Scalar-pseudoscalar pair production at the Large Hadron Collider at NLO+NLL accuracy in QCD

TL;DR

This paper analyzes scalar-pseudoscalar pair production at the LHC, incorporating NLO+NLL QCD resummation effects and introducing a new factorization method for threshold resummation, highlighting the significance of resummed PDFs.

Contribution

It introduces a novel factorization approach to combine soft-gluon resummation with PDFs and assesses their impact on scalar-pseudoscalar production at the LHC.

Findings

Threshold-resummation improved PDFs significantly affect high invariant mass predictions.

Electroweak quark-antiquark annihilation dominates over gluon fusion by 10-100 times.

Resummation effects are comparable to matrix element resummation, especially at high energies.

Abstract

We thoroughly investigate both transverse momentum and threshold resummation effects on scalar-pseudoscalar pair production via quark-antiquark annihilation at the $13~ \text{TeV}$ Large Hadron Collider at QCD NLO+NLL accuracy. A factorization method is introduced to properly supplement the soft-gluon (threshold) resummation contribution from parton distribution functions to the resummed results obtained by the Collins-Soper-Sterman resummation approach. We find that the impact of the threshold-resummation improved PDFs is comparable to the resummation effect of the partonic matrix element and can even predominate in high invariant mass regions. Moreover, the loop-induced gluon-gluon fusion channel in the type-I two-Higgs-doublet model is considered in our calculation. The numerical results show that the electroweak production via quark-antiquark annihilation dominates over the gluon-initiated QCD production by $1 \sim 2$ orders of magnitude.