Reggeon and pion contributions in semi-exclusive diffractive processes at HERA

A detailed analysis of semi-exclusive diffractive processes in e-p DIS at HERA, with the diffractive final states in the forward direction is presented. The contributions of the subleading f_2, \omega, a_2, \rho reggeons and the pion exchanges to the diffractive structure function with the forward proton or neutron are estimated. It is found that the (a_2,\rho) reggeons are entirely responsible for the forward neutron production at x_P < 10^{-3}. The \pi N production in the forward region is estimated using the Deck mechanism. The significance of this reaction for the processes measured at HERA, especially with the leading neutron, is discussed.Comment: Strongly revised version accepted for publication in Phys.Rev.D. Latex, 14 pages with 5 eps figures include

On the Flavor Structure of the Constituent Quark

We discuss the dressing of constituent quarks with a pseudoscalar meson cloud within the effective chiral quark model. SU(3) flavor symmetry breaking effects are included explicitly. Our results are compared with those of the traditional meson cloud approach in which pions are coupled to the nucleon. The pionic dressing of the constituent quarks explains the experimentally observed violation of the Gottfried Sum Rule and leads to an enhanced nonperturbative sea of quark-antiquark pairs in the constituent quark and consequently in the nucleon. We find 2.5 times more pions and 10-15 times more kaons in the nucleon than in the traditional picture.Comment: 7 pages, LaTeX, 4 Postscript figures, to appear in J. Phys.

Wild Boars Carry Extended-Spectrum β-Lactamase- and AmpC-Producing Escherichia coli

Extended-spectrum β-lactamase (ESBL)-producing Escherichia coli and methicillin-resistant Staphylococcus aureus (MRSA) represent major healthcare concerns. The role of wildlife in the epidemiology of these bacteria is unclear. The purpose of this study was to determine their prevalence in wild boars in Germany and to characterize individual isolates. A total of 375 fecal samples and 439 nasal swabs were screened for the presence of ESBL-/AmpC-E. coli and MRSA, respectively. The associations of seven demographic and anthropogenic variables with the occurrence of ESBL-/AmpC-E. coli were statistically evaluated. Collected isolates were subjected to antimicrobial susceptibility testing, molecular typing methods, and gene detection by PCR and genome sequencing. ESBL-/AmpC-E. coli were detected in 22 fecal samples (5.9%) whereas no MRSA were detected. The occurrence of ESBL-/AmpC-E. coli in wild boars was significantly and positively associated with human population density. Of the 22 E. coli, 19 were confirmed as ESBL-producers and carried genes belonging to blaCTX-M group 1 or blaSHV-12. The remaining three isolates carried the AmpC-β-lactamase gene blaCMY-2. Several isolates showed additional antimicrobial resistances. All four major phylogenetic groups were represented with group B1 being the most common. This study demonstrates that wild boars can serve as a reservoir for ESBL-/AmpC-producing and multidrug-resistant E. coli

Leptogenesis via multiscalar coherent evolution with supersymmetric neutrino see-saw

A novel scenario of leptogenesis is investigated in the supersymmetric neutrino see-saw model. The right-handed sneutrino ${\tilde N}$ and the $\phi$ field in the ${\tilde L} H_u$ direction of the slepton and Higgs doublets start together coherent evolution after the inflation with right-handed neutrino mass $M_N$ smaller than the Hubble parameter of inflation. Then, after some period the motion of ${\tilde N}$ and $\phi$ is drastically changed by the cross coupling $M_N h_\nu {\tilde N}^* \phi \phi$ from the $M_N N N$ and $h_\nu N L H_u$ terms, and the significant asymmetries of ${\tilde N}$ and ${\tilde L}$ are generated. The ${\tilde L}$ asymmetry is fixed later by the thermal effect as the lepton number asymmetry for baryogenesis, while the ${\tilde N}$ asymmetry disappears through the decays ${\tilde N} \to {\bar L} {\bar{\tilde H}}_u, {\tilde L} H_u$ with almost the same rate but opposite final lepton numbers.Comment: 4pages, 1 figure; submitted to Physical Review D. The renormalization group effects were include

Pion and Rho Structure Functions from Lattice QCD

We calculate the lower moments of the deep-inelastic structure functions of the pion and the rho meson on the lattice. Of particular interest to us are the spin-dependent structure functions of the rho. The calculations are done with Wilson fermions and for three values of the quark mass, so that we can perform an extrapolation to the chiral limit.Comment: 30pp, LaTeX2e with 15 eps figures using epsfig. Postscript file also available from ftp://ftp.th.physik.uni-frankfurt.de/pub/cbest/pionrho.ps or http://www.th.physik.uni-frankfurt.de/~cbest/pionrho.p

Nonperturbative versus perturbative effects in generalized parton distributions

Generalized parton distributions (GPDs) are studied at the hadronic (nonperturbative) scale within different assumptions based on a relativistic constituent quark model. In particular, by means of a meson-cloud model we investigate the role of nonperturbative antiquark degrees of freedom and the valence quark contribution. A QCD evolution of the obtained GPDs is used to add perturbative effects and to investigate the GPDs' sensitivity to the nonperturbative ingredients of the calculation at larger (experimental) scale.Comment: 17 pages, 10 figures; submitted to Phys. Rev.