Disformal couplings in cosmology and astrophysics, Room 516

The London Relativity and Cosmology Seminar
Carsten van de Bruck (Sheffield)
March 16th, 2016 at 16:30
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In this talk I will discuss the consequences of disformal couplings of matter and radiation to a scalar field in cosmology and astrophysics. I will present several scenarios. I will first outline how disformally coupled dark matter affects the cosmological evolution and how one can distinguish this scenario from conformally coupled dark matter (such as in coupled quintessence). I will then discuss how disformal couplings affect the evolution of the CMB and show that the CMB is no longer of blackbody form if it is disformally coupled to a scalar field. Motivated by this, I will discuss in detail a model of electrodynamics non-minimally coupled to a scalar degree of freedom and describe some observational consequences such as a time-varying fine-structure constant and vacuum Cherenkov radiation.