Centrality and rapidity dependences of negative pions in He-C collisions at 4.2 A GeV/c

In the current research paper, we investigated the dependence of p(T) spectra of pi(-) mesons on centrality of collision and different rapidity (y) range. These negative pions are produced in Alpha-Carbon collisions at a momentum of 4.2 A GeV/c. We used Boltzmann and Hagedorn functions for one and two temperature fitting, of transverse momentum spectra obtained from experimental data and Model (Quark Gluon String Model, QGSM) data. By fitting these mathematical functions, we analyzed the change in shape of slopes of p(T) spectra. The fitting results for spectral temperatures were consistently larger (both in the experiment and QGSM) for the p(T) spectra of negative pions produced in range of mid-rapidity in comparison with those produced in fragmentation regions of colliding nuclei. It was also observed that extracted spectral temperatures from experimental data have a weak dependence on the collision centrality. The pion spectra can be described nicely by fitting two temperature functions for the experimental pT spectra for whole range and for the interval 0.1 <= p(T) <= 1.3 GeV/c. In the p(T) range of 0.1 <= p(T) <= 0.8 GeV/c, one temperature functions were found sufficient for fitting the experimental p(T) spectra. The extracted temperatures from experimental data were found more sensitive to the fitting range of p(T), in contrast with temperatures obtained from QGSM data.