arXiv subjects

David d'Enterria

Publications and source records attributed to David d'Enterria.

124 records · Page 7Linked to original sources

arXiv2007

Photoproduction at collider energies: from RHIC and HERA to the LHC

We present the mini-proceedings of the workshop on ``Photoproduction at collider energies: from RHIC and HERA to the LHC'' held at the European Centre for Theoretical Studies in Nuclear Physics and Related Areas (ECT*, Trento) from January 15 to 19, 2007. The workshop gathered both theorists and experimentalists to discuss the current status of investigations of high-energy photon-induced processes at different colliders (HERA, RHIC, and Tevatron) as well as preparations for extension of these studies at the LHC. The main physics topics covered were: (i) small-$x$ QCD in photoproduction studies with protons and in electromagnetic (aka. ultraperipheral) nucleus-nucleus collisions, (ii) hard diffraction physics at hadron colliders, and (iii) photon-photon collisions at very high energies: electroweak and beyond the Standard Model processes. These mini-proceedings consist of an introduction and short summaries of the talks presented at the meeting.

hep-ph↗

arXiv2006

Low-x QCD physics from RHIC and HERA to the LHC

We present a summary of the physics of gluon saturation and non-linear QCD evolution at small values of parton momentum fraction $x$ in the proton and nucleus in the context of recent experimental results at HERA and RHIC. The rich physics potential of low-x studies at the LHC, especially in the forward region, is discussed and some benchmark measurements in pp, pA and AA collisions are introduced.

hep-ex↗

arXiv2006

High-energy heavy-ions physics: from RHIC to LHC

A selection of experimental results in high-energy nucleus-nucleus collisions after five years of operation of the Relativistic Heavy-Ion Collider (RHIC) is presented. Emphasis is put on measurements that provide direct information on fundamental properties of high-density QCD matter. The new experimental opportunities accessible at LHC are introduced, in particular those that may help clarify some of the current open issues at RHIC.

nucl-ex↗

arXiv2006

Low-x QCD with CMS at the LHC

The physics of gluon saturation and non-linear evolution at small values of parton momentum fraction x in the proton and nucleus is discussed in the context of experimental results at HERA and RHIC. The rich physics potential of low-x QCD studies at the LHC is discussed and some measurements in pp, pA and AA collisions accessible with the Compact Muon Solenoid (CMS) experiment are presented.

hep-ex↗

arXiv2006

High pT leading hadron suppression in nuclear collisions at sqrt(s_NN) = 20 -- 200 GeV: data versus parton energy loss models

Experimental results on high transverse momentum (leading) hadron spectra in nucleus-nucleus collisions in the range sqrt(s_NN) = 20 -- 200 GeV are reviewed with an emphasis on the observed suppression compared to free space production in proton-proton collisions at the corresponding center-of-mass energies. The transverse-momentum and collision-energy (but seemingly not the in-medium path length) dependence of the experimental suppression factors measured in central collisions is consistent with the expectations of final-state non-Abelian parton energy loss in a dense QCD medium.

nucl-ex↗

arXiv2006

Probing the QCD equation of state with thermal photons in nucleus-nucleus collisions at RHIC

Thermal photon production at mid-rapidity in Au+Au reactions at $\sqrt{s_{NN}}$ = 200 GeV is studied in the framework of a 2D+1 hydrodynamical model that describes efficiently the bulk identified hadron spectra at RHIC. The combined thermal plus NLO pQCD photon spectrum is in good agreement with the yields measured by the PHENIX experiment for all Au+Au centralities. Within our model, we demonstrate that the correlation of the thermal photon slopes with the charged hadron multiplicity in each centrality bin provides direct empirical information on the underlying degrees of freedom and on the equation of state, $s(T)/T^3$, of the strongly interacting matter.

nucl-th↗

arXiv2006

Coherent photoproduction of J/Psi and high-mass e+e- pairs in ultra-peripheral Au+Au collisions at sqrt(s_NN) = 200 GeV

High energy ultra-peripheral collisions (UPC) of heavy-ions generate strong electromagnetic fields which open the possibility to study gamma-gamma and gamma-nucleus processes in a kinematic regime so far unexplored. We report on preliminary PHENIX results of J/Psi and high-mass e+e- photoproduction at mid-rapidity in coherent electromagnetic Au+Au interactions at sqrt(s_NN) = 200 GeV tagged with forward neutron emission from the Au* dissociation.

nucl-ex↗

arXiv2005

Jet quenching: RHIC results and phenomenology

I review the main experimental results on jet physics in high-energy nucleus-nucleus collisions as studied via inclusive leading hadron spectra and di-hadron correlations at high transverse momentum. In central Au+Au at RHIC (sqrt(s_NN) = 200 GeV), the observed large suppression of high-$p_T$ hadron spectra as well as the strongly modified azimuthal dijet correlations compared to baseline p+p results in free space, provide crucial information on the thermodynamical and transport properties of QCD matter.

nucl-ex↗

arXiv2004

Relevance of baseline hard proton-proton spectra for high-energy nucleus-nucleus physics

We discuss three different cases of hard inclusive spectra in proton-proton collisions: high $p_T$ single hadron production at $\sqrt{s}\approx$ 20 GeV and at $\sqrt{s}$ = 62.4 GeV, and direct photon production at $\sqrt{s}$ = 200 GeV; with regard to their relevance for the search of Quark Gluon Plasma signals in A+A collisions at SPS and RHIC energies.

nucl-ex↗

arXiv2004

Quantum Chromo (many-body) Dynamics probed in the hard sector at RHIC

The most significant experimental results on hard processes in heavy-ion collisions at RHIC collider energies are reviewed. Emphasis is put on measurements that provide insights on strongly interacting media like the ``Quark Gluon Plasma'' and the ``Color Glass Condensate''.

nucl-ex↗

arXiv2004

Hard spectra and QCD matter: experimental review

The most significant experimental results on hadron spectra at large transverse momentum available at the time of Quark Matter 2004 conference are reviewed. Emphasis is put on those measurements that provide insights on the properties of the QCD media, ``Quark Gluon Plasma'' and ``Color Glass Condensate'', expected to be present in nucleus-nucleus collisions at collider energies.

nucl-ex↗

arXiv2004

Indications of suppressed high p_T hadron production in nucleus-nucleus collisions at CERN-SPS

Inclusive pion production at high transverse momenta (p_T > 2 GeV/c) in nucleus-nucleus (A+A) collisions at CERN SPS (sqrt(s_NN)~20 GeV) is revisited and systematically compared to all existing proton-proton data in the same range of center-of-mass energies. The ratio of A+A to p+p pion cross-sections (nuclear modification factor) for 0-8% central Pb+Pb, Pb+Au and S+Au reactions does not show a strong enhancement as a function of p_T as previously found, but is consistent with scaling with the number of nucleon-nucleon (NN) collisions. Neutral pion yields per NN collision in head-on Pb+Pb reactions are suppressed, whereas peripheral yields are enhanced. These results together indicate that some amount of ``jet quenching'' may already be present in central heavy-ion reactions at sqrt(s_NN)~20 GeV.

nucl-ex↗

arXiv2004

Hard scattering at RHIC: Experimental review

The most significant results on hard scattering processes in Au+Au, p+p, and d+Au collisions at sqrt(s_NN) = 200 GeV obtained after 3 years of operation at the BNL Relativistic Heavy-Ion Collider (RHIC) are summarized. Hadron production at high transverse momentum (p_T) in central Au+Au collisions shows very different properties (production yields, flavor composition, azimuthal correlations, ...) in comparison to p+p, d+Au, and peripheral Au+Au collisions, and this fact constitutes arguably the most interesting outcome of the experimental program so far. Four main topics are covered in this report: (i) the depletion of high p_T inclusive hadron spectra, (ii) the ``anomalous'' baryon-meson composition at intermediate p_T's, (iii) the disappearance of away-side azimuthal (jet) correlations, and (iv) the large value of collective azimuthal (elliptic flow) correlations. Additionally, the observed high p_T ``Cronin enhancement'' in d+Au collisions will be discussed. A succinct comparison of experimental data to theoretical models is also provided.

nucl-ex↗

arXiv2004

QCD hard scattering results from PHENIX at RHIC

Data on hadron production at high transverse momentum ($p_T>$ 2 GeV/$c$) in p+p, d+Au, and Au+Au collisions at $\sqrt{s_{NN}$ = 200 GeV from the PHENIX experiment at RHIC are reviewed. The single inclusive spectrum of light hadrons produced in central Au+Au reactions shows significant differences compared to p+p and d+Au collisions, and provides interesting information on the properties of the underlying QCD medium present in heavy-ion reactions at collider energies.

nucl-ex↗

arXiv2003

High p_T identified particles in PHENIX: data vs. theory

Two of the most interesting experimental results of heavy-ion reactions at RHIC collider energies are in the hard scattering sector where central Au+Au data show a very different behaviour compared to p+p and peripheral Au+Au collisions. The so-called ``high p_T pi^0 suppression'' and the ``anomalous'' baryon/meson ratio observed by PHENIX in central Au+Au collisions at sqrt(s_{NN}) = 200 GeV are reviewed and compared to various theoretical calculations based on different strongly interacting medium scenarios.

nucl-ex↗

arXiv2002

High-p_T pi^0 suppression in Au+Au collisions at sqrt(s_NN) = 200 GeV

Neutral pions with p_T = 1 - 8 GeV/c have been measured for 9 different centrality classes in Au+Au collisions at sqrt(s_NN) = 200 GeV by the PHENIX experiment at RHIC. The pi^0 multiplicity in central reactions is significantly below the binary collision scaled yields from both peripheral Au+Au and pp reactions. The observed suppression sets in for the 50-70% centrality class and increases with p_T and centrality. For the most central bin, the deficit amounts to a factor ~2.5 at p_T ~ 2 GeV/c gradually increasing to a factor ~6 at p_T ~ 8 GeV/c.

hep-ex↗