The absolute branching fractions for the decays $D^-_s\rightarrow\ell^-\bar{\nu}_{\ell}$ ($\ell=e$, $\mu$, or $\tau$) are measured using a data sample corresponding to an integrated luminosity of 521 fb$^{-1}$ collected at center of mass energies near 10.58 GeV with the BABAR detector at the PEP-II $e^+e^-$ collider at SLAC. The number of $D_s^-$ mesons is determined by reconstructing the recoiling system $DKX\gamma$ in events of the type $e^+e^-{\rightarrow}DKXD^{*-}_s$, where $D^{*-}_s\rightarrow D^-_s\gamma$ and $X$ represents additional pions from fragmentation. The $D^-_s\rightarrow\ell^-\nu_{\ell}$ events are detected by full or partial reconstruction of the recoiling system $DKX\gamma\ell$. The following results are obtained: $B(D^-_s \to \mu^- \nu) = (6.02 \pm 0.38 \pm 0.34) \times 10^{-3}$, $B(D^-_s \to \tau^- \nu) = (5.00 \pm 0.35 \pm 0.49) \times 10^{-2}$, and $B(D^-_s \to e^- \nu)

The absolute branching fractions for the decays $D^-_s\rightarrow\ell^-\bar{\nu}_{\ell}$ ($\ell=e$, $\mu$, or $\tau$) are measured using a data sample corresponding to an integrated luminosity of 521 fb$^{-1}$ collected at center of mass energies near 10.58 GeV with the BABAR detector at the PEP-II $e^+e^-$ collider at SLAC. The number of $D_s^-$ mesons is determined by reconstructing the recoiling system $DKX\gamma$ in events of the type $e^+e^-{\rightarrow}DKXD^{*-}_s$, where $D^{*-}_s\rightarrow D^-_s\gamma$ and $X$ represents additional pions from fragmentation. The $D^-_s\rightarrow\ell^-\nu_{\ell}$ events are detected by full or partial reconstruction of the recoiling system $DKX\gamma\ell$. The following results are obtained: $B(D^-_s \to \mu^- \nu) = (6.02 \pm 0.38 \pm 0.34) \times 10^{-3}$, $B(D^-_s \to \tau^- \nu) = (5.00 \pm 0.35 \pm 0.49) \times 10^{-2}$, and $B(D^-_s \to e^- \nu)

The absolute branching fractions for the decays D-s 2!l-$\bar{v}$-(l = e, [mu], or [tau]) are measured using a data sample corresponding to an integrated luminosity of 521 fb-1 collected at center of mass energies near 10.58 GeV with the BABAR detector at the PEPII e+e- collider at SLAC. The number of Ds- mesons is determined by reconstructing the recoiling system DKX[gamma] in events of the type e+e- 2!DKXD*s-, where D*s- 2!Ds- [gamma] and X represents additional pions from fragmentation. The Ds- 2!l-vl events are detected by full or partial reconstruction of the recoiling system DKX[gamma]l. The following results are obtained: [beta](Ds- 2![mu]-v) = (6.02 ± 0.38 ± 0.34) x 10-3, [Beta](Ds-2![tau]-v) = (5.00 ± 0.35 ± 0.49) x 10-2, and B(Ds- 2!e-[nu])

In Particle physics, a flavor-less meson whose constituents are a quark and an anti-quark is known as quarkonium. Mesons which are formed by a bound state of charm quark and anti-charm quark are known as charmonium states. Different inspections of exotic charmonium states have been understood as 4-quark states. Charmonium states are produced via e+e− annihilation. We search at Belle, based on 119000 tagged events in the Υ (4S) and Υ (5S) energy regions, to look for Ds → π0 l ν, Ds →ρ l ν, Ds →Ks l ν ; considering the electron candidates as well the heavy electron counterpart muon candidates as the leptons. The reconstruction of e+ e- → cc ̅ containing Ds meson events proceeds in two steps. In the first step the inclusive Ds events are reconstructed and in the second step we look for the exclusive decays of our interests. We intend to probe the 4-quark content of Ds by looking for decays Ds → π0 l ν, Ds →ρ l ν. Also we look for Ds →Ks l ν decay because it is a Cabibbo suppressed decay and Ks shares the same final states with ρ. The Ds →Ks l ν is the world's best. Our final results are presented and discussed.

We present the leptonic decay constants f{sub D{sub s}} and f{sub D{sup +}} computed on the MILC collaboration's 2+1 flavor asqtad gauge ensembles. We use clover heavy quarks with the Fermilab interpretation and improved staggered light quarks. The simultaneous chiral and continuum extrapolation, which determines both decay constants, includes partially-quenched lattice results at lattice spacings a (almost equal to) 0.09, 0.12 and 0.15 fm. We have made several recent improvements in our analysis: (a) we include terms in the fit describing leading order heavy-quark discretization effects, (b) we have adopted a more precise input r1 value consistent with our other D and B meson studies, (c) we have retuned the input bare charm masses based upon the new r1. Our preliminary results are f{sub D{sub s}} = 260 ± 10 MeV and f{sub D{sup +}} = 217 ± 10 MeV.

Enthält: K meson leptonic decay / P.B. Jones. The anomalous magnetic moment of the muon and related topics / J. Bailey and E. Picasso.