scholarly journals ϒ Production in Heavy-Ion Collisions from the STAR Experiment

2017 ◽  
Vol 289-290 ◽  
pp. 401-404 ◽  
Author(s):  
Zaochen Ye
Keyword(s):  
Heavy Ion Collisions ◽  
Heavy Ion ◽  
Ion Collisions ◽  
Star Experiment

scholarly journals Quarkonium measurements in heavy-ion collisions with the STAR experiment

2018 ◽  
Vol 171 ◽  
pp. 18015
Author(s):  
Xinjie Huang
Keyword(s):  
Transverse Momentum ◽  
Nuclear Matter ◽  
Heavy Ion Collisions ◽  
Theoretical Calculations ◽  
Heavy Ion ◽  
Matter Effects ◽  
Nuclear Modification ◽  
Ion Collisions ◽  
Star Experiment ◽  
Nuclear Modification Factors

In these proceedings, we present the latest measurements of J/ψ and ϒ by the STAR experiment. The J/ψ and ϒ production measured in p+p collisions provide new baselines for similar measurements in Au+Au collisions, while the measurements in p+Au collisions can help quantify the cold nuclear matter effects. The J/ψ υ2 is measured in both U+U and Au+Au collisions to place constraints on the amount of J/ψ arising from recombination of deconfined charm and anti-charm pairs. Furthermore, the nuclear modification factors for ground and excited ϒ states as a function of transverse momentum and centrality are presented, and compared to those measured at the LHC as well as to theoretical calculations.

scholarly journals Particle Yields in Heavy Ion Collisions and the Influence of Strong Magnetic Fields

2014 ◽  
Vol 2014 ◽  
pp. 1-13 ◽  
Author(s):  
M. G. de Paoli ◽  
D. P. Menezes
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Heavy Ion Collisions ◽  
Particle Production ◽  
Heavy Ion ◽  
Data Sets ◽  
Ion Collisions ◽  
Particle Ratios ◽  
Klein Gordon ◽  
Star Experiment

It is expected that the magnetic fields in heavy ion collisions are very high. In this work, we investigate the effects of a strong magnetic field on particle ratios within a thermal model of particle production. We model matter as a free gas of baryons and mesons under the influence of an external magnetic field varying from zero to30mπ2through an  χ2fitting to some data sets of the STAR experiment. For this purpose, we use the Dirac, Rarita-Schwinger, Klein-Gordon, and Proca equations subject to magnetic fields in order to obtain the energy expressions and the degeneracy for spin 1/2, spin 3/2, spin 0, and spin 1 particles, respectively. Our results show that, if the magnetic field can be considered as slowly varying and leaves its signature on the particle yields, a field of the order of6mπ2produces an improved fitting to the experimental data as compared to the calculations without magnetic field.

scholarly journals DEPENDENCE OF ASYMMETRIES FOR CHARGE DISTRIBUTION WITH RESPECT TO THE REACTION PLANE ON INITIAL ENERGY IN HEAVY-ION COLLISIONS

2013 ◽  
Vol 22 (06) ◽  
pp. 1350041 ◽  
Author(s):  
V. A. OKOROKOV
Keyword(s):  
Heavy Ion Collisions ◽  
Degrees Of Freedom ◽  
Heavy Ion ◽  
Initial Energy ◽  
Reaction Plane ◽  
Strong Interactions ◽  
Intermediate Energies ◽  
Ion Collisions ◽  
Invariance Violation ◽  
Star Experiment

In this paper, two combinations of correlators are defined in order to investigate the evolution of possible [Formula: see text] invariance violation in strong interactions with initial energy for heavy-ion collisions. These combinations correspond to absolute and relative asymmetry of distribution of electrically charge particles with respect to the reaction plane in heavy-ion collisions. Energy dependence of parameters under study was derived from data of STAR and ALICE experiments. Significant decreasing both absolute and relative asymmetry is observed at energies [Formula: see text]. This feature agrees qualitatively with other results of stage-I beam energy scan program in STAR experiment. General behavior of dependence of absolute asymmetry on initial energy agrees reasonably with behavior of similar dependence of Chern–Simons diffusion rate calculated at different values of external Abelian magnetic field. The observed behavior of parameters under study versus energy can be considered as indication on possible transition to predominance of hadronic states over quark–gluon degrees of freedom in the mixed phase created in heavy-ion collisions at intermediate energies.

scholarly journals DI-JET MEASUREMENTS IN HEAVY-ION COLLISIONS AT STAR

2011 ◽  
Vol 20 (07) ◽  
pp. 1551-1555
Author(s):  
◽  
ELENA BRUNA
Keyword(s):  
Energy Loss ◽  
Heavy Ion Collisions ◽  
Heavy Ion ◽  
Electromagnetic Calorimeter ◽  
Dense Medium ◽  
Ion Collisions ◽  
Star Experiment ◽  
Time Projection ◽  
Jet Structure ◽  
Selection Of

Jets are produced from hard scatterings in the early stages of heavy-ion collisions. It is expected that these high-pT partons travel through the hot and dense medium before fragmenting. Therefore they are expected to suffer energy loss in the QGP via gluon radiation and elastic collisions along their path. Measurements of fully reconstructed jets help understand the effect of the energy loss on the jet structure and energy profile. A data-driven characterization of the background in Au + Au is needed in order to compare the results to p + p . The full azimuthal coverage of STAR Time Projection Chamber and Electromagnetic Calorimeter allows measurements of fully reconstructed di-jets, defined by jets that match the online trigger and recoil jets on the away side. A tight selection of the trigger jets allows for a selection of those coming from the surface. Hence, the population of jets on the recoil side is biased towards a maximal energy loss because of the extreme in-medium pathlength. We present measurements of di-jets, exploring their structure and properties in Au + Au and p + p at [Formula: see text] in the STAR experiment.

scholarly journals Recent highlights from STAR

2018 ◽  
Vol 171 ◽  
pp. 01004
Author(s):  
Wangmei Zha
Keyword(s):  
Quark Matter ◽  
Heavy Ion Collisions ◽  
Star Collaboration ◽  
Heavy Ion ◽  
Particle Identification ◽  
Heavy Flavor ◽  
Ion Collisions ◽  
Star Experiment ◽  
Electro Magnetic ◽  
Magnetic Probes

The Solenoidal Tracker at RHIC (STAR) experiment takes advantage of its excellent tracking and particle identification capabilities at mid-rapidity to explore the properties of strongly interacting QCD matter created in heavy-ion collisions at RHIC. The STAR collaboration presented 7 parallel and 2 plenary talks at Strangeness in Quark Matter 2017 and covered various topics including heavy flavor measurements, bulk observables, electro-magnetic probes and the upgrade program. This paper highlights some of the selected results.

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