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Majorana neutrino spectroscopy and measuring relic neutrino M. Yoshimura

Majorana neutrino spectroscopy and measuring relic neutrino M. Yoshimura. hep-ph/0611362 Why atoms ? Another or perhaps a unique way of Majorana detection Measurement of absolute mass scale Possibility of detecting relic neutrino hep-ph/0703019. Significance of discovering Majorana neutrino.

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Majorana neutrino spectroscopy and measuring relic neutrino M. Yoshimura

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  1. Majorana neutrino spectroscopy and measuring relic neutrinoM. Yoshimura hep-ph/0611362 • Why atoms ? • Another or perhaps a unique way of Majorana detection • Measurement of absolute mass scale • Possibility of detecting relic neutrino hep-ph/0703019

  2. Significance of discovering Majorana neutrino • Neutral fermions follow economic Majorana eq or the same Dirac eq as charged ? • Leading to lepton number violation and lepto-genesis particle = anti-particle missing partner for leptogenesis • Contributing to better understanding of seesaw mechanism and GUT

  3. M vs D

  4. Merits and demerits of atomic process • Infinitely many small energies • Small pair emission rate • How to enhance is crucial resonance by energy input strong field

  5. Majorana ｖｓ　Dirac equations:chirally projected solutions

  6. Unique signature of Majorana = interference of identical fermions • Effective only for pair emission • Appear only (ii) threshold; proportional to m_i^2 • Can be positive or negative • Direct test of Majorana nature cf LV in

  7. 2 promissing atomic processes • Low level metastable atoms laser irradiated • Rydberg atoms microwave irradiated (not discussed here)

  8. Neutrino pair emission from laser irradiated metastable state

  9. Rough estimate of rate

  10. Refinement

  11. Majorana vs Dirac 6 channels available

  12. Numerical estimate w.Y. Okabayashi • Input angles and masses: case of normal hierarchy

  13. Red Blue M : ~4% M : ~2% M : ~9% M : ~1% 500(meV) 700(meV) 300(meV) D : ~3% D : ~1% D : ~7% 900(meV) D : ~0.8% Mass varied Effect

  14. Large mass effects

  15. Mixing angle varied Red Blue M : ~3% M : ~2% M : ~8% M : ~1% 500(meV) 700(meV) 300(meV) D : ~2% D : ~1% D : ~6% 900(meV) D : ~0.8% Finite masseffect

  16. Theta_12 effect

  17. Case of inverted mass hierarchy ① ② ① ③ ④ ② ③ ④ ⑤ ⑥ ⑤ ⑥

  18. Observability of relic neutrino w. T. Takahashihep-ph/0703019 • Pauli blocking effect

  19. Crucial question how large the “threshold ” region

  20. Magnitude of Pauli blocking

  21. m_1 dependence for standard 1.9 K For m_1 > 5 meV, the “threshold” region is narrow For m_1 < 1 meV, the “threshold” region is wide

  22. Temperature measurement possible ? For m_1 < 1meV, temperature measurement is not difficult

  23. 12 threshold Smaller effect with a larger rate

  24. Early universe probed by relic neutrino • Decoupling temperature • Early universe after neutrino decoupling and before e^+ annihilation • Large lepton asymmetry • Constraint on sterile neutrino • Surprizes ?

  25. Measuring the lepton asymmetry • Definitive test of leptogenesis • Extremely difficult, (12) threshold most promissing

  26. Experiments are not easy: a possible strategy • Discovery of atomic pair emission • Mass measurement • M/D distinction • Relic detection

  27. Level structure of candidate atom

  28. Summary • Discussed laser irradiated pair emission to determine the magnitude and the nature of neutrino masses • Identical particle effect of Majorana particles • Neutrino mass spectroscopy towards 1 meV range • Relic neutrino search

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