Two-loop BSM contributions to Higgs pair production in the aligned THDM

TL;DR

This paper analyzes how two-loop BSM Higgs couplings affect Higgs pair production in the aligned THDM, providing new calculations and assessing their numerical impact on cross section predictions.

Contribution

It presents the first computation of two-loop corrections to the $ ext{h} ext{h} ext{H}$ coupling and reassesses the $ ext{h} ext{h} ext{h}$ coupling in the aligned THDM.

Findings

Two-loop BSM contributions significantly modify Higgs pair production cross sections.

New calculations improve the precision of Higgs coupling predictions.

Numerical analysis shows notable effects in benchmark scenarios.

Abstract

We study the impact of the two-loop corrections controlled by the BSM Higgs couplings on the cross section for the production of a pair of SM-like Higgs bosons via gluon fusion in the aligned THDM. To this aim, we reassess the two-loop calculation of $\lambda_{hhh}$, we compute for the first time the two-loop corrections to $\lambda_{hhH}$, and we include the relevant corrections to the Higgs-gluon couplings and to the s-channel propagators entering the $gg \rightarrow hh$ amplitude. We discuss the numerical impact of the two-loop BSM contributions, first on the individual couplings and then on the prediction for the pair-production cross section, in two benchmark scenarios for the aligned THDM.