The two-loop fully differential soft function for $$Q\overline{Q }V$$ production at lepton colliders

Abstract We consider the production of a pair of heavy quarks $$Q\overline{Q }$$ in association with a generic colour singlet system V at lepton colliders, and present the first analytic calculation of the two-loop soft function differential in the total momentum of the real radiation. The calculati...

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Main Authors: Ze Long Liu, Pier Francesco Monni
Format: Article
Language:English
Published: SpringerOpen 2025-03-01
Series:Journal of High Energy Physics
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Online Access:https://doi.org/10.1007/JHEP03(2025)096
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author Ze Long Liu
Pier Francesco Monni
author_facet Ze Long Liu
Pier Francesco Monni
author_sort Ze Long Liu
collection DOAJ
description Abstract We consider the production of a pair of heavy quarks $$Q\overline{Q }$$ in association with a generic colour singlet system V at lepton colliders, and present the first analytic calculation of the two-loop soft function differential in the total momentum of the real radiation. The calculation is performed by reducing the relevant Feynman integrals into a canonical basis of master integrals by means of integration-by-parts identities. The resulting integrals are then evaluated by solving a system of differential equations in the kinematic invariants, whose boundary conditions are determined analytically with some care due to the presence of Coulomb singularities. The fully differential soft function is expressed in terms of Goncharov polylogarithms. This result is an essential ingredient for a range of N3LL resummations for key collider observables at lepton colliders, such as the $$Q\overline{Q }V$$ production cross section at threshold and observables sensitive to the total transverse momentum of the radiation in heavy-quark final states. Moreover, it constitutes the complete final-final dipole contribution to the fully differential soft function needed for the description of $$Q\overline{Q }V$$ production at hadron colliders, which plays an important role in the LHC physics programme.
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spelling doaj-art-b5646268bc864a87bf79be7a13a4b3402025-08-20T02:16:56ZengSpringerOpenJournal of High Energy Physics1029-84792025-03-012025312110.1007/JHEP03(2025)096The two-loop fully differential soft function for $$Q\overline{Q }V$$ production at lepton collidersZe Long Liu0Pier Francesco Monni1Theoretical Physics Division, Institute of High Energy Physics, Chinese Academy of SciencesCERN, Theoretical Physics DepartmentAbstract We consider the production of a pair of heavy quarks $$Q\overline{Q }$$ in association with a generic colour singlet system V at lepton colliders, and present the first analytic calculation of the two-loop soft function differential in the total momentum of the real radiation. The calculation is performed by reducing the relevant Feynman integrals into a canonical basis of master integrals by means of integration-by-parts identities. The resulting integrals are then evaluated by solving a system of differential equations in the kinematic invariants, whose boundary conditions are determined analytically with some care due to the presence of Coulomb singularities. The fully differential soft function is expressed in terms of Goncharov polylogarithms. This result is an essential ingredient for a range of N3LL resummations for key collider observables at lepton colliders, such as the $$Q\overline{Q }V$$ production cross section at threshold and observables sensitive to the total transverse momentum of the radiation in heavy-quark final states. Moreover, it constitutes the complete final-final dipole contribution to the fully differential soft function needed for the description of $$Q\overline{Q }V$$ production at hadron colliders, which plays an important role in the LHC physics programme.https://doi.org/10.1007/JHEP03(2025)096FactorizationRenormalization GroupResummation
spellingShingle Ze Long Liu
Pier Francesco Monni
The two-loop fully differential soft function for $$Q\overline{Q }V$$ production at lepton colliders
Journal of High Energy Physics
Factorization
Renormalization Group
Resummation
title The two-loop fully differential soft function for $$Q\overline{Q }V$$ production at lepton colliders
title_full The two-loop fully differential soft function for $$Q\overline{Q }V$$ production at lepton colliders
title_fullStr The two-loop fully differential soft function for $$Q\overline{Q }V$$ production at lepton colliders
title_full_unstemmed The two-loop fully differential soft function for $$Q\overline{Q }V$$ production at lepton colliders
title_short The two-loop fully differential soft function for $$Q\overline{Q }V$$ production at lepton colliders
title_sort two loop fully differential soft function for q overline q v production at lepton colliders
topic Factorization
Renormalization Group
Resummation
url https://doi.org/10.1007/JHEP03(2025)096
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