Searching for lepton number violating $\Lambda$ baryon decays mediated by GeV-scale Majorana neutrino with LHCb

Abstract

We consider the lepton-number-violating processes in ${\Lambda }_b$/${\Lambda }_c$ decays mediated by on-shell GeV-scale sterile neutrino. We calculate the branching ratio for the following processes: ${\Lambda }_b^0\to {\mathcal{B}}^{+}{\mu }^{-}{\mu }^{-}{\pi }^{+}$, where ${\mathcal{B}}^{+}$ is ${\Lambda }_c^{+}$ or proton, and ${\Lambda }_c^{+}\to \Lambda {\mu }^{+}{\mu }^{+}{\pi }^{-}$, as function of the mass of the sterile neutrino $m_N$ and the heavy-light mixing coefficient of the extended Pontecorvo-Maki-Nakagawa-Sakata (PMNS) matrix $|U_{\mu N}{|}^2$. The effect of finite detector size is included in our calculation. After comparing the theoretical effective branching ratio with the expected experimental ability of LHCb, we give the sensitivity upper bounds on $|U_{\mu N}{|}^2$ on the ($|U_{\mu N}{|}^2$-$m_N$) plane. These channels give comparable results with the bounds given by different search strategies (e.g., at Belle, NuTeV, DELPHI and BEBC) in the mass region $m_N\simeq$ 0.25 GeV - 4.5 GeV, and the limits are stronger in the mass range 2 GeV $<m_N<$ 4.5 GeV.

10 pages, 4 figures

References in corpus (9)

• Status and Future of Nuclear Matrix Elements for Neutrinoless Double-Beta Decay: A Review
• Sterile Neutrinos as the Origin of Dark and Baryonic Matter
• ${\Lambda }_c\to \Lambda {\ell }^{+}{\nu }_{\ell }$ form factors and decay rates from lattice QCD with physical quark masses
• ${\Lambda }_c^{\pm }$ production in pp collisions with a new fragmentation function
• Measurement of the $B^{\pm }$ production cross-section in pp collisions at $\sqrt{s}=$ 7 and 13 TeV
• Remarks on the lifetime of sterile neutrinos and the effect on detection of rare meson decays M+ -> M'- lepton+ lepton+
• Lepton number violating four-body tau lepton decays
• Lepton number violation by heavy Majorana neutrino in $B$ decays
• $\Delta L=2$ hyperon semileptonic decays

Cited by in corpus (2)

• CP violation with GeV-scale Majorana neutrino in ${\Lambda }_b\to ({\Lambda }_c^{+},p^{+}){\pi }^{+}{\mu }^{-}{\mu }^{-}$ decays
• CP violation in $B_s$ decays mediated by two nearly-degenerate Majorana neutrinos