CP violation in a light Higgs boson decay from tau-spin correlations at a linear collider

TL;DR

This paper proposes a new method to measure CP violation in Higgs boson decays to tau pairs at a linear collider, focusing on transverse spin correlations and robustness against beamstrahlung effects.

Contribution

It introduces a novel technique for analyzing tau-spin correlations in Higgs decays that is insensitive to beamstrahlung, with promising error estimates for CP phase measurement.

Findings

Method effectively measures CP violation in Higgs decays.

Estimated error on CP phase measurement is promising.

Technique is robust against beamstrahlung effects.

Abstract

We present a new method to measure the transverse spin correlation in the $H\to\tau^+\tau^-$ decay. The method has been devised to be insensitive to the beamstrahlung which affects the definition of the beam energy at a linear collider. In the case of two $\tau\to\pi^\nu$ decays, using the anticipated detector performance of the TESLA project, we get a promising estimation of the error expected on the measurement of a CP violating phase.