Neutral Higgs-pair Production at one-loop from a Generic 2HDM

TL;DR

This paper analyzes neutral Higgs-pair production at one-loop in a general 2HDM, revealing large radiative corrections and distinctive signatures that could be observed at future linear colliders like ILC and CLIC.

Contribution

It provides the first detailed one-loop analysis of neutral Higgs-pair production in a general 2HDM, highlighting the impact of triple-Higgs self-interactions on production rates.

Findings

Radiative corrections can reach 50%, significantly affecting cross sections.

Higgs-pair production cross sections can be up to 30 fb at 500 GeV.

Distinctive signatures of 2HDM compared to other models are identified.

Abstract

We present a one-loop analysis of the pairwise production of neutral Higgs bosons (h0A0, H0A0) at linear colliders, such as the ILC and CLIC, within the general Two-Higgs-Doublet Model (2HDM). We single out sizable radiative corrections, which can well reach the level of 50 % and may be either positive (typically for \sqrt{s} \sim 0.5 TeV) and negative (for \sqrt{s} of 1 TeV and above). These large quantum effects, obtained in full agreement with the current phenomenological bounds and the stringent theoretical constraints on the parameter space of the model, can be traced back to the enhancement capabilities of the triple-Higgs self-interactions -- a trademark feature of the 2HDM, with no counterpart in e.g. the Minimal Supersymmetric Standard Model. In the most favorable scenarios, the Higgs-pair cross sections may be boosted up to barely 30 fb at the fiducial center-of-mass energy of 500 GeV -- amounting to a few thousand events per 500 inverse femtobarn of integrated luminosity. We also compare these results with several complementary double and triple Higgs-boson production mechanisms at order \alpha^3_{ew} and leading \alpha^4_{ew}, and we spotlight a plethora of potentially distinctive signatures of a Two-Higgs-Doublet structure of non-supersymmetric nature.