Top Decays with Flavor Changing Neutral Higgs Interactions at the LHC

TL;DR

This paper explores the potential to detect flavor-changing neutral Higgs decays of the top quark at the LHC, focusing on the decay $t o c ext{Higgs}$ within a two Higgs doublet model, and assesses the discovery prospects at different collider energies.

Contribution

It provides a detailed analysis of the LHC's sensitivity to top quark flavor-changing decays involving Higgs bosons in a general two Higgs doublet model, including realistic background and efficiency considerations.

Findings

Potential to discover $t o c\phi^0$ decay at 8 TeV with 20 fb$^{-1}$ for large couplings.

Enhanced discovery prospects at 14 TeV with full energy.

Signal significance achievable for Higgs mass around 125 GeV.

Abstract

We investigate the prospects for discovering a top quark decaying into one light Higgs boson along with a charm quark in top quark pair production at the CERN Large Hadron Collider (LHC). A general two Higgs doublet model is adopted to study the signature of flavor changing neutral Higgs decay $t \to c\phi^0$, %or $\bar{t} \to \bar{c}\phi^0$ where $\phi^0$ could be CP-even ($H^0$) or CP-odd ($A^0$). The dominant physics background is evaluated with realistic acceptance cuts as well as tagging and mistagging efficiencies. For a reasonably large top-charm-Higgs coupling ($\lambda_{tc}/\lambda_{t} \agt 0.09$), the abundance of signal events and the %that our acceptance cuts reduction in physics background allow us to establish a $5\sigma$ signal for $M_\phi \sim 125$ GeV at the LHC with a center of mass energy ($\sqrt{s}$) of 8 TeV and an integrated luminosity of 20 fb$^{-1}$. The discovery potential will be greatly enhanced with the full energy of $\sqrt{s} = 14$ TeV.