1. Lepton-Number Violating Heavy Meson Decays
Jinmei Zhang
Harbin Institute of Technology
Aug 26, 2009

2. Outline I. Introduction II. Lepton-number Violating Heavy Meson Decays
III. Conclusions

3. Introduction Are neutrinos massless or massive?
Are neutrinos Dirac or Majorana particles ?

4. The answer to the first question:
During the past few years, neutrino oscillation experiments have provided us with very convincing evidence that neutrinos are not strictly massless as predicted in the SM, but are massive.
But they provide no information on the absolute neutrino mass scale.

5. The answer to the second question:
The Dirac mass term preserves the
lepton number, and the Majorana mass
term violates it by two units
Thus, the experimental observation of
lepton-number violating processes can
be used the only signature for the
Majoranar nature of neutrinos.

6. Lepton-Number Violating Heavy Meson Decays
Fig. 1 Feynman diagram corresponding to the lepton-number violating decays

7. The decay amplitude as follows:
(1)
(2)
(3)
JHEP 0905:030,2009[arXiv: v2]
Anupama Atre, Tao Han, Silvia Pascoli, Bin Zhang

8. Fig. 2 Excluded regions above the curve for versus
from searches.

9. Fig. 3 Excluded regions above the curve for versus
from searches.

10. Fig. 4 Excluded regions above the curve for versus
from searches.

11. Table 1 The decay modes of the leptonic-number violatong.

12. Fig. 5 Theoretically excluded regions inside the curve for the branching fraction of .

13. Fig. 6 Theoretically excluded regions inside the curve for the branching fraction of .

14. Fig. 7 Theoretically excluded regions inside the curve for the branching fraction of .

15. Conclusions
We have calculated the decay widths and branching ratios of the leptonic-number violating heavy meson decays.
We have sampled the constrain on branching ratios as a function of the Majorana neutrino mass.
A detection in one of the heavy meson decay modes studied in our analysis would imply the existence of
a Majorana neutrino.
The experiments at the current LHC may have the opportunity to discover it.

16. Thank You!