# Pseudoscalar Higgs boson pair production at a photon-photon collision in the two Higgs doublet model

## TL;DR

This paper investigates pseudoscalar Higgs boson pair production in photon-photon collisions within the two Higgs doublet model, analyzing one-loop contributions, polarization effects, and parameter space implications to understand potential signals of new physics.

## Contribution

It provides a detailed analysis of pseudoscalar Higgs pair production at one-loop level in the THDM, including polarization effects and parameter space scans, which is novel in this context.

## Key findings

- Box diagrams dominate at high energies.
- Cross section can be doubled with opposite photon polarization.
- Threshold effects significantly enhance production rates.

## Abstract

In this study, the direct pair production of the pseudoscalar Higgs boson at a photon-photon collision is analyzed in the context of two Higgs doublet model, taking account the complete one-loop contributions. In order to illustrate the effect of the new physics, four benchmark points scenarios, which are consistent with theoretical and current experimental constraints, are chosen in the type-I of THDM with an exact alignment limit. In these benchmark points, the CP even lightest Higgs boson ($h^0$) have the Standard Model like couplings to the gauge bosons. The effect of individual contributions from each type of one-loop diagrams on the total cross section are examined in detail. The dependence of total cross section on the center-of-mass energy is also presented at the various polarization configurations of the incoming photons. Moreover, the regions $m_{12}^2-\tan\beta$ and $m_A-\tan\beta$ in the parameter space of the THDM are scanned for some fixed values of other parameters. The box-type diagrams make a much larger contribution to the total cross section than the others at high energies. Total cross section can be enhanced by a two factor thanks to opposite polarized photons as well as threshold effects.