Hamburg 2016 – scientific programme
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T: Fachverband Teilchenphysik
T 21: Theorie und Experiment in Kosmologie und Neutrinophysik
T 21.3: Talk
Monday, February 29, 2016, 11:30–11:45, VMP9 SR 30
Strong Washout Approximation to Resonant Leptogenesis — Björn Garbrecht, Florian Gautier, and •Juraj Klaric — Physik Department T70, James-Franck-Straße, Techniche Universität München, 85748 Garching, Germany
We study resonant Leptogenesis with two sterile neutrinos with masses M1 and M2, Yukawa couplings Y1 and Y2, and a single active flavor. Specifically, we focus on the strong washout regime, where the decay width dominates the mass splitting of the two sterile neutrinos.
We show that one can approximate the effective decay asymmetry by it’s late time limit ε = X sin(2 ϕ)/(X2+sin2ϕ), where X=8 π Δ/(|Y1|2+|Y2|2), Δ=4(M1−M2)/(M1+M2), and ϕ=arg(Y2/Y1), and establish criteria for the validity of this approximation. We compare the approximate results with numerical ones, obtained by solving the mixing and oscillations of the sterile neutrinos.
We generalize the formula to the case of several active flavors, and demonstrate how it can be used to calculate the lepton asymmetry in phenomenological scenarios which are in agreement with the neutrino oscillation data. We find that that using the late time limit is an applicable approximation throughout the phenomenologically viable parameter space.