306 research outputs found

    Lifetime Differences in Heavy Mesons With Time Independent Measurements

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    Heavy meson pairs produced in the decays of heavy quarkonium resonances at e+ e- machines (beauty and tau-charm factories) have the useful property that the two mesons are in the CP-correlated states. By tagging one of the mesons as a CP eigenstate, a lifetime difference of heavy neutral meson mass eigenstates width difference may be determined by measuring the leptonic branching ratio of the other meson. We discuss the use of this and related methods both in the case where time dependent mixing is small and when it is significant. We consider the impact of possible CP-violating effects and present the complete results for CP-entangled decay rates with CP-violation taken into account.Comment: 14 pages, 0 figures; 2 references added, results unchange

    Bounds on gamma from CP violation measurements in B -> pi+ pi- and B -> psi K_S

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    We study the determination of gamma from CP-violating observables in B -> pi+ pi- and B -> psi K_S. This determination requires theoretical input to one combination of hadronic parameters. We show that a mild assumption about this quantity may allow bounds to be placed on gamma, but we stress the pernicious effects that an eightfold discrete ambiguity has on such an analysis. The bounds are discussed as a function of the direct (C) and interference (S) CP-violating observables obtained from time-dependent B -> pi+ pi- decays, and their behavior in the presence of new physics effects in B-Bbar mixing is studied. (V2: Misprints corrected. Slightly improved discussion.)Comment: 11 pages, RevTex 4, 5 eps figures include

    Detecting new physics contributions to the D0-D0bar mixing through their effects on B decays

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    New physics effects may yield a detectable mass difference in the D0-D0bar system, Delta m_D. Here we show that this has an important impact on some B --> D decays. The effect involves a new source of CP violation, which arises from the interference between the phases in the B --> D decays and those in the D0-D0bar system. This interference is naturally large. New physics may well manifest itself through Delta m_D contributions to these B decays.Comment: 10 pages, Revtex, no figures. To appear in PR

    Life cycle of Bilharziella polonica (Trematoda, Schistosomatidae) parasite of semi-aquatic birds in Uzbekistan

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    Schistosomatidae are an actively studied ecological group of trematodes. Their ability to cause various parasitic diseases in animals and humans makes them an interesting object of study for a number of research centres worldwide. One of the commonest species in this group is Bilharziella polonica (Kowalewsky, 1895), whose mature stages have been recorded in aquatic and semi-aquatic birds in Uzbekistan. Our research team established that the following birds were infected with mature trematodes B. polonica: Anas platyrhynchos (23%), A. crecca (18%), Podiceps ruficollis (11%), Ardea cinerea (14%) and one individual of Oxyura leucocephala. The highest infection rate was shown by the mallard A. platyrhynchos (23%) and common teal A. crecca (18%). The infection intensity ranged between 2 and 27 individuals. Research into various types of water bodies in Karakalpakstan identified 10 mollusc species – Lymnaeidae (4 species), Planorbidae (4 species) and Physidae (2 species). Cercariae morphologically similar to larvae of B. polonica were found in two species, Planorbis planorbis and P. tangitarensis. 6 chicks of domestic ducks were experimentally infected with those cercariae to track the life cycle of B. polonica in the organism of a definitive host. Helmintholological dissections showed that every duck was infected with B. polonica, which became mature 23–27 days after the infection. Eggs of B. polonica were recorded in the excrement of one of the birds 33–35 days after the infection. Based on field and experimental research, we identify the mollusc P. tangitarensis as a new intermediate host for B. polonica in Uzbekistan

    DIFFERENT CRYPTOPHITES OF THE AHANGARAN BASIN AND THEIR MODERN ENVIRONMENTAL CONDITION

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    This article is devoted to a brief description of the vegetation cover of the Akhangaran river basin and provides information on the widespread types of cryptophytes. The article gives the species composition and phytocenology of cryptophytes, the laws of distribution, the ecological state and the factors influencing them

    METHODS FOR OPTIMAL CONTROL OF GRINDING PROCESSING ACCURACY ON LOW RIGIDITY SHAFTS

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    This article addresses the application of modern methods and algorithms for the optimal control of technological processes and the efficient design of grinding process for low rigidity shafts. The investigation of the dynamic processing characteristics of the system identifies the influence of disturbing and regulatory influences on the amount of elastic deformation of the details in the transient and steady modes in order to minimize shape error of the shafts. The necessary conditions for optimal control of the technological systems under consideration are investigated using the Pontryagin maximum principle. The components of the cutting forces and the optimal values of the geometric, structural and functional parameters of the work-in-process parts are determined

    Schistosomatidae from the trematode fauna of aquatic and semi-aquatic birds in Uzbekistan

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    The article discusses the infection of wetland birds in Uzbekistan with the trematodes Schistosomatidae Stiles et Hassall, 1898. The research covered 282 individuals from the main groups of birds represented by the orders Pelecaniformes, Ciconiformes, Anseriformes, Gruiformes, Podicipediformes and Charadriiformes. The Schistosomatidae fauna of Uzbekistan includes 13 species: Bilharziella polonica (Kowalewsky, 1895), Trichobilharzia ocellata (La Valette, 1854), T. filiformis (Szidat, 1938), T. kowalewskii (Ejsmont, 1929), T. tatianae (Spasskaja, 1953), Macrobilharzia macrobilharzia Trawassos, 1923, Ornithobilharzia canaliculata (Rudolphi, 1819), O. baeri Fain, 1955, Dendritobilharzia pulverulenta (Braun, 1901), D. loossi Skrjabin, 1924, D. anatinarum Cheatum, 1941, Gigantobilharzia acotylea Odhner, 1910 and Gigantobilharziella monocotylea (Szidat, 1930). Predominant are representatives of the genera Trichobilharzia and Dendritobilharzia. The species composition of Schistosomatidae is most diverse in birds from the lower reaches of the Amu Darya, where a high rate of infection with larvae of some of these trematodes was also recorded in aquatic molluscs. 11 species of molluscs were registered in the studied regions: Galba truncatula (Muller, 1774), Stagnicola corvus (Gmelin, 1791), Radix auricularia (Linnaeus, 1758), Lymnaea stagnalis (Linnaeus, 1758), Physa fontinalis (Linnaeus, 1758), Physella acuta (Draparnaud, 1805), Planorbis planorbis (Linnaeus, 1758), P. tangitarensis Germain, 1918, Anisus spirorbis (Linnaeus, 1758), Gyraulus albus (Muller, 1774), Melanoides kainarensis Starobogatov et Izzatullaev, 1980, from the families Lymnaeidae (4 species), Planorbidae (4 species), Physidae (2 species) and Thiaridae (1 species). They are identified as intermediate hosts of Schistosomatidae and were infected with 7 species of flukes. The total rate of infection with larval stages of Schistosomatidae in molluscs was about 2.0%. The highest infection rate was observed in Melanoides kainarensis – 5.3%. Morpho-biological indicators for mature forms of B. polonica from different bird species (Anas platyrhynchos and Oxyura leucocephala) were confirmed by molecular genetic studies. The study identified foci of birds’ infection with Schistosomatidae and the occurrence of human cercarial dermatitis

    Weak radiative hyperon decays, Hara's theorem and the diquark

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    Weak radiative hyperon decays are discussed in the diquark-level approach. It is pointed out that in the general diquark formalism one may reproduce the experimentally suggested pattern of asymmetries, while maintaining Hara's theorem in the SU(3) limit. At present, however, no detailed quark-based model of parity-violating diquark-photon coupling exists that would have the necessary properties.Comment: 10 pages, LaTe

    Comment on ``Evidence for Narrow Baryon Resonances in Inelastic pp Scattering''

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    Compton scattering data are sensitive to the existence of low-mass resonances reported by Tatischeff et al. We show that such states, with their reported properties, are excluded by previous Compton scattering experiments.Comment: One page, submitted to PR
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