2,666 research outputs found

    Lifetimes of Heavy-Flavour Hadrons -- Whence and Whither?

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    A theoretical treatment for the weak decays of heavy-flavour hadrons has been developed that is genuinely based on QCD. Its methodology as it applies to total lifetimes and the underlying theoretical issues are sketched. Predictions are compared with present data. One discrepancy emerges: the beauty baryon lifetime appears to be significantly shorter than expected. The ramifications of those findings are analyzed in detail.Comment: 15 pages, no figures, LATEX, two references added and new information concerning a lower charm content in B decays incorporate

    Open Questions in Charm Decays Deserving an Answer

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    A list is given of those open questions concerning the dynamics of charm decays where there exists a strong need for an answer. Such a need is based on lessons to be learnt about QCD -- either in their own right or for a better understanding of BB physics -- or on searches for New Physics with a small background from the Standard Model. The major items on this list are: lifetimes of the Ξc0,+\Xi _c^{0,+} baryons; semileptonic branching ratios of DsD_s, Λc\Lambda _c and Ξc\Xi _c hadrons and absolute branching ratios for those states; radiative decays DγK,γρ/ω,Dsγϕ/ω,Dl+lK/KD\rightarrow \gamma K^*,\, \gamma \rho /\omega , \, D_s \rightarrow \gamma \phi /\omega ,\, D\rightarrow l^+l^-K/K^*; D0Dˉ0D^0-\bar D^0 oscillations down to a sensitivity below 10410^{-4} and CP asymmetries in non-leptonic DD decays down to 0.1\%. Ongoing and already approved experiments will produce important new insights, which are unlikely to provide sufficient answers to all these questions yet. It is discussed how a third-generation fixed-target experiment like CHARM2000 or a τ\tau-charm factory can fill the bill.Comment: 9 pages, LATEX, preprint CERN-TH.7370/9

    CP, T and CPT Symmetries at the Turn of a New Millenium

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    After summarizing the status concerning CP violation in 1998 I describe the exciting developments of the last two years and extrapolate to the future. I comment on recent lessons about T and CPT invariance maninly from CPLEAR and emphasize the potential of finding New Physics by analyzing Kμ3K_{\mu 3} and charm decays and searching for electric dipole moments.Comment: 21 pages, LaTex, Lecture given at LEAP2000, Venice, Italy, Aug. 21 - 26, 200