Discovering heavy neutrino-antineutrino oscillations at the $Z$-pole

Fuente: arXiv
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Autores principales: Antusch, Stefan, Hajer, Jan, Oliveira, Bruno M. S.
Formato: Preprint
Publicado: 2024
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author Antusch, Stefan
Hajer, Jan
Oliveira, Bruno M. S.
author_facet Antusch, Stefan
Hajer, Jan
Oliveira, Bruno M. S.
contents Collider-testable type I seesaw extensions of the Standard Model are generally protected by an approximate lepton number (LN) symmetry. Consequently, they predict pseudo-Dirac heavy neutral leptons (HNLs) composed of two nearly degenerate Majorana fields. The interference between the two mass eigenstates can induce heavy neutrino-antineutrino oscillations (NNOs) leading to observable lepton number violation (LNV), even though the LN symmetry is approximately conserved. These NNOs could be resolved in long-lived HNL searches at collider experiments, such as the proposed Future Circular $e^+e^-$ Collider (FCC-$ee$) or Circular Electron Positron Collider (CEPC). However, during their $Z$-pole runs, the LN carried away by the light (anti)neutrinos produced alongside the HNLs prevents LNV from being observed directly. Nevertheless, NNOs materialise as oscillating signatures in final state distributions. We discuss and compare a selection of such oscillating observables, and perform a Monte Carlo simulation to assess the parameter space in which NNOs could be resolved.
format Preprint
id arxiv_https___arxiv_org_abs_2408_01389
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Discovering heavy neutrino-antineutrino oscillations at the $Z$-pole
Antusch, Stefan
Hajer, Jan
Oliveira, Bruno M. S.
High Energy Physics - Phenomenology
High Energy Physics - Experiment
Collider-testable type I seesaw extensions of the Standard Model are generally protected by an approximate lepton number (LN) symmetry. Consequently, they predict pseudo-Dirac heavy neutral leptons (HNLs) composed of two nearly degenerate Majorana fields. The interference between the two mass eigenstates can induce heavy neutrino-antineutrino oscillations (NNOs) leading to observable lepton number violation (LNV), even though the LN symmetry is approximately conserved. These NNOs could be resolved in long-lived HNL searches at collider experiments, such as the proposed Future Circular $e^+e^-$ Collider (FCC-$ee$) or Circular Electron Positron Collider (CEPC). However, during their $Z$-pole runs, the LN carried away by the light (anti)neutrinos produced alongside the HNLs prevents LNV from being observed directly. Nevertheless, NNOs materialise as oscillating signatures in final state distributions. We discuss and compare a selection of such oscillating observables, and perform a Monte Carlo simulation to assess the parameter space in which NNOs could be resolved.
title Discovering heavy neutrino-antineutrino oscillations at the $Z$-pole
topic High Energy Physics - Phenomenology
High Energy Physics - Experiment
url https://arxiv.org/abs/2408.01389