401 research outputs found
Detecting new physics contributions to the D0-D0bar mixing through their effects on B decays
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
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
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
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
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
We introduce a classification number which describes the baryon mass
information in a fuzzy manner. According to and of baryons, we put
all known light baryons in a simple table in which some baryons with same (,
) 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
We present results from a new Monte Carlo simulation for jet fragmentation in
QCD and SUSY QCD for large primary energies up to 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 . 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
VІ Міжнародна науково-практична конференція «Чиста вода. Фундаментальні, прикладні та промислові аспекти»
Schistosomatidae from the trematode fauna of aquatic and semi-aquatic birds in Uzbekistan
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
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 that follows from a power-enhanced beta function,
and discuss how this 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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