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NEUTRINOLESS DOUBLE BETA DECAY ANGULAR CORRELATION AND NEW PHYSICS. Dmitry Zhuridov Particles and Fields Journal club Department of Physics National Tsing Hua University. The talk is based mostly on the paper: Probing new physics in the neutrinoless double beta decay
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NEUTRINOLESS DOUBLE BETA DECAYANGULAR CORRELATIONAND NEW PHYSICS Dmitry Zhuridov Particles and Fields Journal club Department of Physics National Tsing Hua University
The talk is based mostly on the paper: Probing new physics in the neutrinoless double beta decay using electron angular correlation.A. Ali (DESY) , A.V. Borisov, D.V. Zhuridov (Moscow State U.) . DESY-07-097, Jun 2007. 36pp. e-Print: arXiv:0706.4165 [hep-ph] (to appear in Phyical Review D) High Energy Physics Journal club
Popularity of the theme • M. Doi, T. Kotani, E. Takasugi, Prog.Theor.Phys.Suppl.83 (1985) 329 • T. Tomoda, Rep.Prog.Phys.54 (1991) 133 • S.L. Adler et al., Phys.Rev.D11 (1975) 74 • H. Pas, M. Hirsch, H.V. Klapdor-Kleingrothaus, S.G. Kovalenko, Phys.Lett.B453 (1999) 26 SPIRES-HEP: • FIND TITLE NEUTRINOLESS DOUBLE BETA DECAY 470 • FIND K NEUTRINOLESS DOUBLE BETA DECAY 476 E-print arXiv: Abstract: NEUTRINOLESS DOUBLE BETA DECAY • 1991-1995 29 • 1996-2000 139 • 2001-2005 251 • 2006-p.t. 87 High Energy Physics Journal club
Contents • Introduction • Neutrinoless Double Beta Decay • Angular Correlation in Long-Range Mechanism • Analysis of theAngular Correlation • Conclusion High Energy Physics Journal club
Introduction SNO, Super-Kamiokande, KamLAND–ν oscillations Neutrinos have non-zero masses and they mix with each other Bounds on the neutrino masses: High Energy Physics Journal club
It is largely anticipated that the neutrinos are Majorana particles: Correspondence between Dirac and Majoana fields Dirac field can be constructed from two Majorana fields Dirac field has additional freedom of phase trasformation High Energy Physics Journal club
How to induce small neutrino masses? Other possible mechanisms • Model with scalar triplet: • Model with right-handed neutrino and scalar singlet: • In Zee model (with charged scalar singlet and additional scalar doublets) Majorana neutrino masses arise at one loop level; • In models with doubly charged scalar singlet Majorana neutrino masses arise at two loop level; • Models with effective nonrenormalizable term in Lagrangian: High Energy Physics Journal club
See-saw mechanism High Energy Physics Journal club
p p Neutrinoless Double Beta Decay n n Lepton number is changed by 2 units. 02 decay is forbidden in the SM. Extended version of the SM could contain tiny nonrenormalizable terms that violate LN and allow 02 decay. High Energy Physics Journal club
d u d u u d u d Probable mechanisms of LN violation may include exchanges by: Majorana neutrinos Scalar bilinears, e.g. doubly charged dileptons SUSY particles Leptoquarks Right-handed W_R bosons etc. Two possible classes of mechanisms for the 02 decay: Long range Short range (with the light s in the intermediate state) High Energy Physics Journal club
According to the Schechter-Valle theorem, any mechanisminducing the 02 decay produces an effective Majorana mass for the neutrino, which must therefore contribute to this decay. e e u u d d Purpose:to examine the possibility to discriminate among the various possible mechanisms contributing to the 02decaysusing the information on the angular correlation of the final electrons. High Energy Physics Journal club
Angular Distribution in Long-Range Mechanism Most general Lorentz invariant effective Lagrangian for the long-range mechanism of 0ν2β decay is: High Energy Physics Journal club
Approximations: • leading order in the Fermi constant • leading contribution of the parameters \epsilon • relativistic electrons and non-relativistic nucleons • S_{1/2} and P_{1/2} waves for the outgoing electrons High Energy Physics Journal club
Expressions for A for one ∈, considered at a time High Energy Physics Journal club
Expressions for B for one ∈ at a time High Energy Physics Journal club
Analysis of the Electron Angular Correlation If the ``nonstandard" effects, are zero then K = B01/A01. Its values are given in the Table for various decaying nuclei of current experimental interest: • The angular correlation coefficient K for various SM extensions for decays • of : High Energy Physics Journal club
Particular cases for the parameter space: Constraints on the couplings of the effective LQ-quark-lepton interactions: High Energy Physics Journal club
1a 1b 2a 2b High Energy Physics Journal club
Angular correlation in left-right symmetric models High Energy Physics Journal club
10^3*ς 10^3*ς High Energy Physics Journal club
Conclusion • We have presented a detailed study of the electron angular correlation for the long range mechanism of 02 decays in a general theoretical context. This information, together with the ability of observing these decays in several nuclei, would help greatly in identifying the dominant mechanism underlying these decays. • The running experimental facility that in principle can measure the electron angular correlation in the 02 decay NEMO3 possibly has no the sufficient sensitivity. The proposed facilities are SuperNEMO, MOON and EXO. We have argued that there is a strong case in building at least one of them. High Energy Physics Journal club
