Related papers: Upper Limit on the Decay K+ --> e+ nu mu+ mu-

A search for the D0 to \pi+ \pi- \mu+ \mu- decay, where the muon pair does not originate from a resonance, is performed using proton-proton collision data corresponding to an integrated luminosity of 1.0 fb-1 recorded by the LHCb experiment…

The dispersive two-photon contribution to the K_L --> mu+ mu- decay amplitude is analyzed, using chiral perturbation theory techniques and large-N_C considerations. A consistent description of the decays Pi^0 --> e+ e-, Eta --> mu+ mu- and…

An upper limit for the tau-neutrino mass has been determined from the decay tau -> 5pi+- \nu_tau using data collected with the OPAL detector from 1991 to 1995 in e+e- collisions at \sqrt{s} ~ M_Z. A limit of 43.2 MeV at 95% CL is obtained…

The $D^+_s\to K^+K^-\mu^+\nu_\mu$ decay is studied based on 7.33 fb$^{-1}$ of $e^+e^-$ collision data collected with the BESIII detector at center-of-mass energies in the range from 4.128 to 4.226 GeV. The absolute branching fraction is…

We report results from a search for the decay Bs --> mu+ mu- using 1.3/fb of pbar p collisions at sqrt(s)= 1.96 TeV collected by the D0 experiment at the Fermilab Tevatron Collider. We find two candidate events, consistent with the expected…

From analysis of data produced by the BABAR experiment, the first upper bounds (90% C.L.) were obtained on the branching ratios $Br(\tau \to e \gamma\gamma)<2.5 \times 10^{-4}$ and $Br(\tau \to \mu \gamma\gamma)<5.8 \times 10^{-4}$. In…

Upper bound 6*10^{-4} with 90% confidence is reported for the eta -> pi^0 pi^0 decay from the SND experiment at the VEPP-2M collider.

We report on results of a search for the decay mode K_L -> pi^0 gamma e^+ e^- conducted by the E162 experiment at KEK. We observed no events and set a 90% confidence level upper limit of Br(K_L -> pi^0 gamma e^+ e^-)< 7.1x10^{-7} for its…

The first search for the decay K^+ -> pi^+ pi^0 nu nubar has been performed with the E787 detector at BNL. Based on zero events observed in the kinematical search region defined by 90 MeV/c < P_{pi^+} < 188 MeV/c and 135 MeV < E_{pi^0} <…

The process e^+e^- ->mu^+mu^- has been studied with SND detector at VEPP-2M e^+e^- collider in the vicinity of phi(1020) resonance. The product of branching ratios of phi meson into leptons \sqrt{B(phi->mu^+mu^-) B(phi->…

We consider the most general new physics effective Lagrangian for b --> s l+ l-. We derive the upper limit on the branching ratio for the processes B_s --> l+ l- where l=e, mu, subject to the current experimental bounds on related…

We measure the branching ratio of the purely leptonic decay of the D+ meson with unprecedented precision as B(D+ -> mu+ nu) = (3.82 +/- 0.32 +/- 0.09)x10^(-4), using 818/pb of data taken on the psi(3770) resonance with the CLEO-c detector…

Using the upper bound on the effective number of light neutrino species during primordial nucleosynthesis and the cosmological pion-pole mechanism $\gamma\gamma\rightarrow \pi^0\rightarrow \gamma X$, we obtain an upper limit on the…

We study the branching ratios of rare K and B decays in models with minimal flavour violation, using the presently available information from the universal unitarity triangle analysis and from the measurements of Br(B -> X_s gamma), Br(B ->…

A search for the rare decays (Bs -> \mu \mu) and (B0 -> \mu\mu) performed in pp collisions at sqrt{s} = 7 TeV is presented. The data sample, collected by the CMS experiment at the LHC, corresponds to an integrated luminosity of 1.14 /fb. In…

The decay branching fractions of the three narrow Upsilon resonances to mu+ mu- have been measured by analyzing about 4.3 1/fb e+e- data collected with the CLEO III detector. The branching fraction B(Y(1S) -> mu+ mu-) = (2.49 +- 0.02 +-…

We report on a search for Bs->mu+mu- and Bd->mu+mu- decays in ppbar collisions at sqrt(s)=1.96 TeV using 171 pb-1 of data collected by the CDF II experiment at the Fermilab Tevatron Collider. The decay rates of these rare processes are…

Based on 3.26 fb$^{-1}$ data sample collected at CLEO III, we study the decay $\tau^-\to K^+K^-\pi^-\nu_\tau$, and improve the measurement of the branching ratio ${\cal B}(\tau^-\to K^+K^-\pi^-\nu_\tau)= (1.59\pm0.06\pm0.13)\times10^{-3}$,…

I review the status of the rare decays B_s --> mu+mu- and B_d --> mu+mu-. The latest Standard Model predictions for the corresponding branching ratios are discussed. An overview of additional observables that are accessible in the B_s -->…

Evidence of the $K^+\to\mu^+\nu\bar\nu\nu$ decay was searched for using E949 experimental data with an exposure of $1.70\times 10^{12}$ stopped kaons. The data sample is dominated by the backgrond process $K^+\to\mu^+\nu_\mu\gamma$. An…