635 research outputs found
The rare decays B --> K(*) anti-K(*) and R-parity violating supersymmetry
We study the branching ratios, the direct CP asymmetries in decays and the polarization fractions of decays by employing the QCD factorization in the minimal
supersymmetric standard model with R-parity violation. We derive the new upper
bounds on the relevant R-parity violating couplings from the latest
experimental data of , and some of these constraints
are stronger than the existing bounds. Using the constrained parameter spaces,
we predict the R-parity violating effects on the other quantities in decays which have not been measured yet. We find that the
R-parity violating effects on the branching ratios and the direct
asymmetries could be large, nevertheless their effects on the longitudinal
polarizations of decays are small. Near future
experiments can test these predictions and shrink the parameter spaces.Comment: 31 pages with 10 figure
Nottingham Prognostic Index Plus (NPI+): a modern clinical decision making tool in breast cancer
Current management of breast cancer (BC) relies on risk stratification based on well-defined clinicopathologic factors. Global gene expression profiling studies have demonstrated that BC comprises distinct molecular classes with clinical relevance. In this study, we hypothesized that molecular features of BC are a key driver of tumour behaviour and when coupled with a novel and bespoke application of established clinicopathologic prognostic variables, can predict both clinical outcome and relevant therapeutic options more accurately than existing methods. In the current study, a comprehensive panel of biomarkers with relevance to BC was applied to a large and well-characterised series of BC, using immunohistochemistry and different multivariate clustering techniques, to identify the key molecular classes. Subsequently, each class was further stratified using a set of well-defined prognostic clinicopathologic variables. These variables were combined in formulae to prognostically stratify different molecular classes, collectively known as the Nottingham Prognostic Index Plus (NPI+). NPI+ was then used to predict outcome in the different molecular classes with.Seven core molecular classes were identified using a selective panel of 10 biomarkers. Incorporation of clinicopathologic variables in a second stage analysis resulted in identification of distinct prognostic groups within each molecular class (NPI+). Outcome analysis showed that using the bespoke NPI formulae for each biological breast cancer class provides improved patient outcome stratification superior to the traditional NPI. This study provides proof-of-principle evidence for the use of NPI+ in supporting improved individualised clinical decision making
Elastic scattering and breakup of 17^F at 10 MeV/nucleon
Angular distributions of fluorine and oxygen produced from 170 MeV 17^F
incident on 208^Pb were measured. The elastic scattering data are in good
agreement with optical model calculations using a double-folding potential and
parameters similar to those obtained from 16^O+208^Pb. A large yield of oxygen
was observed near \theta_lab=36 deg. It is reproduced fairly well by a
calculation of the (17^F,16^O) breakup, which is dominated by one-proton
stripping reactions. The discrepancy between our previous coincidence
measurement and theoretical predictions was resolved by including core
absorption in the present calculation.Comment: 9 pages, 5 figure
Rare Decays of \Lambda_b->\Lambda + \gamma and \Lambda_b ->\Lambda + l^{+} l^{-} in the Light-cone Sum Rules
Within the Standard Model, we investigate the weak decays of and with the light-cone
sum rules approach. The higher twist distribution amplitudes of
baryon to the leading conformal spin are included in the sum rules for
transition form factors. Our results indicate that the higher twist
distribution amplitudes almost have no influences on the transition form
factors retaining the heavy quark spin symmetry, while such corrections can
result in significant impacts on the form factors breaking the heavy quark spin
symmetry. Two phenomenological models (COZ and FZOZ) for the wave function of
baryon are also employed in the sum rules for a comparison, which can
give rise to the form factors approximately 5 times larger than that in terms
of conformal expansion. Utilizing the form factors calculated in LCSR, we then
perform a careful study on the decay rate, polarization asymmetry and
forward-backward asymmetry, with respect to the decays of , .Comment: 38 pages, 15 figures, some typos are corrected and more references
are adde
Analysis and simulations for a phaseâfield fracture model at finite strains based on modified invariants
Phaseâfield models have already been proven to predict complex fracture patterns for brittle fracture at small strains. In this paper we discuss a model for phaseâfield fracture at finite deformations in more detail. Among the identification of crack location and projection of crack growth the numerical stability is one of the main challenges in solid mechanics. Here we present a phaseâfield model at finite strains, which takes into account the anisotropy of damage by applying an anisotropic split of the modified invariants of the right CauchyâGreen strain tensor. We introduce a suitable weak notion of solution that also allows for a spatial and temporal discretization of the model. In this framework we study the existence of solutions and we show that the timeâdiscrete solutions converge in a weak sense to a solution of the timeâcontinuous formulation of the model. Numerical examples in two and three space dimensions illustrate the range of validity of the analytical results
Annihilation-Type Charmless Radiative Decays of B Meson in Non-universal Z^\prime Model
We study charmless pure annihilation type radiative B decays within the QCD
factorization approach. After adding the vertex corrections to the naive
factorization approach, we find that the branching ratios of
, and
within the standard model are at the order of
, and ,
respectively. The smallness of these decays in the standard model makes them
sensitive probes of flavor physics beyond the standard model. To explore their
physics potential, we have estimated the contribution of boson in
the decays. Within the allowed parameter space, the branching ratios of these
decay modes can be enhanced remarkably in the non-universal model:
The branching ratios can reach to for and for the , which are large enough for LHC-b and/or Super B-factories to detect
those channels in near future. Moreover, we also predict large CP asymmetries
in suitable parameter space. The observation of these modes could in turn help
us to constrain the mass within the model.Comment: 13 pages, 8 figure
The , , and electromagnetic form factors
The rainbow truncation of the quark Dyson-Schwinger equation is combined with
the ladder Bethe-Salpeter equation for the meson amplitudes and the dressed
quark-photon vertex in a self-consistent Poincar\'e-invariant study of the pion
and kaon electromagnetic form factors in impulse approximation. We demonstrate
explicitly that the current is conserved in this approach and that the obtained
results are independent of the momentum partitioning in the Bethe-Salpeter
amplitudes. With model gluon parameters previously fixed by the condensate, the
pion mass and decay constant, and the kaon mass, the charge radii and spacelike
form factors are found to be in good agreement with the experimental data.Comment: 8 pages, 6 figures, Revte
The Glauber model and the heavy ion reaction cross section
We reexamine the Glauber model and calculate the total reaction cross section
as a function of energy in the low and intermediate energy range, where many of
the corrections in the model, are effective.
The most significant effect in this energy range is by the modification of
the trajectory due to the Coulomb field. The modification in the trajectory due
to nuclear field is also taken into account in a self consistent way.
The energy ranges in which particular corrections are effective, are
quantified and it is found that when the center of mass energy of the system
becomes 30 times the Coulomb barrier, none of the trajectory modification to
the Glauber model is really required.
The reaction cross sections for light and heavy systems, right from near
coulomb barrier to intermediate energies have been calculated. The exact
nuclear densities and free nucleon-nucleon (NN) cross sections have been used
in the calculations. The center of mass correction which is important for light
systems, has also been taken into account.
There is an excellent agreement between the calculations with the modified
Glauber model and the experimental data. This suggests that the heavy ion
reactions in this energy range can be explained by the Glauber model in terms
of free NN cross sections without incorporating any medium modification.Comment: RevTeX, 21 pages including 9 Postscript figures, submitted to Phys.
Rev.
Proton-Antiproton Annihilation into a Lambda_c-Antilambda_c Pair
The process p-pbar -> Lambda_c-Antilambda_c is investigated within the
handbag approach. It is shown that the dominant dynamical mechanism,
characterized by the partonic subprocess u-ubar -> c-cbar factorizes in the
sense that only the subprocess contains highly virtual partons, a gluon to
lowest order of perturbative QCD, while the hadronic matrix elements embody
only soft scales and can be parameterized in terms of helicity flip and
non-flip generalized parton distributions. Modelling these parton distributions
by overlaps of light-cone wave functions for the involved baryons we are able
to predict cross sections and spin correlation parameters for the process of
interest.Comment: 39 pages, 7 figures, problems with printout of figures resolved, Ref.
33 and referring sentences in section 4 change
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