44,104 research outputs found

    Direct test of time reversal invariance violation in B mesons

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    In this letter we reinterpret and reanalyze the available data of the B meson factories showing the existence of direct experimental evidence of time reversal invariance violation in B mesons. This reinterpretation consists of using the available observables to define a new observable which, in a model independent way and without assuming CPT invariance, compares a transition between a B0B^0 and a here-defined BαB_\alpha-state, with its time reversed transition. The observable then offers a direct way to probe time reversal invariance and it is therefore independent of any conclusion obtained from current experimental information on CP violation and CPT invariance. As far as the authors are concerned, this is the first direct evidence of time reversal invariance violation in B mesons and also the first one obtained from decaying particles whose mean life time difference is negligible.Comment: 9 pages, no figures. Refined version matching published article in Modern Physics Letters

    Standard Model Higgs and Top Mass Measurements at the Tevatron

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    A summary of the present Standard Model Higgs search and measurement of top quark mass at the Tevatron are presented. The sensitivity of the present Higgs search at the Tevatron is limited by statistics to a cross section approximately two orders of magnitude higher than the predicted cross section for Standard Model Higgs production. With 30/fb of integrated luminosity, the Tevatron offers an unique potential discovery window for the Standard Model Higgs mass up to 130 GeV before LHC era. The study of top at the Tevatron has moved from discovery phase to one of characterizing its properties. The combined result of top quark mass is 174.3+- 5.1 GeV.Comment: 7 pages, latex source-file, 5 figures as ps-file. Talk given at The Division of Particles and Fields Conference 1999, January 5-9, 1999, UCLA, US

    Quark and lepton mass matrices with A4A_4 family symmetry

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    Realistic quark masses and mixing angles are obtained applying the successful A4A_4 family symmetry for leptons, motivated by the quark-lepton assignments of SU(5). The A4A_4 symmetry is suitable to give tri-bimaximal neutrino mixing matrix which is consistent with current experimental data. We study new scenario for the quark sector with the A4A_4 symmetry.Comment: 16 pages, 2 figures, Talk given at International Workshop on Neutrino Masses and Mixings, Shizuoka, Japan, 17-19 December 200

    Charm mixing in the Standard Model and beyond

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    The motivation most often cited in searches for D0-anti-D0 mixing and CP-violation in charm system lies with the possibility of observing a signal from New Physics which dominates that from the Standard Model. We review recent theoretical predictions and experimental constraints on D0-anti-D0 mixing parameters, concentrating on possible effects of New Physics.Comment: 8 pages, 2 figures, Invited talk at International Workshop on Tau-Charm Physics (Charm 2006), Beijing, China, 5-7 Jun 200

    Shell Cracking In Investment Casting with Laser Stereolithography Patterns

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    This paper presents an investigation of ceramic shell cracking during the burnout process in investment casting with internally webbed laser stereolithography patterns. We hypothesize that shell cracking will occur when the rupture temperature of the ceramic shell is lower than both the glass transition temperature of the pattern material and the web· link buckling temperature. The hypothesis is validated by our experimental observations which confirm the numerical predictions from our fillite element analysis. This provides a basis for design of the internal web geometry of a lithography pa.tternand evaluation ofthe burnolltprocesswithsuch a pattern. We show the shell cracking and web link buckling temperatures to be functiollsofthe pattern geometry (including the cross~sectional dimensions and span length of the web link) and the shell thickness.Mechanical Engineerin

    Search for Rare b-hadron Decays at CDF

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    We report on searches for B^0_s to \mu^+ \mu^-, B^0_d to \mu^+ \mu^- decays and b to s \mu^+\mu^- transitions in exclusive decays of B mesons. Using 2 fb^{-1} of data collected by the CDF II detector we find upper limits on the branching fractions B(B^0_s to \mu^+ \mu^-) < 5.8 x 10^{-8} and B(B^0_d to \mu^+ \mu^-) < 1.8 x 10^{-8} at 95% confidence level. Using 924 pb^{-1} of data we measure the branching fractions B(B^+ to \mu^+ \mu^- K^+) = (0.60 \pm 0.15 \pm 0.04) x 10^{-6}, B(B^0_d to \mu^+ \mu^- K^{*0}) = (0.82 \pm 0.31 \pm 0.10) x 10^{-6} and the limit B(B^0_s to \mu^+ \mu^- phi)/B(B^0_s to J/\psi\phi) < 2.61(2.30) x 10^{-3} at 95(90)% confidence level.Comment: 3 pages, 5 figures, conference proceedings to the 2007 Europhysics Conference on High Energy Physics (Manchester, July 2007

    Final stare interaction enhancement effect on the near threshold p\bar p system in B^\pm\to p\bar p \p^\pm decay

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    We discuss the low-mass enhancement effect in the baryon-antibaryon invariant mass in three-body baryonic B decays using final state interactions in the framework of Regge theory. We show that the rescattering between baryonic pair can reproduce the observed mass spectrum.Comment: 7 pages, 11 figure
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