Transverse Momentum Fluctuations in Nuclear Collisions at 158 A GeV The NA49 Collaboration

Results are presented on event-by-event fluctuations in transverse momentum of charged particles, produced at forward rapidities in p+p, C+C, Si+Si and Pb+Pb collisions at 158 A GeV. Three different characteristics are discussed: the average transverse momentum of the event, the Φ p T fluctuation measure and two-particle transverse momentum correlations. In the kinematic region explored, the dynamical fluctuations are found to be small. However, a significant system size dependence of Φ p T is observed, with the largest value measured in peripheral Pb+Pb interactions. The data are compared with predictions of several models.