Olimov Kh.K., Yuldashev B.S., Haseeb M.Q. et al. On centrality and rapidity dependences of transverse momentum spectra of negative pions in 12C+ 12C collisions at 4.2GeV/c per nucleon.

The dependences of the experimental transverse momentum spectra of the negative pions, produced in minimum bias 12C+ 12C collisions at a momentum of 4.2AGeV/c,on the collision centrality and the pion rapidity range were studied. To analyze quanti-tatively the change in the pt spectra of π−mesons with the changes of collision centrality and pion rapidity range, the extracted pt spectra were fitted by Hagedorn, Boltzmann, Simple Exponential and Gaussian functions. The values of the extracted spectral tem-peratures T1 and T2 were consistently larger for the pt spectra of π− mesons coming from midrapidity range as compared to those of the negative pions generated in the target and projectile fragmentation regions. The spectral temperatures T1 and T2 extracted from fitting the pt spectra of π− mesons in range pt =0.1–1.2GeV/c practically coincided with each other in peripheral, semicentral and central 12C+ 12C collision events, and thus did not show any collision centrality dependence. However, the values of T1 and T2 extracted from fitting in range pt =0.1–0.7GeV/c were consistently and noticeably larger in case of central collisions as compared to peripheral and semicentral 12C+ 12C collisions. Hagedorn and Boltzmann functions provided significantly better fits of the transverse momentum spectra of the negative pions with the physically acceptable values of the extracted temperatures as compared to Gaussian and Simple Exponential
functions.