Leptogenesis triggered by a first-order phase transition

Abstract

We propose a new scenario of leptogenesis, which is triggered by a first-order phase transition (FOPT). The right-handed neutrinos (RHNs) are massless in the old vacuum, while they acquire a mass in the new vacuum bubbles, and the mass gap is huge compared with the FOPT temperature. The ultra-relativistic bubble walls sweep the RHNs into the bubbles, where the RHNs experience fast decay and generate the lepton asymmetry, which is further converted to the baryon asymmetry of the Universe (BAU). Since the RHNs are out of equilibrium inside the bubble, the generated BAU does not suffer from the thermal bath washout. We first discuss the general feature of such a FOPT leptogenesis mechanism, and then realize it in an extended B − L model. The gravitational waves from U(1)B−L breaking could be detected at the future interferometers.

Leptogenesis and dark matter through relativistic bubble walls with observable gravitational waves

“…( 5.3), we can see that in FOPT scenario there arises an extra dilution factor (T n /T RH ) 3 compared to the standard case. This was also noticed in earlier works [34,35]. However, due to a different structure of our model in the absence of any additional gauge symmetry, we have T inf < T n resulting in T RH = T n .…”

“…Thus, leptogenesis from decay, in general, has limited direct experimental probe [26]. This has led to some recent attempts in finding ways to probe leptogenesis via stochastic gravitational wave (GW) observation [27][28][29][30][31][32][33][34][35]. While some of these works rely upon topological defects like cosmic strings, domain walls formed as a result of symmetry breaking [27][28][29][30][31], others consider a first order phase transition (FOPT) to be responsible for generating GW [32][33][34][35].…”

“…This has led to some recent attempts in finding ways to probe leptogenesis via stochastic gravitational wave (GW) observation [27][28][29][30][31][32][33][34][35]. While some of these works rely upon topological defects like cosmic strings, domain walls formed as a result of symmetry breaking [27][28][29][30][31], others consider a first order phase transition (FOPT) to be responsible for generating GW [32][33][34][35]. Similarly, there have been attempts in finding complementary DM probes like stochastic GW background [36][37][38][39][40][41][42][43][44], specially in view of the continued null results at direct detection experiments [45].…”

“…Motivated by this, we consider a minimal scenario where both leptogenesis and DM are triggered by a strong first order phase transition with observable GW signatures. Similar to the baryogenesis mechanism adopted in [32] followed by leptogenesis implementation in [34,35], we consider a scenario where DM as well as right handed neutrino responsible for leptogenesis acquire masses in a FOPT by crossing the relativistic bubble walls. 2 Unlike additional gauge symmetries considered in these works, here we consider a minimal scenario without any gauge extension of the SM.…”

Gravitational waves-tomography of Low-Scale-Leptogenesis

“…has discussed it with a long-lived RH neutrino and showed a possible connection of BGWs with the lightest active neutrino mass. In addition, recently, there have been efforts to probe leptogenesis with gravitational waves from various cosmological sources[39,[46][47][48][49][50][51][52][53][54][55].…”