Explaining the $b \to s \ell^+ \ell^-$ anomalies in $Z^\prime$ scenarios with top-FCNC couplings

Abstract

Motivated by the recent anomalies in b → s + − transitions, we explore a minimal Z scenario, in which the Z boson has a flavour-changing coupling to charm and top quarks and a flavour-conserving coupling to muons. It is found that such a Z boson can explain the current b → s + − anomalies, while satisfying other flavour and collider constraints simultaneously. The Z boson can be as light as few hundreds GeV. In this case, the t → cµ + µ − decay and the tZ associated production at the LHC could provide sensitive probes of such a Z boson. As a special feature, the Z contributions to all rare B-and Kmeson processes are controlled by one parameter. This results in interesting correlations among these processes, which could provide further insights into this scenario. In addition, an extended scenario, in which the Z boson interacts with the SU (2) L fermion doublets with analogous couplings as in the minimal scenario, is also investigated.

Angular distributions for $Λ_b\to Λ^*_J (pK^-)J/ψ$ Decays

“…Flavourchanging neutral current b → s + − is forbidden at tree level and thus sensitive to new physics beyond the standard model. Thus the B → K + − and B → K * + − have received great attentions in the past decades and have provide very stringent constraints on NP models beyond the SM [7][8][9][10][11][12][13][14][15][16]. Meanwhile in these decays, the so-called flavor anomalies are also found [17][18][19][20][21][22][23][24][25].…”

Single top production via FCNC couplings at an $e^{-}e^{+}$ collider with center-of-mass energy $\sqrt{s}=240$ GeV

“…The top quark FCNC decays include the modes: t → cX, with X = h, Z, γ, g, which were calculated first in [4,5], and later on they were studied for other models [6][7][8][9][10][11][12][13][14] including its search at the LHC [15][16][17]. One can also consider the FCNC decays of heavy particles (H , Z ) that can decay into t c [18][19][20]. Future colliders offer the possibility to probe models of new physics including, among other goals, searches for FCNC processes [21][22][23].…”