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NEUTRINOLESS DOUBLE BETA DECAY ANGULAR CORRELATION AND NEW PHYSICS

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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 – PowerPoint PPT presentation

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Title: NEUTRINOLESS DOUBLE BETA DECAY ANGULAR CORRELATION AND NEW PHYSICS


1
NEUTRINOLESS DOUBLE BETA DECAY ANGULAR
CORRELATION AND NEW PHYSICS
Dmitry Zhuridov Particles and Fields Journal
club Department of Physics National Tsing Hua
University
2
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 arXiv0706.4165 hep-ph (to appear in
Phyical Review D)
3
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

4
Contents
  • Introduction
  • Neutrinoless Double Beta Decay
  • Angular Correlation in Long-Range Mechanism
  • Analysis of the Angular Correlation
  • Conclusion

5
Introduction
SNO, Super-Kamiokande, KamLAND ? oscillations
Neutrinos have non-zero masses and they mix with
each other
Bounds on the neutrino masses
6
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
7
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

8
See-saw mechanism
9
Neutrinoless Double Beta Decay
n
n
Lepton number is changed by 2 units. 0?2? decay
is forbidden in the SM. Extended version of the
SM could contain tiny nonrenormalizable terms
that violate LN and allow 0?2? decay.
10
  • 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 0?2?
    decay
  • Long range
    Short range
  • (with the light ?s in the intermediate state)

11
According to the Schechter-Valle theorem, any
mechanism inducing the 0?2? 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 0?2? decays using
the information on the angular correlation
of the final electrons.
12
Angular Distribution in Long-Range Mechanism
Most general Lorentz invariant effective
Lagrangian for the long-range mechanism of 0?2ß
decay is
13
  • 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

14
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15
Expressions for A for one ?, considered at a time
16
Expressions for B for one ? at a time
17
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18
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19
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
20
Particular cases for the parameter space
Constraints on the couplings of the effective
LQ-quark-lepton interactions
21
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22
1a 1b 2a 2b
23
Angular correlation in left-right symmetric models
24
103?
103?
25
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26
Conclusion
  • We have presented a detailed study of the
    electron angular correlation for the long range
    mechanism of 0?2? 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 0?2? 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.
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