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Top quark pair production near threshold: single/double distributions and mass determination
Journal of High Energy Physics ( IF 5.0 ) Pub Date : 2020-06-01 , DOI: 10.1007/jhep06(2020)158
Wan-Li Ju , Guoxing Wang , Xing Wang , Xiaofeng Xu , Yongqi Xu , Li Lin Yang

We investigate top quark pair production near the threshold where the pair invariant mass M t t ¯ $$ {M}_{t\overline{t}} $$ approaches 2 m t , which provides sensitive observables to extract the top quark mass m t . Using the effective field theory methods, we derive a factorization and resummation formula for kinematic distributions in the threshold limit up to the next-to- leading power, which resums higher order Coulomb corrections to all orders in the strong coupling constant. Our formula is similar to those in the literature but differs in several important aspects. We apply our formula to the M t t ¯ $$ {M}_{t\overline{t}} $$ distribution, as well as to the double differential cross section with respect to M t t ¯ $$ {M}_{t\overline{t}} $$ and the rapidity of the t t ¯ $$ t\overline{t} $$ pair. We find that the resummation effects significantly increase the cross sections near the threshold, and lead to predictions better compatible with experimental data than the fixed-order ones. We demonstrate that incorporating resummation effects in the top quark mass determination can shift the extracted value of m t by as large as 1.4 GeV. The shift is much larger than the estimated uncertainties in previous experimental studies, and leads to a value of the top quark pole mass more consistent with the current world average.

中文翻译:

接近阈值的顶夸克对产生:单/双分布和质量测定

我们在阈值附近调查顶夸克对的产生,其中对不变质量 M tt¯ $$ {M}_{t\overline{t}} $$ 接近 2 mt ,这提供了敏感的观测值来提取顶夸克质量 mt 。使用有效的场论方法,我们推导出了阈限内运动学分布的分解和求和公式,直到次领先功率,它恢复了对强耦合常数中所有阶次的高阶库仑校正。我们的公式与文献中的公式相似,但在几个重要方面有所不同。我们将我们的公式应用于 M tt ¯ $$ {M}_{t\overline{t}} $$ 分布,以及关于 M tt ¯ $$ {M}_{t 的双微分横截面\overline{t}} $$ 和 tt ¯ $$ t\overline{t} $$ 对的快速性。我们发现恢复效应显着增加了阈值附近的横截面,并导致预测与实验数据比固定顺序更好地兼容。我们证明,在顶夸克质量测定中加入恢复效应可以将 mt 的提取值移动 1.4 GeV。这种转变比之前实验研究中估计的不确定性要大得多,并导致顶夸克极质量的值与当前的世界平均值更加一致。
更新日期:2020-06-01
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