Low-p(T) e(+)e(-) Pair Production in Au plus Au Collisions at root s(NN)=200 GeV and U plus U Collisions at root s(NN)=193 GeV at STAR
Result description
We report first measurements of e(+)e(-) pair production in the mass region 0.4 < M-ee < 2.6 GeV/c(2) at low transverse momentum (p(T) < 0.15 GeV/c) in noncentral Au + Au collisions at root s(NN) = 200 GeV and U + U collisions at root s(NN) = 193 GeV. Significant enhancement factors, expressed as ratios of data over known hadronic contributions, are observed in the 40%-80% centrality of these collisions. The excess yields peak distinctly at low p(T) with a width (root < p(T)(2)>) between 40 and 60 MeV/c. The absolute cross section of the excess depends weakly on centrality, while those from a theoretical model calculation incorporating an in-medium broadened rho spectral function and radiation from a quark gluon plasma or hadronic cocktail contributions increase dramatically with an increasing number of participant nucleons. Model calculations of photon-photon interactions generated by the initial projectile and target nuclei describe the observed excess yields but fail to reproduce the p(T)(2) distributions.
Keywords
The result's identifiers
Result code in IS VaVaI
Alternative codes found
RIV/68407700:21340/18:00324790
Result on the web
DOI - Digital Object Identifier
Alternative languages
Result language
angličtina
Original language name
Low-p(T) e(+)e(-) Pair Production in Au plus Au Collisions at root s(NN)=200 GeV and U plus U Collisions at root s(NN)=193 GeV at STAR
Original language description
We report first measurements of e(+)e(-) pair production in the mass region 0.4 < M-ee < 2.6 GeV/c(2) at low transverse momentum (p(T) < 0.15 GeV/c) in noncentral Au + Au collisions at root s(NN) = 200 GeV and U + U collisions at root s(NN) = 193 GeV. Significant enhancement factors, expressed as ratios of data over known hadronic contributions, are observed in the 40%-80% centrality of these collisions. The excess yields peak distinctly at low p(T) with a width (root < p(T)(2)>) between 40 and 60 MeV/c. The absolute cross section of the excess depends weakly on centrality, while those from a theoretical model calculation incorporating an in-medium broadened rho spectral function and radiation from a quark gluon plasma or hadronic cocktail contributions increase dramatically with an increasing number of participant nucleons. Model calculations of photon-photon interactions generated by the initial projectile and target nuclei describe the observed excess yields but fail to reproduce the p(T)(2) distributions.
Czech name
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Czech description
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Classification
Type
Jimp - Article in a specialist periodical, which is included in the Web of Science database
CEP classification
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OECD FORD branch
10304 - Nuclear physics
Result continuities
Project
Result was created during the realization of more than one project. More information in the Projects tab.
Continuities
I - Institucionalni podpora na dlouhodoby koncepcni rozvoj vyzkumne organizace
Others
Publication year
2018
Confidentiality
S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů
Data specific for result type
Name of the periodical
Physical Review Letters
ISSN
0031-9007
e-ISSN
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Volume of the periodical
121
Issue of the periodical within the volume
13
Country of publishing house
US - UNITED STATES
Number of pages
8
Pages from-to
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UT code for WoS article
000445603400009
EID of the result in the Scopus database
2-s2.0-85054011284
Basic information
Result type
Jimp - Article in a specialist periodical, which is included in the Web of Science database
OECD FORD
Nuclear physics
Year of implementation
2018