Deep Neural Network application: Higgs boson CP state mixing angle in H to tau tau decay and at LHC

Abstract

The consecutive steps of cascade decay initiated by H → ττ can be useful for the measurement of Higgs couplings and in particular of the Higgs boson parity. In the previous papers we have found, that multi-dimensional signatures of the τ ± → π ± π 0 ν and τ ± → 3π ± ν decays can be used to distinguish between scalar and pseudoscalar Higgs state. The Machine Learning techniques (ML) of binary classification, offered break-through opportunities to manage such complex multidimensional signatures.The classification between two possible CP states: scalar and pseudoscalar, is now extended to the measurement of the hypothetical mixing angle of Higgs boson parity states. The functional dependence of H → ττ matrix element on the mixing angle is predicted by theory. The potential to determine preferred mixing angle of the Higgs boson events sample including τ-decays is studied using Deep Neural Network. The problem is addressed as classification or regression with the aim to determine the per-event: a) probability distribution (spin weight) of the mixing angle; b) parameters of the functional form of the spin weight; c) the most preferred mixing angle. Performance of methods are evaluated and compared. Numerical results are collected.

$CP$ violation from $τ$, $t$ and $b$ dimension-6 Yukawa couplings -- interplay of baryogenesis, EDM and Higgs physics

“…An experimental HL-LHC projection [36] and several phenomenological analyses [37][38][39][40] have already been performed in this direction. Machine Learning (ML) may also play a useful role in further scrutinizing the CP nature of the Higgs-τ interaction [41,42]. In addition, CP analyses of the t-Higgs coupling have been proposed, including ML [43][44][45].…”

Testing CP Properties of Extra Higgs States at the HL-LHC

“…• The CP transformation property of the H i can be inferred from its decays to tau lepton pairs. To be specific, the correlation of the tau lepton polarisation planes are directly linked to the CP properties of the parent, and they can be reconstructed via the hadronic decay modes of the two tau leptons [19,[39][40][41][42][43]. In the following we will focus on this method in the main part of the paper.…”