Heavy quark jet production near threshold
Heavy quark jet production near threshold
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DOI：
10.1007/jhep09(2021)148
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发表时间：
2021-04
影响因子：
5.4
通讯作者：
L. Dai;Chul Kim;A. Leibovich
中科院分区：
文献类型：
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作者：
L. Dai;Chul Kim;A. Leibovich
在本文中，我们研究了在阈值附近重夸克碎裂成喷注的过程，这意味着末态喷注携带了碎裂重夸克的大部分能量。利用重夸克碎裂函数，我们同时求出喷流半径R和1− z的大值，其中z是喷流能量与初始重夸克能量的比值。由于这一重申，对领先订单率有数值上的显著修正。我们还研究了重夸克碎裂到修饰喷流，使用软滴修饰算法作为一个例子。为了做到这一点，我们引入了共线超软模式敏感的梳理区域所确定的算法的z切割参数。这使得我们可以对z cut/（1− z）的大范围求和，再次导致端点附近的大数值修正。分析重夸克碎裂成修饰喷流的一个很好的特点是，重夸克质量m使算法具有红外有限性，允许微扰计算。我们对EJ R m和EJ R» m进行分析，其中EJ是射流能量。为了实现后一种情况，我们引入了一个超共线软模式，使我们能够恢复大的EJR/m的矩阵。最后，作为一个应用，我们计算了e+ e−碰撞在端点区域产生重夸克喷流的速率，在那里我们表明梳理效应在端点附近有相当大的贡献。
In this paper, we study the fragmentation of a heavy quark into a jet near threshold, meaning that final state jet carries most of the energy of the fragmenting heavy quark. Using the heavy quark fragmentation function, we simultaneously resum large logarithms of the jet radius R and 1− z, where z is the ratio of the jet energy to the initiating heavy quark energy. There are numerically significant corrections to the leading order rate due to this resummation. We also investigate the heavy quark fragmentation to a groomed jet, using the soft drop grooming algorithm as an example. In order to do so, we introduce a collinear-ultrasoft mode sensitive to the grooming region determined by the algorithm’s z cut parameter. This allows us to resum large logarithms of z cut/(1− z), again leading to large numerical corrections near the endpoint. A nice feature of the analysis of the heavy quark fragmenting to a groomed jet is the heavy quark mass m renders the algorithm infrared finite, allowing a perturbative calculation. We analyze this for E J R∼ m and E J R» m, where E J is the jet energy. To do the latter case, we introduce an ultracollinear-soft mode, allowing us to resum large logarithms of E J R/m. Finally, as an application we calculate the rate for e+ e− collisions to produce a heavy quark jet in the endpoint region, where we show that grooming effects have a sizable contribution near the endpoint.