Electric dipole moment of the neutron in gauge theory

Shabalin, E.P.

doi:10.3367/ufnr.0139.198304a.0561

Cited by 44 publications

(45 citation statements)

References 13 publications

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“…In the case of the neutron EDM, uncertainties in low-energy strong interaction physics prevent a precise comparison between an experimental value for d n and CP-violating parameters at the quark level [13,14]. In contrast, the electron EDM is free from such uncertainties and can be computed unambiguously once a model is fully specified.…”

Section: = -'2dl'i/j(1ljv/s'i/jfijvmentioning

confidence: 99%

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The electric dipole moment of the electron

1991

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Section: = -'2dl'i/j(1ljv/s'i/jfijvmentioning

confidence: 99%

“…For instance, for the neutron one expects (dn)KM < 10-30 e em (cf. [13,14,[46][47][48][49][50][51][52][53][54][55]). Ifneutrinos are massless, no CP-violating couplings occur among leptons.…”

Section: The Electron Edm In the Standard Modelmentioning

confidence: 99%

The electric dipole moment of the electron

1991

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“…The Standard Model has two explicit CP-violating parameters: the phase in the CKM matrix, and the coefficient θ in the SM strong interaction Lagrangian. EDMs arising from the CKM-matrix vanish up to three loops for the electron (Bernreuther and Suzuki, 1991) and up to two loops for quarks (Shabalin, 1978a(Shabalin, ,b, 1983a. The leading SM contributions to the neutron EDM, however, arise from a combination of hadronic one-loop and resonance contributions, each a combination of two ∆S = 1 hadronic interactions (one CP violating and one CPconserving).…”

Section: B Theoretical Interpretationmentioning

confidence: 99%

Electric dipole moments of atoms, molecules, nuclei, and particles

et al. 2019

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A permanent electric dipole moment (EDM) of a particle or system is a separation of charge along its angular-momentum axis and is a direct signal of T-violation and, assuming CPT symmetry, CP violation. For over sixty years EDMs have been studied, first as a signal of a parity-symmetry violation and then as a signal of CP violation that would clarify its role in nature and in theory. Contemporary motivations include the role that CP violation plays in explaining the cosmological matter-antimatter asymmetry and the search for new physics. Experiments on a variety of systems have become ever-more sensitive, but provide only upper limits on EDMs, and theory at several scales is crucial to interpret these limits. Nuclear theory provides connections from Standard-Model and Beyond-Standard-Model physics to the observable EDMs, and atomic and molecular theory reveal how CP-violation is manifest in these systems. EDM results in hadronic systems require that the Standard Model QCD parameter ofθ must be exceptionally small, which could be explained by the existence of axions -also a candidate darkmatter particle. Theoretical results on electroweak baryogenesis show that new physics is needed to explain the dominance of matter in the universe. Experimental and theoretical efforts continue to expand with new ideas and new questions, and this review provides a broad overview of theoretical motivations and interpretations as well as details about experimental techniques, experiments, and prospects. The intent is to provide specifics and context as this exciting field moves forward.

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“…(See the reviews in Refs. [2,6].) One of the problems of these approaches is that it is not clear whether the results and the approximations adopted are consistent with the anomalous Ward-Takahashi (WT) identity.…”

Section: Introductionmentioning

confidence: 99%

StrongCPviolation and the neutron electric dipole moment reexamined

Aoki

Hatsuda

1992

Phys. Rev. D

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Emission from high-dipole moment molecules such as HCN allows determination of the density in molecular clouds, and is often considered to trace the "dense" gas available for star formation. We assess the importance of electron excitation in various environments. The ratio of the rate coefficients for electrons and H 2 molecules, 10 5 for HCN, yields the requirements for electron excitation to be of practical importance if n(H 2) ≤ 10 5.5 cm −3 and X(e −) ≥ 10 −5 , where the numerical factors reflect critical values n c (H 2) and X * (e −). This indicates that in regions where a large fraction of carbon is ionized, X(e −) will be large enough to make electron excitation significant. The situation is in general similar for other "high density tracers", including HCO + , CN, and CS. But there are significant differences in the critical electron fractional abundance, X * (e −), defined by the value required for equal effect from collisions with H 2 and e −. Electron excitation is, for example, unimportant for CO and C +. Electron excitation may be responsible for the surprisingly large spatial extent of the emission from dense gas tracers in some molecular clouds (Pety et al. 2017; Kauffmann, Goldsmith et al. 2017). The enhanced estimates for HCN abundances and HCN/CO and HCN/HCO + ratios observed in the nuclear regions of luminous galaxies may be in part a result of electron excitation of high dipole moment tracers. The importance of electron excitation will depend on detailed models of the chemistry, which may well be non-steady state and non-static.

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Electric dipole moment of the neutron in gauge theory

Cited by 44 publications

References 13 publications

The electric dipole moment of the electron

The electric dipole moment of the electron

Electric dipole moments of atoms, molecules, nuclei, and particles

StrongCPviolation and the neutron electric dipole moment reexamined

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