有效场论在粒子物理唯象学的应用

The applicant has actively worked in the forefront of heavy quark physics for many years. Recently, he and his team have for the first time conducted the next-to-next-to-leading order (NNLO) radiative corrections calculation for several important heavy quarkonium exclusive production and inclusive decay processes, and pointed out that influential NRQCD approach might face crisis when applied to charmonium. Moreover, the applicant has recently done important work in higher order perturbative corrections for Higgs boson production at CEPC. As for this NSFC grant, the applicant plans to carry out the following studies in the forthcoming four years: investigating the NNLO radiative corrections to double charmonium exclusive production at B factory, within the NRQCD factorization framework; Computing a number of important parton-to-quarkonium fragmentation function to NLO in αs, hopeful to offer some help on alleviating the J/ψ production and polarization puzzle at large pT at LHC; Verifying the correctness of NRQCD factorization for the color-octet production mechanism at three-loop level; Conducting high precision calculation for the Higgs production cross section at CEPC; Promoting heavy-quark recombination mechanism to NLO in αs, for heavy-flavored meson production; Studying the exotic multi-quark state in two-dimensional QCD through large Nc expansion and discretized light-cone quantization (DLCQ) approach, hoping to provide some insight for understanding the properties of exotic X, Y, Z particles in the real world.

申请人多年来一直活跃在重夸克物理领域前沿。最近在重夸克偶素遍举产生和单举衰变过程率先计算了次次领头阶(NNLO）辐射修正，揭示了著名的NRQCD方法在应用到粲偶素是面临困境。另外，近年来申请人也在希格斯物理，尤其在CEPC上希格斯玻色子产生的高阶微扰修正方向做出了重要工作。对于本项目，申请人计划在接下的四年中做如下研究：在NRQCD因子化的框架内，考察B工厂双粲偶素遍举产生的次次领头阶辐射修正的效应；将一系列重要的部分子到夸克偶素的碎裂函数计算到αs的次领头阶，期待对阐释LHC上大横动量J/ψ产生极化疑难有所帮助；对NRQCD因子化应用于夸克偶素色八重态产生是否在三圈水平成立做检验；对CEPC上希格斯产生截面进行高精度计算；对于重味强子遍举产生，将重夸克重组机制推广到αs的次领头阶；在两维QCD下通大N展开及过离散化的光前量子化方法研究多夸克态，争取对理解X,Y, Z粒子的性质有所助益。

本项目基于非相对论性量子色动力学（NRQCD）的有效场论框架研究重夸克偶素物理。本项目计算了矢量夸克偶素ϒ和J/ψ单举强衰变宽度的O(αsv^2)阶联合修正；计算了B工厂粲偶素伴随光子遍举产生的次次领头阶辐射修正；在维数正规化方案下计算了胶子到P波自旋单态夸克偶素的碎裂函数；计算了胶子到Bc^(*)介子的碎裂函数；研究了矢量电中性介子衰变到四个带电轻子的稀有过程; 发展了HQET因子化框架描述重味介子遍举产生，并提出了一个新的因子化定理，揭示了关于刻画重味介子内秉性质的两个基本非微扰函数之间的深刻联系，对精确预言重味介子高能遍举产生有所裨益。 此外，本项目发展了模型无关的NRQCD因子化方法来研究全重四夸克态的产生，并预言了偶C宇称全粲四夸克态在LHC上的大横动量产生、S波全粲四夸克态在B工厂的单举及遍举产生截面。这一系列工作对于深入理解全重四夸克态的产生机制有着积极意义。