First Measurement of the rho Spectral Function in High-Energy Nuclear Collisions

We report on a precision measurement of low-mass muon pairs in 158 AGeV indium-indium collisions at the CERN SPS. A significant excess of pairs is observed above the yield expected from neutral meson decays. The unprecedented sample size of 360 000 dimuons and the good mass resolution of about 2% al...

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Detalles Bibliográficos
Autores principales: Arnaldi, R., Averbeck, R., Banicz, K., Castor, J., Chaurand, B., Cicalo, C., Colla, A., Cortese, P., Damjanovic, S., David, Andre, De Falco, A., Devaux, A., Drees, A., Ducroux, L., Enyo, H., Fargeix, J., Ferretti, A., Floris, M., Forster, A., Force, P., Guettet, N., Guichard, A., Gulkanian, H., Heuser, J.M., Keil, M., Kluberg, L., Lourenco, C., Lozano, J., Manso, F., Masoni, A., Martins, P., Neves, A., Ohnishi, H., Oppedisano, C., Parracho, P., Pillot, Ph., Puddu, G., Radermacher, E., Ramalhete, P., Rosinsky, P., Scomparin, E., Seixas, J., Serci, S., Shahoyan, R., Sonderegger, P., Specht, H.J., Tieulent, R., Usai, G., Veenhof, R., Wohri, H.K.
Lenguaje:eng
Publicado: 2006
Materias:
Nuclear Physics - Experiment
Acceso en línea:https://dx.doi.org/10.1103/PhysRevLett.96.162302
http://cds.cern.ch/record/947619
Descripción
Sumario:We report on a precision measurement of low-mass muon pairs in 158 AGeV indium-indium collisions at the CERN SPS. A significant excess of pairs is observed above the yield expected from neutral meson decays. The unprecedented sample size of 360 000 dimuons and the good mass resolution of about 2% allow us to isolate the excess by subtraction of the decay sources. The shape of the resulting mass spectrum is consistent with a dominant contribution from pi+pi-->rho-->mu+mu- annihilation. The associated space-time averaged rho spectral function shows a strong broadening, but essentially no shift in mass. This may rule out theoretical models linking hadron masses

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