Identified hadron spectra at large transverse momentum in p+p and d+Au collisions at,root(NN)-N-S=200 GeV

Abstract We present the transverse momentum ( p T ) spectra for identified charged pions, protons and anti-protons from p + p and d + Au collisions at s NN = 200 GeV . The spectra are measured around midrapidity ( | y | 0.5 ) over the range of 0.3 p T 10 GeV / c with particle identification from the ionization energy loss and its relativistic rise in the time projection chamber and time-of-flight in STAR. The charged pion and proton + anti-proton spectra at high p T in p + p and d + Au collisions are in good agreement with a phenomenological model (EPOS) and with next-to-leading order perturbative quantum chromodynamic (NLO pQCD) calculations with a specific fragmentation scheme and factorization scale. We found that all proton, anti-proton and charged pion spectra in p + p collisions follow x T -scaling for the momentum range where particle production is dominated by hard processes ( p T ≳ 2 GeV / c ). The nuclear modification factor around midrapidity is found to be greater than unity for charged pions and to be even larger for protons at 2 p T 5 GeV / c .