Motivated by searches for $0\mathrm{<ruby><rb>\nu </rb><rt>にゅー</rt></ruby>}\mathrm{<ruby><rb>\beta </rb><rt>べーた</rt></ruby>}\mathrm{<ruby><rb>\beta </rb><rt>べーた</rt></ruby>}$ decay in nuclear experiments and collider probes of lepton number violation at dimension $d\ge 7$, we investigate the sensitivity to the $d=5$ Weinberg operator using the nonresonant signature $pp\to {\ell }^{\pm }{{\ell }^{\prime }}^{\pm }jj$ at the LHC. We develop a prescription for the operator that is applicable in collisions and decays, and focus on the $\ell {\ell }^{\prime }=\mathrm{<ruby><rb>\mu </rb><rt>みゅー</rt></ruby>}\mathrm{<ruby><rb>\mu </rb><rt>みゅー</rt></ruby>}$ channel, which is beyond the reach of nuclear decays. For a Wilson coefficient $C_5^{\mathrm{<ruby><rb>\mu </rb><rt>みゅー</rt></ruby>}\mathrm{<ruby><rb>\mu </rb><rt>みゅー</rt></ruby>}}=1$, scales as heavy as $\mathrm{<ruby><rb>\Lambda </rb><rt>らむだ</rt></ruby>}\sim 8.3(11)\mathrm{TeV}$ can be probed with $\mathcal{L}=300{\mathrm{fb}}^{-1}(3{\mathrm{ab}}^{-1})$. This translates to an effective $\mathrm{<ruby><rb>\mu </rb><rt>みゅー</rt></ruby>}\mathrm{<ruby><rb>\mu </rb><rt>みゅー</rt></ruby>}$ Majorana mass of $|m_{\mathrm{<ruby><rb>\mu </rb><rt>みゅー</rt></ruby>}\mathrm{<ruby><rb>\mu </rb><rt>みゅー</rt></ruby>}}|\sim 7.3(5.4)\mathrm{GeV}$ and establishes a road map for testing the Weinberg operator at accelerators.

• Received 5 March 2021
• Accepted 10 May 2021

DOI:https://doi.org/10.1103/PhysRevD.103.115014

Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI. Funded by SCOAP³.

Published by the American Physical Society