Searches for top-Higgs FCNC couplings via the $Whj$ signal with $h\to \gamma \gamma$ at the LHC

In this paper, we investigated the process $pp\to W^{-}hj$ induced by the top-Higgs flavor-changing neutral current couplings at the LHC. We found that the cross section of $pp\to W^{-}hj$ mainly comes from the resonant process $pp\to W^{-}t\to W^{-}hq$ due to the anomalous $tqH$ couplings (where $q$ denotes up and charm quarks). We further studied the observability of the top-Higgs flavor-changing neutral current couplings through the process $pp\to W^{-}(\to {\ell }^{-}{\overline{\nu }}_{\ell })h(\to \gamma \gamma )j$ and found that the branching ratios $\mathrm{Br}(t\to qh)$ can be probed to 0.16% at $3\sigma$ level at 14 TeV LHC with an integrated luminosity of $3000{\mathrm{fb}}^{-1}$.

Figure 1

Feynman diagrams for the partonic process $bg\to W^{-}hq$ at the LHC through flavor-violating top-Higgs interactions. Here, $q=u$, $c$.

Figure 2

Feynman diagrams for the partonic process $\overline{q}b\to W^{-}hg$ at the LHC through flavor-violating top-Higgs interactions. Here, $q=u$, $c$.

Figure 3

The dependence of the cross sections $\sigma$ at 14 TeV LHC on the top-Higgs FCNC couplings ${\lambda }_{tqh}$ for Case I to Case III.

Figure 4

Normalized distributions of transverse momentum $p_T^{{\gamma }_1}$, $p_T^{{\gamma }_2}$, $p_T^j$; the transverse missing energy ${\cancel{E}}_T$; and various separations $\mathrm{\Delta }{R}_{{\gamma }_1{\gamma }_2,{\gamma }_{1}j}$ in the signals and backgrounds at 14 TeV LHC.

Figure 5

Normalized invariant-mass distribution of two photons (left) and the diphoton and light jet system (right) at the 14 TeV LHC.

Figure 6

Contour plots in the $L-{\lambda }_{tqh}$ plane for $3\sigma$ significance of $pp\to W^{-}hj$ (solid line) and the resonant production $pp\to W^{-}t\to W^{-}hq$ (dashed line) at 14 TeV LHC.