Simultaneous multiplicity and forward energy characterization of particle spectra in Au+Au collisions at 11.6A GeV/c

In this paper Au+Au collisions at 11.6A GeV/c are characterized by two glob al observables: the energy measured near zero degrees (E-ZCAL) and the tota l event multiplicity. Particle spectra are measured for different event cla sses that are defined in a two-dimensional grid of both global observables. For moderately central events (sigma/sigma(int) < 12%) the proton dN/dy di stributions do not depend on E-ZCAL but only on the event multiplicity. In contrast the shape of the proton transverse spectra shows little dependence on the event multiplicity. The change in the proton dN/dy distributions su ggests that different conditions are formed in the collision for different event classes. These event classes are studied for signals of new physics b y measuring pion and kaon spectra and yields. In the event classes doubly s elected on E-ZCAL and multiplicity there is no indication of any unusual pi on or kaon yields, spectra, or K/pi ratio even in the events with extreme m ultiplicity. [S0556-2813(99)03704-8].