Reconciling the 2 TeV Excesses at the LHC in a Linear Seesaw Left-Right Model

TL;DR

This paper proposes a left-right symmetric model with Higgs doublets and spontaneous D-parity violation to explain 2 TeV excesses at the LHC, including CMS $eejj$, diboson, and dijet signals, while also discussing implications for neutrinoless double beta decay.

Contribution

It introduces a novel linear seesaw mechanism within a left-right model with high D-parity breaking, explaining multiple LHC excesses and neutrino properties.

Findings

Reconciliation of CMS $eejj$, diboson, and dijet excesses within the model.

Large light-heavy neutrino mixing could lead to significant neutrinoless double beta decay contributions.

Suppressed right-handed gauge coupling $g_R / g_L \\approx 0.6$ consistent with $SO(10)$ embedding.

Abstract

We interpret the 2 TeV excesses at the LHC in a left-right symmetric model with Higgs doublets and spontaneous $D$-parity violation. The light neutrino masses are understood via a linear seesaw, suppressed by a high $D$-parity breaking scale, and the heavy neutrinos have a pseudo-Dirac character. In addition, with a suppressed right-handed gauge coupling $g_R / g_L \approx 0.6$ in an $SO(10)$ embedding, we can thereby interpret the observed $eejj$ excess at CMS. We show that it can be reconciled with the diboson and dijet excesses within a simplified scenario based on our model. Moreover, we find that the mixing between the light and heavy neutrinos can be potentially large which would induce dominant non-standard contributions to neutrinoless double beta decay via long-range $\lambda$ and $\eta$ neutrino exchange.