Probing the CP-Violation effects in the $h\tau\tau$ coupling at the LHC

TL;DR

This paper introduces a novel method for neutrino reconstruction in tau decays at the LHC, enabling precise measurement of the Higgs CP-violation effects in the $h\tau\tau$ coupling with improved accuracy over previous methods.

Contribution

It presents a new neutrino reconstruction technique that allows event-by-event Higgs mass and CP phase measurement in $h\tau\tau$ decays at the LHC.

Findings

Achieves a CP mixing angle measurement precision of 5.2 degrees.

Outperforms current lepton EDM constraints in sensitivity.

Demonstrates the feasibility with detailed detector simulation and 3 ab$^{-1}$ data.

Abstract

A new method used to calculate the neutrino for all major tau hadronic decay event by event at the LHC is presented. It is possible because nowadays better detector description is available. With the neutrino fully reconstructed, matrix element for each event can be calculated, the mass of the Higgs particle can also be calculated event by event with high precision. Based on these, the prospect of measuring the Higgs CP mixing angle with $h\to\tau\tau$ decays at the LHC is analyzed. It is predicted that, with a detailed detector simulation, with 3 ab$^{-1}$ of data at $\sqrt{s}=13$ TeV, a significant improvement of the measurement of the CP mixing angle to a precision of $5.2^\circ$ can be achieved at the LHC, which outperforms the sensitivity from lepton EDM searches up to date in the $h\tau\tau$ coupling.