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Neutrinoless Double-Beta Decay and Neutrinoless Double-Electron Capture Fedor Š imkovic

Lomonosov conference , Moscow, August 18, 201 1. Neutrinoless Double-Beta Decay and Neutrinoless Double-Electron Capture Fedor Š imkovic JINR Dubna Comenius University, Bratislava. OUTLINE. 0 nbb -decay Relation between 0 nbb and 2 nbb NMEs 0 n ee -decay Outlook.

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Neutrinoless Double-Beta Decay and Neutrinoless Double-Electron Capture Fedor Š imkovic

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  1. Lomonosov conference, Moscow, August 18, 2011 Neutrinoless Double-Beta Decay and Neutrinoless Double-Electron Capture FedorŠimkovic JINR Dubna Comenius University, Bratislava Fedor Simkovic

  2. OUTLINE • 0nbb-decay • Relation between 0nbb and 2nbb NMEs • 0nee-decay • Outlook Fedor Simkovic

  3. Neutrinoless Double-Beta Decay (A,Z)  (A,Z+2) + e- + e- What is the nature of neutrinos? Study of the 0nbb-decay is one of the highest priority issues in particle and nuclear physics  GUT’s Only the 0νββ-decay can answer this fundamental question (plus absolute mass scale of n’s, hierarchy, CP violation) Fedor Simkovic

  4. Mixing, hierarchies, LNV Flavor eigenstates Large off diagonal elements ! Mass eigenstates 0nbb-decay Majorana condition Effective mass of Majorana neutrinos Fedor Simkovic

  5. T2K: 0.03(0.04) < sin2 2q13< 0.28(0.34) for NH(IH) Si=1,2,3=0.28 eV 0.084 eV Fedor Simkovic

  6. The double beta decay process can be observed due to nuclear pairing interaction that favors energetically the even-even nuclei over the odd-odd nuclei The NMEs for 0nbb-decay must be evaluated using tools of nuclear theory Fedor Simkovic

  7. Nuclear structure approaches In NSM (Madrid-Strassbourg group) a limited valence space is used but all configurations of valence nucleons are included. Describes well properties of low-lying nuclear states. Technically difficult, thus only few 0nbb-decay calculations In QRPA(Tuebingen-Caltech-Bratislava and Jyvaskula-La Plata groups) a large valence space is used, but only a class of configurations is included. Describe collective states, but not details of dominantly few particle states. Relative simple, thus more 0nbb-decay calculations In IBM (Iachello, Barea) the low lying states of the nucleus are modeled in terms of bosons. The bosons have either L=0 (s boson) or L=2 (d boson). The bosons can interact through one and to body forces giving rise to bosonic wave functions. In PHFB (India/Mexico groups) w.f. of good angular momentum are obtained by making projection on the axially symmetric intrinsic HFB states. Nuclear Hamiltonian contains only quadrupole interaction. Differences: i) mean field; ii) residual interaction; iii) size of the model space iv) many-body approximation Fedor Simkovic

  8. Nuclear structure approaches Large Scale Shell Model: Caurier, Menendez, Nowacki, Poves, PRL 100, 052503 (2008). (Renormalized) QRPA: Šimkovic, Faessler, Müther, Rodin, Stauf, PRC 79, 055501 (2009). Projected Hartree-Fock-Bogoliubov: Rath, Chandra, et al. PRC 82, 064310 (2010). Interacting Boson Model: Barea, Iachello, PRC 79, 044301 (2009). Energy Dendity Functional appr.: Rodrígez, Martínez-Pinedo, arXiv:1008.5260 [nucl-th]. gA=1.25, Jastrow s.r.c., r0=1.20 fm The 0nbb-decay NMEs (Status:2011) Jyvaskula –La Plata QRPA NMEs are in good a agreement with Tuebingen-Bratislava- CALTECH NMEs QRPA: Kortelainen, Suhonen, PRC 76, 024315 (2007)

  9. A claim of evidence and other experiments (current status) Fedor Simkovic Faessler, Fogli, Lisi, Rodin, Rotunno, F.Š., PRD 79, 053001 (2009)

  10. 0nbb-decay half-life mbb=50 meV Fedor Simkovic

  11. On the relation between 0nbb-decay and 2nbb-decay (GT) NMEs F.Š., R. Hodák, A. Faessler, P. Vogel, PRC 83, 015502 (2011) Fedor Simkovic

  12. 2nbb-decay NMEs Why the spread of the 2nbbNMEs is large and of the 0nbbNMEs is small? Are both type of NMEs related? Why 2nbbof 136Xe has been not observed yet? Do this affect the value of 0nbbNME Differencies among 2nbb-decay NMEs: up tofactor 10 Fedor Simkovic

  13. The cross sections of (t,3He) and (d,2He) reactions give B(GT±) for b+ and b-, product of the amplitudes (B(GT)1/2) entering the numerator of M2nGT Closure 2nbb-decay NME SSD hypothesis Fedor Simkovic Grewe, …Frekers at al, PRC 78, 044301 (2008)

  14. Going to relative coordinates: A connection between closure 2nbb and 0nbb GT NMEs F.Š., R. Hodák, A. Faessler, P. Vogel, PRC 83, 015502 (2011) r- relative distance of two nucleons Neutrino potential Fedor Simkovic Neutrino potential prefer short distances

  15. Closure 2nbb GT NME The only non-zero contribution from Jp=1+ = Fedor Simkovic

  16. There is no proportionality between 0nbb-decay and 2nbb-decay NME Frekers et al. Charge exchange reactions Fedor Simkovic

  17. There is a need for supporting experiments to restrict parameters of nuclear Hamiltonian • Nuclear matrix elements: • Mean field p and n removing transfer reactions • b-and b+ strengths Charge-changing reactions and muon • capture • deformation Exp. to remeasure deformetion needed • 2nbb-decay Double beta decay experiments Fedor Simkovic

  18. Neutrinoless Double-Electron Capture e- + e- + (A,Z)  (A,Z-2)** M. Krivoruchenko, F.Š., D. Frekers,A. Faessler, Nucl. Phys. A 859, 140171 (2011) Fedor Simkovic

  19. Neutrinoless double electron capture (resonance transitions) (A,Z)→(A,Z-2)*HH’ J. Bernabeu, A. DeRujula, C. Jarlskog, Nucl. Phys. B 223, 15 (1983) Atom mixing amplitude DM Decay rate 2nECEC-background depends strongly on Q-value Fedor Simkovic

  20. Modes of the 0nECEC-decay: eb + eb+ (A,Z) → (A,Z-2) + g + 2g + e+e- + M Neutrinoless double electron capture (perturbation theory approach) • Theoretically, not well understood yet: • which mechanism is important? • which transition is important? eb + eb+ (A,Z) → (A,Z-2) + g  Sujkowski, Wycech, PRC 70, 052501 (2004) D.Frekers, hep-ex/0506002 Fedor Simkovic

  21. Different types of Oscillations (Effective Hamiltonian) Oscillations ofnl-nl’ (lepton flavor) Oscillation ofK0-anti{K0} (strangeness) Oscillation ofn-anti{n} (baryon number) Oscillation ofAtoms (OoA) (total lepton number) F.Š., M. Krivoruchenko, Phys.Part.Nucl.Lett. 6 (2009) 485. Full width of unstable atom/nucleus Eigenvalues Fedor Simkovic

  22. Light n-exchange potential for the 0nEEC b-decay Hamiltonian n-mixing decay Potential Fedor Simkovic

  23. 0nEEC potential - approximations Non-relativistic impulse approximation for nucleon current Closure approximation Factorization of atomic and nuclear part Similar form as for 0nbb-decay Fedor Simkovic

  24. Capture of s1/2 and p1/2 atomic electrons is prefered Jp=0+,0-,1+,1- Fedor Simkovic

  25. Widths of atomic excited states (2 holes) Fedor Simkovic

  26. For comparison 0nbb-half-life Normalized 0nECEC half-lives = 3 Tmin1/2: Mi=Mf (full degeneracy) 18476Os→ 18474W* (0.02%) 18074W→ 18472Hf (0.13%) Half-lives in years 10648Cd→ 10646Pd (1.25%) All masses/energies in keV Fedor Simkovic

  27. Data analysis of most likely resonant transitions Half-life of a particular isotope 1chance of100 forT1/2< 1025 y 10 100 < 1027 y Number of transitions n with half –life Ta1/2 < T1/2 M. Krivoruchenko, F.Š., D. Frekers,A. Faessler, Nucl. Phys. A 859, 140171 (2011) Fedor Simkovic

  28. Experiment in Bratislava! 74Se Muenster and Bratislava groups T1/2 > 4.3 1019 years Frekers, Puppe, Thies, Povinec, F.Š., Staníček, Sýkora, accepted in NPA Fedor Simkovic

  29. TGV experiment in Modane underground laboratory New level 2737 keV (Jp=?) 10 g of 106Cd T1/2 2nee (106Cd) > 3.6 1020 y TGV Coll, Rukhadze et al., NPA 852, 197 (2011) T1/2 0nee (106Cd) > 1.1 1020 y Fedor Simkovic

  30. Improved Q-value measurements Klaus Blaum (MPI Heidelberg) 152Gd152Sm (Eliseev, et al., F.Š, M. Krivoruchenko, PRL 106, 052504 (2011)) (F.Š., Krivoruchenko, Faessler, PPNP 66, 446 (2011) Remeasured Q-value:112Sn, 74Se, 136Ce, 96Ru, 152Gd, 162Er, 168Yb, 106Cd, 156Dy need to be remeasured: 124Xe, 130Ba, 180W, 184Os, 190Pt Fedor Simkovic

  31. 0nee mbb=50 meV 0nbb Fedor Simkovic F.Š.,Faessler, Muether, Rodin, Stauf, PRC 79, 055501 (2009)

  32. Summary (A,Z)  (A,Z+2) + e- + e- e- + e- + (A,Z)  (A,Z-2)** Perturbation theory Breit-Wigner form • 2nbb-decay background • can be a problem • Uncertainty in NMEs • factor ~2, 3 • 0+0+,2+ transitions • Large Q-value • 76Ge, 82Se, 100Mo, 130Te, 136Xe … • Many exp. in construction, • potential for observation in the • case of inverted hierarchy (2020) • 2nee-decay strongly suppressed • NMEs need to be calculated • 0+0+ ,0 -, 1+, 1- transitions • Small Q-value • Q-value needs to be measured • at least with 100 eV accuracy • 152Gd, looking for additional • small experiments yet Fedor Simkovic

  33. Neutrino physics is full of surprices Mathematics is Egyptian Neutrino physics is Babylonian Fedor Simkovic

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