401 research outputs found

    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

    Regge-cascade hadronization

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    We argue that the evolution of coloured partons into colour-singlet hadrons has approximate factorization into an extended parton-shower phase and a colour-singlet resonance--pole phase. The amplitude for the conversion of colour connected partons into hadrons necessarily resembles Regge-pole amplitudes since qq-bar resonance amplitudes and Regge-pole amplitudes are related by duality. A `Regge-cascade' factorization property of the N-point Veneziano amplitude provides further justification of this protocol. This latter factorization property, in turn, allows the construction of general multi-hadron amplitudes in amplitude-squared factorized form from (1->2) link amplitudes. We suggest an algorithm with cascade-decay configuration, ordered in the transverse momentum, suitable for Monte-Carlo simulation. We make a simple implementation of this procedure in Herwig++, obtaining some improvement to the description of the event-shape distributions at LEP.Comment: 10 pages, 9 figure

    A comparative analysis of gamma and hadron families at the superhigh energies recorded in experiment Pamir

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    A comparative analysis of hadron and gamma families which have undergone the decascading procedure is made. Results are compared with different models of interactions. In hadron families with energies Summary E sub H sup gamma 20 TeV as well as in gamma families with energies Summary E sub gamma 70 TeV, increasing azimuthal anisotropy is observed

    K*-couplings for the antidecuplet excitation

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    We estimate the coupling of the K* vector meson to the N-->Theta+ transition employing unitary symmetry, vector meson dominance, and results from the GRAAL Collaboration for eta photoproduction off the neutron. Our small numerical value for the coupling constant is consistent with the non-observation of the Theta+ in recent CLAS searches for its photoproduction. We also estimate the K*-coupling for the N-->Sigma* excitation, with Sigma* being the Sigma-like antidecuplet partner of the Theta+-baryon.Comment: 9 pages, 1 figure. Minor changes in text and abstract, references added; version to appear in Phys. Rev.

    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

    Simple Classification of Light Baryons

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    We introduce a classification number nn which describes the baryon mass information in a fuzzy manner. According to nn and JpJ^p of baryons, we put all known light baryons in a simple table in which some baryons with same (nn, JpJ^p) are classified as members of known octets or decuplets. Meanwhile, we predict two new possible octets.Comment: 5 latex pages, 5 tables, no figur

    Monte Carlo simulation for jet fragmentation in SUSY-QCD

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    We present results from a new Monte Carlo simulation for jet fragmentation in QCD and SUSY QCD for large primary energies s\sqrt s up to 101610^{16} GeV. In the case of SUSY QCD the simulation takes into account not only gluons and quarks as cascading particles, but also their supersymmetric partners. A new model-independent hadronization scheme is developed, in which the hadronization functions are found from LEP data. An interesting feature of SUSY QCD is the prediction of a sizeable flux of the lightest supersymmetric particles (LSPs), if R-parity is conserved. About 10% of the jet energy is transferred to LSPs which, owing to their harder spectra, constitute an important part of the spectra for large x=E/Ejetx=E/E_{jet}. Spectra of protons and of secondary particles, photons and neutrinos, are also calculated. These results have implications for the decay of superheavy particles with masses up to the GUT scale, which have been suggested as a source of ultrahigh energy cosmic rays.Comment: latex, 25 pages with 17 eps figure

    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

    Local charge compensation from colour preconfinement as a key to the dynamics of hadronization

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    If, as is commonly accepted, the colour-singlet, `preconfined', perturbative clusters are the primary units of hadronization, then the electric charge is necessarily compensated locally at the scale of the typical cluster mass. As a result, the minijet electric charge is suppressed at scales that are greater than the cluster mass. We hence argue, and demonstrate by means of Monte Carlo simulations using HERWIG, that the scale at which charge compensation is violated is close to the mass of the clusters involved in hadronization, and its measurement would provide a clue to resolving the nature of the dynamics. We repeat the calculation using PYTHIA and find that the numbers produced by the two generators are similar. The cluster mass distribution is sensitive to soft emission that is considered unresolved in the parton shower phase. We discuss how the description of the splitting of large clusters in terms of unresolved emission modifies the algorithm of HERWIG, and relate the findings to the yet unknown underlying nonperturbative mechanism. In particular, we propose a form of αS\alpha_S that follows from a power-enhanced beta function, and discuss how this αS\alpha_S that governs unresolved emission may be related to power corrections. Our findings are in agreement with experimental data.Comment: 37 pages, 20 figure
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