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arXiv 0802.0139hep-ph
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用RHIC数据对核部分子分布函数进行改进的整体分析

An improved global analysis of nuclear parton distribution functions including RHIC data

K. J. Eskola, H. Paukkunen, C. A. Salgado

摘要:

我们提出了一个改进的领先级的核部分子分布函数(nPDFs)的全球DGPs分析,补充了传统上使用的数据,从深非弹性轻子-核散射和Drell-Yan双轻子生产的质子-核碰撞,包括高$p_T$强子生产数据测量在RHIC在d+Au碰撞。借助$χ^2$函数的扩展定义,我们现在可以更有效地利用不同数据集提供的约束,特别是胶子阴影,并在自动$χ^2$最小化过程中考虑整体数据归一化的不确定性。与所使用的核硬工艺数据的非常好的同时拟合证明了一套通用nPDF的可行性,但局限性也变得明显。BRAHMS的高$p_T$前向快度强子数据为分析增加了一个新的关键约束,它提供了对核胶子分布的直接探测--这是nPDF中传统上受到非常严重约束的一个部分。我们得到了一个显着更强的胶子阴影比已经在以前的全球分析估计。获得的nPDF作为称为EPS 08的参数化发布。

英文摘要:

We present an improved leading-order global DGLAP analysis of nuclear parton distribution functions (nPDFs), supplementing the traditionally used data from deep inelastic lepton-nucleus scattering and Drell-Yan dilepton production in proton-nucleus collisions, with inclusive high-$p_T$ hadron production data measured at RHIC in d+Au collisions. With the help of an extended definition of the $χ^2$ function, we now can more efficiently exploit the constraints the different data sets offer, for gluon shadowing in particular, and account for the overall data normalization uncertainties during the automated $χ^2$ minimization. The very good simultaneous fit to the nuclear hard process data used demonstrates the feasibility of a universal set of nPDFs, but also limitations become visible. The high-$p_T$ forward-rapidity hadron data of BRAHMS add a new crucial constraint into the analysis by offering a direct probe for the nuclear gluon distributions -- a sector in the nPDFs which has traditionally been very badly constrained. We obtain a strikingly stronger gluon shadowing than what has been estimated in previous global analyses. The obtained nPDFs are released as a parametrization called EPS08.

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