The Search for Heavy Majorana Neutrinos

By Anupama Atre, T. Han, Silvia Pascoli, Bin Zhang. 2009

798 citations recorded by the source corpus.

The Majorana nature of neutrinos can be experimentally verified only via lepton-number violating processes involving charged leptons. We study 36 lepton-number violating (LV ) processes from the decays of tau leptons and pseudoscalar mesons. These decays are absent in the Standard Model but, in presence of Majorana neutrinos in the mass range ∼ 100 MeV to 5 GeV, the rates for these processes would be enhanced due to their resonant contribution. We calculate the transition rates and branching fractions and compare them to the current bounds from direct experimental searches forL = 2 tau and rare meson decays. The experimental non-observation of such LV processes places stringent bounds on the Majorana neutrino mass and mixing and we summarize the existing limits. We also extend the search to hadron collider experiments. We find that, at the Tevatron with 8 fb −1 integrated luminosity, there could be 2σ (5σ) sensitivity for resonant production of a Majorana neutrino in the � ± � ± modes in the mass range of ∼ 10 − 180 GeV (10 − 120 GeV). This reach can be extended to ∼ 10 − 375 GeV (10 − 250 GeV) at the LHC of 14TeV with 100 fb −1 . The production cross section at the LHC of 10TeV is also presented for comparison. We study the � ± e ± modes as well and find that the signal could be large enough even taking into account the current bound from neutrinoless double-beta decay. The signal from the gauge boson fusion channel W + W + → l + l + at the LHC is found to be very weak given the rather small mixing parameters. We comment on the search strategy when a τ lepton is involved in the final state.

Subfields: Nuclear and High Energy Physics

View Paper: https://www.semanticscholar.org/paper/edba18d6f1f19c1fef949e9a6db81fa8636f98a0

How researchers see this paper

The researchers whose trusted networks rank it highest, strongest advocate first. Every researcher gets a different order.

In Nuclear and High Energy Physics

Citations in the corpus

Physics case for an LHCb Upgrade II - Opportunities in flavour physics, and beyond, in the HL-LHC era (2018, background): “The principal motivation is the sensitivity to contributions from Majorana neutrinos [302], which may be on-shell or off-shell, depending on the decay mode.”
Implications of LHCb measurements and future prospects - eScholarship (2013, neutral): “These indirect searches are performed by analysing the production of same sign charged leptons in D or B decays such as D+ s → π−μ+μ+ or B+ → π−μ+μ+ [28, 195].”
Neutrinoless double beta decay versus other probes of heavy sterile neutrinos (2019, background): “where fM is the order of magnitude of the meson decay constants [39].”
Neutrinoless Double Beta Decay: 2015 Review (2016, methodology): “In fact, in this case, the mixingUeI is not strongly suppressed and RH neutrinos can give an important contribution to the transition [105].”
Rare $B$ Decays as Tests of the Standard Model (2016, methodology): “violating decay modes (upper limits are at 90 % CL). W + + u N W b B Figure 14: Diagram for the lepton number violating decay B +!ˇ ‘+‘ mediated by a Majorana neutrino in the s-channel. neutrino mass [317,318]. Note that it is possible for virtual Majorana neutrinos of any mass to contribute to this”
Warm dark matter in low scale left-right theory (2012, background): “On the other hand, one can search for indirect signals using low-energy processes, similarly to the sterile neutrino case [103–105] (see also [106– 109]), which have a correlated dependence on both, the mixing parameters and the mass spectrum.”
Vector boson fusion at multi-TeV muon colliders (2020, methodology): “For our purposes, we neglect subtleties related to decoupling of lepton number-violating processes in simplified models with only heavy neutrinos [151, 154, 155], and consider the well-studied [156–158] Phenomenological Type I Seesaw benchmark model, as implemented in the HeavyN UFO libraries of Ref”
Neutrino non-standard interactions: A status report (2019, background): “The region above the red curve is excluded at 99% CL by meson decays, the muon decay Michel spectrum and lepton universality [112, 176].”
A White Paper on keV sterile neutrino Dark Matter (2016, background): “[67, 71, 170, 241] and references therein for a recent summary.”
Heavy Majorana neutrinos from Wγ fusion at hadron colliders (2014, background): “[24–29], the production channel most sensitive to heavy Majorana neutrinos (N) at hadron colliders is the resonant Drell-Yan (DY) process,”