Low-mass lepton pair production in Pb-Au collisions at 40 A.GeV |
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| Affiliation: | (1) NPI/ASCR, Reiz, Czech Republic;(2) GSI, Darmstadt, Germany;(3) Physikalisches Institut, Universit?t Heidelberg, Germany;(4) JINR, Dubna, Russia;(5) Weizmann Institute, Rehovot, Israel;(6) Department for Physics and Astronomy, SUNY Stony Brook, USA;(7) CERN, Geneva, Switzerland;(8) Brookhaven National Laboratory, Upton, USA;(9) Max-Planck-Institut für Kernphysik, Heidelberg, Germany;(10) LBNL, Berkeley, USA |
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| Abstract: | ![]()
The CERES/NA45 experiment at the CERN SPS has previously measurede + e - pair production in 160 A.GeV Pb-Au collisions. In the mass regionm > 02 GeV/c2, an enhancement of 2.7±04(stat.)±0.5(syst.) compared to the expectation from known hadronic decay sources was observed. In the 40 A.GeV data taken in 1999, an enhancement is again found; a preliminary analysis gives an even larger value of 50 ±13(stat.). The results are compared to theoretical model calculations based on π+π- annihilation with a modified ρ-propagator; they may be related to chiral symmetry restoration. |
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| Keywords: | Heavy-ion collisions lepton pairs |
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