1. Thermal Dimuon Emission in In-In at the CERN SPS
- Author
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Arnaldi, R., Banicz, K., Castor, J., Chaurand, B., Cicalò, C., Colla, A., Cortese, P., Damjanovic, S., David, A., De Falco, A., Devaux, A., Ducroux, L., Enyo, H., Ferretti, J., Fargeix, A., Floris, M., Förster, A., Force, P., Guettet, N., Guichard, A., R. Gulkanian, H., Heuser, J., Keil, M., Kluberg, L., Lourenço, C., Lozano, J., Manso, F., Martins, P., Masoni, A., Neves, A., Ohnishi, H., Oppedisano, C., Parracho, P., Pillot, Philippe, Poghosyan, T., Puddu, G., Radermacher, E., Ramalhete, P., Rosinsky, P., Scomparin, E., Seixas, J., Serci, S., Shahoyan, R., Sonderegger, P., J. Specht, H., Tieulent, R., Usai, G., Veenhof, R., K. Wöhri, H., Laboratoire de Physique Corpusculaire - Clermont-Ferrand (LPC), Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Laboratoire Leprince-Ringuet (LLR), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-École polytechnique (X)-Centre National de la Recherche Scientifique (CNRS), Institut de Physique Nucléaire de Lyon (IPNL), Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), NA60, Centre National de la Recherche Scientifique (CNRS)-École polytechnique (X)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3), Centre National de la Recherche Scientifique (CNRS)-Université Claude Bernard Lyon 1 (UCBL), and Université de Lyon-Université de Lyon-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)
- Subjects
presenté par M. Floris ,FOS: Physical sciences ,Nuclear Physics - Experiment ,High Energy Physics::Experiment ,Nuclear Experiment (nucl-ex) ,[PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex] ,Nuclear Experiment - Abstract
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., Comment: 4 pages, 4 figures, presented at the XLIIIth Rencontres de Moriond
- Published
- 2008