Supersimple analysis of $e^-e^+\to ZH$ at high energy

TL;DR

This paper derives simple one-loop amplitude expressions for the $e^-e^+ o ZH$ process, aiding in distinguishing SM, MSSM, and other BSM effects through cross sections and asymmetries.

Contribution

It introduces supersimple expressions for one-loop helicity amplitudes in $e^-e^+ o ZH$, simplifying analysis and comparison of SM, MSSM, and BSM contributions.

Findings

Supersimple expressions accurately approximate one-loop amplitudes.

These expressions effectively differentiate SM, MSSM, and BSM effects.

Analysis of polarization and asymmetries enhances model discrimination.

Abstract

We study the process $e^-e^+\to ZH$ where $H$ represents the standard model (SM) Higgs particle $H_{SM}$, or the MSSM ones $h^0$ and $H^0$. In each case, we compute the one-loop effects and establish very simple expressions, called supersimple (sim), for the helicity conserving (dominant) and the helicity violating (suppressed) amplitudes. Such expressions, are then used to construct various cross sections and asymmetries, involving polarized or unpolarized beams and Z-polarization measurements. We examine the adequacy of such expressions to distinguish SM or MSSM effects, from other types of BSM (beyond the standard model) contributions.