Heavy neutrino search in accelerator-based experiments

Asaka, Takashi; Eijima, Shintaro; Watanabe, Atsushi

doi:10.1007/jhep03(2013)125

Cited by 40 publications

(46 citation statements)

References 59 publications

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“…The recent NA62 experiment provides [43] R exp K = (2.488 ± 0.010) × 10 −5 . (12) It is seen that the observational data agrees with the SM value at the 1σ level. Consequently, the deviation…”

Section: Lepton Universality In the νMsmsupporting

confidence: 76%

“…The recent analysis [7] shows that M N > 163 MeV for the normal hierarchy (NH), while M N = 188-269 MeV and M N > 285 MeV for the inverted hierarchy (IH) of active neutrino masses. It is remarkable that, thanks to the smallness of masses, the heavy neutral leptons in the νMSM, especially N 2 and N 3 , can be directly tested by a variety of experiments and/or observations [9,8,[10][11][12]. * Corresponding author.…”

Section: Introductionmentioning

confidence: 99%

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Lepton universality in the ν MSM

2015

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We consider the νMSM which is an extension of the Standard Model by three right-handed neutrinos with masses below the electroweak scale, in which the origins of neutrino masses, dark matter, and baryon asymmetry of the universe are simultaneously explained. Among three heavy neutral leptons, N 2 and N 3 , which are responsible to the seesaw mechanism of active neutrino masses and the baryogenesis via flavor oscillation, can induce sizable contributions to various lepton universality in decays of charged mesons. Then the possible deviations of the universality in the νMSM are investigated.We find that the deviation in kaon decay can be as large as O(10 −3 ), which will be probed in near future experiments.

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Section: Lepton Universality In the νMsmsupporting

confidence: 76%

Section: Introductionmentioning

confidence: 99%

Lepton universality in the ν MSM

2015

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“…[74]). It is exciting to note that current and upcoming neutrino oscillation experiments will be able to perform beam dump style measurements [75][76][77]. A crucial difference between oscillation detectors and dedicated beam dump searches of the past is that the former tries to maximise its Standard Model neutrino scattering rate, while the latter goes to lengths to suppress it in order to reduce backgrounds.…”

Section: Contentsmentioning

confidence: 99%

Heavy Neutral Leptons from low-scale seesaws at the DUNE Near Detector

Ballett

Boschi

Pascoli

2020

J. High Energ. Phys.

113

142

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Heavy nearly-sterile neutrinos are a common ingredient in extensions of the Standard Model which aim to explain neutrino masses, like for instance in Type I seesaw models, or one of its variants. If the scale of the new Heavy Neutral Leptons (HNLs) is sufficiently low, observable signatures can arise in a range of current and upcoming experiments, from the LHC to neutrino experiments. In this article, we discuss the phenomenology of sterile neutrinos in the MeV to GeV mass range, focusing on their decays. We embed our discussion in a realistic mass model and consider the resulting implications. We focus in particular on the impact on the signal of the strong polarisation effects in the beam for Majorana and (pseudo-)Dirac states, providing formulae to incorporate these in both production and decay. We study how the Near Detector of the upcoming Deep Underground Neutrino Experiment can constrain HNL states by searching for their decay products inside the detector. We conduct a Monte Carlo background analysis for the most promising signatures, incorporating the detector's particle identification capabilities, and estimate the experimental sensitivity of DUNE to these particles. We also present an estimate of the ν τ -derived HNL flux at DUNE, currently missing in the literature, which allows us to discuss searches for HNLs at higher masses.The evidence for three neutrino flavour oscillation is well established [1,2] and can be accounted for only if neutrino mass splittings are non zero [3]. This implies that neutrinos are massive and mix, forcing to consider extensions of the Standard Model (SM) to explain their origin. A simple means of doing so is to introduce the right-handed counterpart of SM neutrinos, which are singlet with respect to all SM gauge symmetries. The Lagrangian includes a Yukawa coupling between these sterile states, the Higgs boson and the leptonic doublet, which generates Dirac mass-terms below the scale of Electroweak Symmetry Breaking (EWSB), and Majorana mass terms for the new singlet states. On diagonalisation of the resulting neutrino mass matrix, the heavy neutrino states, commonly known as nearlysterile neutrinos or Heavy Neutral Leptons (HNLs) in experimental contexts, remain mainly in the sterile neutrino direction and have sub-weak interactions suppressed by elements of the extended Pontecorvo-Maki-Nakagawa-Sakata (PMNS) mixing matrix.These states have been connected to a vast range of phenomenological behaviours and even to cosmological implications (for a recent review on sterile neutrinos, see e.g. ref.[4]). For instance, nearly-sterile neutrinos in the keV region are viable warm Dark Matter candidates (see e.g. ref.[5]), whereas heavier HNLs could play a role in leptogenesis [6][7][8][9][10][11][12][13][14][15][16][17][18]. So far, some possible hints in favour of heavy neutrinos have emerged in neutrino appearance oscillation experiments, specifically LSND [19] and MiniBooNE [20][21][22] but are disfavoured by disappearance experiments [23][24][25], unless non-standard effects ar...

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“…Recently, searches for the sterile neutrino signal has been done by Belle Collaboration [5] in e + e − -collisions at KEK, similar studies are planned for LHCb [6] at CERN. Special investigation of sterile neutrinos from kaon decays is undertaken in E494 experiment [7] at BNL, and is suggested for T2K experiment [8]. GeV-scale sterile neutrinos are considered in physical programs of proposed next generation long-base line neutrino oscillation experiments: near detectors in LBNE [9], NuSOnG [10], HiResMν [11].…”

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confidence: 99%

Minimal active-sterile neutrino mixing in seesaw type I mechanism with sterile neutrinos at GeV scale

Gorbunov

Panin

2014

Phys. Rev. D

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Renewed interest in GeV-scale sterile neutrinos capable of explaining active neutrino oscillations via see-saw type I mechanism has been expressed in several proposals of direct searches. Given this activity we estimate the minimal values of sterile-active mixing angles provided one, two, or three sterile neutrinos are lighter than D-meson.1. Neutrino oscillations definitely ask for some extension of the Standard Model of particle physics (SM), and may be the simplest, yet complete and renormalizable, version is introducing three new Majorana massive fermions, N I , I = 1, 2, 3, sterile with respect to all SM gauge interactions. One can write down the most general renormalizable Lagrangianwhere M I are the Majorana masses and Y αI stand for Yukawa couplings with lepton doublets L α , α = e, µ, τ and SM Higgs doublet H (H a = ab H * b , a = 1, 2). When the Higgs field gains vacuum expectation value v = 246 GeV, Yukawa couplings in (1) yield mixing between sterile N I and active ν α neutrino states. Diagonalization of the neutral fermion mass matrix provides active neutrinos with masses m i and mixing which are responsible for neutrino oscillation phenomena.With some hierarchy between model parameters Y αI and M I /v, when the Dirac mass scale Y v is well below the Majorana mass scale M , active-sterile neutrino mixing angles are small, U ∼ Y v/M 1, and active neutrino masses are double suppressed, m ∼ U 2 M . This is a type I seesaw mechanism (for a review see e.g., Ref.[1]) which explains naturally why active neutrino mass scale is much lower than masses of other SM particles. However, the Dirac mass scale and hence the size of Yukawa couplings are not fixed from this reasoning: the seesaw mechanism determines not Y and M but ratio Y 2 /M . 1

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Heavy neutrino search in accelerator-based experiments

Cited by 40 publications

References 59 publications

Lepton universality in the ν MSM

Lepton universality in the ν MSM

Heavy Neutral Leptons from low-scale seesaws at the DUNE Near Detector

Minimal active-sterile neutrino mixing in seesaw type I mechanism with sterile neutrinos at GeV scale

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