2,037 research outputs found
Two body non-leptonic decays in quark model with factorization ansatz
The two body non-leptonic decays are analyzed in factorization
approximation, using quark model, as a free parameter. It is
shown that the experimental branching ratio for restricts and this ratio can be understood for a value
of which lies in the range suggested by two body
B meson decays. The branching ratios for are predicted to be larger than the previous estimates. Finally it
is pointed that CKM-Wolfenstein parameter , where is CP
phase, can be determined from the ratio of widths of and or that of
and
independent of the parameter .Comment: 18 pages, latex, 1 figure available on request, please send any
questions or comments to [email protected]
Innovative in silico approaches to address avian flu using grid technology
The recent years have seen the emergence of diseases which have spread very
quickly all around the world either through human travels like SARS or animal
migration like avian flu. Among the biggest challenges raised by infectious
emerging diseases, one is related to the constant mutation of the viruses which
turns them into continuously moving targets for drug and vaccine discovery.
Another challenge is related to the early detection and surveillance of the
diseases as new cases can appear just anywhere due to the globalization of
exchanges and the circulation of people and animals around the earth, as
recently demonstrated by the avian flu epidemics. For 3 years now, a
collaboration of teams in Europe and Asia has been exploring some innovative in
silico approaches to better tackle avian flu taking advantage of the very large
computing resources available on international grid infrastructures. Grids were
used to study the impact of mutations on the effectiveness of existing drugs
against H5N1 and to find potentially new leads active on mutated strains. Grids
allow also the integration of distributed data in a completely secured way. The
paper presents how we are currently exploring how to integrate the existing
data sources towards a global surveillance network for molecular epidemiology.Comment: 7 pages, submitted to Infectious Disorders - Drug Target
Lower critical field and SNS-Andreev spectroscopy of 122-arsenides: Evidence of nodeless superconducting gap
Using two experimental techniques, we studied single crystals of the 122-FeAs
family with almost the same critical temperature, Tc. We investigated the
temperature dependence of the lower critical field of a single crystal under
static magnetic fields parallel to the axis. The temperature dependence of the
London penetration depth can be described equally well either by a single
anisotropic -wave-like gap or by a two-gap model, while a d-wave approach
cannot be used to fit the London penetration depth data. Intrinsic multiple
Andreev reflection effect spectroscopy was used to detect bulk gap values in
single crystals of the intimate compound, with the same Tc. We estimated the
range of the large gap value 6-8 meV (depending on small variation of and its a
space anisotropy of about 30%, and the small gap 1.7 meV. This clearly
indicates that the gap structure of our investigated systems more likely
corresponds to a nodeless s-wave two gaps.Comment: 9 pages, 6 figure
Two-subband electron transport in nonideal quantum wells
Electron transport in nonideal quantum wells (QW) with large-scale variations
of energy levels is studied when two subbands are occupied. Although the mean
fluctuations of these two levels are screened by the in-plane redistribution of
electrons, the energies of both levels remain nonuniform over the plane. The
effect of random inhomogeneities on the classical transport is studied within
the framework of a local response approach for weak disorder. Both short-range
and small-angle scattering mechanisms are considered. Magnetotransport
characteristics and the modulation of the effective conductivity by transverse
voltage are evaluated for different kinds of confinement potentials (hard wall
QW, parabolic QW, and stepped QW).Comment: 10 pages, 6 figure
Raman-Scattering Detection of Nearly Degenerate -Wave and -Wave Pairing Channels in Iron-Based BaKFeAs and RbFeSe Superconductors
We show that electronic Raman scattering affords a window into the essential
properties of the pairing potential of
iron-based superconductors. In BaKFeAs we observe band
dependent energy gaps along with excitonic Bardasis-Schrieffer modes
characterizing, respectively, the dominant and subdominant pairing channel. The
symmetry of all excitons allows us to identify the subdominant
channel to originate from the interaction between the electron bands.
Consequently, the dominant channel driving superconductivity results from the
interaction between the electron and hole bands and has the full lattice
symmetry. The results in RbFeSe along with earlier ones in
Ba(FeCo)As highlight the influence of the Fermi
surface topology on the pairing interactions.Comment: 5 pages, 4 figure
A Simple Linear Time Algorithm for Computing a 1-Median on Cactus Graphs
We address the problem of finding a 1-median on a cactus graph. The problem has already been solved in linear time by the algorithms of Burkard and Krarup (1998), and Lan and Wang (2000). These algorithms are complicated and need efforts. Hence, we develop in this paper a simpler algorithm. First, we construct a condition for a cycle that contains a 1-median or for a vertex that is indeed a 1-median of the cactus. Based on this condition, we localize the search for deriving a 1-median on the underlying cactus. Complexity analysis shows that the approach runs in linear time
Tannaka-Krein duality for Hopf algebroids
We develop the Tannaka-Krein duality for monoidal functors with target in the
categories of bimodules over a ring. The \coend of such a functor turns out
to be a Hopf algebroid over this ring. Using the result of a previous paper we
characterize a small abelian, locally finite rigid monoidal category as the
category of rigid comodules over a transitive Hopf algebroid.Comment: 25 pages, final version, to appear in Israel Journal of Mathematic
A SOCIAL SURVEY ON COMMUNITY RESPONSE TO ROAD TRAFFIC NOISE IN HANOI
Joint Research on Environmental Science and Technology for the Eart
CP-violating asymmetries in B^0 decays to K^+K^-K_{S(L)}^0 and K_S^0K_S^0K_{S(L)}^0
Decay rates and time-dependent and direct CP asymmetries in the decays
and are studied. Resonant and
nonresonant contributions to the three-body decays are carefully investigated.
Nonresonant effects on 2-body and 3-body matrix elements are constrained by QCD
counting rules. The predicted branching ratios are consistent with the data
within the theoretical and experimental errors, though the theoretical central
values are somewhat smaller than the experimental ones. Owing to the presence
of color-allowed tree amplitudes in , this
penguin-dominated mode is subject to a significant tree pollution and the
deviation of the mixing-induced \CP asymmetry from that measured in , namely, , can be as large as O(0.10).
In contrast, the modes appear theoretically very clean in our
picture with negligible . Direct CP
asymmetries in and modes are found to be
very small.Comment: 17 pages and 2 figures, the tree contribution is modified due to the
new data from BaBar, to appear in Phys. Rev.
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