Probe the Mixing Parameter $|V_{\tau N}{|}^2$ for Heavy Neutrinos

Abstract

Because of the difficulty in detecting final state taus, the mixing parameter $|V_{\tau N}{|}^2$ for heavy neutrino $N$ is not well studied at current experiments, compared with other mixing parameters $|V_{eN}{|}^2$ and $|V_{\mu N}{|}^2$. In this paper, we focus on a challenging scenario where $N$ mixes with active neutrino of tau flavour only, i.e. $|V_{\tau N}{|}^2\ne 0$ and $|V_{eN}{|}^2=|V_{\mu N}{|}^2=0$. We derive current constraints on $|V_{\tau N}{|}^2$ from the rare $Z$-boson decay and electroweak precision data (EWPD). To forecast the future limits, we also investigate the signal $pp\to {\tau }^{\pm }{\tau }^{\pm }jj$ via a Majorana heavy neutrino at future proton-proton colliders. To suppress the background, both taus are required to decay leptonically into muons, leading to the final state containing two same sign muons, at least two jets plus moderate missing energy. The signal and relevant background processes are simulated at the HL-LHC and SppC/FCC-hh with center-of-mass energy of 14 TeV and 100 TeV. The preselection and multivariate analyses based on machine-learning are performed to reduce background. Limits on $|V_{\tau N}{|}^2$ are shown for heavy neutrino mass in the range 10-1000 GeV based on measurements from the rare $Z$-boson decay and EWPD, and searches at the HL-LHC and SppC/FCC-hh with integrated luminosities of 3 and 20 ab${}^{-1}$.

9 figures, 4 tables. arXiv admin note: text overlap with arXiv:2210.17050

References in corpus (15)

• PYTHIA 6.4 Physics and Manual
• The automated computation of tree-level and next-to-leading order differential cross sections, and their matching to parton shower simulations
• Effects of new leptons in Electroweak Precision Data
• Heavy Majorana Neutrinos from $W\gamma$ Fusion at Hadron Colliders
• Search for heavy neutral lepton production in $K^{+}$ decays to positrons
• Probing the Majorana neutrinos and their CP violation in decays of charged scalar mesons $\pi ,K,D,D_s,B,B_c$
• Distinguishing Dirac/Majorana Sterile Neutrinos at the LHC
• Long-lived Sterile Neutrinos at Belle II in Effective Field Theory
• Rare meson decays with three pairs of quasi-degenerate heavy neutrinos
• Search for heavy neutral leptons in $W^{+}\to {\mu }^{+}{\mu }^{\pm }\text{jet}$ decays
• Expanding the Reach of Heavy Neutrino Searches at the LHC
• Monojet search for heavy neutrinos at future $Z$-factories
• Search for heavy Majorana neutrinos at electron-proton colliders
• Discovering heavy neutrino oscillations in rare Bc meson decays at HL-LHCb
• CP violation in the rare Higgs decays via exchange of on-shell almost degenerate Majorana neutrinos, $H\to {\nu }_k{N}_j\to {\nu }_k{\ell }^{-}U\bar{D}$ and $H\to {\nu }_k{N}_j\to {\nu }_k{\ell }^{+}\bar{U}D$

Cited by in corpus (1)

• Search for heavy Majorana neutrinos in the $\tau$ final state at proton-electron colliders