权益分类	功能权益	普通用户	{{item.name}}会员
{{category.name}}	{{benefitItem.name}}

Global analysis of light-hadron fragmentation functions with small-x improvement through soft-gluon logarithm resummation

通过软胶子对数恢复进行小 x 改进的轻强子碎裂函数的全局分析

基本信息

批准号：
5434013
负责人：
Professor Dr. Bernd A. Kniehl
金额：
--
依托单位：
II. Institut für Theoretische Physik
依托单位国家：
德国
项目类别：
Research Grants
财政年份：
2004
资助国家：
德国
起止时间：
2003-12-31 至 2016-12-31
项目状态：
已结题

来源：
https://gepris.dfg.de/gepris/projekt/5434013?language=en
关键词：
Global analysis light hadron fragmentation

项目摘要

Fragmentation functions (FF's) for charged light hadrons have been well determined over large and intermediate values of the hadronic momentum fraction z, where z is the variable of integration in the convolution of FF's with coefficient functions, by fitting to a wealth of experimental data. However, small x data, where x is the experimentally set kinematic variable equal to the lower bound on z in the voncolution, have always been excluded since the current fixed-order calculation of the hard part is believed to be too inaccurate in this region due to singularities that arise as x vanishes, and so FF's are not well understood at small z. However, it is possible to resum these singularities via the modified leading logarithmic approximation (MLLA), and so improve the accuracy of the hard part at smaller x. The aim of this project is to extend current analyses of FF's over a wider range of z. This will also provide a test of the MLLA in the perturbative region without using the assumptions of the local parton-hadron duality (LPHD) model as is normally the case. From the conceptual point of view, a new theoretical framework needs to be elaborated that properly combines the MLLA, appropriate for the small x region, with the conventional evolution by Dokshitser, Gribov, Lipatov, Altarelli and Parisi (DGLAP), valid at higher x, such that all leading and next-to-leading of x and energy are simultaneously resummed to all orders.

通过对大量实验数据的拟合，很好地确定了带电轻强子的碎裂函数在强子动量分数z的大值和中值范围内的值，其中z是强子碎裂函数与系数函数卷积的积分变量。然而，小的x数据一直被排除在外，其中x是实验设置的运动变量等于卷积中z的下界，因为当前的硬部分的定阶计算由于x消失时出现的奇点而被认为在该区域太不准确，因此在小z处不能很好地理解Ff。然而，通过改进的领先对数近似(MLLA)来重新求出这些奇点是可能的，这个项目的目的是在更大的z范围内扩展目前对FF的分析。这也将在微扰区提供对MLLA的测试，而不像通常情况下使用局部部分子-强子对偶(LPHD)模型的假设。从概念的角度来看，需要制定一个新的理论框架，将适用于小x区域的MLLA与Dokshitser、Gribov、Lipatov、Altarelli和Parisi的传统进化(DGLAP)恰当地结合在一起，从而使x和能量的所有前导和次前导同时恢复到所有阶。