Abstract

When a TeV-scale leptoquark has a sizeable Yukawa coupling, its dominant production mechanism at hadron colliders is the partonic-level lepton-quark fusion. Even though the parton distribution functions for leptons inside the proton are minuscule, they get compensated by the resonant enhancement. We present the first computation of higher order radiative corrections to the resonant leptoquark production cross section at the Large Hadron Collider (LHC). Next-to-leading (NLO) QCD and QED corrections are similar in size but come with the opposite sign. We compute NLO K-factors for a wide range of scalar leptoquark masses, as well as, all possible combinations of quark and lepton flavors and leptoquark charges. Theoretical uncertainties due to the renormalisation and factorisation scale variations and the limited knowledge of parton distribution functions are quantified. We finally discuss how to disentangle the flavor structure of leptoquark interactions by exploiting the interplay between different production channels.

Highlights

  • Scalar leptoquark resonant productionThe inevitable condition for a field coupling quarks and leptons at the tree level is to transform in the (anti)fundamental representation of the SU(3) part of the SM gauge group

  • L (c) entirely by the strong coupling αs and the leptoquark mass mLQ

  • A discovery of a leptoquark at the Large Hadron Collider would fundamentally change our understanding of particle physics, pointing towards a microscopic theory where quarks and leptons unify

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Summary

Scalar leptoquark resonant production

The inevitable condition for a field coupling quarks and leptons at the tree level is to transform in the (anti)fundamental representation of the SU(3) part of the SM gauge group. In the absence of fermion masses, possible interference terms involving left- and right-handed Yukawa couplings vanish This allows us to independently treat processes in which leptoquark is resonantly produced by the same flavor combination of quarks and leptons, but of the opposite chirality. We summarize that scalar leptoquarks (SLQs) are SU(3) triplets, with four possible values of the electric charge, and their resonant production cross section is determined by the entries in the Yukawa matrices without interference. This exhausts all possibilities for SLQs and we conclude that our computation could be matched to any model containing these particles.

Next-to-leading order QCD corrections
Next-to-leading order QED corrections
Numerical results and discussion
Conclusions
A NLO QED corrections to resonant production
Virtual QCD corrections
Real QCD corrections
Findings
C Supplemental numerical results
Full Text
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