Extra Dimensions and Varying Alpha
نویسنده
چکیده
I review recent constraints on and claimed detections of a time-varying fine-structure constant α. Our results are consistent with no variation in α from the epoch of recombination to the present day, and restrict any such variation to be less than about 4%. The forthcoming MAP and Planck experiments will be able to break most of the currently existing degeneracies between α and other cosmological parameters, and measure α in the early universe with an accuracy comparable to current claimed recent-universe detections.
منابع مشابه
Varying Alpha, Mass Generation and Extra Dimensions
We consider variation of coupling strengths and mass ratios in and beyond the Standard Model, in the light of various mechanisms of mass generation. In fourdimensional unified models, variations in charged particle thresholds, light quark masses and the electron mass can completely alter the (testable) relation between ∆ lnα and ∆ lnμ, where μ ≡ mp/me. In extra-dimensional models where a compac...
متن کاملVarying alpha, thresholds and extra dimensions
We consider variations of coupling strengths and mass ratios in and beyond the Standard Model, in the light of various mechanisms of mass generation. In four-dimensional unified models, heavy quark and superparticle thresholds and the electron mass can completely alter the (testable) relation between ∆ lnα and ∆ lnμ, where μ ≡ mp/me. In extra-dimensional models where a compactification scale be...
متن کاملOn fixed points and fermion mass structure from large extra dimensions
We examine the fixed point behaviour of Yukawa couplings in supersymmetric theories with varying numbers of dimensions. We show that Pendleton-Ross fixed point behaviour is greatly amplified in the MSSM with no extra dimensions and 4 extra 5 + 5 multiplets or the MSSM with one extra large dimension and 3 extra 5+5 multiplets. We also show that power law running in models with large extra dimens...
متن کاملBrane Cosmology, Varying Speed of Light and Inflation in Models with One or More Extra Dimensions *
We summarise the approach to brane cosmology known as " mirage cosmology " and use it to determine the Friedmann equation on a 3-brane embedded in different bulk spacetimes all with one or more extra dimensions. Usually, when there is more than one extra dimension the junction conditions, central to the usual brane world scenarios, are difficult to apply. This problem does not arise in mirage c...
متن کاملStructural Equation Modeling of Effective Dimensions of Job Alienation
Purpose: Considering the importance of human resources and increase leaving job positions, the aim of this study was structural equations modeling of effective dimensions of job alienation. Methodology: The present study was a cross-sectional from type of correlation. The research population was the employees of the government organizations of Isfahan city in 2021 year, which number of 400 peo...
متن کامل