منابع مشابه
Supersymmetry and the Nelson-Barr mechanism.
One possible solution to the strong CP problem is that CP is an exact symmetry, spontaneously broken at some scale. Some years ago, Nelson and Barr suggested a mechanism for obtaining θ = 0 at tree level in this framework, and showed that radiative corrections were small in some non-supersymmetric models. Further investigations suggested that the same could be true in supersymmetric theories. I...
متن کاملThe Strong Cp Problem, String Theory and the Nelson-barr Mechanism
We review recent work on the strong CP problem in the context of realistic stringinspired models. We discuss the various solutions, review the conjecture that CP is generally a gauged discrete symmetry in string theory and then consider models of the Nelson-Barr type. We note that squark non-degeneracy spoils the NelsonBarr structure at the one loop level. We stress that string theory expectati...
متن کاملGenetics: Nelson and Lederberg
* Th(e work reporte(I in this article( was carried( out und(ler Contract No. AT-(30-1)-1151, United St at4s Atomiic Energy Conimnissioi. S. Wright and Th. Dohzhansky, Genetics, 31, 125-156, 1946. 2 E. Spiess, Evolution, 4, 14-33, 1950. 3 A. B. Da Cunha, Evolution, 5, 395-404, 1951. 4Th. Dobzhansky and 0. Pavlovsky, Evolution, 7, 198-210, 1953. 5 H. Levene, 0. Pavlovsky, and Th. Dobzhansky, Evol...
متن کاملCharacterisations of Nelson Algebras
Nelson algebras arise naturally in algebraic logic as the algebraic models of Nelson’s constructive logic with strong negation. This note gives two characterisations of the variety of Nelson algebras up to term equivalence, together with a characterisation of the finite Nelson algebras up to polynomial equivalence. The results answer a question of Blok and Pigozzi and clarify some earlier work ...
متن کاملNelson–Aalen Estimator
The Nelson–Aalen estimator is a nonparametric estimator which may be used to estimate the cumulative hazard rate function from censored survival data (see Survival Distributions and Their Characteristics). Since no distributional assumptions are needed, one important use of the estimator is to check graphically the fit of parametric models, and this is the reason why it was originally introduce...
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ژورنال
عنوان ژورنال: Physical Review D
سال: 2019
ISSN: 2470-0010,2470-0029
DOI: 10.1103/physrevd.99.035014