16,048 research outputs found

    New Charm Results from Focus

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    New results from the photoproduction experiment FOCUS are reported: Dalitz plot analysis, semileptonic form factor ratios and excited meson spectroscopy.Comment: 8 pages, 5 figures, Frascati preprint style lnfprep.sty (included). Presented by S.Bianco at the 18th Rencontres de Physique de la Vallee d'Aoste 29 February-6 March, La Thuile, Vallee d'Aoste, Italy. Frascati preprint LNF-04/14(P), Fermilab preprint FERMILAB-CONF-04-372-

    Prospect of D0 mixing and CPV at LHCb

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    Precision measurements in charm physics offer a window into a unique sector of potential New Physics interactions. LHCb is poised to become a world leading experiment for charm studies, recording enormous statistics with a detector tailored for flavor physics. This article presents recent charm CPV and mixing studies from LHCb, including LHCb's first CP asymmetry measurement with 37 inverse pb of data collected in 2010. The difference of the CP asymmetries of D0 decays to the K-K+ and \pi-\pi+ final states is determined to be \Delta A_{CP} = (-0.28 +/- 0.70 +/- 0.25)%. Significant updates to the material presented at the 4th International Workshop on Charm Physics are included.Comment: 5 pages, 4 figures. Submitted to the proceedings of the 4th International Workshop on Charm Physics (Charm2010), Beijing, Chin

    Space-time nature of causality

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    Peer reviewedPostprintPublisher PD

    Practical Algorithms for Multicast Support in Input Queues Switches

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    Abstract — This paper deals with multicast flow support in N × N Input Queued switch architectures. A practical approach to support multicast traffic is presented, assuming that O(N) queues are available at each input port. The focus is on dynamic queueing policies, where, at each input port, multicast flows are assigned to one among the available queues when flows become active: flows are assigned to queues according to switch queue status and, possibly, to flow information. We discuss queueing assignments, scheduling algorithms and flow activity definition models. We explain why dynamic queueing disciplines may outperform static policies, and we show that, even in the most favorable conditions for static policies, they provide comparable performance. I

    Effects of Littlest Higgs model in rare D meson decays

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    A tree-level flavor changing neutral current in the up-like quark sector appears in one of the variations of the Littlest Higgs model. We investigate the effects of this coupling in the D+ -> pi+ l+ l- and D0 -> rho0 l+ l- decays, which are the most appropriate candidates for the experimental studies. However, the effects are found to be too small to be observed in the current and the foreseen experimental facilities. These decays are still dominated by the standard model long-distance contributions, which are reevaluated based on the new experimental input.Comment: 13 pages, 3 figures; new constraint on scale f taken into account and effects on charm meson decays recalculate

    On the physical processes which lie at the bases of time variability of GRBs

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    The relative-space-time-transformation (RSTT) paradigm and the interpretation of the burst-structure (IBS) paradigm are applied to probe the origin of the time variability of GRBs. Again GRB 991216 is used as a prototypical case, thanks to the precise data from the CGRO, RXTE and Chandra satellites. It is found that with the exception of the relatively inconspicuous but scientifically very important signal originating from the initial ``proper gamma ray burst'' (P-GRB), all the other spikes and time variabilities can be explained by the interaction of the accelerated-baryonic-matter pulse with inhomogeneities in the interstellar matter. This can be demonstrated by using the RSTT paradigm as well as the IBS paradigm, to trace a typical spike observed in arrival time back to the corresponding one in the laboratory time. Using these paradigms, the identification of the physical nature of the time variablity of the GRBs can be made most convincingly. It is made explicit the dependence of a) the intensities of the afterglow, b) the spikes amplitude and c) the actual time structure on the Lorentz gamma factor of the accelerated-baryonic-matter pulse. In principle it is possible to read off from the spike structure the detailed density contrast of the interstellar medium in the host galaxy, even at very high redshift.Comment: 11 pages, 5 figure