HEPData

Abstract

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 |y|<1 in d+Au collisions of R_dAu = 0.79 +/- 0.24 (stat.) +/- 0.03 (sys.) +/- 0.10 (pp sys.). 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 (sys.) +/- 0.06 (pp sys.), 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.

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Figure 1a

10.17182/hepdata.102940.v1/t1

Invariant mass distributions of electron pairs in the region $|y_{ee}| < 0.5$, p+p.
https://www.hepdata.net/record/data/982159yaml https://www.hepdata.net/record/data/982159/csvcsv
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Figure 1b

10.17182/hepdata.102940.v1/t2

Invariant mass distributions of electron pairs in the region $|y_{ee}| < 0.5$, d+Au.
https://www.hepdata.net/record/data/982160yaml https://www.hepdata.net/record/data/982160/csvcsv
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Figure 2a

10.17182/hepdata.102940.v1/t3

(a) $B_{ee} \times d\sigma/dy$ vs. $y$ for p+p collisions and for d+Au collisions (scaled down by 103).
https://www.hepdata.net/record/data/982161yaml https://www.hepdata.net/record/data/982161/csvcsv
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Figure 2b

10.17182/hepdata.102940.v1/t4

$R_{dAu}$ vs. $y$.
https://www.hepdata.net/record/data/982162yaml https://www.hepdata.net/record/data/982162/csvcsv
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Figure 3a

10.17182/hepdata.102940.v1/t5

Comparison of our d+Au measurements to the pA measurements from E772. Ratio of $\Upsilon$ production in pA to pp scaled...
https://www.hepdata.net/record/data/982163yaml https://www.hepdata.net/record/data/982163/csvcsv
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Figure 3b

10.17182/hepdata.102940.v1/t6

Comparison of our d+Au measurements to the pA measurements from E772. Exponent $\alpha$ as a function of $x_{F}$.
https://www.hepdata.net/record/data/982164yaml https://www.hepdata.net/record/data/982164/csvcsv
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Figure 4a

10.17182/hepdata.102940.v1/t7

Invariant mass distributions of electron pairs in the region $|y_{ee}| < 1.0$ for the centrality selections $30-60\%$.
https://www.hepdata.net/record/data/982165yaml https://www.hepdata.net/record/data/982165/csvcsv
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Figure 4b

10.17182/hepdata.102940.v1/t8

Invariant mass distributions of electron pairs in the region $|y_{ee}| < 1.0$ for the centrality selections $10-30\%$.
https://www.hepdata.net/record/data/982166yaml https://www.hepdata.net/record/data/982166/csvcsv
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Figure 4c

10.17182/hepdata.102940.v1/t9

Invariant mass distributions of electron pairs in the region $|y_{ee}| < 1.0$ for the centrality selections $0-10\%$.
https://www.hepdata.net/record/data/982167yaml https://www.hepdata.net/record/data/982167/csvcsv
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Figure 5a

10.17182/hepdata.102940.v1/t10

Nuclear modification factor for $\Upsilon$(1S+2S+3S), in $|y| < 1.0$ in d+Au and Au+Au collisions as a function of $N_{part}$.
https://www.hepdata.net/record/data/982168yaml https://www.hepdata.net/record/data/982168/csvcsv
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Figure 5b

10.17182/hepdata.102940.v1/t11

Nuclear modification factor for $\Upsilon$(1S+2S+3S), in $|y| < 0.5$, in d+Au and Au+Au collisions as a function of $N_{part}$.
https://www.hepdata.net/record/data/982169yaml https://www.hepdata.net/record/data/982169/csvcsv
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Figure 5c

10.17182/hepdata.102940.v1/t12

Nuclear modification factor for $\Upsilon$(1S) in $|y| < 1.0$, in d+Au and Au+Au collisions as a function of $N_{part}$.
https://www.hepdata.net/record/data/982170yaml https://www.hepdata.net/record/data/982170/csvcsv
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10.17182/hepdata.102940.v1/t13

Nuclear modification factor for $\Upsilon$(1S) in $|y| < 0.5$, in d+Au and Au+Au collisions as a function of $N_{part}$.
https://www.hepdata.net/record/data/982171yaml https://www.hepdata.net/record/data/982171/csvcsv
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Figure 6

10.17182/hepdata.102940.v1/t14

Nuclear modification factor of quarkonium states as a function of binding energy as measured by STAR.
https://www.hepdata.net/record/data/982172yaml https://www.hepdata.net/record/data/982172/csvcsv

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