Abstract
We propose a novel mechanism for production of baryonic asymmetry in the early Universe. The mechanism takes advantage of the strong first order phase transition that produces runaway bubbles in the hidden sector that propagate almost without friction with ultra-relativistic velocities. Collisions of such bubbles can non-thermally produce heavy particles that further decay out-of-equilibrium into the SM and produce the observed baryonic asymmetry. This process can proceed at the very low temperatures, providing a new mechanism of post-sphaleron baryogenesis. In this paper we present a fully calculable model which produces the baryonic asymmetry along these lines as well as evades all the existing cosmological constraints. We emphasize that the Gravitational Waves signal from the first order phase transition is completely generic and can potentially be detected by the future eLISA interferometer. We also discuss other potential signals, which are more model dependent, and point out the unresolved theoretical questions related to our proposal.
Highlights
Can one generate a baryon asymmetry at temperatures lower than about 100 GeV, when the baryon number violation provided by the SM sphalerons is switched off? The three required ingredients for baryogenesis are of baryon number violation, C and CP violation and out-of-equilibrium dynamics [13]
It is not easy to generate the baryon asymmetry in a universe that reheats after inflation to a low temperature because the first and third ingredients are hard to come by: it is difficult to introduce baryon number violation at low temperatures without contradicting laboratory bounds on baryon number violation, and the universe is expanding so slowly at low temperatures that it is very close to equilibrium
The mechanism that we propose relies on an assumption, that heavy particles, ψ, which decay out of equilibrium via CPV and baryon-number violating (BNV) or lepton-number violating (LNV) operators, are produced non-thermally at temperatures much lower than their masses
Summary
The mechanism that we propose relies on an assumption, that heavy particles, ψ, which decay out of equilibrium via CPV and baryon-number violating (BNV) or lepton-number violating (LNV) operators, are produced non-thermally at temperatures much lower than their masses. A non-thermal particle production mechanism, which can efficiently produce the particles much heavier than the equilibrium temperature, we will take advantage of is the runaway bubble collisions in the strong first order cosmological phase transition. This mechanism has been discovered lots of time ago [24, 28] and was mostly discussed in the context of the SM and the potentially first order EWPT. Because we can produce even at low scales much bigger abundances of the heavy decaying particles that one expects from the thermal scenarios, we will be able to get the observed baryonic asymmetry with much smaller values of the CPV, than one needs in the “WIMPy” scenarios
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