Beam Energy and Centrality Dependence of Direct-Photon Emission from Ultrarelativistic Heavy-Ion Collisions

(PHENIX Collaboration)

doi:10.1103/PhysRevLett.123.022301

Beam Energy and Centrality Dependence of Direct-Photon Emission from Ultrarelativistic Heavy-Ion Collisions

(PHENIX Collaboration)

University of Colorado Boulder
Joint Institute for Nuclear Research
Columbia University
Los Alamos National Laboratory
University of Massachusetts
University of Michigan, Ann Arbor
Stony Brook University
RIKEN
Brookhaven National Lab
The University of Tokyo
New Mexico State University
Howard University
High Energy Accelerator Research Organization, Tsukuba
Kyoto University
Iowa State University
Nantes Université
Brookhaven National Laboratory
Laboratoire Leprince-Ringuet
Oak Ridge National Laboratory
Institute for High Energy Physics
Eötvös Loránd University
Florida Institute of Technology
CEA Saclay
University of California at Riverside
University of New Mexico
Abilene Christian University
City University of New York
Petersburg Nuclear Physics InstituteGatchina
University of Münster

Research output: Contribution to journal › Article › peer-review

45 Scopus citations

Abstract

The PHENIX collaboration presents first measurements of low-momentum (0.4<pT<3 GeV/c) direct-photon yields from Au+Au collisions at sNN=39 and 62.4 GeV. For both beam energies the direct-photon yields are substantially enhanced with respect to expectations from prompt processes, similar to the yields observed in Au+Au collisions at sNN=200. Analyzing the photon yield as a function of the experimental observable dNch/dη reveals that the low-momentum (>1 GeV/c) direct-photon yield dNγdir/dη is a smooth function of dNch/dη and can be well described as proportional to (dNch/dη)α with α≈1.25. This scaling behavior holds for a wide range of beam energies at the Relativistic Heavy Ion Collider and the Large Hadron Collider, for centrality selected samples, as well as for different A+A collision systems. At a given beam energy, the scaling also holds for high pT (>5 GeV/c), but when results from different collision energies are compared, an additional sNN-dependent multiplicative factor is needed to describe the integrated-direct-photon yield.

Original language	English
Article number	022301
Journal	Physical Review Letters
Volume	123
Issue number	2
DOIs	https://doi.org/10.1103/PhysRevLett.123.022301
State	Published - Jul 10 2019

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10.1103/PhysRevLett.123.022301

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@article{e2b70bedcebe43998efb4ee438eb135b,

title = "Beam Energy and Centrality Dependence of Direct-Photon Emission from Ultrarelativistic Heavy-Ion Collisions",

abstract = "The PHENIX collaboration presents first measurements of low-momentum (0.41 GeV/c) direct-photon yield dNγdir/dη is a smooth function of dNch/dη and can be well described as proportional to (dNch/dη)α with α≈1.25. This scaling behavior holds for a wide range of beam energies at the Relativistic Heavy Ion Collider and the Large Hadron Collider, for centrality selected samples, as well as for different A+A collision systems. At a given beam energy, the scaling also holds for high pT (>5 GeV/c), but when results from different collision energies are compared, an additional sNN-dependent multiplicative factor is needed to describe the integrated-direct-photon yield.",

author = "\{(PHENIX Collaboration)\} and A. Adare and S. Afanasiev and C. Aidala and Ajitanand, \{N. N.\} and Y. Akiba and R. Akimoto and H. Al-Bataineh and J. Alexander and M. Alfred and A. Al-Jamel and H. Al-Ta'Ani and A. Angerami and K. Aoki and N. Apadula and L. Aphecetche and Y. Aramaki and R. Armendariz and Aronson, \{S. H.\} and J. Asai and H. Asano and Aschenauer, \{E. C.\} and Atomssa, \{E. T.\} and R. Averbeck and Awes, \{T. C.\} and B. Azmoun and V. Babintsev and A. Bagoly and M. Bai and G. Baksay and L. Baksay and A. Baldisseri and B. Bannier and Barish, \{K. N.\} and Barnes, \{P. D.\} and B. Bassalleck and Basye, \{A. T.\} and S. Bathe and S. Batsouli and V. Baublis and F. Bauer and C. Baumann and S. Baumgart and A. Bazilevsky and S. Belikov and Klaus Dehmelt and Abhay Deshpande and A. Drees and Hemmick, \{T. K.\} and J. Jia and R. Lacey",

note = "Publisher Copyright: {\textcopyright} 2019 authors. Published by the American Physical Society.",

year = "2019",

month = jul,

day = "10",

doi = "10.1103/PhysRevLett.123.022301",

language = "English",

volume = "123",

journal = "Physical Review Letters",

issn = "0031-9007",

number = "2",

}

TY - JOUR

T1 - Beam Energy and Centrality Dependence of Direct-Photon Emission from Ultrarelativistic Heavy-Ion Collisions

AU - (PHENIX Collaboration)

AU - Adare, A.

AU - Afanasiev, S.

AU - Aidala, C.

AU - Ajitanand, N. N.

AU - Akiba, Y.

AU - Akimoto, R.

AU - Al-Bataineh, H.

AU - Alexander, J.

AU - Alfred, M.

AU - Al-Jamel, A.

AU - Al-Ta'Ani, H.

AU - Angerami, A.

AU - Aoki, K.

AU - Apadula, N.

AU - Aphecetche, L.

AU - Aramaki, Y.

AU - Armendariz, R.

AU - Aronson, S. H.

AU - Asai, J.

AU - Asano, H.

AU - Aschenauer, E. C.

AU - Atomssa, E. T.

AU - Averbeck, R.

AU - Awes, T. C.

AU - Azmoun, B.

AU - Babintsev, V.

AU - Bagoly, A.

AU - Bai, M.

AU - Baksay, G.

AU - Baksay, L.

AU - Baldisseri, A.

AU - Bannier, B.

AU - Barish, K. N.

AU - Barnes, P. D.

AU - Bassalleck, B.

AU - Basye, A. T.

AU - Bathe, S.

AU - Batsouli, S.

AU - Baublis, V.

AU - Bauer, F.

AU - Baumann, C.

AU - Baumgart, S.

AU - Bazilevsky, A.

AU - Belikov, S.

AU - Dehmelt, Klaus

AU - Deshpande, Abhay

AU - Drees, A.

AU - Hemmick, T. K.

AU - Jia, J.

AU - Lacey, R.

PY - 2019/7/10

Y1 - 2019/7/10

N2 - The PHENIX collaboration presents first measurements of low-momentum (0.41 GeV/c) direct-photon yield dNγdir/dη is a smooth function of dNch/dη and can be well described as proportional to (dNch/dη)α with α≈1.25. This scaling behavior holds for a wide range of beam energies at the Relativistic Heavy Ion Collider and the Large Hadron Collider, for centrality selected samples, as well as for different A+A collision systems. At a given beam energy, the scaling also holds for high pT (>5 GeV/c), but when results from different collision energies are compared, an additional sNN-dependent multiplicative factor is needed to describe the integrated-direct-photon yield.

AB - The PHENIX collaboration presents first measurements of low-momentum (0.41 GeV/c) direct-photon yield dNγdir/dη is a smooth function of dNch/dη and can be well described as proportional to (dNch/dη)α with α≈1.25. This scaling behavior holds for a wide range of beam energies at the Relativistic Heavy Ion Collider and the Large Hadron Collider, for centrality selected samples, as well as for different A+A collision systems. At a given beam energy, the scaling also holds for high pT (>5 GeV/c), but when results from different collision energies are compared, an additional sNN-dependent multiplicative factor is needed to describe the integrated-direct-photon yield.

UR - https://www.scopus.com/pages/publications/85069921283

U2 - 10.1103/PhysRevLett.123.022301

DO - 10.1103/PhysRevLett.123.022301

M3 - Article

C2 - 31386493

AN - SCOPUS:85069921283

SN - 0031-9007

VL - 123

JO - Physical Review Letters

JF - Physical Review Letters

IS - 2

M1 - 022301

ER -

Beam Energy and Centrality Dependence of Direct-Photon Emission from Ultrarelativistic Heavy-Ion Collisions

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