Revisiting large neutrino magnetic moments

Lindner, M.; Radovčić, Branimir; Welter, Johannes Maria René

doi:10.1007/jhep07(2017)139

“…In the limit of this symmetry, owing to differences in the Lorentz structures in the operators, the neutrino mass vanishes while the magnetic moment does not [11][12][13][14][15][16][17][18]. We propose a simplified model based on approximate SU (2) H symmetry that induces sufficiently large neutrino magnetic moment to explain the XENON1T excess. While the old models almost always relied on exact symmetries, here we show that an approximate SU(2) H is sufficient, with explicit breaking of the symmetry provided by the electron and muon masses.…”

Section: Jhep10(2020)040mentioning

confidence: 99%

Large neutrino magnetic moments in the light of recent experiments

Babu

¹

,

Jana

²

,

Lindner

³

2020

J. High Energ. Phys.

Self Cite

View full text Add to dashboard Cite

The excess in electron recoil events reported recently by the XENON1T experiment may be interpreted as evidence for a sizable transition magnetic moment $$ {\mu}_{v_e{v}_{\mu }} $$ μ v e v μ of Majorana neutrinos. We show the consistency of this scenario when a single component transition magnetic moment takes values $$ {\mu}_{v_e{v}_{\mu }}\in \left(1.65-3.42\right)\times {10}^{-11}{\mu}_B $$ μ v e v μ ∈ 1.65 − 3.42 × 10 − 11 μ B . Such a large value typically leads to unacceptably large neutrino masses. In this paper we show that new leptonic symmetries can solve this problem and demonstrate this with several examples. We first revive and then propose a simplified model based on SU(2)H horizontal symmetry. Owing to the difference in their Lorentz structures, in the SU(2)H symmetric limit, mν vanishes while $$ {\mu}_{v_e{v}_{\mu }} $$ μ v e v μ is nonzero. Our simplified model is based on an approximate SU(2)H, which we also generalize to a three family SU(3)H-symmetry. Collider and low energy tests of these models are analyzed. We have also analyzed implications of the XENON1T data for the Zee model and its extensions which naturally generate a large $$ {\mu}_{v_e{v}_{\mu }} $$ μ v e v μ with suppressed mν via a spin symmetry mechanism, but found that the induced $$ {\mu}_{v_e{v}_{\mu }} $$ μ v e v μ is not large enough to explain recent data. Finally, we suggest a mechanism to evade stringent astrophysical limits on neutrino magnetic moments arising from stellar evolution by inducing a medium-dependent mass for the neutrino.

show abstract

“…Given our knowledge of the Standard Model (SM) interactions, the active neutrino lifetimes are considerably larger than the age of the Universe τ ν > 10 35 yr, and therefore are too large to have any measurable implication for laboratory experiments, for astrophysics or for cosmology. However, many extensions of the SM do predict substantially shorter neutrino lifetimes, see for example [7][8][9][10][11][12][13][14][15][16][17][18].…”

Section: Introductionmentioning

confidence: 99%

Cosmological constraints on invisible neutrino decays revisited

Escudero

¹

,

Fairbairn

²

2019

View full text Add to dashboard Cite

Neutrinos could decay. Invisible neutrino decay modes are difficult to target at laboratory experiments, and current bounds on such decays from solar neutrino and neutrino oscillation experiments are somewhat weak. It has been known for some time that Cosmology can serve as a powerful probe of invisible neutrino decays. In this work, we show that in order for Big Bang Nucleosynthesis to be successful, the invisible neutrino decay lifetime should be τν > 10 −3 s. We revisit Cosmic Microwave Background constraints on invisible neutrino decays, and by using the latest Planck observations we find that neutrino lifetimes τν < (1.2 − 0.3) × 10 9 s (mν /0.05 eV) 3 are excluded at 95% CL. We show that this bound is robust to modifications of the cosmological model, in particular that it is independent of the presence of dark radiation. We find that typical invisible neutrino decay modes with rates τν < 10 5 s (mν /0.05 eV) 3 are disfavoured at more than 5 σ with respect to ΛCDM given the latest Planck CMB observations. Finally, we show that when including high-Planck polarization data, neutrino lifetimes τν = (2 − 14) × 10 9 s (mν /0.05 eV) 3 are mildly preferred -with a 1-2 σ significance -over neutrinos being stable.

show abstract

“…In particular, Ref. [25] proposed a model with SU(2) horizontal symmetry, allowing Majorana transition neutrino magnetic moments of order 10 −12 µ B while protecting the small mass of the neutrinos.…”

Section: Introductionmentioning

confidence: 99%

Precision constraints on radiative neutrino decay with CMB spectral distortion

Aalberts

¹

,

Ando

²

,

Borg

³

et al. 2018

View full text Add to dashboard Cite

We investigate the radiative decay of the cosmic neutrino background, and its impact on the spectrum of the cosmic microwave background (CMB) that is known to be a nearly perfect black body. We derive exact formulae for the decay of a heavier neutrino into a lighter neutrino and a photon, νj → νi + γ, and of absorption as its inverse, νi + γ → νj, by accounting for the precise form of the neutrino momentum distribution. Our calculations show that if the neutrinos are heavier than O(0.1) eV, the exact formulae give results that differ by ∼50%, compared with approximate ones where neutrinos are assumed to be at rest. We also find that spectral distortion due to absorption is more important for heavy neutrino masses (by a factor of ∼10 going from a neutrino mass of 0.01 eV to 0.1 eV). By analyzing the CMB spectral data measured with COBE-FIRAS, we obtain lower limits on the neutrino lifetime of τ12 4 × 10 21 s (95% C.L.) for the smaller mass splitting and τ13 ∼ τ23 10 19 s for the larger mass splitting. These represent up to one order of magnitude improvement over previous CMB constraints. With future CMB experiments such as PIXIE, these limits will improve by roughly 4 orders of magnitude. This translates to a projected upper limit on the neutrino magnetic moment (for certain neutrino masses and decay modes) of µν < 3 × 10 −11 µB, where µB is the Bohr magneton. Such constraints would make future precision CMB measurements competitive with lab-based constraints on neutrino magnetic moments. PACS numbers: 13.35.Hb, 95.30.Cq, 98.70.Vc, 98.80.-k arXiv:1803.00588v2 [astro-ph.CO]

show abstract

Revisiting large neutrino magnetic moments

Cited by 38 publications

References 38 publications

Large neutrino magnetic moments in the light of recent experiments

Large neutrino magnetic moments in the light of recent experiments

Cosmological constraints on invisible neutrino decays revisited

Precision constraints on radiative neutrino decay with CMB spectral distortion

Contact Info

Product

Resources

About