Neutrino Electromagnetic Properties Research Articles

Effect of neutrino electromagnetic form factors on the neutrino cross section in dense matter

The sensitivity of the differential cross section of the interaction between a neutrino-electron and dense matter to the possibly nonzero neutrino electromagnetic properties has been investigated. Here, the relativistic mean field model inspired by effective field theory has been used to describe nonstrange dense matter, both with and without the neutrino trapping. We have found that the cross section becomes more sensitive to the constituent distribution of the matter, once electromagnetic properties of the neutrino are taken into account. The effects of neutrino electromagnetic properties on the cross section become more significant for the neutrino magnetic moment ${\ensuremath{\mu}}_{\ensuremath{\nu}}>{10}^{\ensuremath{-}10}{\ensuremath{\mu}}_{B}$ and for the neutrino charge radius $R>{10}^{\ensuremath{-}5}\phantom{\rule{0.3em}{0ex}}{\mathrm{MeV}}^{\ensuremath{-}1}$.

Study of neutrino electromagnetic properties with the prototype of the Borexino detector

The results of background measurements with the prototype of the Borexino detector (CTF) have been used to obtain an upper bound on the neutrino magnetic moment, μν. The new upper limit for μν from pp and 7Be solar neutrinos is (5.5×10−10)μB (90% c.l.) in the Standard Solar Model scenario. This is the first limit on μν obtained using sub-MeV neutrinos. The sensitivity of the prototype to the neutrino charge radius and the neutrino radiative decay are also presented.

Constraining Majorana neutrino electromagnetic properties from the LMA-MSW solution of the solar neutrino problem

In this paper we use solar neutrino data to derive stringent bounds on Majorana neutrino transition moments (TMs). Should such be present, they would contribute to the neutrino–electron scattering cross section and hence alter the signal observed in Super-Kamiokande. Motivated by the growing robustness of the LMA-MSW solution of the solar neutrino problem indicated by recent data, and also by the prospects of its possible confirmation at KamLAND, we assume the validity of this solution, and we constrain neutrino TMs by using the latest global solar neutrino data. We find that all elements of the TM matrix can be bounded at the same time. Furthermore, we show how reactor data play a complementary role to the solar neutrino data, and use the combination of both data sets to improve the current bounds. Performing a simultaneous fit of LMA-MSW oscillation parameters and TMs we find that 6.3×10 −10 μ B and 2.0×10 −10 μ B are the 90% C.L. bounds from solar and combined solar + reactor data, respectively. Finally, we perform a simulation of the upcoming Borexino experiment and show that it will improve the bounds from today's data by roughly one order of magnitude.

Tests of physics beyond the standard model with future low energy neutrino experiments

Neutrino-electron scattering can be used to probe neutrino electromagnetic properties at low-threshold underground detectors with good recoil electron energy resolution. We study the sensitivity of Helium detector experiments, such as HELLAZ, for artificial anti-neutrino sources. We show that, for a 90 Sr — Y source, one expects a sensitivity to the neutrino magnetic moment at the level of μ ν = 2 × 10 −11 μ B . We also report the sensitivity that these experiments could have in searching for an additional gauge boson in E 6 models.

Limits on neutrino electromagnetic properties — an update

Limits on neutrino electromagnetic properties from laboratory experiments and astrophysical arguments are reviewed with an emphasis on the currently favored range of small neutrino masses. We derive a helioseismological limit on the charge and dipole moment for all flavors of e ν ≲6×10 −14 e and μ ν ≲4×10 −10 μ B (Bohr magneton). The most restrictive limits remain those from the plasmon decay in globular-cluster stars of e ν ≲2×10 −14 e and μ ν ≲3×10 −12 μ B.

Electromagnetic properties of neutrinos and pion radiative decay.

We investigate the implications of neutrino electromagnetic dipole moments for the radiative decay $\pi \rightarrow e \nu \gamma$. We show that the dominant new effect comes from the interference between the amplitude of the process with the photon emitted by the neutrino and the structure dependent standard amplitude. Such interference takes place only if the massive neutrino is a Majorana fermion. Moreover, since electric and magnetic dipole moments give rise to contributions with opposite signs, future experiments might be able to distinguish between them.

Electron Bremsstrählung induced by neutrinos with magnetic- and electric-dipole momenta

The electron bremsstrählung induced, in a metallic detector, by relic neutrinos can be used to test the hypothesis of a big enhancement of the neutrino electromagnetic properties, suggested to explain the famous solar-neutrino puzzle. The problems connected with the presence in the above reaction of coherence effects are discussed. In particular, we show the strong suppression of the electromagnetic contributions occurring forE γ<10−4 eV due to the large value of the plasma frequence in a metal. To partially overcome this problem, the corresponding flavour-changing reaction has been considered. As a result, to obtain an experimental reasonable rate for the photon production, large values for magnetic-and/or electric-dipole momenta are required . A remarkable feature of the e.m.-dominated process is also the very small value of the asymmetry in the photon helicity, while the weak part would imply an effect of about 20%.

Electromagnetic interactions and chirality flip of neutrinos in a thermal background

We investigate the finite temperature and density effects on the electromagnetic properties of neutrinos. For a standard model neutrino we find a left-handed effective charge and a chirality flipping term associated with the longitudinal photon exchange. We find that in the supernova the chirality flipping rate is two orders of magnitude larger than the previous estimates using the vacuum magnetic moment.

Core mass at the helium flash from observations and a new bound on neutrino electromagnetic properties

Existing measurements of the bolometric magnitudes of the brightest red giants in 26 globular clusters are used to determine the brightness difference between the tip of the red giant branch (on average found to be 0.1 mag brighter than the brightest red giant) and RR Lyrae stars. The metallicity variation of the result agrees perfectly with theoretical predictions. In conjunction with previous determinations of the number ratio of horizontal-branch versus red giant stars, with statistical parallax determinations of RR Lyrae absolute luminosities, and with theoretical predictions based on the Sweigart and Gross evolutionary sequences, this result yields an allowed range for a hypothetical core mass variation relative to the standard results of (0.009 + or - 0.012) solar mass. If neutrinos had anomalous electromagnetic dipole moments, the increased energy loss near the helium flash would lead to an increased core mass. Constraints on neutrino electromagnetic properties are determined from the color-magnitude diagrams of the globular clusters.

Limits on the ? neutrino electromagnetic properties from single photon searches ate + e ? colliders

We set limits on the magnetic moment and charge radius of the τ neutrino by examining the contributions to the processe+e−→v\(\bar \nu \)γ due to such interactions. We find thatK(ντ)<4×10−6 (i.e.μ(ντ)<4×10−6μB, μB=e/2me) and 〈r2〉<2×10−31 cm2 using the combined data of the MAC, ASP, CELLO, and Mark J collaborations for this process. We briefly discuss whether these bounds can be improved in any futuree+e− experiments.

Electromagnetic and weak interactions in stochastic space-time: A review

A scheme for a nonlocal theory of quantized fields based on the hypothesis of stochastic space is proposed. Within this scheme the gauge-invariant quantum electrodynamics of particles with spin 0, 1/2, 1 and four-fermion weak interactions are constructed, and nonlocal corrections to the anomalous magnetic moments of leptons and to the Lamb shift are calculated. Some consequences of the neutrino oscillations and the electromagnetic properties of neutrinos are considered in detail. Further the rare decayK L 0 →Μ+Μ− and the mass difference ofK L 0 andK S 0 mesons are investigated in this model. It is shown that the parameter of nonlocality (elementary lengthl) of weak interactions which can characterize a domain of unification of weak and electromagnetic interactions is ∼10−16 cm. The low-energy experiments imply that quantum electrodynamics is valid up to distances of order ∼10−15 cm.

Properties of neutrinos in a class of gauge theories

We discuss the properties of neutrinos in a class of gauge theories characterized by manifest left-right symmetry and spontaneous genesis of parity nonconservation. Topics discussed in detail include: currents with anomalous Lorentz structure (herein called class III currents), electromagnetic properties of neutrinos, and rare processes involving neutrinos which are forbidden in the two-component theory. Calculations of the relevant coupling parameters and reaction rates are presented and compared to the best limits available from terrestrial experiments and astrophysical considerations. Some cosmological implications are also discussed, and it is suggested that all long-lived low-mass neutrinos have been discovered.