Calculation of Gluon Distribution Functions in Leading Order by Regge-like Behavior at Low-x

An approximate analytical form of the gluon distribution function from the derivative F2 proton structure function data at low-x assuming the Regge-like behavior of the gluon distribution function at this limit is presented. In this method, we calculate λ and C parameters for each low-x value at several Q^2 values using the scaling violation of the F2 proton structure function. For low-x, A is found to be independent of x within the experimental accuracy. We make use of the leading order Altarelli-Parisi （A-P） evolution equations in our analysis. To test the validity of our new determined gluon distribution functions, we compare them with the QCD parton distribution functions at low-x region.

Gottfried sum rule from maximum entropy method quark distributions with DGLAP evolution and with DGLAP evolution with GLR-MQ-ZRS corrections

A new method to test the valence quark distribution of nucleons obtained from the maximum entropy method using the Gottfried sum rule by performing the DGLAP equations with GLR-MQ-ZRS corrections and the original leading-order/next-to-leading-order （LO/NLO） DGLAP equations is outlined. The test relies on knowledge of the unpolarized electron proton structure function F2^ep and the electron neutron structure function F2^en and the assumption that Bjorken scaling is satisfied. In this work, the original Gottfried summation value obtained by the integrals of the structure function at different Q2 is in accordance with the theoretical value of 1/3 under the premise of light-quark flavor symmetry of the nucleon sea, whether it results from dynamical evolution equations or from global quantum chromodynamics fits of PDFs. Finally, we present the summation value of the LO/NLO DGLAP global fits of PDFs under the premise of light-quark flavor asymmetry of the nucleon sea. According to analysis of the original Gottfried summation value with two evolution equations at different Q2 we find that the valence quark distributions of nucleons obtained by using the maximum entropy method are effective and reliable.

Analysis of the gluon distribution with next-to-leading order splitting function at small-x^(*)

An approximated solution for the gluon distribution from DGLAP evolution equations with the NLO splitting function in the small-x limit is presented.We first obtain simplified forms of the LO and NLO splitting functions in the small-x limit.With these approximated splitting functions,we obtain the analytical gluon distribution using the Mellin transform.The free parameters in the boundary conditions are obtained by fitting the CJ15 gluon distribution data.We find that the asymptotic behavior of the gluon distribution is consistent with the CJ15 data;however,the NLO results considering the"ladder"structure of gluon emission are slightly better than the LO results.These results indicate that the corrections from NLO have a significant influence on the behavior of the gluon distribution in the small-x region.In addition,we investigate the DGLAP evolution of the proton structure function using the analytical solution of the gluon distribution.The differential structure function reveals that our results have a similar tendency to the CJ15 data at small-x.

Relativistic correction to gluon fragmentation function into pseudoscalar quarkonium

Inspired by the recent measurements of the ηc meson production at LHC experiments, we investigate the relativistic correction effect for the fragmentation functions of gluon/charm quark fragmenting into ηc, which constitute the crucial nonperturbative element for the ηc production at high pT. Employing three distinct methods,we calculate the next-to-leading-order（NLO） relativistic correction to g →ηc fragmentation function in the NRQCD factorization framework, as well as verifying the existing NLO result for the c →ηc fragmentation function. We also study the evolution behavior of these fragmentation functions with the aid of the DGLAP equation.