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

Neutrinos are massive Anupama Atre

There are only three “active” light neutrinos 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

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

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Charged current and Neutral current Anupama Atre

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

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

Determination of effective neutrino masses Parameter Input |ma2| 1.9£10-3 eV2 - 3.0£10-3 eV2 |ms2| 90% CL m2s vs tan2s plot a 90% CL m2a vs sin22a plot s 90%CL m2s vs tan2s plot x 90% CL CHOOZ exclusion plot  0 to 2 2 3  0.42 eV at 95% CL 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

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Neutrinoless Double Beta Decay (0) Isotope Half-life (yrs) hmiee (eV) Year 48Ca > 1.4 £ 1022 <7.2 – 44.7 2004 76Ge > 1.9 £ 1025 <0.35 2001 > 1.6 £ 1025 <0.33 – 1.35 2002 = 1.2 £ 1025 = 0.44 82Se > 2.7 £ 1022 <5 1992 100Mo > 5.5 £ 1022 <2.1 116Cd > 1.7 £ 1023 <1.7 2003 128Te > 7.7 £ 1024 <1.1 – 1.5 1993 130Te > 5.5 £ 1023 <0.37 – 1.9 136Xe > 4.4 £ 1023 <1.8 – 5.2 1998 150Nd > 1.2 £ 1021 < 3.0 1997 (A,Z) Nuclear Physics (A,Z+2) S.R. Elliott and J. Engel, J. Physics G30 (2004) R183, [arXiv:hep-ph/0405078] = 0.14 (0.06) eV Anupama Atre

Lepton Number Violating Tau Decays Decay Mode Bexp - ! e+ - - 1.9 £ 10-6 12 TeV - ! e+ - K- 2.1 £ 10-6 46 TeV - ! e+ K- K- 3.8 £ 10-6 730 TeV - ! + - - 3.4 £ 10-6 20 TeV - ! + - K- 7.0 £ 10-6 100 TeV - ! + K- K- 6.0 £ 10-6 1000 TeV CLEO Collaboration, D.Bliss et al., Phys. Rev. D 57 (1998) 5903, [arXiv:hep-ex/9712010] Anupama Atre

Rare Meson Decays Decay Mode Bexp TeV D+ ! K- e+ e+ 1.2 £ 10-4 1900 1.3 £ 10-5 670 D+ ! K- e+ + 1.3 £ 10-4 1500 Ds+ ! K- e+ e+ 6.3 £ 10-4 990 Ds+ ! K- + + 150 Ds+ ! K- e+ + 6.8 £ 10-4 740 B+ ! K- e+ e+ 1.0 £ 10-6 1300 B+ ! K- + + 1.8 £ 10-6 1800 B+ ! K- e+ + 2.0 £ 10-6 Decay Mode Bexp TeV D+ ! - e+ e+ 9.6 £ 10-5 320 D+ ! - + + 4.8 £ 10-6 76 D+ ! - e+ + 5.0 £ 10-5 170 Ds+ ! - e+ e+ 6.9 £ 10-4 200 Ds+ ! - + + 2.9 £ 10-5 42 Ds+ ! - e+ + 7.3 £ 10-4 150 B+ ! - e+ e+ 1.6 £ 10-6 420 B+ ! - + + 1.4 £ 10-6 400 B+ ! - e+ + 1.3 £ 10-6 270 K+ ! - e+ e+ 6.4 £ 10-10 0.11 K+ ! - + + 3.0 £ 10-9 0.48 K+ ! - e+ + 5.0 £ 10-10 0.09 Anupama Atre

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

Summary 0 - - e+ conversion - ! e+ - - - ! + - - Cosmo Bounds Exp Bounds Experiment 0.14 (0.06) eV 0.33 eV 0 17 MeV* - - e+ conversion 12 TeV - ! e+ - - 480 GeV K+ ! - + + 19 TeV - ! + - - none B- ! M- t+ t+ * 90 GeV from K+  - e+ + Anupama Atre

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

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

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

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

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

Thank You !!!!! Anupama Atre