Search for a heavy pseudoscalar Higgs boson decaying to a 125 GeV Higgs boson and a Z boson in final states with two tau and two light leptons in proton-proton collisions at $\sqrt{s}$ = 13 TeV

TL;DR

This paper reports a search for a heavy pseudoscalar Higgs boson decaying into a 125 GeV Higgs and a Z boson, using proton-proton collision data at 13 TeV, setting limits on production cross sections and constraining supersymmetric model parameters.

Contribution

First search to set experimental limits on heavy pseudoscalar Higgs decaying to Zh in final states with tau and light leptons at 13 TeV.

Findings

Upper limits on production cross sections range from 0.049 to 1.02 pb.

Excluded tanβ values below 2.2 for certain mass ranges.

Constraints on supersymmetric model parameters.

Abstract

A search for a heavy pseudoscalar Higgs boson, A, decaying to a 125 GeV Higgs boson h and a Z boson is presented. The h boson is identified via its decay to a pair of tau leptons, while the Z boson is identified via its decay to a pair of electrons or muons. The search targets the production of the A boson via the gluon-gluon fusion process, gg $\to$ A, and in association with bottom quarks, $\mathrm{b\bar{b}}$A. The analysis uses a data sample corresponding to an integrated luminosity of 138 fb$^{-1}$ collected with the CMS detector at the CERN LHC in proton-proton collisions at a centre-of-mass energy of $\sqrt{s}$ = 13 TeV. Constraints are set on the product of the cross sections of the A production mechanisms and the A $\to$ Zh decay branching fraction. The observed (expected) upper limit at 95% confidence level ranges from 0.049 (0.060) pb to 1.02 (0.79) pb for the gg $\to$ A process and from 0.053 (0.059) pb to 0.79 (0.61) pb for the $\text{b}\bar{\text{b}}$A process in the probed range of the A boson mass, $m_\text{A}$, from 225 GeV to 1 TeV. The results of the search are used to constrain parameters within the ${\text{M}_{\text{h,EFT}}^{\text{125}}}$ benchmark scenario of the minimal supersymmetric extension of the standard model. Values of $\tan\beta$ below 2.2 are excluded in this scenario at 95% confidence level for all $m_\text{A}$ values in the range from 225 to 350 GeV.