出版社：SISSA, Scuola Internazionale Superiore di Studi Avanzati
摘要：The NA60 experiment studied low-mass dimuon production in proton-nucleus and indium-indium
collisions at the CERN SPS. While the p-A data can be well described by a superposition of
light neutral meson decays, an excess is observed in the heavy-ion data, increasing with collision
centrality, with respect to these expected sources. Thanks to the high statistics and good quality
of our measurement, we can subtract the muon pairs due to h, h0, w and f decays from the
signal dimuon mass distribution. The resulting spectra are compatible with a r spectral function
broadening from peripheral to central collisions, with no change in the pole mass.
