Importance of Lorentz structure in the parton model: Target mass corrections, transverse momentum dependence, positivity bounds
Importance of Lorentz structure in the parton model: Target mass corrections, transverse momentum dependence, positivity bounds
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洛伦兹结构在部分子模型中的重要性：目标质量修正、横向动量依赖性、正界
DOI：
10.1103/physrevd.81.036010
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发表时间：
2009
影响因子：
5
通讯作者：
UK.
中科院分区：
文献类型：
--
作者：
U. D’Alesio;E. Leader;F. Cagliari;I. Infn;Cagliari;I. I. College;London;UK.
我们表明，在帕顿模型中尊重潜在的洛伦兹结构具有非常强大的后果。没有坚持正确的洛伦兹协方差是导致极化结构函数g{sub 2}(x)在文献中存在矛盾结果的原因，而在正确的强制下，我们能够推导出g{sub 2}(x)的Wandzura-Wilczek关系和极化深度非弹性散射的目标质量修正，而无需诉诸算子积展开。我们简要地评论了目标质量修正存在时的阈值行为问题。对洛伦兹结构的仔细关注也对经常用于强子产生的部分子模型处理的横向动量依赖的部分子密度的结构有深远的影响，允许k{下标T}的依赖得到明确的推导。它还导致比通常用于共线密度的更强的正性和更软的类型边界。
We show that respecting the underlying Lorentz structure in the parton model has very strong consequences. Failure to insist on the correct Lorentz covariance is responsible for the existence of contradictory results in the literature for the polarized structure function g{sub 2}(x), whereas with the correct imposition we are able to derive the Wandzura-Wilczek relation for g{sub 2}(x) and the target-mass corrections for polarized deep inelastic scattering without recourse to the operator product expansion. We comment briefly on the problem of threshold behavior in the presence of target-mass corrections. Careful attention to the Lorentz structure has also profound implications for the structure of the transverse momentum dependent parton densities often used in parton model treatments of hadron production, allowing the k{sub T} dependence to be derived explicitly. It also leads to stronger positivity and Soffer-type bounds than usually utilized for the collinear densities.