Measuring Higgs CP and couplings with hadronic event shapes

TL;DR

This paper proposes using hadronic event shapes as a novel method to determine the CP properties and couplings of the Higgs boson, offering potentially more sensitive discrimination than traditional jet angular correlations.

Contribution

It introduces hadronic event shapes as a new tool for Higgs CP and coupling measurements, surpassing azimuthal angle correlations in sensitivity.

Findings

Hadronic event shapes effectively distinguish CP even and CP odd Higgs bosons.

Event shapes show increased sensitivity to Higgs CP properties over traditional methods.

Strategies are proposed to separate weak boson fusion and gluon fusion production modes using event shapes.

Abstract

Experimental falsification or validation of the Standard Model of Particle Physics involves the measurement of the CP quantum number and couplings of the Higgs boson. Both ATLAS and CMS have reported an SM Higgs-like excess around m_H=125 GeV. In this mass range the properties of the Higgs boson can be extracted from an analysis of the azimuthal angle distribution of the two jets in pp->Hjj events. This channel is also important to measure the couplings of the Higgs boson to electroweak gauge bosons and fermions, hereby establishing the exceptional role of the Higgs boson in the Standard Model. Instead of exploiting the jet angular correlation, we show that hadronic event shapes exhibit substantial discriminative power to separate a CP even from a CP odd Higgs. Some event shapes even show an increased sensitivity to the Higgs CP compared to the azimuthal angle correlation. Constraining the Higgs couplings via a separation of the weak boson fusion and the gluon fusion Higgs production modes can be achieved applying similar strategies.