Atomic mass, Bjorken variable, and scale dependence of quark transport coefficient in Drell-Yan process for proton incident on nucleus

By means of the nuclear parton distributions determined without the fixed-target Drell-Yan experimental data and the analytic expression of quenching weight based on the BDMPS formalism, next-to-leading order analyses were performed on the Drell-Yan differential cross section ratios from the Fermilab E906 and E866 collaborations. It was found that the results calculated only with the nuclear effects of the parton distribution were not in agreement with the E866 and E906 experimental data. The incoming parton energy loss effect cannot be ignored in the nuclear Drell-Yan reactions. The predicted results indicate that, with the quark transport coefficient as a constant, the suppression due to the target nuclear geometry effect is approximately% for the quark transport coefficient. It was shown that we should consider the target nuclear geometry effect in studying the Drell-Yan reaction on nuclear targets. On the basis of the Bjorken variable and scale dependence of the quark transport coefficient, the atomic mass dependence was incorporated. The quark transport coefficient was determined as a function of the atomic mass, Bjorken variable x(2) , and scale Q(2 )by the global fit of the experimental data. The determined constant factor of the quark transport coefficient is 0 0.062 +/- 0.006 GeV2/fm. It was found that the atomic mass dependence has a significant impact on the constant factor q(0)( circumflex expressionccent ) in the quark transport coefficient in cold nuclear matter.

Automated summary

By using nuclear parton distributions and the analytic expression of quenching weight, next-to-leading order analyses were performed on Drell-Yan differential cross section ratios. It was found that considering only nuclear effects could not match the experimental data. The energy loss effect of incoming partons cannot be ignored in nuclear Drell-Yan reactions. The determined quark transport coefficient shows a significant dependence on atomic mass in cold nuclear matter.