胶子到重夸克偶素的碎裂函数抽取问题讨论

On the Application of Gluon to Heavy Quarkonium Fragmentation Function

分析胶子到重夸克偶素的碎裂函数使用中,不同动量分数z的定义所带来的不确定性,用数值方法计算了常用的非协变z定义所给出的有限胶子动量下g→J/ψ的初始碎裂函数D_g→J/ψ(z,Qo),发现非协变定义给出的碎裂函数对胶子动量k有较大的依赖性.当|k|→∞时,相应碎裂函数趋于光锥定义下的碎裂函数;但k较小时(如在加速器Tevatron和LHC上产生胶子的典型能动量范围内),按非协变形式定义和使用碎裂函数会给计算带来较大的不确定性.

We analyze the uncertainties induced by different of gluon to heavy quarkonium fragmentation function. We definitions of the momentum fraction z in the application numerically calculate the initial g → J/ψ fragmentation functions by using the non-covariant definitions of z with finite gluon momentum and find that these fragmentation functions have strong dependence on the gluon momentum k. As ｜k｜→ ∞, these fragmentation functions approach to the fragmentation function in the light-cone definition. We find that when ｜k｜ is small （for instance in the typical energy scale （about 4-20GeV） of the gluon production at the hadron colliders, such as Tevatron and LHC）, large uncertainty remains while the in-covariant definitions of z are employed in the application of the fragmentation functions.