NLO massive event-shape differential and cumulative distributions

Author(s)
Christopher Lepenik, Vicent Mateu
Abstract

We provide a general method to effectively compute differential and cumulative event-shape distributions to $\mathcal{O}(\alpha_s)$ precision for massive quarks produced primarily at an $e^+e^-$ collider. In particular, we show that at this order, due to the screening of collinear singularities by the quark mass, for all event shapes linearly sensitive to soft dynamics, there appear only two distributions at threshold: a Dirac delta function and a plus distribution. Furthermore, we show that the coefficient of the latter is universal for any infra-red and collinear safe event shape, and provide an analytic expression for it. Likewise, we compute a general formula for the coefficient of the Dirac delta function, which depends only on the event-shape measurement function in the soft limit. Finally, we present an efficient algorithm to compute the differential and cumulative distributions, which does not rely on Monte Carlo methods, therefore achieving a priory arbitrary precision even in the extreme dijet region. We implement this algorithm in a numeric code and show that it agrees with analytic results on the distribution for 2-jettiness, heavy jet mass and a massive generalization of C-parameter.

Organisation(s)
Particle Physics
External organisation(s)
Journal
Journal of High Energy Physics
Volume
2020
No. of pages
52
ISSN
1029-8479
DOI
https://doi.org/10.1007/JHEP03(2020)024
Publication date
12-2019
Peer reviewed
Yes
Austrian Fields of Science 2012
103034 Particle physics
Keywords
Portal url
https://ucris.univie.ac.at/portal/en/publications/nlo-massive-eventshape-differential-and-cumulative-distributions(8daa68cb-c793-4b8b-8d46-f430c89c0b42).html