2,773 research outputs found
Charm mixing in the Standard Model and beyond
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 decay
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 , (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 , but are quite
likely to be significant at ~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
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
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 production in
neutrino-nucleon collision is dominated by the color octet 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
We provide a new estimate of the long-distance component to the radiative
transition . Our mechanism involves the soft-scattering of
on-shell hadronic products of nonleptonic decay, as in the chain . We employ a phenomenological fit to scattering data
to estimate the effect. The specific intermediate states considered here modify
the decay rate at roughly the 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 channel and hence will provide an uncertainty in the extraction of
. This mechanism also affects the isospin relation between the rates
for and and may generate CP
asymmetries at experimentally observable levels.Comment: 15 pages, RevTex, 3 figure
Biliary Microbiota, Gallstone Disease and Infection with Opisthorchis felineus.
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
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
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 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
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
- …