Sphaleron erasure of primordial baryogenesis

Broken R-parity in the sky and at the LHC

“…From eqs. (2.18), (3.6) and η ≃ 0.06, one obtains for the R-parity breaking parameter 31) which is consistent with the present upper bound (5.10) within the theoretical uncertainties. The dependence of the mixing angle θ τ on m e τ 1 is shown in figure 5 for the boundary condition (5.2).…”

“…As we shall see, the lower bound on the neutralino decay length is a direct consequence of the Fermi-LAT constraints on decaying dark matter. On the other hand, the lower bound on the τ -decay length is determined by the cosmological bounds on R-parity breaking couplings, which follow from the requirement that the baryon asymmetry is not washed out [29][30][31][32].…”

“…We are now ready to evaluate the implications of recent Fermi-LAT data [21,22] and cosmological constraints [29][30][31][32] for signatures of decaying dark matter at the LHC. We shall first discuss monochromatic gamma-rays produced by gravitino decays and then analyze the implications for a neutralino and a τ -NLSP, respectively.…”

Protecting the baryon asymmetry with thermal masses

“…Also, any source of new exotic baryon or lepton number violation together with the sphalerons has the potential to destroy the baryon asymmetry, even with a nonzero primordial component of B − L. To avoid this outcome, it appeared to be necessary to place stringent limits on various effective operators [8][9][10][11] . These limits however, were shown to be weakened significantly due to the effective conservation of e R -number at temperatures T > ∼ 10 TeV, and to only apply to flavour independent couplings [7,10,12,13] .…”

GUT's have the guts to defy sphalerons

“…They observe that if there is no mixing of lepton generations and lepton number violating interactions are in thermal equilibrium for just one or two (but not all three) generations simultaneously with the sphaleron interactions, then a non-zero value of B can survive even if initially B−L = 0; but 1/3B − L i or 2/3B − (L i + L j ) must be non-zero where i(and j) is (are) the generation(s) for which the lepton number violating interactions are not in thermal equilibrium. Dreiner and Ross [8] have shown that, for a second or weakly first order EWPT, inclusion of the particle masses while analyzing the chemical equilibrium equations for T < T EW gives B ∼ 10 −7 ∆L for (B − L) initial = 0, where ∆L is the initial lepton generations' asymmetry ∆L = i>j (L i − L j ) and it is expected to be of the same order of magnitude as the initial lepton number. While Davidson et al [9] show that the inclusion of thermal mass effects for T > ∼ T EW also gives B ∼ 10 −7 ∆L at T ∼ T EW .…”