Lepton-Number Violating Heavy Meson Decays Jinmei Zhang Harbin Institute of Technology Aug 26, 2009
Outline I. Introduction II. Lepton-number Violating Heavy Meson Decays III. Conclusions
Introduction Are neutrinos massless or massive? Are neutrinos Dirac or Majorana particles ?
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.
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.
Lepton-Number Violating Heavy Meson Decays Fig. 1 Feynman diagram corresponding to the lepton-number violating decays .
The decay amplitude as follows: (1) (2) (3) JHEP 0905:030,2009[arXiv:0901.3589v2] Anupama Atre, Tao Han, Silvia Pascoli, Bin Zhang
Fig. 2 Excluded regions above the curve for versus from searches.
Fig. 3 Excluded regions above the curve for versus from searches.
Fig. 4 Excluded regions above the curve for versus from searches.
Table 1 The decay modes of the leptonic-number violatong.
Fig. 5 Theoretically excluded regions inside the curve for the branching fraction of .
Fig. 6 Theoretically excluded regions inside the curve for the branching fraction of .
Fig. 7 Theoretically excluded regions inside the curve for the branching fraction of .
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.
Thank You!