TeV Leptogenesis in the Minimal Seesaw Model Zhi-zhong Xing & Shun Zhou IHEP, Beijing (1) Ingredients of the Model (2) Neutrino Mixing Pattern (3) Resonant Leptogenesis (4) Concluding Remarks Based on our latest preprint hep-ph/0607302 (today)

Ingredients of the Model (1) 2 Right-handed neutrinos added into the SM: Frampton, Glashow, Yanagida (2002): • Principle of minimal particle content • SU(2)_LU(1)_Y gauge symmetry preserved • Lepton number violating To simultaneously account for neutrino oscillations & cosmological baryon number asymmetry: one stone kills two new physics birds Works on the MSM (an incomplete list): Endoh et al 02; Raidal and Strumia 03; Raby 03; Dutta and Mohapatra 03; Guo and Xing 04; Mei and Xing 04; Barger et al 04; Felipe, Joaquim and Nobre 04; Ibarra and Ross 04; Turzynski 04; Chang, Kang and Kim 04; Fujihara et al 05; Branco, Rebelo and Silva-Marcos 06; Ibarra 06; ……

Ingredients of the Model (2) Seesaw: Salient feature: there is a massless -eigenstate! • Normal -mass hierarchy: • Inverted -mass hierarchy: x,y real Basis: charged-lepton and heavy Majorana neutrino mass matrices are diagonal Observation 1: flavor mixing of light neutrinos depends primarily on V_0 in the chosen basis Observation 2: decays of heavy neutrinos rely mainly on U in the chosen basis

Ingredients of the Model (3) Assumptions 1 & 2 (the only source of CP violation is from ): They might be able to result from certain flavor symmetries Assumption 3 (M_1 and M_2 are highly degenerate and at TeV): The goals of this talk: • To account for current neutrino oscillation data and to predict the smallest neutrino mixing angle and CP violation • To realize the successful TeV-scale leptogenesis, which can be tested at the forthcoming LHC or ILC experiments

Neutrino Mixing Pattern Masses: Mixing: Results: Correlation:

Neutrino Mixing Pattern Masses: Mixing: Results: This scenario is now okay, but less interesting in phenomenology

TeV Resonant Leptogenesis (1) Lepton number violation: Amplitude: tree + vertex correction + self-energy correction interference CP violation:

TeV Resonant Leptogenesis (2) Dynamic generation of the baryon number asymmetry: (Sakharov 1967) (WMAP 06) (Kuzmin, Rubakov, Shaposhnikov 1985; Fukugita, Yanagida 1986) Lepton number asymmetry Here k_1≈k_2 are the efficiency factors measuring the washout effects in the out-of-equilibrium decays of N_1 and N_2 (Blanchet, Di Bari 06)

TeV Resonant Leptogenesis (3) Numerical illustration (m_1 = 0 case): Region 1

TeV Resonant Leptogenesis (4) Numerical illustration (m_1 = 0 case): Region 2

Concluding Remarks This phenomenological model works: Nearly tri-bimaximal neutrino mixing pattern achieved Successful TeV-scale resonant leptogenesis achieved Can be extended to accommodate the supersymmetry Testable in both neutrino experiments and LHC / ILC Although many questions about it remain unanswered, at least, now everything is touchable on the ground.