Abstract
We use the results of CMS and ATLAS searches for resonances that decay to tau nu or tb and tau ^+tau ^- or t{bar{t}} final states to constrain the parameters of non-universal W^prime and Z^prime gauge bosons that couple preferentially to the third generation. For the former we consider production from cbar{b} annihilation and find very weak constraints on the strength of the interaction and only for the mass range between 800 and 1100 GeV from the pp rightarrow tau _h p_T^{mathrm{miss}} channel. The constraints on the latter are much stronger and arise from both t{bar{t}} and tau ^+tau ^- production. Treated separately, we find that the weak constraints on the W^prime still permit an explanation of the R(D^{(star )}) anomalies with a light sterile neutrino whereas the stronger constraints on the Z^prime exclude significant light sterile neutrino contributions to the K rightarrow pi nu bar{nu } rates. Within specific models the masses of W^prime and Z^prime are of course related and we briefly discuss the consequences.
Highlights
A recent model independent analysis of LHC constraints on a W with dominant couplings to third generation fermions [18] serves as motivation for this study
The current ATLAS result from 13 TeV does not yet constrain this model as illustrated in Fig. 5 where we show the model prediction for gR = 4.24 in blue
Its coupling to third generation fermions is allowed to be as large as its perturbative unitarity limit for almost all values of MW 500 GeV
Summary
Our starting point will be the non-universal LR model of [19,20]. To single out the third generation we augment the SM gauge group with a second SU (2) under which only the third generation right handed fermions are charged. In the weak interaction basis, the first two generations of quarks This model has been studied at length before and here we summarize known constraints with appropriate numerical updates. The complete set of constraints can be found in [21,22], but the most relevant for this study are obtained by combining Bs and Bd mixing to yield. This constraint (and others found in [21,22]) can be satisfied in a simple manner with the ansatz described in Ref. Eq (8) defines the simplified model used in this study
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