Transverse-momentum Spectra of Hadrons in $p+p$ Collisions at CERN SPS Energies from the UrQMD Transport Model

The UrQMD transport model, version 3.4, is used to study the new experimental data on total yields, rapidity distributions and transversemomentum spectra of π ± and K± produced in inelastic p + p interactions at SPS energies, recently published by the NA61/SHINE Collaboration. The comparison of model predictions to these new measurements is presented as a function of collision energy for central and forward particle rapidity intervals. In addition, the inverse slope parameters characterising the transverse-momentum distributions are extracted from the predicted spectra and compared to corresponding values obtained from experimental distributions, as a function of particle rapidity and collision energy. A complex pattern of deviations between the experimental data and the UrQMD model emerges. We conclude that new experimental data at SPS energies still constitute a challenge for specific transport models, at least as far as the present version of the UrQMD code is concerned.