Reexamination of astrophysical and cosmological constraints on the magnetic moment of neutrinos

Fukugita, M.; Yazaki, S.

doi:10.1103/physrevd.36.3817

Cited by 113 publications

(87 citation statements)

References 26 publications

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“…I, however, cuts on various backgrounds dictate 3 < (T = E vis ) < 5 MeV. We assume that the term associated with the neutrino magnetic moment (µ e ) is negligible, based on astrophysical constraints [31,32,33,34]. We note, though, that the lab-based limits on the neutrino magnetic moment are two orders of magnitude higher [35].…”

Section: νE Event Rate and Identificationmentioning

confidence: 99%

Precision measurement ofsin2θWat a reactor

2005

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This paper presents a strategy for measuring sin 2 θW to ∼1% at a reactor-based experiment, using νe elastic scattering. This error is comparable to the NuTeV, SLAC E158, and APV results on sin 2 θW , but with substantially different systematic contributions. The measurement can be performed using the near detector of the presently proposed reactor-based oscillation experiments. We conclude that an absolute error of ∼ δ(sin 2 θW ) = 0.0019 may be achieved. This paper outlines a method for measuring sin 2 θ W (Q 2 ≈ 0) at a reactor-based experiment. The study is motivated by the NuTeV result, a 3σ deviation of sin 2 θ W from the Standard Model prediction [1], measured in deep inelastic neutrino scattering (Q 2 = 1 to 140 GeV 2 , Q 2 ν = 26 GeV 2 , Q 2 ν = 15 GeV 2 ). Various Beyond-the-Standard Model explanations have been put forward [2,3,4], and, to fully resolve the issue, many require a follow-up experiment which probes the neutral weak couplings specifically with neutrinos, such as the one described here.This proposed measurement is also interesting as an additional precision study at Q 2 = 4×10 −6 GeV 2 . The two existing low Q 2 measurements are from atomic parity violation (APV) [5], which samples Q 2 ∼ 10 −10 GeV 2 ; and SLAC E158, a Møller scattering experiment at average Q 2 = 0.026 GeV 2 [6]. Using the measurements at the Z-pole with Q 2 = M 2 z to fix the value of sin 2 θ W , and evolving to low Q 2 , Fig. 1 shows that these results are in agreement with the Standard Model. However, the radiative corrections to neutrino interactions allow sensitivity to high mass particles which are complementary to the APV and Møller scattering corrections. Thus, this proposed measurement will provide valuable additional information.The technique we employ uses the rate of the purely leptonic νe scattering to measure sin 2 θ W . This signal was first detected by Reines, Gurr, and Sobel [7], who measured sin 2 θ W = 0.29 ± 0.05. In this paper, we explore what is necessary to improve on their idea and make a competitive measurement today. One important step is to normalize the νe "elastic scatters" using the νp inverse beta decay events, to reduce the error on the flux. Other crucial improvements are that the detector is located beneath an overburden of ∼300 mwe (meters, water-equivalent) and built in a clean environment. We find that a measurement of ±0.0020 is achievable. This is comparable to the NuTeV error of ±0.00164, and may help clarify the theoretical situation, as shown in references [8,9].The proposed design employs spherical scintillator oil detectors similar to those used by CHOOZ [10] and by other experiments which have been proposed to measure the oscillation parameter θ 13 [11].This style of detector has been optimized to reconstruct νp → e + n events, which dominate the rate when

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Section: νE Event Rate and Identificationmentioning

confidence: 99%

Precision measurement ofsin2θWat a reactor

2005

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“…In order to arrive at a first estimate we recall that Ref. [5] implies that the main contribution to the neutrino spin relaxation rate arises from spin-flip scattering ν L + e ± → e ± + ν R . The cross section for this process has an infrared divergence which is regularized by screening with a scale of order the photon plasma mass M = eT /3.…”

Section: Depolarization In a Relativistic Plasmamentioning

confidence: 99%

“…In the early universe, the radiation density and thus expansion rate would increase due to the new thermally excited degree of freedom, modifying the predicted primordial light-element abundances. A comparison with observations again allows one to derive limits on µ [4,5,6].…”

Section: Introductionmentioning

confidence: 99%

Neutrinos with magnetic moment: Depolarization rate in plasma

Elmfors¹,

Enqvist

Raffelt

et al. 1997

Nuclear Physics B

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Neutrinos with a magnetic moment µ change their helicity when interacting with an electromagnetic field. Various aspects of this effect have been described as spin precession, spin-flip scattering, and magnetic Cherenkov radiation. These perspectives are unified in an expression for the ν L → ν R transition rate which involves the correlators of the electromagnetic field distribution. Our general formula corrects a previous result and generalizes it to the case where the fields cannot be viewed as classical and where the momentum transfers need not be small. We evaluate our result explicitly for a relativistic QED plasma and determine the depolarization rate to leading order in the fine structure constant. Assuming that big-bang nucleosynthesis constraints do not allow a right-handed neutrino in equilibrium we derive the limit µ < 6.2×10 −11 µ B on the neutrino magnetic moment. Bounds on µ from a possible large scale magnetic fields are found to be more stringent even for very weak fields.

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“…(28), and taking L 0 l H we see that the tightest possible constraint which in principle can be obtained in this manner is < 3 10 19 B . Cosmological [26] and astrophysical [27] constraints on , based on the direct production of wrong-helicity neutrinos in photon mediated collisions are typically less severe by several orders of magnitude. Thus the presence of a primordial magnetic eld is a potential bonus for neutrino physics.…”

Section: Direct Constraints On Magnetic Eldsmentioning

confidence: 99%

Dirac neutrinos and primordial magnetic fields

Engvist¹,

Rez²,

Semikoz³

1995

Nuclear Physics B

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We consider random primordial magnetic elds and discuss their dissipation, coherence length L 0 , scaling behaviour and constraints implied by the primoridal nucleosynthesis. Such magnetic elds could excite the right-helicity states of Dirac neutrinos, with adverse consequences for nucleosynthesis. We present solutions to the spin kinetic equation of a Dirac neutrino traversing a random magnetic eld in the cases of large and small L 0 , taking also into account elastic collisions. Depending on the scaling behaviour and on the magnetic coherence length, the lower limit on the neutrino magnetic moment t h us obtained could be as severe as 10 20 B . 1 enqvist@phcu.helsinki. ; on a leave of absence f r om NORDITA,

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Reexamination of astrophysical and cosmological constraints on the magnetic moment of neutrinos

Cited by 113 publications

References 26 publications

Precision measurement ofsin2θWat a reactor

Precision measurement ofsin2θWat a reactor

Neutrinos with magnetic moment: Depolarization rate in plasma

Dirac neutrinos and primordial magnetic fields

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Reexamination of astrophysical and cosmological constraints on the magnetic moment of neutrinos

Cited by 113 publications

References 26 publications

Precision measurement ofsin﻿2θWat a reactor

Precision measurement ofsin﻿2θWat a reactor

Neutrinos with magnetic moment: Depolarization rate in plasma

Dirac neutrinos and primordial magnetic fields

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Product

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Precision measurement ofsin2θWat a reactor

Precision measurement ofsin2θWat a reactor