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Committee for collaboration of Czech Republic

with Joint Institute for Nuclear Research in Dubna Login
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

Author
Adam J. Creighton University, Omaha
Lednický Richard, promovaný fyzik DrSc. dr. h. c. Institute of physics of the ASCR, JINR Dubna
et al.  STAR collaboration

Year
2018

Scientific journal
Physical Review Letters, 121 (13), 132301

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Abstract
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.

Cite article as:
J. Adam, R. Lednický, . et al., "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", Physical Review Letters, 121 (13), 132301 (2018)