The European Physical Journal C

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

List of Papers (Total 3,036)

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 ...

Identification and rejection of fake reconstructed jets from a fluctuating heavy ion background in ATLAS

Full jet reconstruction in relativistic heavy ion collisions provides new and unique insights to the physics of parton energy loss. Because of the large underlying event multiplicity in A+A collisions, random and correlated fluctuations in the background can result in the reconstruction of fake jets. These fake jets must be identified and rejected to obtain the purest jet sample ...

On the resolution of singularities of multiple Mellin–Barnes integrals

One of the two existing strategies of resolving singularities of multifold Mellin–Barnes integrals in the dimensional regularization parameter, or a parameter of the analytic regularization, is formulated in a modified form. The corresponding algorithm is implemented as a Mathematica code MBresolve.m

An overview of J/ψ production in heavy ion collisions at PHENIX

This is an overview of the PHENIX J/ψ results in hot nuclear matter from heavy ion collisions. Current results for R AA and v 2 in Au+Au collisions, as well as R AA from Cu+Cu collisions are included and discussed. A comparison is also done to cold nuclear matter effects using R dAu results.

Centrality dependence of v 2 in Au + Au at \(\sqrt{s_{NN}}=200\) GeV

One of the most striking results is the large elliptic flow (v 2) at RHIC. Detailed mass and transverse momentum dependence of elliptic flow are well described by ideal hydrodynamic calculations for p T<1 GeV/c, and by parton coalescence/recombination picture for p T=2–6 GeV/c. The systematic error on v 2 is dominated by so-called “non-flow effects”, which are correlations other ...

Perspectives for the measurement of D s + mesons via the D s + →K + K − π + channel in the ALICE experiment

Heavy quarks, such as charm, are produced in hard scatterings in the early stages of high energy nucleus-nucleus collisions and are expected to be a powerful tool to investigate the properties of the quark gluon plasma (QGP). The tracking detectors of the ALICE apparatus will allow to track and identify particles in central rapidity range down to low P t . Among D mesons it would ...

Identified hadron production at high transverse momenta in p+p collisions at \(\sqrt{s_{NN}}=200\) GeV in STAR

We report the transverse momentum (p T ) distributions for identified charged pions, protons and anti-protons using events triggered by high deposit energy in the Barrel Electro-Magnetic Calorimeter (BEMC) from p+p collisions at \(\sqrt{s_{NN}}=200\) GeV. The spectra are measured around mid-rapidity (|y|<0.5) over the range of 3<p T <15 GeV/c with particle identification (PID) by ...

Analysis of non-photonic electrons in Cu + Cu collisions at \(\sqrt{s_{NN}}=200\) GeV

Heavy-flavor semileptonic decays are expected to dominate the spectrum of non-photonic electrons produced from collisions at the energies of the Relativistic Heavy Ion Collider. The non-photonic electron yield is suppressed by approximately a factor of 5 in central Au + Au events at \(\sqrt{s_{NN}}=200\) GeV relative to p+p events with the same collision energy. Most theoretical ...

How to make sense of the jet correlations results at RHIC?

We review the di-hadron correlation results from RHIC. A consistent physical picture was constructed based on the correlation landscape in p T , Δφ, Δη and particle species. We show that the data are consistent with competition between fragmentation of survived jets and response of the medium to quenched jets. At intermediate p T where the medium response are important, a large ...

B-hadron cross-section measurement in pp collisions at \(\sqrt{s}=14\) TeV with the ALICE muon spectrometer

ALICE (A Large Ion Collider Experiment) is the LHC detector designed to measure nucleus-nucleus (AA) collisions where the formation of the Quark Gluon Plasma is expected. The experiment will also study proton-proton (pp) collisions at 14 TeV. Amongst the relevant observables to be investigated in pp collisions, the B-hadron cross-section is particularly interesting since it ...

Successes and failures with hard probes

The two major pillars of searches for the Quark Gluon Plasma have been: J/Ψ suppression, proposed in 1986, and observed at both SPS fixed target energies and at RHIC; and, more recently, the suppression of π 0 with p T ≥3 GeV/c by a factor ∼5 in Au+Au central collisions, observed at RHIC in 2001, which had been predicted in advance as a consequence of Landau-Pomeranchuck-Migdal ...

NA60 results on thermal dimuons

The NA60 experiment at the CERN SPS has measured muon pairs with unprecedented precision in 158 A GeV In–In collisions. A strong excess of pairs above the known sources is observed in the whole mass region 0.2<M<2.6 GeV. The mass spectrum for M<1 GeV is consistent with a dominant contribution from π + π −→ρ→μ + μ − annihilation. The associated ρ spectral function shows a strong ...

Recent results from PHOBOS on particle production at high p T

A selection of experimental results from the PHOBOS Collaboration relevant for probing high-energy nuclear collisions with high transverse momentum particles is presented. The inclusive yields of charged particles and comparisons between nuclear and elementary collisions already reveal a large amount of parton energy loss in the hot and dense medium created in heavy ion collisions. ...

Near-side high-p T correlations: the ridge

An overview of results on near-side high-p T triggered correlations in heavy-ion collisions at RHIC energy is presented. These correlations reveal a novel, long-range pseudo-rapidity correlation, commonly referred to as the ridge which is not present in p+p or d+Au collisions. The centrality, collision system, energy, transverse momentum, path length dependence as well as particle ...

First fragmentation function measurements from full jet reconstruction in heavy-ion collisions at \(\sqrt{s_{\mathrm{NN}}}=200\) GeV by STAR

Measurements of inclusive hadron suppression and di-hadron azimuthal correlations in ultra-relativistic nuclear collisions at RHIC have provided important insights into jet quenching in hot QCD matter, but are limited in their sensitivity due to well-known biases. Full jet reconstruction in heavy-ion collisions would conceptually provide a direct measurement of the energy of the ...

Quarkonia measurements with STAR

We report results on quarkonium production from the STAR experiment at the Relativistic Heavy-Ion Collider (RHIC). J/ψ spectra in p+p and Cu+Cu collisions at \(\sqrt{s_{\mathit{NN}}}=200\) GeV with transverse momenta in the range of 0.5–14 GeV/c and 5–8 GeV/c, respectively, are presented. We find that for p T >5 GeV/c yields in p+p collisions are consistent with those in ...

J/ψ production measurements by the PHENIX experiment

Quarkonia suppression is considered to be one of the key probes of the Quark Gluon Plasma (QGP) created in heavy ion collisions. The PHENIX experiment has measured J/ψ production in a variety of colliding systems. Measurements made in p+p collisions show good agreement with pQCD predictions and serve as baseline for other systems at the same collision energy. The cold nuclear ...