pair excess measured by the DLS collaboration in C + C and Ca + Ca collisions at 1 A GeV. For this purpose dedicated measurements with the C + C ...

Study of jet fragmentation in p+p collisions at 200 GeV in the STAR experiment

The measurement of jet fragmentation functions in p+p collisions at 200 GeV is of great interest because it provides a baseline to study jet quenching in heavy-ion collisions. It is expected that jet quenching in nuclear matter modifies the jet energy and multiplicity distributions, as well as the jet hadrochemical composition. Therefore, a systematic study of the fragmentation ...