R(D(∗)) from W ′ and right-handed neutrinos

Abstract

We provide an ultraviolet (UV) complete model for the R(D (*)) anomalies, in which the additional contribution to semi-tauonic b → c transitions arises from decay to a right-handed sterile neutrino via exchange of a TeV-scale SU(2) L singlet W. The model is based on an extension of the Standard Model (SM) hypercharge group, U(1) Y , to the SU(2) V × U(1) gauge group, containing several pairs of heavy vector-like fermions. We present a comprehensive phenomenological survey of the model, ranging from the lowenergy flavor physics, direct searches at the LHC, to neutrino physics and cosmology. We show that, while the W and Z-induced constraints are important, it is possible to find parameter space naturally consistent with all the available data. The sterile neutrino sector also offers rich phenomenology, including possibilities for measurable dark radiation, gamma ray signals, and displaced decays at colliders.

Charged current b→cτν¯τ anomalies in a general W′ boson scenario

“…In this scenario the W is the gauge boson associated with the interaction between the RH quark and RH lepton currents involving a RH sterile neutrino. This RH current interpretation to the R(D ( * ) ) anomalies have been discussed recently in the literature within different NP realizations [62,[106][107][108][109][110][111][112][113]. We plot in Figs.…”

“…• The authors of Refs. [108,109] presented a model where the SM is extended by the gauge group SU (3) C × SU (2) L × SU (2) V × U (1) , with g V and g the corresponding new gauge couplings. After the spontaneous symmetry breaking SU (2) V × U (1) → U (1) Y , new heavy vector bosons are generated.…”

“…[33][34][35][36][37]) 1 . On the other hand, particular NP scenarios such as: charged scalars [46][47][48][49][50][51][52][53][54][55][56][57][58][59][60][61][62], leptoquarks (both scalar and vector) , extra gauge bosons [47,94,[98][99][100][101][102][103][104][105][106][107][108][109][110][111], right-handed neutrinos [62,[106][107][108][109][110][111][112][113], R-parity violating (RPV) supersymmetric couplings [31,[114][115][116]…”

“…We also analyze the effect of including into account all the charged transition b → cτν τ observables, namely R(J/ψ), P τ (D * ), F L (D * ), R(X c ), and BR(B − c → τ −ν τ ). We present a phenomenological analysis of parameter space allowed by the experimental data and for comparison we include some of the W boson NP realizations that have already been studied in the literature [94,99,100,[103][104][105][107][108][109]. Most of these models were implemented by considering the previous HFLAV averages and, in addition, not all them considered the polarization observables P τ (D * ), F L (D * ); therefore, we explore which of these benchmark models are still favored (or disfavored) by the new b → cτν τ data.…”

“…It is important to remark that since we are not implementing any NP realization in our analysis, we will get out from our discussion the possible connection with a Z boson that appears in particular UV completions, as done for instance in Refs. [94,103,105,[108][109][110][111].…”