相关论文: Centrality Issues In Asymmetric Collisions: Direct…
Centrality, as a geometrical property of the collision, is crucial for the physical interpretation of nucleus-nucleus and proton-nucleus experimental data. However, it cannot be directly accessed in event-by-event data analysis. Common…
The recently published PHENIX data of direct photons at low pt from Au+Au collisions at the BNL relativestic Heavy Ion Collider (RHIC) energy 200 GeV have attracted a lot of theoretic interest. Here I review our theoretical calculation…
Direct photons are ideal tools to investigate kinematical and thermodynamical conditions of heavy ion collisions since they are emitted from all stages of the collision and once produced they leave the interaction region without further…
We calculate the centrality-dependence of transverse momentum ($\pt$) spectra for direct photons in Au+Au collisions at the RHIC energy, based on a realistic data-constrained (3+1) dimensional hydrodynamic description of the expanding hot…
We calculate the spectra of high energy photons emitted in relativistic Au+Au collisions for various centralities and compare to data recently collected at the Relativistic Heavy Ion Collider by the PHENIX collaboration. Our results for…
High-energy proton- and deuteron-nucleus collisions provide an excellent tool for studying a wide array of physics effects, including modifications of parton distribution functions in nuclei, gluon saturation, and color neutralization and…
The PHENIX experiment has measured direct photons in $\sqrt{s_{NN}} = 200$ GeV Au+Au collisions and p+p collisions. The fraction of photons due to direct production in Au+Au collisions is shown as a function of $p_T$ and centrality. This…
Direct real photons are arguably the most versatile tools to study relativistic heavy ion collisions. They are produced, by various mechanisms, during the entire space-time history of the strongly interacting system. Also, being colorless,…
Measurements indicate that the centrality dependence of the direct photon multiplicity scales approximately with the number of binary nucleon collisions. Importantly, these same measurements suggest that this scaling does not depend on the…
Event-by-event reconstruction of the collision geometry using some incarnation of the Glauber-model is a widely accepted method in studying heavy ion collisions. While there is no known problem with the procedure when applied to the…
Direct photons are a powerful probe to study the properties of the unique matter created in ultrarelativistic heavy-ion collisions. They carry information on the various stages of a heavy-ion collision. At different transverse momenta (pT),…
We attempt, in this paper, to deal with the direct photon production phenomena in $p+p$, $d+Au$ and $Au+Au$ collisions at RHIC energy, $\sqrt{s_{NN}}$ = 200 GeV and in $Pb+Pb$-collisions at LHC energy, $\sqrt{s_{NN}}$ = 2.76 TeV on the…
In this paper, we show that multiplicity spectra of direct photons in A+A and d+Au collisions at different centrality classes and different energies exhibit geometrical scaling, {\em i.e.}, they depend on a specific combination of number of…
The concept of centrality in high-energy nuclear collisions has recently become a subject of an active debate. In particular, the experimental methods to determine the centrality that have given reasonable results for many observables in…
The PHENIX experiment at RHIC has measured the centrality dependence of the direct photon yield from Au$+$Au collisions at $\sqrt{s_{_{NN}}}=200$ GeV down to $p_T=0.4$ GeV/$c$. Photons are detected via photon conversions to $e^+e^-$ pairs…
Dilepton and direct photon measurements in heavy ion collisions provide access to the early stages of the collision. Dilepton continuum measurements at SPS and RHIC show an excess consistent with broadening of the rho meson spectral…
Results from the PHENIX experiment at RHIC on direct photon production in p+p, d+Au, and Au+Au collisions at sqrt(s_NN) = 200 GeV are presented. In p+p collisions, direct photon production at high p_T behaves as expected from perturbative…
After years of experimental and theoretical efforts, direct photons become a strong and reliable tool to establish the basic characteristics of a hot and dense matter produced in heavy ion collisions. The recent direct photon measurements…
Results from the PHENIX experiment at RHIC in p-p and Au+Au collisions are reviewed from the perspective of measurements in p-p collisions at the CERN-ISR which serve as a basis for many of the techniques used. Issues such as J/Psi…
Measurement of neutral pions and direct photons are closely connected experimentally, on the other hand they probe quite different aspects of relativistic heavy ion collisions. In this short review of the $\pi^0$ results from the PHENIX…