Low-mass $e^{+}e^{-}$ pair production in 158 A GeV Pb - Au collisions at the CERN SPS, its dependence on multiplicity and transverse momentum

We report a measurement of low-mass electron pairsobserved in 158 GeV/nucleon Pb-Au collisions. The pair yield integrated over the range of invariant masses 0.2 < m < 2.0 GeV is enhanced by a factor of 3.5 +/- 0.4 (stat) +/- 0.9 (syst) over the expectation from neutral meson decays. As observe...

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Detalles Bibliográficos
Autores principales: Agakichiev, G., Baur, R., Braun-Munzinger, P., Ceretto, F., Drees, A., Esumi, S., Faschingbauer, U., Fraenkel, Z., Fuchs, Ch., Gatti, E., Glässel, P., de los Heros, C.P., Holl, P., Jung, Ch., Lenkeit, B., Messer, M., Panebrattsev, Y., Pfeiffer, A., Rak, J., Ravinovich, I., Razin, S., Rehak, P., Richter, M., Sampietro, M., Saveljic, N., Schukraft, J., Shimansky, S., Seipp, W., Socol, E., Specht, H.J., Stachel, J., Tel-Zur, G., Tserruya, I., Ullrich, T., Voigt, C., Weber, C., Wessels, J.P., Wienold, T., Wurm, J.P., Yurevich, V.
Lenguaje:eng
Publicado: 1998
Materias:
Particle Physics - Experiment
Acceso en línea:https://dx.doi.org/10.1016/S0370-2693(98)00083-5
http://cds.cern.ch/record/362780
Descripción
Sumario:We report a measurement of low-mass electron pairsobserved in 158 GeV/nucleon Pb-Au collisions. The pair yield integrated over the range of invariant masses 0.2 < m < 2.0 GeV is enhanced by a factor of 3.5 +/- 0.4 (stat) +/- 0.9 (syst) over the expectation from neutral meson decays. As observed previously in S-Au collisions, the enhancement is most pronounced in the invariant-mass region 300-700 MeV. For Pb-Au we find evidencefor a strong increase of the enhancement with centrality. In addition, we show that the enhancement covers a wide range in transverse momentum, but is largest at the lowest observed pt.

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