A ‘neglected’ neutrino may hold the key to why the Universe exists

Humanity’s biggest question is always knowing the cause or reason of its existence. And in a recent breakthrough, scientists have revealed a new theory tackling this question: Why do humans exist?

Surprisingly, the answer lies in a “neglected and ancient particle.”

For years, the researchers have been puzzling over how matter was able to win out over antimatter as standard Physics models predict that matter and antimatter should have completely annihilated each other after the Big Bang, thereby leaving behind a universe of pure energy.

This new research was reported in a new paper, 'Delayed Charged Lepton Yukawa Equilibration in Minimal Seesaw', published in the journal Physical Review Letters, unlocked a mystery about how matter managed to survive and dominate.

Researchers from the University of Southampton and the Indian Institute of Technology Kanpur identified a previously dismissed "decoupled" heavy neutrino as the missing puzzle piece.

It is a neglected relative of those particles called a decoupled heavy neutrino as it could have helped matter to survive with the existence of the universe.

Rishav Roshan, from the University of Southampton, an author on the new paper, said, "However, it decays incredibly slowly. As the cosmos cooled after the Big Bang, the particle lived long enough that it temporarily took over the energy density of the universe and triggered a matter-dominated period."

The particle shifted the temperature threshold at which fundamental particles like electrons and leptrones interacted with antiparticles through the Standard Model Higgs boson, locking in the matter-antimatter imbalance.

"This temperature acts like a switch that shapes how the matter-antimatter imbalance was built up."

This dramatic shift in early cosmic expansion left distinct imprints on primordial gravitational waves, providing scientists with a measurable way to test and verify the theory.