David Kaplan "[HET seminar] Relaxing the Cosmological Constant and Dark Energy Radiation"



The smallness of the cosmological constant has yet to be understood in our current theories of nature. 
I will argue that a dynamical (and non-antropic) explanation suggests that today’s dark energy has a dynamical component.   
I will  show that if dark energy evolves in time, its dynamical component could be dominated by a bath of dark radiation.  
Within current constraints this radiation could have up to $\sim 10^3$ times more energy density than the cosmic microwave background.
I will show models that produce different forms of dark radiation such as hidden photons, milli-charged particles and even Standard Model neutrinos.
I will also show that the late-time cosmology is potentially distinguishable from a cosmological constant or normal quintessence.  If
the radiation couples to the standard model, it may be directly testable in laboratory experiments!
The agenda of this meeting is empty