Resonant Enhancement for the transfer of baryon number from a CP-violating hidden sector

Abstract We consider a scenario where the baryon asymmetry in the SM arises from a portal coupling to a CP-violating hidden sector, without any explicit violation of baryon or lepton number in either sector. While no net baryon number is generated, equal and opposite baryon numbers can be sequestered between the two sectors in this scenario. The observed asymmetry must be generated below the electroweak scale in order to avoid washout. By considering a benchmark model incorporating the baryon portal and a minimal hidden sector, we review the prospects of this scenario. When the asymmetry is generated via the decay of top quarks, generic input parameters for the model are sufficient. If however the asymmetry is to be generated via the decay of bottom quarks, a resonant enhancement is needed to sequester the baryon number with maximal efficiency. The scenario of mesogenesis assisted by CP-violation in a hidden sector falls into this latter category. We use analytical and numerical methods to quantify the amount of resonant enhancement that can be achieved, and we remark that the mesogenesis scenario can be discovered or ruled out in full if the bounds on the relevant branching ratios can be improved by 2–3 orders of magnitude.