Timelike Transition Form Factor for CP-odd Higgs Boson Production

TL;DR

This paper calculates the timelike transition form factor for CP-odd Higgs boson production in electron-positron collisions, highlighting the dominant top-quark loop contribution and its relation to spacelike form factors, with minimal impact from supersymmetric particles.

Contribution

It provides the first detailed calculation of the timelike transition form factor for CP-odd Higgs production, linking it to spacelike form factors and assessing supersymmetric contributions.

Findings

Top-quark loops dominate the production amplitude.

The timelike form factor is related to the spacelike form factor.

Supersymmetric contributions are negligible.

Abstract

We investigate the production of CP-odd Higgs boson $A^0$ associated with a real $\gamma$ in $e^+e^-$ collisions. Because of the properties of $A^0$ coupling to the other fields, the main contribution comes from the top-quark triangle loop diagrams. We obtain the timelike transition form factor which describes the production amplitude of $A^0$ in the $e^+e^-$ collisions. This timelike transition form factor is related to the spacelike transition form factor relevant for the $A^0$ production in $e^-\gamma$ collisions. It turns out that the possible extra contributions from chargino-sneutrino and neutralino-selectron box diagrams do not give sizable effects.