Baryon flow from SIS to AGS energies

We analyze the baryon sideward and elliptic flow from SIS (0.25-2A GeV) to AGS (2-11.0A GeV) energies for Au + Au collisions in the relativistic trans port model RBUU that includes all baryon resonances up to a mass of 2 GeV a s well as string degrees of freedom for the higher mass continuum. There ar e two factors which dominantly determine the baryon flow at these energies: the momentum dependence of the scalar and vector potentials and the resona nce-string degrees of freedom. We fix the explicit momentum dependence of t he nucleon-meson couplings within the NL3 parameter set by the nucleon opti cal potential up to 1 GeV of kinetic energy. When assuming the optical pote ntial to vanish identically for E-kin greater than or equal to 3.5 GeV we s imultaneously reproduce the sideward flow data of the FOPI, EOS, E895 and E 877 collaborations, the elliptic flow data of the EOS, E895 and E877 collab orations, and approximately the rapidity and transverse mass distribution o f protons at ACS energies. The gradual change from hadronic to string degre es of freedom with increasing bombarding energy can be viewed as a transiti on from hadronic to string matter, i.e. a dissolution of hadrons, (C) 2000 Elsevier Science B.V. All rights reserved.