Improving the understanding of jet grooming in perturbation theory
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Springer
Received: July 9, 2020 Accepted: August 12, 2020 Published: September 9, 2020
Andrew J. Larkoski Physics Department, Reed College, 3203 SE Woodstock Blvd., Portland, OR 97202, U.S.A.
E-mail: [email protected] Abstract: Jet grooming has emerged as a necessary and powerful tool in a precision jet physics program. In this paper, we present three results on jet grooming in perturbation theory, focusing on heavy jet mass in e+ e− → hadrons collisions, groomed with the modified mass drop tagger. First, we calculate the analytic cross section at leading-order. Second, using the leading-order result and numerical results through next-to-next-to-leading order, we show that cusps in the distribution on the interior of phase space at leading-order are softened at higher orders. Finally, using analytic and numerical results, we show that terms that violate the assumptions of the factorization theorem for groomed jet mass are numerically much smaller than expected from power counting. These results provide important information regarding the convergence of perturbation theory for groomed jet observables and reliable estimates for residual uncertainties in a precision calculation. Keywords: Jets, NLO Computations ArXiv ePrint: 2006.14680
c The Authors. Open Access, Article funded by SCOAP3 .
https://doi.org/10.1007/JHEP09(2020)072
JHEP09(2020)072
Improving the understanding of jet grooming in perturbation theory
Contents 1
2 Leading-order distribution
2
3 Cusps at fixed order
5
4 Factorization-violating contributions
8
5 Conclusions
1
12
Introduction
A precision program for jet substructure calculations and measurements has developed through advances in jet grooming algorithms. Because of its mitigation of non-global logarithms [1] that would inhibit systematic improvability of theoretical predictions, the modified mass drop tagger (mMDT) groomer [2, 3], and its generalization soft drop [4], have emerged as the necessary tools for the precision task. Following the original papers that introduced the groomers, a large literature of calculations and applications has resulted [5– 26] and demonstrated that standard jet observables like the mass that have been groomed exhibit significantly improved sensitivity to the value of the strong coupling αs and over a much wider dynamic range than its ungroomed counterpart. This explosion of theoretical advances has been accompanied by measurements of groomed jet masses by both the ATLAS and CMS collaborations at the Large Hadron Collider (LHC) [27–29]. For simplicity, much of these theoretical analyses have focused on jet production in + − e e collisions, even further focused on center-of-mass energies of the Z pole. Recently, a re-analysis of archived data from the ALEPH experiment [30] at the Large ElectronPositron Collider (LEP) has demonstrated the proof-of-principle that studying jet grooming in e+ e− collisions can be more than just a purely academic exercise. In this paper, we restrict to jets in e+ e− collisions for these reasons. A precision prediction o
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