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We study the effect of a strong constant magnetic field, generated in relativistic heavy ion collisions, on the heavy quark complex potential. We work in the strong magnetic field limit with the lowest Landau level approximation. We find that the screening of the real part of the potential increases with the increase in the magnetic field. Therefore, we expect less binding of the QQ pair in the presence of a strong magnetic field. The imaginary part of the potential increases in magnitude with the increase in magnetic field, leading to an increase of the width of the quarkonium state with the magnetic field. All of these effects result in the early dissociation of QQ states in a magnetized hot quark-gluon plasma medium.

identified hadrons π ± , K ± , p, andp produced at midrapidity in Cu+Au collisions at

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The PHENIX Collaboration at the Relativistic Heavy Ion Collider has measured open heavy flavor production in minimum bias Au+Au collisions at √ s N N = 200 GeV via the yields of electrons from semileptonic decays of charm and bottom hadrons. Previous heavy flavor electron measurements indicated substantial modification in the momentum distribution of the parent heavy quarks due to the quark-gluon plasma created in these collisions. For the first time, using the PHENIX silicon vertex detector to measure precision displaced tracking, the relative contributions from charm and bottom hadrons to these electrons as a function of transverse momentum are measured in Au+Au collisions. We compare the fraction of electrons from bottom hadrons to previously published results extracted from electron-hadron correlations in p+p collisions at √ s N N = 200 GeV and find the fractions to be similar within the large uncertainties on both measurements for pT > 4 GeV/c. We use the bottom electron fractions in Au+Au and p+p along with the previously measured heavy flavor electron RAA to calculate the RAA for electrons from charm and bottom hadron decays separately. We find that electrons from bottom hadron decays are less suppressed than those from charm for the region 3 < pT < 4 GeV/c.

1 nuclear collisions of p+Al, p+Au, d+Au, and 3 He+Au at √ s N N = 200 GeV 2 121 4Asymmetric nuclear collisions with a light projectile nucleus striking a heavier target nucleus have proven to be an 123 excellent testing ground for particle production models and the longitudinal dynamics following the initial collision -124 for an early review see Ref. [1]. Many calculations have successfully described the longitudinal (or rapidity) distribution 125 of produced particles in proton-nucleus (p+A) collisions via the fragmentation of color strings and with counting rules 126 based on the number of "wounded" or struck nucleons or quarks in the projectile and target. Recently, a proposal 127 for testing the wounded-quark model [2] was put forth that specifically called for the measurement of dN ch /dη over a 128 broad range of pseudorapidity in p+Au, d+Au, and 3 He+Au collisions [3]. Fully three-dimensional hydrodynamical 129 models also require input on the longitudinal distribution of initial deposited energy and gradients thereof [4]. Once 130 the initial partons or fluid elements are populated, the models evolve the system dynamically. Measurements of elliptic 131 flow as a function of pseudorapidity provide constraints on the longitudinal dynamics of the evolution. 132As the incoming hadrons or nuclei break up, the rapidity distribution of liberated partons may be determined by 133 the longitudinal parton distribution functions [5, 6] or via a universal color field breakup for each struck nucleon 134 or quark [7]. For that reason, calculations based on Monte Carlo Glauber models have been developed to calculate 135 the number of struck nucleons and struck quarks (see for example Refs. [8-10]). The PHOBOS collaboration has 136 previously published charged hadron dN ch /dη measurements over |η| < 5.4 in d+Au collisions at √ s N N = 200 GeV [11]. 137 PHENIX has also published dN ch /dη measurements in high-multiplicity d+Au collisions at √ s N N = 200, 62, 39, and 138 19.6 GeV [12]. The wounded-quark model has been constrained by the d+Au data and found to be in reasonable 139 agreement with the centrality dependence, while the wounded-nucleon model cannot describe the data [3]. A crucial 140 test of the wounded-quark model is to see if it is universal across different colliding systems. Additional measurements 141 in light and heavy systems at the Relativistic Heavy Ion Collider (RHIC) and the Large Hadron Collider (LHC) can 142 also be tested in this context-see for example different geometry tests in Refs. [13-15]. 143 157 section of 2.30, 2.26, 1.76, 0.54 barns for 3 He+Au, d+Au, p+Au, and p+Al respectively. The dN ch /dη analysis has 158 negligible statistical uncertainties and thus a subset of runs with the most stable detector configuration are utilized 159and the run-to-run variation is used in the determination of systematic uncertainties. For the elliptic flow v 2 analysis 160 in high-multiplicity events, also referred to as central events, an additional trigger was used that required the number 161 of fi...