Kavli Affiliate: Hitoshi Murayama
| First 5 Authors: Hitoshi Murayama, Bea Noether, Jan Schütte-Engel, ,
| Summary:
Leptogenesis is arguably the best motivated theory of baryogenesis given the
discovery of finite neutrino masses, yet its experimental test is elusive given
its high energy scale. We discuss gravitational waves (GWs) produced via
graviton bremsstrahlung in right-handed neutrino decays during leptogenesis.
The presence of right-handed neutrinos in the early universe can lead to a
period of early matter domination. In this context, the resultant GW spectrum
scales quadratically with the right-handed neutrino mass, while its peak
frequency scales inversely with the Yukawa coupling. Detecting such a spectrum
would provide strong evidence for leptogenesis and the existence of heavy
right-handed neutrinos. We also discuss how the GW spectrum emitted from the
thermal plasma is altered by an era of early matter domination. We show that it
can mimic the effects of additional relativistic degrees of freedom and a
higher reheating temperature, and that information from the graviton
bremsstrahlung GW spectrum can break this degeneracy.
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