295 articles – 2208 Notices  [english version]
 HAL : in2p3-00342023, version 1
 arXiv : 0806.0577
 Thermal Dimuon Emission in In-In at the CERN SPS
 NA60 Collaboration(s)
 (2008)
 The NA60 experiment at the CERN SPS has studied low-mass dimuon production in 158A GeV In-In collisions. A significant excess of pairs is observed above the yield expected from neutral meson decays, consistent with a dominant contribution from $\pi\pi\to\rho\to\mu\mu$. This paper presents precision results on the mass and transverse momentum spectra of the excess pairs. The space-time averaged rho spectral function associated to the measured mass distribution shows a significant broadening, but essentially no mass shift. The slope parameter $T_{eff}$ extracted from the spectra rises with dimuon mass up to the $\rho$, followed by a sudden decline above. While the initial rise is consistent with the expectations for radial flow of a hadronic decay source, the decline indicates a transition to an emission source with much smaller flow, possibly of partonic origin.
 Thème(s) : Physique/Physique Nucléaire Expérimentale
 Mot(s)-clé(s) : presenté par M. Floris
 Lien vers le texte intégral : http://fr.arXiv.org/abs/0806.0577
 in2p3-00342023, version 1 http://hal.in2p3.fr/in2p3-00342023 oai:hal.in2p3.fr:in2p3-00342023 Contributeur : Jeanine Pellet <> Soumis le : Mercredi 26 Novembre 2008, 15:21:16 Dernière modification le : Jeudi 27 Novembre 2008, 10:48:56