Implication of Z-mediated FCNC on semileptonic decays Bs→φl+l–and B+→K+l+l–

Abstract

Rare B meson decays mediated by flavour changing neutral current (FCNC) transition play interesting role to probe the flavour sector of the standard model (SM). Generally at the tree level, FCNC processes are not allowed in the SM but occurs at the loop levels. This gives an excellent hunting ground for new physics (NP). From various experimental studies it is found that the FCNC processes having quark level transition are challenging. Here, we investigate different kinematic observables like forward-backward asymmetry, differential branching ratio and lepton polarization asymmetry for semileptonic rare B decay modes and considering the contribution of Z-mediated FCNC. A noticeable deviation of the observables for these decay channels from the SM value is found because of non-universal coupling.

Lepton flavour violating $${\Lambda }_{{b}}$$ decays in non-universal $${Z}^{\prime }$$ model

“…Various lepton flavour violating decays, such as τ → 3μ, μ → 3e, l → l M (where l, l are different leptons and M is meson) and radiative decays μ → eγ etc are studied in different NP models though there are no direct experimental evidence of these decays but their experimental bounds exist. These decays previously explained with the effect of FCNC mediated Z boson [4,17], in non-universal Z model [18][19][20], in lepto-0123456789(). : V,-vol quark model [21][22][23][24], in MSSM [25][26][27] and other NP models [28] and also in model independent way [29].…”

Impact of non-universal $${{Z}}^{{'}}$$ in the lepton flavour violating $${{B}}\left( {{B}}_{{{s}}} \right) {\rightarrow }{{K}}^{{*}}\left( {\varphi } \right) {{l}}_{{{1}}}^{{-}}{{l}}_{{{2}}}^{{+}}$$ decays

“…The LFV decays, such as τ → 3μ, μ → 3e, l → l M (where l, l are leptons of different flavours and M reprsents meson) and radiative decays μ → eγ etc, all are analysed in different NP models though they are not evidently seen experimentally but their experimental upper limits exist. The LFV decays are successfully illustrated with the effect of FCNC mediated Z boson [4,17], non-universal Z boson [18], leptoquarks [19] and other NP models and also in model independent way [20].…”