Lepton pair emission in the top quark decay t → b W + ℓ − ℓ +
2014; American Physical Society; Volume: 89; Issue: 9 Linguagem: Inglês
10.1103/physrevd.89.093014
ISSN1550-7998
AutoresNéstor Quintero, J. Lorenzo Díaz-Cruz, G. López Castro,
Tópico(s)Neutrino Physics Research
ResumoThe heaviness of the top quark makes its two-body Cabibbo-favored decay mode $t\ensuremath{\rightarrow}b{W}^{+}$ to be dominant, at such a level that hardly any other decay mode reaches a detectable branching ratio within the Standard Model. Here we study the decay $t\ensuremath{\rightarrow}b{W}^{+}{\ensuremath{\ell}}^{\ensuremath{-}}{\ensuremath{\ell}}^{+}$ ($\ensuremath{\ell}=e,\ensuremath{\mu},\ensuremath{\tau}$), which diverges for massless leptons, and it can reach a branching ratio $\ensuremath{\sim}\mathcal{O}(1{0}^{\ensuremath{-}5}\ensuremath{\sim}1{0}^{\ensuremath{-}6})$ for reasonable values of the low energy cut in the lepton pair invariant mass. This rate surpasses almost any other rare decays such as $t\ensuremath{\rightarrow}cX$ ($X=\ensuremath{\gamma},Z,g,H,{W}^{+}{W}^{\ensuremath{-}}$), and thus offers the possibility of being detectable. Furthermore, the estimate of this channel is relevant because it can mimic the signal arising from the lepton number violating decay $t\ensuremath{\rightarrow}b{W}^{\ensuremath{-}}{\ensuremath{\ell}}^{+}{\ensuremath{\ell}}^{+}$, when the $W$ boson decays into lepton channels.
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