Relaxing LHC constraints on the $W_R$ mass

TL;DR

This paper explores how relaxing certain assumptions in left-right symmetric models can significantly lower the experimental mass bounds on the $W_R$ gauge boson, expanding the viable parameter space.

Contribution

It introduces a comprehensive analysis of $W_R$ mass bounds considering non-universal gauge couplings and mixing, relaxing previous constraints and exploring new scenarios.

Findings

$W_R$ mass bounds can be relaxed under certain model assumptions.

Experimental limits depend on the relative masses of $W_R$ and $ u_R$.

Mass bounds extend to about 3.3 TeV for $W_R$ in relaxed scenarios.

Abstract

We study mass bounds of the $W_R$ gauge boson in generic left-right symmetric models. Assuming that the gauge bosons couple universally to quarks and leptons, we allow different gauge couplings $g_R \ne g_L$ and mass mixing, $V_{CKM}^L \ne V_{CKM}^R$ in the left and right sectors. Imposing constraints from collider experiments and $K^0$, $B_d$, $B_s$ physics, we investigate scenarios where $W_R$ is lighter, or heavier than the right handed neutrino $\nu_R$. In these scenarios, $W_R$ mass bounds can be considerably relaxed, while $Z_R$ mass bounds are much more stringent. In the case where $M_{W_R} \le M_{\nu_R}$, the experimental constraints come from $W_R \to tb $ and $W_R \to jj$ channels, while if $M_{W_R} \ge M_{\nu_R}$, the dominant constraints come from $W_R \to \ell \ell jj $. The observed (expected) limits in the two-dimensional ($M_{W_R}$, $M_{\nu_R}$) mass plane excluded at 95\% confidence level extend to approximately $M_{W_R}$= 3.1 (3.3) TeV in the $ee$ channel and 3.3 (3.4) TeV in the ($\mu\mu$) channel, for a large range of right-handed neutrino masses up to $M_{\nu_R}$= 2.1 (2.1) TeV in the $ee$ channel and 2.6 (2.5) in the ($\mu\mu$) channel, representing a significant relaxation of the mass bounds.

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