Ameliorating Higgs induced flavor constraints on TeV scale WR

Abstract

In the TeV scale minimal left-right symmetric model (LRSM) for neutrino masses, there is a tension between the flavor changing Higgs effects which prefer an SU(2)R breaking scale vR≳(15−25) TeV depending on whether the theory is kept invariant under charge conjugation (QL→(QR)c) or under parity (QL→QR) respectively and an LHC accessible few-TeV range mass of WR boson which would require vR≲10(15) TeV if gR/gL=1(0.65). This requires one quartic coupling in the scalar potential to go non-perturbative, posing a theoretical problem if the WR is discovered at LHC. We propose a simple extension of the minimal LRSM that adds a B−L=0 scalar triplet and study how this can ameliorate this tension. We find that such a model is also constrained from various considerations and implies a lower bound on the WR mass of 8.1 (5.26) TeV for the parity case with gR/gL=1(0.65) and 4.85 (3.16) TeV for the case of charge conjugation, if the flavor constraints have to be avoided while keeping all couplings perturbative. These mass ranges are accessible at the high-luminosity LHC. The model also implies new decay mode of WR to two scalars which is absent in the minimal LRSM. Finally we comment on the impact of such a scalar multiplet for a class of dark matter extension of LRSM discussed in the literature recently.