The European Physical Journal C

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

List of Papers (Total 3,055)

Comparing trimaximal mixing and its variants with deviations from tri-bimaximal mixing

We analyze in detail the predictions of “trimaximal” neutrino mixing, which is defined by a mixing matrix with identical second column elements. This column is therefore identical to the second column in the case of tri-bimaximal mixing. We also generalize trimaximal mixing by assuming that the other rows and columns of the mixing matrix individually can have the same forms as for ...

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 ...

The Forward Vertex upgrade detector for PHENIX

The PHENIX detector at RHIC has been built with a strong heavy quark particles identification capability. These unique probes of matter are essential to adequately understand in-medium energy loss and to test the basic properties of QCD. The current PHENIX heavy flavor physics program will be significantly enhanced by the addition of the Forward Silicon Vertex upgrade detector ...

ϒ production in STAR

The study of formation and interaction of heavy quarkonia in relativistic heavy ion collisions provides important insight into the properties of the produced medium. Lattice QCD studies show sequential suppression of quarkonia states with increasing temperature; which affirms that a full spectroscopy, including bottomonium, can provide us a thermometer for the matter produced under ...

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 ...

Recent charm measurements through hadronic decay channels with STAR at RHIC in 200 GeV Cu+Cu collisions

We report on the measurements of D 0 and D s meson production in 200 GeV Cu+Cu collisions at the STAR at RHIC experiment. Results are discussed with reference to pQCD predictions of the open charm cross-section as well as the statistical hadronization model.

A short review on jet identification

Jets can be used to probe the physical properties of the high energy density matter created in collisions at the Relativistic Heavy Ion Collider (RHIC). Measurements of strong suppression of inclusive hadron distributions and di-hadron correlations at high p T have already provided evidence for partonic energy loss. However, these measurements suffer from well-known geometric ...

STAR inner tracking upgrade—a performance study

Anisotropic flow measurements have demonstrated development of partonic collectivity in 200 GeV Au+Au collisions at RHIC. To understand the partonic EOS, thermalization must be addressed. Collective motion of heavy-flavor (c, b) quarks can be used to indicate the degree of thermalization of the light-flavor quarks (u, d, s). Measurement of heavy-flavor quark collectivity requires ...

Nose-cone calorimeter: PHENIX forward upgrade

PHENIX is a high rate experiment efficient at measuring rare processes, but has limited acceptance in azimuth and pseudorapidity (η). The Nose Cone Calorimeter (NCC), a W–Si sampling calorimeter in the region of 0.9<η<3, is one of the upgrades which will significantly increase coverage in both azimuth and pseudorapidity. The NCC will expand PHENIX’s precision measurements of ...

Universal centrality and collision energy trends for v 2 measurements from 2D angular correlations

We have measured the p t -integrated quadrupole component of two-particle azimuth correlations (related to quantity v 2, denoted in this case by v 2{2D}) via two-dimensional (2D) angular autocorrelations on (η,φ) for unidentified hadrons in Au-Au collisions at 62 and 200 GeV. The 2D autocorrelation provides a method to remove non-quadrupole contributions to v 2 (conventionally ...

What do we really know about cold nuclear matter effects?

The measurement of charmonium suppression in relativistic heavy ion collisions is posited to be an unambiguous probe of the properties of the strongly interacting quark gluon plasma (sQGP). In hot and dense QCD matter Debye color screening prevents charm and anti-charm quark pairs from forming J/ψ mesons if the screening radius is smaller than the binding radius. However, one must ...

Bulk matter physics and its future at the Large Hadron Collider

Measurements at low transverse momentum will be performed at the LHC for studying particle production mechanisms in pp and heavy-ion collisions. Some of the experimental capabilities for bulk matter physics are presented, focusing on tracking elements and particle identification. In order to anticipate the study of baryon production for both colliding systems at multi-TeV energies, ...

Hot quarks and gluons at an electron-ion collider

The nuclear wave-function is dominated at low- and medium-x by gluons. As the rapid growth of the gluon distribution towards low x, as derived from current theoretical estimates, would violate unitarity, there must be a mechanism that tames this explosive growth. This is most efficiently studied in colliders running in e+A mode, as the nucleus is an efficient amplifier of ...

Energy and system dependence of high-p T triggered two-particle near-side correlations

Previous studies have indicated that the near-side peak of high-p T triggered correlations can be decomposed into two parts, the Jet and the Ridge. We present data on the yield per trigger of the Jet and the Ridge from d+Au, Cu+Cu and Au+Au collisions at \(\sqrt{s_{\mathit{NN}}}=62.4\) GeV and 200 GeV and compare data on the Jet to PYTHIA 8.1 simulations for p+p. PYTHIA describes ...

Resonance production from jet fragmentation

Short lived resonances are sensitive to the medium properties in heavy-ion collisions. Heavy hadrons have larger probability to be produced within the quark gluon plasma phase due to their short formation times. Therefore heavy mass resonances are more likely to be affected by the medium, and the identification of early produced resonances from jet fragmentation might be a viable ...

New search for processes violating the Pauli exclusion principle in sodium and in iodine

In this paper a new search for non-Paulian nuclear processes, i.e. processes normally forbidden by the Pauli Exclusion Principle (PEP), is presented. It has been carried out at the Gran Sasso National Laboratory of the INFN by means of the highly radiopure DAMA/LIBRA set-up (sensitive mass of about 250 kg highly radiopure NaI(Tl)). In particular, a new improved upper limit for the ...

Elliptic flow and the high p T ridge in Au+Au collisions

In this paper we look for correlations between intermediate p T particle pairs and the v 2 of the remaining low p T particles. We find that the shape of the flow vector distribution, which is calculated from all low p T tracks, depends in a non-trivial way on the angular separation between the high p T particle pairs in the event. Our analysis is based on 200 GeV Au+Au collisions ...