1. 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/ (today)

2. 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; ……

3. 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

4. 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

5. Neutrino Mixing Pattern
Masses:
Mixing:
Results:
Correlation:

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

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

8. 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)

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

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

11. 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.