Speaker
Rikard Enberg
Description
The number of effective relativistic neutrino species Neff is a sensitive probe of new physics if there are new particles that couple to SM particles at the time of the neutrino decoupling, which occurs at a temperature of around MeV, one second after the Big Bang. We calculate how the existence of a light Z' boson with generic vector and axial-vector couplings to electrons and neutrinos affects the predicted value of Neff and compare with the measured value to put bounds on the couplings. We further apply this analysis to the case of our previously studied model for the 17 MeV Z' boson that can potentially explain the ATOMKI anomaly and thereby further tighten the constraints on its parameters.
Author
Co-authors
Carlos de los Heros
(Uppsala University)
Stefano Moretti
(Science and Technology Facilities Council STFC (GB))
Yasar Hicyilmaz
(University of Southampton)