arXiv 0902.03722009-02-13hep-ph

从质子结构函数$F_2^{γp}(x,Q^2)$解析推导首阶胶子分布函数$G(x,Q^2)=xg(x,Q^2)$。II。重夸克效应

Analytic derivation of the leading-order gluon distribution function $G(x,Q^2)=xg(x,Q^2)$ from the proton structure function $F_2^{γp}(x,Q^2)$. II. Effect of heavy quarks

Martin M. Block, Loyal Durand

备注：: 19 pages, 6 figures and 1 table Sign typos in Eqs. 32-35 and some typos elsewhere corrected, results unchanged

阅读 PDF

arXiv 页面 ↗HTML 原文 ↗

摘要：

我们扩展了我们以前的推导的精确表达式的领导阶（LO）胶子分布函数$G(x,Q^2)=xg(x,Q^2)$从DGMEX演化方程的质子结构函数$F_2^{γp}(x,Q^2)$深非弹性$γ^* p$散射，包括重夸克质量的影响。我们推导方程$G(x,Q^2)$在两种不同的方式，首先使用我们原来的微分方程的方法，然后使用一种新的方法，拉普拉斯变换的基础上。这些结果不需要使用胶子演化方程，或者，为了更好的近似，不需要知道单个夸克的分布。给出一个解析表达式，它成功地再现了$F_2^{γp}(x,Q^2)$在域${\cal D}(x,Q^2)$中的已知实验数据--其中$x_{\rm min}(Q^2) \le x \le x_{\rm max}(Q^2)$，Bjorken变量$x$的$Q^2_{\rm min}\le Q^2\le Q^2_{\rm max}$和虚$Q^2$ -- $G(x,Q^2)$在同一域中唯一确定。作为该方法的一个应用，我们构造了一个新的全参数化的ZEUS数据集对$F_2^{γp}(x,Q^2)$，并用它确定了5夸克胶子分布$G(x,Q^2)$，对于无质量的$u, d, s$和有质量的$c, b$夸克，并讨论了结果中明显的质量效应.我们将这些结果与CTEQ 6 L的胶子分布进行了比较，在${\cal D}(x,Q^2)$域中，它们应该一致，但它们不一致;差异是由于CTEQ 6 L的结果没有准确描述ZEUS $F_2^{γp}(x,Q^2)$的实验数据。我们强调，我们的方法获得LO胶子分布连接$G(x,Q^2)$ { \em直接}的质子结构函数，而不需要单独的部分子分布或胶子演化方程。

英文摘要：

We extend our previous derivation of an exact expression for the leading-order (LO) gluon distribution function $G(x,Q^2)=xg(x,Q^2)$ from the DGLAP evolution equation for the proton structure function $F_2^{γp}(x,Q^2)$ for deep inelastic $γ^* p$ scattering to include the effects of heavy-quark masses. We derive the equation for $G(x,Q^2)$ in two different ways, first using our original differential-equation method, and then using a new method based on Laplace transforms. The results do not require the use of the gluon evolution equation, or, to good approximation, knowledge of the individual quark distributions. Given an analytic expression that successfully reproduces the known experimental data for $F_2^{γp}(x,Q^2)$ in a domain ${\cal D}(x,Q^2)$--where $x_{\rm min}(Q^2) \le x \le x_{\rm max}(Q^2)$, $Q^2_{\rm min}\le Q^2\le Q^2_{\rm max}$ of the Bjorken variable $x$ and the virtuality $Q^2$--$G(x,Q^2)$ is uniquely determined in the same domain. As an application of the method, we construct a new global parametrization of the complete set of ZEUS data on $F_2^{γp}(x,Q^2)$, and use this to determine the 5 quark gluon distribution, $G(x,Q^2)$, for massless $u, d, s$ and massive $c, b$ quarks and discuss the mass effects evident in the result. We compare these results to the gluon distributions for CTEQ6L, and in the domain ${\cal D}(x,Q^2)$ where they should agree, they do not; the discrepancy is due to the fact that the CTEQ6L results do not give an accurate description of the ZEUS $F_2^{γp}(x,Q^2)$ experimental data. We emphasize that our method for obtaining the LO gluon distribution connects $G(x,Q^2)$ {\em directly} to the proton structure function without either the need for individual parton distributions or the gluon evolution equation.

机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。

摘要：

英文摘要：

相关论文