质子与原子核碰撞J/ψ产生过程中的能量损失效应

The effects of energy loss on J/ψ production in proton-nucleus collisions

在考虑初态部分子分布函数核效应、入射质子的能量损失效应,以及末态粲夸克对能量损失效应的基础上,对质子-原子核碰撞J/ψ产生过程的微分截面比RW/Be(xF)进行了领头阶的唯象分析,并与E866实验数据中代表J/ψ粒子在靶核外产生的实验数据进行比较,确定了粲夸克对的能量损失值(0.69±0.23)Ge V/fm.研究结果表明:当J/ψ粒子在靶核外形成时,末态粲夸克对的能量损失效应是影响J/ψ粒子产额压低的主要核效应;当xF较大时,初态入射质子的能量损失效应也是不可忽略的.

Considering the nuclear effects on parton distribution,the energy loss of beam proton in initial state,and the finial state energy loss of cc pair,the leading-order computations for J / ψ production cross-section ratios RW / Be（ xF） have been explored and compared with the selected E866 experimental data with the J/ψ production occurring outside the nucleus,the obtained energy loss of the color octet is（ 0.69±0.23） Ge V / fm.It has shown that with J / ψ production occurring outside the nucleus the energy loss of color octet in finial state plays a dominant role in the suppression of J / ψ production; in the larger xFrange,the influence of beam proton energy loss effect in initial state can not be ignored.