η meson production of high-energy nuclear collisions at NLO

The transverse momentum spectrum of η meson in relativistic heavy-ion collisions is studied at the Next-to-Leading Order (NLO) within the perturbative QCD, where the jet quenching effect in the QGP is incorporated with the effectively medium-modified η fragmentation functions using the higher-twist approach. We show that the theoretical simulations could give nice descriptions of PHENIX data on η   meson in both p+pp+p and central Au + Au collisions at the RHIC, and also provide numerical predictions of η   spectra in central Pb + Pb collisions with sNN=2.76 TeV at the LHC. The ratios of η/π0η/π0 in p+pp+p and in central Au + Au collisions at 200 GeV are found to overlap in a wide pTpT region, which matches well the measured ratio η/π0η/π0 by PHENIX. We demonstrate that, at the asymptotic region when pT→∞pT→∞ the ratios of η/π0η/π0 in both Au + Au and p+pp+p are almost determined only by quark jets fragmentation and thus approach to the one in e+e−e+e− scattering; in addition, the almost identical gluon (quark) contribution fractions to η and to π   result in a rather moderate variation of η/π0η/π0 distribution at intermediate and high pTpT region in A+AA+A relative to that in p+pp+p; while a slightly higher η/π0η/π0 at small pTpT in Au + Au can be observed due to larger suppression of gluon contribution fraction to π0π0 as compared to the one to η  . The theoretical prediction for η/π0η/π0 at the LHC has also been presented.