?~0 And ? Production Of P+A Collisions At Next-to-leading Order

Heavy-ion Collision will creat extremely hot or dense matter condition on which a new form of matter named the Guark-Gluon Plasma will exist. QGP exists within a very short time in the beginning of the universe or within the extremely dense cold quark matter in the neutron star. The existence was confirmed in the RHIC and LHC. However,the QGP could not be observed directly, but rather quickly goes through hadronization and finally becomes hadrons in the final-state to be observed by the detectors. In this paper,we focus on leading hadron productions (?0 and ? ) in p + A collisions at the RHIC and the LHC, which helps us better understand cold nuclear matter effects in relativistic heavy ion collisions, and thus providing a calibration in studying the formation and properties of the QGP.According to the factorization in pQCD, one can write the inclusive hadron produc-tion cross section in high energy p+p collisions as a convolution of three parts: the distribu-tion functions of partons fa/p(xa,?2) with momentum fraction xa; partonic cross sections d?/dt(ab?cd); parton fragmentation functions Dh/c(za,?2) with momentum fraction za. we utilize the partonic cross sections at leading-order (LO) and next-to-leading-order(NLO) derived from pQCD calculations. For calculations, we employed the AKK pion fragmentation functions, paremetrization for ? fragmentation functions AESSS. For the fact that nucleus is complosed of nucleons, nucleon-nucleus collision could not be treated as a simple superposition of nucleon-nucleon collisions, in which the nuclear matter effectshould be taken into consideration. For p + A collisions, the nuclear parton distribution functions is used from EPPS 16 system paremetrization to take into consideration the cold nuclear matter effect in ? and ? productions. The transverse momentum spectra of ?0 and? in heavy ion collisions are calculated numerically at NLO in the framework of pQCD. In the meantime, the pT dependence of the nuclear modification factors RpA and ratio ?/?0 are studied in numerical calculations. The rapidity dependence of those quantities are also studied within different intervals of pT in the central rapidity region.Our results reveal that the ratios of ?/?0 of p+p collisions and p + A collisions coin-cide with each other in a wide region of PT regardless of pT dependence or y dependence.In other words, the yields of ? and ?0 are almost only determined by quark fragmentation functions. While the rapidity dependence of hadron production is symmetric about y = 0 in nucleon-nucleon collisions, a small deviation to the forward or backward rapidity ra-gion in p + A collisions is observed. Moreover, a similar rapidity dependence of nuclear modification factors RpA? and RpA?0 could be found in the nucleon-nucleus reactions.