Scotogenic top-quark FCNC decays

Abstract

Flavor-changing neutral current (FCNC) top-quark decays are highly suppressed due to the Glashow-Iliopoulos-Maiani mechanism in the standard model (SM). If $t\to qh,qV$ with $V=g,\gamma ,Z$ are all induced via quantum loop levels, then we investigate the effect that can enhance the top-FCNC up to the sensitivity designed at the high-luminosity (HL) LHC. Inspired by the mechanism of the scotogenic neutrino mass, we extend the SM by including $Z_2$-odd colored fermions when a $Z_2$ discrete is imposed. The results show that by taking $BR(t\to ug)\lesssim 0.61\times 10^{-4}$ recently measured by ATLAS as an input, $t\to q\gamma$ can be indirectly bounded to be $BR(t\to q\gamma )\lesssim 3.2\times 10^{-6}$, which is below the expected sensitivity at the HL LHC. After taking potential constraints from various experiments into account, the obtained branching ratios for the loop-induced $t\to qh$ and $t\to qZ$ decays can be $O(10^{-4})$, which falls within the sensitivity at the HL LHC.

28 pages, 9 figures, version accepted by PRD for publication

References in corpus (9)

• Improved Naturalness with a Heavy Higgs: An Alternative Road to LHC Physics
• Inert Doublet Model and LEP II Limits
• Natural Dark Matter from an Unnatural Higgs Boson and New Colored Particles at the TeV Scale
• Two dark matter candidates: the case of inert doublet and singlet scalars
• Constraining $t\to u$ flavor changing neutral Higgs coupling at the LHC
• Searches for anomalous $tqZ$ couplings from the trilepton signal of $tZ$ associated production at the 14 TeV LHC
• Search for flavour-changing neutral-current interactions of a top quark and a gluon in $pp$ collisions at $\sqrt{s}=13$ TeV with the ATLAS detector
• Search for the $t\to ch$ decay at hadron colliders
• Rare top-quark decays $t\to cg(g)$ in the aligned two-Higgs-doublet model

Cited by in corpus (3)

• $CP$ violation in the $HZZ$ vertex and left-right asymmetries
• Up-type FCNC in presence of Dark Matter
• Lepton flavor violating top quark FCNC processes at the $\mu$TRISTAN