CP Asymmetry in Charged Higgs Decays to Chargino-Neutralino

TL;DR

This paper investigates CP asymmetry in charged Higgs decays to chargino-neutralino pairs, analyzing its magnitude, constraints, and observability at the LHC, with a focus on the most promising decay channel.

Contribution

It provides a detailed calculation of CP asymmetry in charged Higgs decays, incorporating experimental constraints and identifying the optimal channel for observation at the LHC.

Findings

Large branching ratio for m_H^- > 600 GeV

Constraints reduce the projected CP asymmetry

H^- -> chargino_1 + neutralino_2 is the best channel for detection

Abstract

We analyze the charge-parity (CP) asymmetry in the charged Higgs boson decays to chargino-neutralino pairs, H^- -> chargino_i + neutralino_j. We show first that these modes have a large branching ratio for m_H^- > 600 GeV. We use Cutkosky rules to obtain the analytical formulas needed for the evaluation of the asymmetry under consideration. We then calculate the CP asymmetry in chargino-neutralino decays by including supersymmetric mass bounds, as well as constraints from b -> s gamma, (g-2)_mu, Delta\rho and electric dipole moments. Finally, we discuss observability of the asymmetry at the LHC by calculating the number of required charged Higgs events to observe the asymmetry for each decay channel. We show that the inclusion of constraints considerably reduces the projected CP asymmetry, and that the optimal channel for observing the asymmetry is H^- -> chargino_1 + neutralino_2.