Sommerfeld corrections to type-II and type-III leptogenesis

Abstract

We study thermal leptogenesis from decays of the electroweak triplets that mediate neutrino masses in type-II and type-III seesaw. We find that Sommerfeld corrections reduce the baryon asymmetry by ∼ 30%, and that successful leptogenesis needs triplets heavier than 1.6 TeV, beyond the discovery reach of LHC.

LeptonicCPviolation

“…We note, however, that in the latter case there is a dependence on M ∆i that strongly suppresses the leptogenesis efficiency when M ∆i ∼ O(TeV). Moreover, the final baryon asymmetry crucially depends on the triplet annihilation rate in the nonrelativistic limit, which is affected by nonperturbative corrections to the s-wave coefficient that reduce further the leptogenesis efficiency by about 30% (Strumia, 2009). Since after the electroweak symmetry breaking, at temperatures T m Higgs , sphaleron interactions are suppressed and no longer can convert the lepton asymmetry into a baryon asymmetry, a stringent lower bound on the triplet mass is obtained.…”

“…Since after the electroweak symmetry breaking, at temperatures T m Higgs , sphaleron interactions are suppressed and no longer can convert the lepton asymmetry into a baryon asymmetry, a stringent lower bound on the triplet mass is obtained. To successfully reproduce the observed baryon asymmetry, a triplet mass M ∆i 1.6 TeV is required (Strumia, 2009), which is too heavy to give detectable effects at the LHC (Nath et al, 2010).…”

“…These bounds are slightly stronger than in type I leptogenesis. On the other hand, if leptogenesis occurs at the TeV scale, the correct amount of baryon asymmetry can only be generated for M Σi 1.6 TeV (Strumia, 2009), which is too large to be within the energy reach of the LHC (Nath et al, 2010). Accounting for flavor effects does not weaken this bound (Aristizabal Sierra et al, 2010b).…”

Implications of flavor dynamics for fermion triplet leptogenesis

“…Given that qualitatively the conditions for producing a lepton asymmetry are also fulfilled in other see-saw realizations (type II [16] and type III [17]) one is tempted to extend the standard type I analysis to these cases, and in fact studies of such scenarios have been considered [18,19,20,21,22]. In these models the lepton asymmetry is generated via the dynamics of either a scalar (type II) or a Majorana fermion (type III) SU (2) triplet and thus the major difference between these cases and the standard one arises from the fact that both, the scalar and fermion, couple to standard model (SM) gauge bosons.…”

Hot QCD vs cosmology

“…[30]- [33]. Subsequently it has also been applied to the question of how fast the number density of charm quarks produced in heavy ion collision experiments approaches its thermal value [34].…”