Early-universe constraints on a time-varying fine structure constant

P. P. Avelino, S. Esposito, G. Mangano, C. J. A. P. Martins, A. Melchiorri, G. Miele, O. Pisanti, G. Rocha, P. T. P. Viana

Abstract
Higher-dimensional theories have the remarkable feature of predicting a time (and hence redshift) dependence of the ``fundamental'' four dimensional constants on cosmological time scales. In this paper, we update the bounds on a possible variation of the fine structure constant α at the time of big bang nucleosynthesis (z~10¹⁰) and cosmic microwave background (CMB) (z~10³). Using the recently released high-resolution CMB anisotropy data and the latest estimates of primordial abundances of ⁴He and D, we do not find evidence for a varying α at more than a one-sigma level at either epoch.

Physical Review D
Volume 64, Page 103505
November 2001