Reconciling the 2 TeV excesses at the LHC in a linear seesaw left-right model

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 nonstandard contributions to neutrinoless double beta decay via long-range $\lambda$ and $\eta$ neutrino exchange.

Figure 1

Majorana mass of the light neutrinos arising through the combined VEVs of $H_L$ and $H_R$.

Figure 2

One loop renormalization group evolution of gauge couplings with Pati-Salam symmetry $G_{224D}$ as the highest intermediate symmetry breaking.

Figure 3

Fitting the diboson $WZ$, $WH$ (blue band), dijet $jj+tb$ (green band), and $eejj$ (red band) excesses in the ($g_R/g_L$-$\sin {\theta }_{LR}^W$) parameter plane. The other parameters are chosen as $M_{W_R}=1.9\mathrm{TeV}$, $M_N=1.6\mathrm{TeV}$, and $\sin {\theta }_{LR}^N=0$.

Figure 4

Fitting the $eejj$ (red band) excess in the ($M_N\text{−}\sin {\theta }_{LR}^N$) parameter plane. The other parameters are chosen as $M_{W_R}=1.9\mathrm{TeV}$, $g_R/g_L=0.57$ and $\sin {\theta }_{LR}^W=1.5\times 10^{-3}$. The vertical green lines denote contours of constant $\mathrm{Br}(W_R\to e{N}_R)$ and the diagonal blue lines of constant $\mathrm{Br}(N_R\to eqq)$ as denoted.