Experimental limit for the charge of the free neutron

Baumann, J.; Gähler, R.; Kalus, J.; Mampe, W.

doi:10.1103/physrevd.37.3107

Cited by 101 publications

(86 citation statements)

References 12 publications

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“…In this device small steel balls (0.2-0.3 mm diameter) are held in (unstable) equilibrium with the gravitational force in a strong magnetic field by a feedback mechanism and exposed to a homogeneous electric field that works in horizontal direction. Carefully evaluating all possible forces on the steel spheres besides the electrostatic one, the authors arrive at a charge difference of ⌬ϭ(0.8Ϯ0.8)ϫ10 Ϫ21 e. A prerequisite for this value to be valid is the neutrality of the neutron, which has been established at high accuracy, q n ϭ(Ϫ0.4Ϯ1.1)ϫ10 Ϫ21 e (Gä hler et al, 1982;Baumann et al, 1988). Thoughts about an improved experiment are described by Baumann et al (1989); no further attempts have, however, been made to perform such a new experiment (Gä hler, 1997).…”

Section: Direct Measurement Of Charge-bulk Matter Methodsmentioning

confidence: 99%

Forty years of antiprotons

Eades

Hartmann

1999

Rev. Mod. Phys.

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The discovery of the antiproton some 40 years ago and the almost synchronous fall of parity (P) and charge conjugation (C) symmetries were soon followed by the realization that CPT rather than C invariance is the fundamental symmetry connecting matter and antimatter, and that consequently any measurement of the antiproton's properties can be interpreted as a test of that symmetry. It is the latter view of the antiproton, as an object of study in its own right, rather than as a means to such other ends as the production of gauge bosons and meson resonances, that is presented here. The authors review the technical steps that have led from the handful of antiprotons observed by Chamberlain, Segrè , Wiegand, and Ypsilantis to the intense, high-quality beams available today and show how the state of rest and isolation required for high precision measurements of their properties can be achieved by confining them in electromagnetic traps or in their microscopic counterparts, exotic atoms. The test bench role of antiprotons and antihydrogen atoms for both CPT symmetry and the gravitational weak equivalence principle is discussed, and the body of experimental results obtained since 1955 critically reviewed from this standpoint. Future experiments are then discussed in the light of the closure of the CERN Low Energy Antiproton Ring (LEAR), its replacement in 1999 by the Antiproton Decelerator (AD), and the likely antiproton source at the Japan Hadron Facility.[S0034-6861(99)00401-8] CONTENTS

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Section: Direct Measurement Of Charge-bulk Matter Methodsmentioning

confidence: 99%

Forty years of antiprotons

Eades

Hartmann

1999

Rev. Mod. Phys.

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“…These contributions are not vanishing even at q 2 = 0. Therefore in addition to the usual four terms in (78) an extra term proportional to γ µ γ 5 appears and the corresponding additional form factor f 5 (q 2 ) can be introduced. This problem is related to the decomposition of the massive neutrino electromagnetic vertex function.…”

Section: Neutrino Form Factors In Gauge Modelsmentioning

confidence: 99%

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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“…The most stringent constraint applies on the electronic neutrino. Assuming charge conservation in β decay, and using the experimental results from [37] and [38]: q p + + q e − = (0.8 ± 0.8)10 −21 e and q n 0 = (−0.4 ± 1.1)10 −21 e, the constraint q νe 10 −21 e is obtained. Independent, less stringent upper bounds also hold from neutrino magnetic dipole moment searches, see e.g.…”

Section: Jhep08(2014)133mentioning

confidence: 99%

Can a millicharged dark matter particle emit an observable γ-ray line?

Aisati

Hambye

Scarna

2014

J. High Energ. Phys.

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If a γ-ray line is observed in the near future, it will be important to determine what kind of dark matter (DM) particle could be at its origin. We investigate the possibility that the γ-ray line would be induced by a slow DM particle decay associated to the fact that the DM particle would not be absolutely neutral. A "millicharge" for the DM particle can be induced in various ways, in particular from a kinetic mixing interaction or through the Stueckelberg mechanism. We show that such a scenario could lead in specific cases to an observable γ-ray line. This possibility can be considered in a systematic modelindependent way, by writing down the corresponding effective theory. This allows for a multi-channel analysis, giving in particular upper bounds on the intensity of the associated γ-ray line from cosmic rays emission. Our analysis includes the possibility that in the twobody decay the photon is accompanied with a neutrino. We show that, given the stringent constraints which hold on the millicharge of the neutrinos, this is not an option, except if the DM particle mass lies in the very light KeV-MeV range, allowing for a possibility of explanation of the recently claimed, yet to be confirmed, ∼ 3.5 KeV X-ray line.

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Experimental limit for the charge of the free neutron

Cited by 101 publications

References 12 publications

Forty years of antiprotons

Forty years of antiprotons

Neutrino electromagnetic properties

Can a millicharged dark matter particle emit an observable γ-ray line?

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