Search for the t \u2192 ch decay at hadron colliders

Abstract

We study the observability for the flavor-changing decay of a top quark t → ch at the Large Hadron Collider (LHC) and future hadron colliders, namely, High-Luminosity LHC (HL-LHC), High-Energy LHC (HE-LHC) and Future Circular hadron-hadron Collider (FCC-hh). Two scenarios in which the Higgs boson could decay: into a quark bottom pair (bb-channel) and two photons (γγ-channel) are analyzed. A Monte Carlo analysis of the signal and the Standard Model (SM) background is computed. Center-of-mass energies of sqrt{s}=14,27 and 100 TeV and integrated luminosities from 0.3 to 30 ab−1 are explored. The theoretical framework adopted in this work is the Type-III Two-Higgs Doublet Model (THDM-III) for which, constraints on the parameter space from the Higgs boson coupling modifiers κi are presented and used in order to evaluate the branching ratio of the t → ch decay and the left( ppto toverline{t}, tto chright) production cross section. We find that with the integrated luminosity achieved at the LHC, the t → ch decay is out of the reach of detection. More promising results emerge for the HL-LHC, HE-LHC and FCC-hh in which potential discoveries could be claimed.