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

Thursday 22 Apr 2021, 11:00 → 12:00 US/Eastern

https://bnl.zoomgov.com/j/1616949369?pwd=dXJzMnlDS0ZPWDJvM0Zyb2ppbjc0UT09

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!

Kaplan - Dark Energy Radiation.pdf