1 / 27

Search for Lepton-number Violating Processes

Anupama Atre presents a comprehensive overview of lepton number violating processes, focusing on neutrinos, which are known to be massive. Key findings include constraints on neutrino masses from various experimental approaches such as direct laboratory measurements, cosmological observations, and the absence of neutrinoless double beta decay. The discussion also emphasizes the importance of distinguishing between Dirac and Majorana neutrinos, and explores the implications of these findings for the underlying physics of lepton number violation. A variety of decay modes and their relevance to mass parameters are detailed.

rianna
Télécharger la présentation

Search for Lepton-number Violating Processes

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Search for Lepton-number Violating Processes Pheno 2006 Anupama Atre

  2. Neutrinos are massive Anupama Atre

  3. We also know • There are only three “active” light neutrinos • N = 2.984 § 0.008, from Z pole at LEP-1. • Direct lab bound: m < 2.2 eV • from Tritium beta decay •  mi < 0.17 – 1 eV • from WMAP, SDSS (Ly spectra), SNIa. • The absence of neutrinoless double beta decay • bound on Majorana mass <m> ee < 1 eV Anupama Atre

  4. m3 m2 m2s m1 m2a m2a m2 m2s m1 m3 Inverted Normal • Absolute mass scale ? • Hierarchy – inverted or normal? • Dirac or Majorana? Anupama Atre

  5. Anupama Atre

  6. Anupama Atre

  7. Charged current and Neutral current Anupama Atre

  8. The transition rates are proportional to: • for light neutrino [1] • for intermediate mass neutrino [2] • for heavy neutrino [3] f1’ f1 [1] AA, V Barger, T Han, Phys. Rev. D 71, 113014 (2005) [arXiv:hep-ph/0502163] f2 f2’ [2] AA, T Han, S Pascoli to appear [3] T Han, B Zhang [arXiv:hep-ph/0604064] AA, T Han, S pascoli, B Zhang to appear L = 2 process  Majorana nature of neutrino generic diagram Anupama Atre

  9. f1’ f1 We have six effective neutrino masses : 0 , rare meson decay :  decay : - e+ conversion, rare meson decay :  decay : rare meson decay : none f2 f2’ Light (active) Majorana neutrino Anupama Atre

  10. Determination of effective neutrino masses • 3 masses: m1, m2 and m3 •  = m1 + m2 + m3 and •  m2a and  m2s • 3 mixing angles: a, s and x • 3 phases: , 2 and 3 AA, V Barger, T Han, Phys. Rev. D 71, 113014 (2005) [arXiv:hep-ph/0502163] Anupama Atre

  11. Anupama Atre

  12. (A,Z) Nuclear Physics (A,Z+2) = 0.14 (0.06) eV Neutrinoless Double Beta Decay (0) S.R. Elliott and J. Engel, J. Physics G30 (2004) R183, [arXiv:hep-ph/0405078] Anupama Atre

  13. Lepton Number Violating Tau Decays CLEO Collaboration, D.Bliss et al., Phys. Rev. D 57 (1998) 5903, [arXiv:hep-ex/9712010] Anupama Atre

  14. Rare Meson Decays Anupama Atre

  15. ·17(82) MeV SINDRUM II Collaboration, J. Kaulard et al., Phys. Lett. B 422 (1998) 334 Nuclear Physics (A,Z-2) (A,Z) Muon – Positron Conversion K. Zuber, [arXiv:hep-ph/0008080] Anupama Atre

  16. Summary * 90 GeV from K+ - e++ Anupama Atre

  17. f1’ f1 f2 f2’ Intermediate mass Majorana neutrino * • resonant enhancement, transition rates • tau decay, rare meson decay Anupama Atre * AA, T Han and S Pascoli, to appear

  18. Width of Intermediate mass Majorana neutrino • 2 body decays : • CC decays  • NC decays  • 3 body decays: • CC decays  • NC decays  • CC + NC decays  combination of CC + NC mixings Anupama Atre

  19. 36 decay modes to look for lepton number violation !!!! • Parameters for MC sampling • mass of neutrino m4 • resonant mass region • three mixings ~ 0 to 1 Anupama Atre

  20. Anupama Atre

  21. Anupama Atre

  22. Anupama Atre

  23. Anupama Atre

  24. Anupama Atre

  25. Current bounds on sterile neutrino: • peak searches • accelerator searches • heavy atmospheric neutrinos • cosmology, BBN, WMAP Anupama Atre

  26. It is of fundamental importance to verify Majorana nature of neutrinos • We look for genuine  L = 2 processes • For the three active ’s 0 is the best hope • For a sterile neutrino N (or 4) • Rare  and meson decays are sensitive to 140 MeV < m4 < 5 GeV, 10-9 < |V l4|2 < 10-2 • Depending on the unknown mixing and mass 4 can show up in any channel • Other processes to look for B+ e++ M-, B+ ++ M-, B+ ++ M- Anupama Atre

  27. Thank You !!!!! Anupama Atre

More Related