First result for the neutrino magnetic moment from measurements with the GEMMA spectrometer

Beda, A. G.; Brudanin, V.; Demidova, É. V.; Vylov, C.; Gavrilov, M. G.; Egorov, V.; Старостин, А. С.; Shirchenko, M.

doi:10.1134/s1063778807110063

Cited by 47 publications

(48 citation statements)

References 12 publications

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“…Therefore, for relativistic neutrino energies the interference between exhibit a quite a different dependence on the experimentally observable electron recoil energy T . The dependence of these two terms on T is shown [99] in Fig. 19 for six fixed values of the neutrino magnetic moment, µ (N ) ν = N × 10 −11 µ B , N = 1, 2, 3, 4, 5, 6.…”

Section: Experimental Limits On Neutrino Magnetic Momentmentioning

confidence: 99%

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Neutrino electromagnetic properties

2009

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The main goal of the paper is to give a short review on neutrino electromagnetic properties. In the introductory part of the paper a summary on what we really know about neutrinos is given: we discuss the basics of neutrino mass and mixing as well as the phenomenology of neutrino oscillations. This is important for the following discussion on neutrino electromagnetic properties that starts with a derivation of the neutrino electromagnetic vertex function in the most general form, that follows from the requirement of Lorentz invariance, for both the Dirac and Majorana cases. Then, the problem of the neutrino form factors definition and calculation within gauge models is considered. In particular, we discuss the neutrino electric charge form factor and charge radius, dipole magnetic and electric and anapole form factors. Available experimental constraints on neutrino electromagnetic properties are also discussed, and the recently obtained experimental limits on neutrino magnetic moments are reviewed. The most important neutrino electromagnetic processes involving a direct neutrino coupling with photons (such as neutrino radiative decay, neutrino Cherenkov radiation, spin light of neutrino and plasmon decay into neutrino-antineutrino pair in media) and neutrino resonant spin-flavor precession in a magnetic field are discussed at the end of the paper.

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Section: Experimental Limits On Neutrino Magnetic Momentmentioning

confidence: 99%

“…The cross section for electron neutrino (antineutrino) scattering on electrons can be written [101] (see also [98,99,102]) as a sum of the Standard Model contribution and the neutrino magnetic moment contribution: The Standard Model contribution in Eq. (120) is…”

Section: Experimental Limits On Neutrino Magnetic Momentmentioning

confidence: 99%

Neutrino electromagnetic properties

2009

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“…Current direct experimental searches [3,4,5] for a magnetic moment of the electron (anti)neutrinos from reactors have lowered the upper limit on µ ν down to µ ν < 3.2 × 10 −11 µ B [5]. These ultra low background experiments use germanium crystal detectors exposed to the neutrino flux from a reactor and search for scattering events by measuring the energy T deposited by the neutrino scattering in the detector.…”

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confidence: 99%

Testing neutrino magnetic moment in ionization of atoms by neutrino impact

2011

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The atomic ionization processes induced by scattering of neutrinos play key roles in the experimental searches for a neutrino magnetic moment. Current experiments with reactor (anti)neutrinos employ germanium detectors having energy threshold comparable to typical binding energies of atomic electrons, which fact must be taken into account in the interpretation of the data. Our theoretical analysis shows that the so-called stepping approximation to the neutrino-impact ionization is well applicable for the lowest bound Coulomb states, and it becomes exact in the semiclassical limit. Numerical evidence is presented using the Thomas-Fermi model for the germanium atom.The neutrino magnetic moments (NMM) expected in the Standard Model are very small and proportional to the neutrino masses [1]: µ ν ≈ 3 × 10 −19 µ B (m ν /1 eV) with µ B = e/2m being the electron Bohr magneton, and m is the electron mass. Thus any larger value of µ ν can arise only from physics beyond the Standard Model (a recent review of this subject can be found in Ref.[2]). Current direct experimental searches [3,4,5] for a magnetic moment of the electron (anti)neutrinos from reactors have lowered the upper limit on µ ν down to µ ν < 3.2 × 10 −11 µ B [5]. These ultra low background experiments use germanium crystal detectors exposed to the neutrino flux from a reactor and search for scattering events by measuring the energy T deposited by the neutrino scattering in the detector. The sensitivity of such a search to NMM crucially depends on lowering the threshold for the energy transfer T , due to the enhancement of the magnetic scattering relative to the standard electroweak one at low T . Namely, the differential cross section dσ/dT is given by the incoherent sum of the magnetic and the standard cross section, and for the scattering on free electrons the NMM contribution is given by the formula [6,7] dσ (µ) dT = 4παµwhere E ν is the energy of the incident neutrino, and displays a 1/T enhancement at low energy transfer. The 1)

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“…The integral of the photon energy spectrum obtained from Eqs. (86)(87)(88) is infrared divergent if extended to arbitrary small photon energy. The total NLO cross section is obtained by implementing an infrared regulator and including the (separately infrared divergent) virtual correction from Section 3.…”

Section: Photon Energy Spectrummentioning

confidence: 99%