Revisiting the LHC reach in the displaced region of the minimal left-right symmetric model

We revisit discovery prospects for a long-lived sterile neutrino $N$ at the LHC in the context of left-right symmetric theories. We focus on a displaced vertex search strategy sensitive to $\mathcal{O}(\mathrm{GeV})$ neutrino masses produced via a right-handed $W_R$ boson. Both on-shell and off-shell Drell-Yan production of $W_R$ are considered. We estimate the reach as a function of $m_N$ and $m_{W_R}$. With $\sqrt{s}=13\mathrm{TeV}$ and $300/\mathrm{fb}$ of integrated luminosity, the LHC can probe neutrino masses as high as approximately 30 GeV and $m_{W_R}$ around 6 TeV. The reach goes up to 11.5 TeV with $3000/\mathrm{fb}$ and $m_N\sim 45\mathrm{GeV}$. This represents an improvement of a factor of 2 in sensitivity with respect to earlier work.

Figure 1

95% C.L. reach in the $(m_{W_R},m_N)$ plane at $\sqrt{s}=13\mathrm{TeV}$ of our proposed displaced strategy for $\mathcal{L}=300/\mathrm{fb}$ (left) and $\mathcal{L}=3000/\mathrm{fb}$ (right). Comparison of the purely on-shell [22] (green region) and off-shell $W_R$ production (purple) is shown. The projected exclusions in the $e+p_T^{\text{miss}}$ channel from Ref. [5] are also shown (orange dashed lines). Plot generated with matplotlib [30].