2,773 research outputs found

    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

    Systematics of soft final state interactions in BB decay

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    By using very general and well established features of soft strong interactions we show, contrary to conventional expectations, that (i) soft final state interactions (FSI) do not disappear for large mBm_B, (ii) inelastic rescattering is expected to be the main source of soft FSI phases, and (iii) flavor off-diagonal FSI are suppressed by a power of mBm_B, but are quite likely to be significant at mB5m_B\simeq 5~GeV. We briefly discuss the influence of these interactions on tests of CP-violation and on theoretical calculations of weak decays.Comment: 11 pages, REVTeX, no figure

    Transport in Nanotubes: Effect of Remote Impurity Scattering

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    Theory of the remote Coulomb impurity scattering in single--wall carbon nanotubes is developed within one--electron approximation. Boltzmann equation is solved within drift--diffusion model to obtain the tube conductivity. The conductivity depends on the type of the nanotube bandstructure (metal or semiconductor) and on the electron Fermi level. We found exponential dependence of the conductivity on the Fermi energy due to the Coulomb scattering rate has a strong dependence on the momentum transfer. We calculate intra-- and inter--subband scattering rates and present general expressions for the conductivity. Numerical results, as well as obtained analytical expressions, show that the degenerately doped semiconductor tubes may have very high mobility unless the doping level becomes too high and the inter--subband transitions impede the electron transport.Comment: 13 pages, 4 figure

    Charmonium production at neutrino factories

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    At existing and planned neutrino factories (high energy and high intensity neutrino beam facilities) precision studies of QCD in neutrino-nucleon interactions are a realistic opportunity. We investigate charmonium production in fixed target neutrino experiments. We find that J/ψJ/\psi production in neutrino-nucleon collision is dominated by the color octet 3S1^3S_1 NRQCD matrix element in a neutral current process, which is not accessible in photo or leptoproduction. Neutrino experiments at a future Muon Collider will acquire sufficient event rate to accurately measure color octet matrix element contributions. The currently running high energy neutrino experiments, NOMAD and NuTeV could also observe several such events.Comment: 13 pages Latex, with five embedded eps figures. Cosmetic fixups in the figures, otherwise unchange

    Final state rescattering as a contribution to BργB \to \rho \gamma

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    We provide a new estimate of the long-distance component to the radiative transition BργB \to \rho \gamma. Our mechanism involves the soft-scattering of on-shell hadronic products of nonleptonic BB decay, as in the chain BρρργB \to \rho\rho \to \rho\gamma. We employ a phenomenological fit to scattering data to estimate the effect. The specific intermediate states considered here modify the BργB \to \rho \gamma decay rate at roughly the 585 \to 8% level, although the underlying effect has the potential to be larger. Contrary to other mechanisms of long distance physics which have been discussed in the literature, this yields a non-negligible modification of the B0ρ0γB^0 \to \rho^0 \gamma channel and hence will provide an uncertainty in the extraction of VtdV_{td}. This mechanism also affects the isospin relation between the rates for BργB^- \to \rho^-\gamma and B0ρ0γB^0 \to \rho^0 \gamma and may generate CP asymmetries at experimentally observable levels.Comment: 15 pages, RevTex, 3 figure

    Biliary Microbiota, Gallstone Disease and Infection with Opisthorchis felineus.

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    BACKGROUND: There is increasing interest in the microbiome of the hepatobiliary system. This study investigated the influence of infection with the fish-borne liver fluke, Opisthorchis felineus on the biliary microbiome of residents of the Tomsk region of western Siberia. METHODOLOGY/PRINCIPAL FINDINGS: Samples of bile were provided by 56 study participants, half of who were infected with O. felineus, and all of who were diagnosed with gallstone disease. The microbiota of the bile was investigated using high throughput, Illumina-based sequencing targeting the prokaryotic 16S rRNA gene. About 2,797, discrete phylotypes of prokaryotes were detected. At the level of phylum, bile from participants with opisthorchiasis showed greater numbers of Synergistetes, Spirochaetes, Planctomycetes, TM7 and Verrucomicrobia. Numbers of \u3e 20 phylotypes differed in bile of the O. felineus-infected compared to non-infected participants, including presence of species of the genera Mycoplana, Cellulosimicrobium, Microlunatus and Phycicoccus, and the Archaeans genus, Halogeometricum, and increased numbers of Selenomonas, Bacteroides, Rothia, Leptotrichia, Lactobacillus, Treponema and Klebsiella. CONCLUSIONS/SIGNIFICANCE: Overall, infection with the liver fluke O. felineus modified the biliary microbiome, increasing abundance of bacterial and archaeal phylotypes

    Phenomenology of V_ub from Ratios of Inclusive B Decay Rates

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    We explore the theoretical feasibility of extracting V_ub from two ratios built from B meson inclusive partial decays, R_1 = Gamma(b-> u cbar s)/3Gamma(b -> c l nu), and R_2 = [Gamma(b -> c X) - Gamma(b -> cbar X)]/Gamma(b -> c ubar d). We discuss contributions to these quantities from perturbative and nonperturbative physics, and show that they can be computed with overall uncertainties at the level of 10%.Comment: 19 pages, 8 embedded EPS figures, uses REVTe

    The flavor puzzle in multi-Higgs models

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    We reconsider the flavor problem in the models with two Higgs doublets. By studying two generation toy models, we look for flavor basis independent constraints on Yukawa couplings that will give us the mass hierarchy while keeping all Yukawa couplings of the same order. We then generalize our findings to the full three generation Standard Model. We find that we need two constraints on the Yukawa couplings to generate the observed mass hierarchy, and a slight tuning of Yukawa couplings of order 10%, much less than the Standard Model. We briefly study how these constraints can be realized, and show how flavor changing currents are under control for KKˉK-\bar{K} mixing in the near-decoupling limit.Comment: 26 pages, typos are corrected, references are added, the final versio

    Final State Interactions and New Physics in B -> pi K Decays

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    Within the Standard Model, and if one assumes that soft rescattering effects are negligible, the CP asymmetry A^dir_CP (B^\pm -> \pi^\pm K) is predicted to be very small and the ratio R = BR(B_d -> \pi^\mp K^\pm)/BR(B^\pm -> \pi^\pm K) provides a bound on the angle \gamma of the unitarity triangle, sin^2 \gamma \leq R. We estimate the corrections from soft rescattering effects using an approach based on Regge phenomenology, and find effects of order 10% with large uncertainties. In particular, we conclude that A^dir_CP \sim 0.2 and sin^2 \gamma \sim 1.2 R could not be taken unambiguously to signal New Physics. Using SU(3) relations, we suggest experimental tests that could constrain the size of the soft rescattering effects thus reducing the related uncertainty. Finally, we study the effect of various models of New Physics on A^dir_CP and on R.Comment: 20 pages, RevTex, no figures; a few typos corrected, references added, brief additional discussion of uncertanties is adde
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