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One-prong $\tau$ decays into final states involving kaons are studied with about 161k $\tau^+\tau^-$ events collected by the ALEPH detector from 1991 to 1995. Charged kaons are identified by dE/dx measurement, while $K^0_L$'s are detected through their interaction in calorimeters. Branching ratios are measured for the inclusive mode, $B(\tau^-\rightarrow K^-X\nu_\tau)=(1.52 \pm 0.04\pm0.04)\%$, where $X$ can be any system of neutral particles, and for the exclusive modes \begin{center} \begin{tabular}{rcl} $B(\tau^-\to K^-\nu_\tau)$ &=& $(6.96\pm0.25\pm0.14)\times 10^{-3}$,\\ $B(\tau^-\to K^-\pi^0\nu_\tau)$ &=& $(4.44\pm0.26\pm0.24)\times 10^{-3}$,\\ $B(\tau^-\to K^-\pi^0\pi^0\nu_\tau)$ &=& $(0.56\pm0.20\pm0.15)\times 10^{-3}$,\\ $B(\tau^-\to K^-\pi^0\pi^0\pi^0\nu_\tau)$ &=& $(0.37\pm0.21\pm0.11)\times 10^{-3}$,\\ $B(\tau^-\to K^-K^{0}...
From a sample of about 160k $\mbox{Z}\!\!\to\!\!\tau^+\tau^-$ candidates collected with the ALEPH detector at LEP between 1991 and 1995, $\tau$ lepton decays involving $K^0_S\!\to\!\pi^+\pi^-$ are studied. The $K^0_SK^0_L$ associated production in $\tau$ decays is also investigated. The branching ratios are measured for the inclusive decay $B(\tau^-\!\!\to\!\!K^0_SX^-\nu_\tau)=(9.70\!\pm\!0.58\!\pm\!0.62)\ times10^{-3}$ , where $X^-$ can be anything, and for the exclusive decays \begin{center} \begin{tabular}{rcl} $B(\tau^-\!\!\to\!\!\overline{K}^0\pi^-\nu_\tau)$&=&$(8.55\!\pm\!1. 17\! \pm\!0.66)\times10^{-3}$,\\ $B(\tau^-\!\!\to\!\!\overline{K}^0\pi ^-\pi^0\nu_\tau)$&=&$(2.94\!\pm\! 0.73\!\pm\!0.37)\times10^{-3}$, \\ $B(\tau^-\!\!\to\!\!\overline{K} ^0K^-\nu_\tau)$&=&$(1.58\!\pm\!0.42\!\pm\! 0.17)\times10^{-3}$, \\ $B(\tau^-\!\!\to\!\...
We report a search for narrow resonances, produced in $p\bar{p}$ collisions at $\sqrt{s}=1.96$ TeV, that decay into muon pairs with invariant mass between 6.3 and 9.0 GeV/c 2. The data, collected with the CDF II detector at the Fermilab Tevatron collider, correspond to an integrated luminosity of 630 pb−1. We use the dimuon invariant mass distribution to set 90% upper credible limits of about 1% to the ratio of the production cross section times muonic branching fraction of possible narrow resonances to that of the ϒ(1S) meson.
We report the results of a study of multi-muon events produced at the Fermilab Tevatron collider and acquired with the CDF II detector using a dedicated dimuon trigger. The production cross section and kinematics of events in which both muon candidates are produced inside the beam pipe of radius 1.5 cm are successfully modeled by known processes which include heavy flavor production. In contrast, we are presently unable to fully account for the number and properties of the remaining events, in which at least one muon candidate is produced outside of the beam pipe, in terms of the same understanding of the CDF II detector, trigger, and event reconstruction.
We revisit the determination of alpha_s(m_tau) using a fit to inclusive tau hadronic spectral moments in light of (1) the recent calculation of the fourth-order perturbative coefficient K_4 in the expansion of the Adler function, (2) new precision measurements from BABAR of e+e- annihilation cross sections, which decrease the uncertainty in the separation of vector and axial-vector spectral functions, and (3) improved results from BABAR and Belle on tau branching fractions involving kaons. We estimate that the fourth-order perturbative prediction reduces the theoretical uncertainty, introduced by the truncation of the series, by 20% with respect to earlier determinations. We discuss to some detail the perturbative prediction and show that the effect of the incomplete knowledge of the series is reduced by using the so-called contour-imp...
We examine the decay modes $\eta/\etp\ra \pi^+ \pi^- \gamma$ within the context of the Hidden Local Symmetry (HLS) Model. Using numerical information derived in previous fits to $VP\gamma$ and $Ve^+e^-$ decay modes in isolation and the $\rho$ lineshape determined in a previous fit to the pion form factor, we show that all aspects of these decays can be predicted with fair accuracy. Freeing some parameters does not improve the picture. This is interpreted as a strong evidence in favor of the box anomaly in the $\eta/\etp$ decays, which occurs at precisely the level expected. We also construct the set of equations defining the amplitudes for $\eta/\etp\ra \pi^+ \pi^- \gamma$ and $ \eta/\etp \ra \ggam $ at the chiral limit, as predicted from the anomalous HLS Lagrangian appropriately broken. This provides a set of four equations depending...
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