Scalar Dark Matter Search at the LHC through FCNC Top Decay

TL;DR

This paper proposes a method to detect scalar dark matter particles at the LHC by analyzing flavor-changing neutral current top decays, specifically t->c D D, within a two Higgs doublet model framework, and estimates the potential observability of such events.

Contribution

It introduces a novel search strategy for scalar dark matter via FCNC top decays at the LHC, with detailed predictions of branching ratios and event rates.

Findings

Branching ratio for t->c D D can reach 10^{-3}.

LHC can probe smaller branching ratios with increased luminosity.

Estimated 80 signal events for certain parameters at 14 TeV.

Abstract

We discuss an extended standard model electroweak sector which contains a stable scalar dark matter particle, the D boson. To search for the D boson at the LHC we exploit the flavor-changing neutral current (FCNC) top quark decay, t->c D D, mediated by the lightest standard model-like Higgs h^0 in a two Higgs doublet model framework. The branching ratio for t->c D D in this case can be as high as 10^{-3}, after taking into account constraints arising from the D boson relic abundance. With an integrated luminosity of 10 (100) fb^{-1}, the 14 TeV LHC can explore values of this branching ratio that are one (two) order of magnitude smaller in t\bar{t} production with t\bar{t}\to c \bar{b} \ell^-(\bar{c}b\ell^+)+missing E_T. For a D boson mass <60 GeV, m_{h^0}< 2 M_Z, 10 fb^{-1} luminosity and a branching ratio BR(t->cDD)~10^{-4}, the estimated number of signal events at the 14 TeV LHC is of order 80.