Abstract
Abstract
We demonstrate that the leptogenesis mechanisms, which are associated with B-L symmetry
breaking mechanism has notable effects on the production of gravitational waves. These
gravitational waves align well with the recent observations of a stochastic gravitational wave
background by NANOGrav and pulsar-timing arrays (PTAs). For these gravitational waves to match the
recent measurements, the critical value of the B-L breaking should be around the GUT
scale. Moreover, we consider the generation of primordial gravitational waves from binary systems
of Primordial Black Holes (PBHs) which could be predicted by the recent detection of
gravitational waves. PBHs with specific masses can be responsible for massive galaxy formation
observed at high redshifts reported by the James Webb Space Telescope (JWST). We contemplate the
potential for a shared source between the NANOGrav and JWST observations, namely primordial black
holes. These black holes could serve as seeds of rapid galaxy formation, offering an explanation
for the galaxies observed by JWST.