Nuclear parton distributions and structure functions

核部分子分布和结构函数

基本信息

批准号：
19540306
负责人：
BENTZ Wolfgang
金额：
$ 1.75万
依托单位：
Tokai University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2007
资助国家：
日本
起止时间：
2007 至 2009
项目状态：
已结题

项目摘要

The parton distributions and structure function of a nucleon bound in the nucleus are different from the case of a free nucleon. We assessed these medium effects quantitatively, and performed calculations for several nuclear targets. We also evaluated the fragmentation functions, which describe meson production in deep inelastic scattering processes.For our model calculations, we used the Nambu-Jona-Lasinio (NJL) model to describe the nucleon as a 3-quark bound state. Nuclear matter and finite nuclei were described in the mean field approximation, taking into account the internal quark structure of the nucleons. The parton distributions in the nuclear medium were obtained by a convolution of the parton distributions in the single nucleon and the nucleon distributions in the medium. Using this method, we predicted the spin-dependent parton distributions for several nuclei, and pointed out the importance of medium modifications. We also assessed the flavor dependence of the nuclear parton distributions, and applied our results to deep inelastic neutrino scattering from nuclear targets (NuTeV experiment) and parity-violating electron scattering. One of our main conclusions was that the famous problem of the NuTeV anomaly can be solved by taking into account the medium modifications of parton distributions.For the description of the fragmentation functions we also used the NJL model. We described pion production in semi-inclusive high energy scattering processes, taking into account the multifragmentation processes in the framework of the jet-model. We compared our results with recent analyses of semi-inclusive pion production data, and pointed out the important role of the multifragmentation processes.

核中结合的核子的Parton分布和结构功能与游离核子不同。我们定量评估了这些培养基，并对几个核靶标进行了计算。我们还评估了碎片函数，这些函数描述了深度非弹性散射过程中的介子产生。对于我们的模型计算，我们使用Nambu-Jona-Lasinio（NJL）模型将核子描述为三夸克结合的状态。考虑到核的内部夸克结构，在平均场近似中描述了核问题和有限核。核培养基中的Parton分布是通过单核中Parton分布的卷积获得的，在培养基中的核子分布。使用这种方法，我们预测了几个核的自旋依赖性parton分布，并指出了培养基修饰的重要性。我们还评估了核部分分布的风味依赖性，并将结果应用于核靶标（NUTEV实验）和奇偶估性电子散射的深度非弹性中微子散射。我们的主要结论之一是，可以通过考虑Parton分布的介质修改来解决NUTEV异常的著名问题。对于碎片函数的描述，我们还使用了NJL模型。我们描述了半散发器散射过程中的pion产生，并考虑了喷射模型框架中的多重碎片化过程。我们将我们的结果与最近对半斜杆生产数据的分析进行了比较，并指出了多碎片化过程的重要作用。