No Arabic abstract
The size of the branching ratios for the $tau to mu gamma$ and $tau to mu gamma gamma$ decays induced by a lepton flavor violating Higgs interaction $Htau mu$ is studied in the frame of effective field theories. The best constraint on the $Htau mu$ vertex, derived from the know measurement on the muon anomalous magnetic moment, is used to impose the upper bounds $Br(tau to mu gamma)<2.5times 10^{-10}$ and $Br(tau to mu gamma gamma)<2.3times 10^{-12}$, which are more stringent than current experimental limits on this class of transitions.
Supposing only Lorentz and the gauge invariances of the Lagrangian, we derive energy and angular distributions for $tau^pm to mu^pm mu^pm mu^mp$ lepton flavor violating decay process. Using these results, we discuss methods to determine the parameters associated with the lepton flavor violating interactions.
In this paper, the lepton flavor violating $tau^- to mu^-PP (PP=K^+K^-,K^0bar{K}^0,pi^+pi^-,pi^0pi^0)$ decays are studied in the framework of the two Higgs doublet model(2HDM) III. We calculate these decays branching ratios and get the bounds of model parameter $|lambda_{taumu}|$ from the experimental upper limits. Our results show that, the neutral Higgs bosons have tree-level contributions to these decays. Among these decays, the $tau^- to mu^- K^+K^-$ decay is most sensitive to $|lambda_{taumu}|$. In the existing parameters space, these decays could reach the measure capability of B factory. These processes can provide some valuable information to future research and furthermore present the reliable evidence to test the 2HDM III model.
We report on a search for the lepton flavor violating tau- -> mu- gamma and tau- -> e- gamma decays based on 535/fb of data accumulated at the Belle experiment. No signal is found and we set 90% confidence level upper limits on the branching ratios Br(tau- -> mu- gamma) < 4.5x10^-8 and Br(tau- -> e- gamma) < 1.2x10^-7.
In this paper, the lepton flavor violating $tau^- to mu^- V^0(V^0=rho^0,phi,omega)$ decays are studied in the framework of the two Higgs doublet model(2HDM) III. We present a computation of the the $gamma-$, $Z$ penguin and box diagrams contributions, and make an analysis of their impacts. Our results show that, among the $gamma-$ penguins, the penguins with neutral Higgs in the loop are very larger than those with charged Higgs in the loop. We find that the model parameter $lambda_{taumu}$ is tightly constrained at the order of $O(10^{-3})$ and the branching ratios of these decays are available at the experiment measure. With the high luminosity, the B factories have considerable capability to find these LFV processes. On the other hand, these processes can also provide some valuable information to future research and furthermore present the reliable evidence to test the 2HDM III model.
In the framework of the seesaw models with triplets of fermions, we evaluate the decay rates of $mu to e gamma$ and $tau to l gamma$ transitions. We show that although, due to neutrino mass constraints, those rates are in general expected to be well under the present experimental limits, this is not necessarily always the case. Interestingly enough, the observation of one of those decays in planned experiments would nevertheless contradict bounds stemming from present experimental limits on the $mu to eee$ and $tau to 3 l$ decay rates. Such detection of radiative decays would therefore imply that there exist sources of lepton flavour violation not associated to triplet fermions.