Dr Basabendu, Dr Amit Chakraborty, and Mr Arindam Basu from the Department of Physics at SRM University-AP jointly authored the study titled, “Testing leptogenesis and dark matter production during reheating with primordial gravitational waves” which was published in Physical Review D (Nature Index). The research looks into different monomial potentials and various decay processes of the inflaton field, providing important insights into fundamental cosmic events.
Abstract:
We study the generation of baryon asymmetry as well as dark matter (DM) in an extended reheating period after the end of slow-roll inflation. Within the regime of perturbative reheating, we consider different monomial potential of the inflaton field during reheating era. The inflaton condensate reheats the Universe by decaying into the Standard Model (SM) bath either via fermionic or bosonic decay modes. Assuming the leptogenesis route to baryogenesis in a canonical seesaw framework with three right handed neutrinos (RHN), we consider both the radiation bath and perturbative inflaton decay to produce such RHNs during the period of reheating when the maximum temperature of the SM bath is well above the reheating temperature. The DM, assumed to be a SM gauge singlet field, also gets produced from the bath during the reheating period via UV freeze-in. In addition to obtaining different parameter space for such nonthermal leptogenesis and DM for both bosonic and fermionic reheating modes and the type of monomial potential, we discuss the possibility of probing such scenarios via spectral shape of primordial gravitational waves.
Practical Implementations & Social Impact:
Imagine the early universe as a giant, chaotic fireball after the Big Bang. But before things settled down into the stars and galaxies we see today, the universe went through a phase called inflation—a rapid expansion driven by a field called the inflaton. Once inflation ended, the inflation’s energy had to somehow convert into all the particles that make up our universe. This process is called reheating. In this study, we explore what happens if reheating takes longer than usual, extending well beyond what’s typically assumed. We look at different ways the inflaton could decay—either into particles like fermions (similar to electrons) or bosons (like the Higgs boson)—and how this affects the formation of two big cosmic mysteries: the matter-antimatter asymmetry (baryon asymmetry) and dark matter. We analyse how different inflaton decay mechanisms and different types of inflaton energy landscapes (represented by mathematical potentials) influence these processes. Beyond just predicting what parameters could make this scenario work, we also suggest a possible way to test it: by looking at primordial gravitational waves, ripples in spacetime left over from the early universe. Their specific features might reveal hints about how reheating played out, offering a new way to probe the origins of matter and dark matter.
This study is not just about abstract physics—it’s about our origins. Understanding how matter and dark matter formed in the early universe connects directly to our existence and could shape future discoveries in physics, technology, and space exploration. Whether it’s through deep-space telescopes, gravitational wave detectors, the quest to understand the first moments of the universe is one that could transform the way we see our place in the cosmos.
Collaborations:
This work has been done in collaboration with Dr Amit Chakraborty and Mr Arindam Basu from the Department of Physics, SRM University-AP
Future Plans:
A closer look at early universe dynamics by performing more involved simulations.
Connection between particle physics models and early Universe cosmology.
Complementary searches from different experiments in unravelling new physics beyond the Standard Model. Searching for new physics at the energy and intensity frontier.
Link: https://journals.aps.org/prd/abstract/10.1103/PhysRevD.111.055016