A neglected right-handed neutrino could explain why matter exists

Physicists from the University of Southampton and IIT Kanpur propose that a hypothetical right-handed neutrino, up to 100 trillion times heavier than a proton, briefly dominated the infant universe's energy. Its dominance sped up cosmic expansion and delayed key interactions, potentially yielding the observed matter-antimatter asymmetry. The study appeared in Physical Review Letters.

• The study examines the third right-handed neutrino usually ignored in the seesaw mechanism
• In their main example it was about 100 trillion times as heavy as a proton
• Its dominance drove early matter domination and delayed lepton flavor interactions
• Tests must be indirect, such as a kink in the early-universe gravitational wave background