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At least 1,135 records · Page 63

Corrigendum to “Suppression of Υ production in d+Au and Au+Au collisions at √ S NN = 200 GeV" [Phys. Lett. B 735 (2014) 127-137]

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 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 made.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗

Single neutral pion production by charged-current ν ¯ μ interactions on hydrocarbon at 〈 E ν 〉 = 3.6 GeV

We studied single neutral pion production via muon antineutrino charged-current interactions in plastic scintillator (CH) using the MINERvA detector exposed to the NuMI low-energy, wideband antineutrino beam at Fermilab. Measurement of this process constrains models of neutral pion production in nuclei, which is important because the neutral-current analog is a background for appearance oscillation experiments. Furthermore, the differential cross sections for π 0 momentum and production angle, for events with a single observed π 0 and no charged pions, are presented and compared to model predictions. These results comprise the first measurement of the π 0 kinematics for this process.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗