Suppression of Upsilon production in d plus Au and Au plus Au collisions at root S-NN=200 GeV

We report measurements of Upsilon meson production in p + p, d + Au, and Au + Au collisions using the STAR detector at RHIC. We compare the Upsilon yield to the measured cross section in p + p collisions in order to quantify any modifications of the yield in cold nuclear matter using d + Au data and in hot nuclear matter using Au + Au data separated into three centrality classes. Our p + p measurement is based on three times the statistics of our previous result. We obtain a nuclear modification factor for Upsilon (1S + 2S + 3S) in the rapidity range vertical bar y vertical bar < 1 in d + Au collisions of R-dAu = 0.79 +/- 0.24(stat.) +/- 0.03(syst.) +/- 0.10(p + p syst.). A comparison with models including shadowing and initial state parton energy loss indicates the presence of additional cold-nuclear matter suppression. Similarly, in the top 10% most-central Au + Au collisions, we measure a nuclear modification factor of R-AA = 0.49 +/- 0.1(stat.) +/- 0.02(syst.) +/- 0.06(p + p syst.), which is a larger suppression factor than that seen in cold nuclear matter. Our results are consistent with complete suppression of excited-state Upsilon mesons in Au + Au collisions. The additional suppression in Au + Au is consistent with the level expected in model calculations that include the presence of a hot, deconfined Quark-Gluon Plasma. However, understanding the suppression seen in d + Au is still needed before any definitive statements about the nature of the suppression in Au + Au can be made735127137CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO - CNPQFUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO - FAPESPRHIC Operations Group; NERSC Center at LBNL; KISTI Center in Korea; Open Science Grid consortium; National Science Foundation (NSF); Centre National de la Recherche Scientifique (CNRS); Ministry of Education and Science, Russian Federation; National Natural Science Foundation of China (NSFC); Chinese Academy of Sciences; Korean Research Foundation, GA; Ministry of Education, Youth & Sports - Czech Republic; FIAS of Germany; Department of Atomic Energy (DAE); Department of Science & Technology (India); Council of Scientific & Industrial Research (CSIR) - India; National Science Center, Poland; RosAtom of Russia ; RCF at BNL; United States Department of Energy (DOE); United States Department of Energy (DOE); Ministry of Education, China; Ministry of Science and Technology, China; Ministry of Science, Education and Sports, Republic of Croatia; National Science Foundation (NSF); NSF - Directorate for Mathematical & Physical Sciences (MPS

Beam Energy Dependence of Moments of the Net-Charge Multiplicity Distributions in Au plus Au Collisions at RHIC

We report the first measurements of the moments-mean (M), variance (sigma(2)), skewness (S), and kurtosis (kappa)-of the net-charge multiplicity distributions at midrapidity in Au + Au collisions at seven energies, ranging from root s(NN) = 7.7 to 200 GeV, as a part of the Beam Energy Scan program at RHIC. The moments are related to the thermodynamic susceptibilities of net charge, and are sensitive to the location of the QCD critical point. We compare the products of the moments, sigma(2)/M, S sigma, and kappa sigma(2), with the expectations from Poisson and negative binomial distributions (NBDs). The S sigma values deviate from the Poisson baseline and are close to the NBD baseline, while the kappa sigma(2) values tend to lie between the two. Within the present uncertainties, our data do not show nonmonotonic behavior as a function of collision energy. These measurements provide a valuable tool to extract the freeze-out parameters in heavy-ion collisions by comparing with theoretical models