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An overview of recent results from LEP concerning the hadronisation process is presented. Emphasis is placed on the $b$-quark. The first presented analysis is the measurement of the $b$-quark fragmentation function. It includes a new, hadronic-model independent method to extract the x-dependence of the non-perturbative QCD component from the measured fragmentation function. This is followed by the results of two analyses on, respectively, production rates of b-excited states and branching fractions of b-quarks to neutral and charged b-hadrons. Multiplicity in the final state is also discussed concerning the difference in multiplicities between b and light quark initiated events, and total multiplicities in three jet events. Finally, recent measurements of \omega and \eta meson production rates are given.
Comment: 4 pages. Talk given at BEACH 2006, Lancaster, England
We present an overview of a few recent results related to CP-violation from the Tevatron. First, we discuss a measurement of the dimuon charge asymmetry from D\O\ , that extracts the CP-violation parameter of $\Bo$ mixing and decay. This is followed by the CDF measurement of the CP-violating asymmetry in $\bdkpi$ decays. Finally we give the CDF result on the ratio $R = \frac{BR(B \rightarrow D^0 K)}{BR(B \rightarrow D^0 \pi)}$
Using recent measurements of the b-quark fragmentation distribution obtained in $e^+e^- \to b \bar{b}$ events registered at the Z pole, the non-perturbative QCD component of the distribution has been extracted independently of any hadronic physics modelling. This distribution depends only on the way the perturbative QCD component has been defined. When the perturbative QCD component is taken from a parton shower Monte-Carlo, the non-perturbative QCD component is rather similar with those obtained from the Lund or Bowler models. When the perturbative QCD component is the result of an analytic NLL computation, the non-perturbative QCD component has to be extended in a non-physical region and thus cannot be described by any hadronic modelling. In the two examples used to characterize these two situations, which are studied at present, it ...
Based on the full BaBar data sample, we report improved measurements of the ratios R(D(*)) = B(B -> D(*) Tau Nu)/B(B -> D(*) l Nu), where l is either e or mu. These ratios are sensitive to new physics contributions in the form of a charged Higgs boson. We measure R(D) = 0.440 +- 0.058 +- 0.042 and R(D*) = 0.332 +- 0.024 +- 0.018, which exceed the Standard Model expectations by 2.0 sigma and 2.7 sigma, respectively. Taken together, our results disagree with these expectations at the 3.4 sigma level. This excess cannot be explained by a charged Higgs boson in the type II two-Higgs-doublet model. We also report the observation of the decay B -> D Tau Nu, with a significance of 6.8 sigma.
We present searches for the rare decay modes D0 to e+e-, D0 to mu+mu- and D0 to e mu in continuum e+e- to cbar c events recorded by the BABAR detector in a data sample that corresponds to an integrated luminosity of 468 f^-1. These decays are highly GIM suppressed but may be enhanced in several extensions of the Standard Model. Our observed event yields are consistent with the expected backgrounds. An excess is seen in the D0 to mu+mu- channel, although the observed yield is consistent with an upward background fluctuation at the 5% level. Using the Feldman-Cousins method, we set the following 90% confidence level intervals on the branching fractions: B(D0 to e+e-)<1.7 x 10^-7, B(D0 to mu+mu-) within [0.6, 8.1] x 10^-7, and B(D0 to e mu)<3.3 x 10^-7.
We present a new measurement of the time-dependent CP asymmetry of B0->D*+D*- decays using (471+-5) million BBbar pairs collected with the BaBar detector at the PEP-II B Factory at the SLAC National Accelerator Laboratory. Using the technique of partial reconstruction, we measure the time-dependent CP asymmetry parameters S=-0.34+-0.12+-0.05$ and C=+0.15+-0.09+-0.04. Using the value for the CP-odd fraction R_perp=0.158+-0.028+-0.006, previously measured by BaBar with fully reconstructed B0->D*+D*- events, we extract the CP-even components S+=-0.49+-0.18+-0.07+-0.04 and C+=+0.15+-0.09+-0.04. In each case, the first uncertainty is statistical and the second is systematic; the third uncertainty on S+ is the contribution from the uncertainty on R_perp. The measured value of the CP-even component S+ is consistent with the value of sin(2Beta...
We search for the rare decay of the $D^{0}$ meson to two photons, $D^0 \rightarrow \gamma \gamma$, and present a measurement of the branching fraction for a $D^0$ meson decaying to two neutral pions, ${B}(D^0 \rightarrow \pi^0 \pi^0)$. The data sample analyzed corresponds to an integrated luminosity of 470.5 {\sl B {-0.4em} {\small\sl A} {-0.37em} \sl B {-0.4em} {\small\sl A {-0.02em}R}} detector at the PEP-II asymmetric-energy $e^{+} e^{-}$ collider at SLAC. We place an upper limit on the branching fraction for the decay of a $D^0$ meson to two photons, ${B}(D^0 \rightarrow \gamma \gamma) < 2.2 \times 10^{-6}$, at 90% confidence level, and find ${B}(D^0 \rightarrow \pi^0 \pi^0) = (8.4 \pm 0.1 \pm 0.4 \pm 0.3) \times 10^{-4}$.
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