We report measurements of Υ meson production in p + p, d + Au, and Au+Au collisions using the STAR detector at RHIC. We compare the Υ 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 |y| < 1 in d + Au collisions of RdAu = 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 made.
(ProQuest: ... denotes formulae and/or non-USASCII text omitted; see image) The ratios of yields of anti-baryons to baryons probes the mechanisms of baryon-number transport. Results for ..., ..., ... ...and ... in pp collisions at ..., measured with the ALICE detector at the LHC, are reported. Within the experimental uncertainties and ranges covered by our measurement, these ratios are independent of rapidity, transverse momentum and multiplicity for all measured energies. The results are compared to expectations from event generators, such as PYTHIA and HIJING/B, that are used to model the particle production in pp collisions. The energy dependence of ..., ..., ... and ..., reaching values compatible with unity for ..., complement the earlier ... measurement of ALICE. These dependencies can be described by exchanges with the Regge-trajectory intercept of ..., which are suppressed with increasing rapidity interval Δy. Any significant contribution of an exchange not suppressed at large Δy (reached at LHC energies) is disfavoured.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Results are presented on event-by-event fluctuations in transverse momentum of charged particles, produced at forward rapidities in p+p, C+C, Si+Si, and Pb+Pb collisions at 158 AGeV. Three different ...characteristics are discussed: the average transverse momentum of the event, the {phi}{sub p{sub T}} fluctuation measure, and two-particle transverse momentum correlations. In the kinematic region explored, the dynamical fluctuations are found to be small. However, a significant system size dependence of {phi}{sub p{sub T}} is observed, with the largest value measured in peripheral Pb+Pb interactions. The data are compared with predictions of several models.
We present a study of the inclusive charged-particle transverse momentum ( Formula omitted) spectra as a function of charged-particle multiplicity density at mid-pseudorapidity, Formula omitted, in ...pp collisions at Formula omitted and 13 TeV covering the kinematic range Formula omitted and Formula omitted GeV/c. The results are presented for events with at least one charged particle in Formula omitted (INEL Formula omitted). The Formula omitted spectra are reported for two multiplicity estimators covering different pseudorapidity regions. The Formula omitted spectra normalized to that for INEL Formula omitted show little energy dependence. Moreover, the high- Formula omitted yields of charged particles increase faster than the charged-particle multiplicity density. The average Formula omitted as a function of multiplicity and transverse spherocity is reported for pp collisions at Formula omitted TeV. For low- (high-) spherocity events, corresponding to jet-like (isotropic) events, the average Formula omitted is higher (smaller) than that measured in INEL Formula omitted pp collisions. Within uncertainties, the functional form of Formula omitted is not affected by the spherocity selection. While EPOS LHC gives a good description of many features of data, PYTHIA overestimates the average Formula omitted in jet-like events.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Here, in this erratum we report changes on the D0 pT spectra and nuclear modification factor (RAA) in Au+Au collisions at √sNN = 200 GeV by fixing the errors in the efficiency and selection criteria ...that affected the Au+Au results. The p+p reference spectrum has changed as well and is updated with new fragmentation parameters
We present three-particle mixed-harmonic correlations 〈$ \cos (m\phi_a + n\phi_b - (m+n) \phi_c)$ 〉for harmonics $m,n=1-3$ for charged particles in $\sqrt{s_{NN}}=$200 GeV Au+Au collisions at RHIC. ...These measurements provide information on the three-dimensional structure of the initial collision zone and are important for constraining models of a subsequent low-viscosity quark-gluon plasma expansion phase. We investigate correlations between the first, second and third harmonics predicted as a consequence of fluctuations in the initial state. The dependence of the correlations on the pseudorapidity separation between particles show hints of a breaking of longitudinal invariance. We compare our results to a number of state-of-the art hydrodynamic calculations with different initial states and temperature dependent viscosities. These measurements provide important steps towards constraining the temperature dependent transport and the longitudinal structure of the initial state at RHIC.
The ALICE Collaboration has measured the energy dependence of exclusive photoproduction of Formula omitted vector mesons off proton targets in ultra-peripheral p-Pb collisions at a centre-of-mass ...energy per nucleon pair Formula omitted TeV. The e Formula omittede Formula omitted and Formula omitted decay channels are used to measure the cross section as a function of the rapidity of the Formula omitted in the range Formula omitted, corresponding to an energy in the Formula omittedp centre-of-mass in the interval Formula omitted GeV. The measurements, which are consistent with a power law dependence of the exclusive Formula omitted photoproduction cross section, are compared to previous results from HERA and the LHC and to several theoretical models. They are found to be compatible with previous measurements.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
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