283 research outputs found
Direct CP Violation in Hadronic B Decays
There are different approaches for the hadronic B decay calculations,
recently. In this paper, we upgrade three of them, namely factorization, QCD
factorization and the perturbative QCD approach based on factorization,
by using new parameters and full wave functions.
Although they get similar results for many of the branching ratios, the
direct CP asymmetries predicted by them are different, which can be tested by
recent experimental measurements of B factories.Comment: 11 pages, 3 figures, revtex4, Talk given at the Workshop on the
Frontiers of Theoretical Physics and Cross-Disciplinary, NSFC, Beijing, March
200
Nonfactorizable contributions to decays
While the factorization assumption works well for many two-body nonleptonic
meson decay modes, the recent measurement of with
, and shows large deviation from this assumption. We
analyze the decays in the perturbative QCD approach based on
factorization theorem, in which both factorizable and nonfactorizable
contributions can be calculated in the same framework. Our predictions for the
Bauer-Stech-Wirbel parameters, and and and , are
consistent with the observed and branching ratios,
respectively. It is found that the large magnitude and the large
relative phase between and come from color-suppressed
nonfactorizable amplitudes. Our predictions for the , branching ratios can be confronted with
future experimental data.Comment: 25 pages with Latex, axodraw.sty, 6 figures and 5 tables, Version
published in PRD, Added new section 5 and reference
Charm multiplicity and the branching ratios of inclusive charmless b quark decays in the general two-Higgs-doublet models
In the framework of general two-Higgs-doublet models, we calculate the
branching ratios of various inclusive charmless b decays by using the low
energy effective Hamiltonian including next-to-leading order QCD corrections,
and examine the current status and the new physics effects on the determination
of the charm multiplicity and semileptonic branching ratio .
Within the considered parameter space, the enhancement to the ratio due to the charged-Higgs penguins can be as large as a factor of 8 (3) in
the model III (II), while the ratio can be increased from
the standard model prediction of 2.49% to 4.91% (2.99%) in the model III (II).
Consequently, the value of and can be decreased simultaneously
in the model III. The central value of will be lowered slightly by
about 0.003, but the ratio can be reduced significantly from the
theoretical prediction of in the SM to , for GeV, respectively. We find that
the predicted and the measured now agree within roughly one
standard deviation after taking into account the effects of gluonic charged
Higgs penguins in the model III with a relatively light charged Higgs boson.Comment: 25 pages, Latex file, axodraw.sty, 6 figures. Final version to be
published in Phys.Rev.
Effects of Acrylamide on the Activity and Structure of Human Brain Creatine Kinase
Acrylamide is widely used worldwide in industry and it can also be produced by the cooking and processing of foods. It is harmful to human beings, and human brain CK (HBCK) has been proposed to be one of the important targets of acrylamide. In this research, we studied the effects of acrylamide on HBCK activity, structure and the potential binding sites. Compared to CKs from rabbit, HBCK was fully inactivated at several-fold lower concentrations of acrylamide, and exhibited distinct properties upon acrylamide-induced inactivation and structural changes. The binding sites of acrylamide were located at the cleft between the N- and C-terminal domains of CK, and Glu232 was one of the key binding residues. The effects of acrylamide on CK were proposed to be isoenzyme- and species-specific, and the underlying molecular mechanisms were discussed
Observation of a ppb mass threshoud enhancement in \psi^\prime\to\pi^+\pi^-J/\psi(J/\psi\to\gamma p\bar{p}) decay
The decay channel
is studied using a sample of events collected
by the BESIII experiment at BEPCII. A strong enhancement at threshold is
observed in the invariant mass spectrum. The enhancement can be fit
with an -wave Breit-Wigner resonance function with a resulting peak mass of
and a
narrow width that is at the 90% confidence level.
These results are consistent with published BESII results. These mass and width
values do not match with those of any known meson resonance.Comment: 5 pages, 3 figures, submitted to Chinese Physics
Spin dynamics in semiconductors
This article reviews the current status of spin dynamics in semiconductors
which has achieved a lot of progress in the past years due to the fast growing
field of semiconductor spintronics. The primary focus is the theoretical and
experimental developments of spin relaxation and dephasing in both spin
precession in time domain and spin diffusion and transport in spacial domain. A
fully microscopic many-body investigation on spin dynamics based on the kinetic
spin Bloch equation approach is reviewed comprehensively.Comment: a review article with 193 pages and 1103 references. To be published
in Physics Reports
Quantum thermal transport in nanostructures
In this colloquia review we discuss methods for thermal transport
calculations for nanojunctions connected to two semi-infinite leads served as
heat-baths. Our emphases are on fundamental quantum theory and atomistic
models. We begin with an introduction of the Landauer formula for ballistic
thermal transport and give its derivation from scattering wave point of view.
Several methods (scattering boundary condition, mode-matching, Piccard and
Caroli formulas) of calculating the phonon transmission coefficients are given.
The nonequilibrium Green's function (NEGF) method is reviewed and the Caroli
formula is derived. We also give iterative methods and an algorithm based on a
generalized eigenvalue problem for the calculation of surface Green's
functions, which are starting point for an NEGF calculation. A systematic
exposition for the NEGF method is presented, starting with the fundamental
definitions of the Green's functions, and ending with equations of motion for
the contour ordered Green's functions and Feynman diagrammatic expansion. In
the later part, we discuss the treatments of nonlinear effects in heat
conduction, including a phenomenological expression for the transmission, NEGF
for phonon-phonon interactions, molecular dynamics (generalized Langevin) with
quantum heat-baths, and electron-phonon interactions. Some new results are also
shown. We also briefly review the experimental status of the thermal transport
measurements in nanostructures.Comment: 24 pages, 10 figures, over 200 reference
The decay in the standard model and the general two-Higgs-doublet model
Based on the low-energy effective Hamiltonian, we calculate the new physics
corrections to the branching ratio and the differential distributions of the
rare decay induced by the new gluonic and electroweak
charged-Higgs penguin diagrams in the general two-Higgs-doublet model with the
restriction for . Within the considered
parameter space, we see the following: (a) the standard model predictions of
and have a moderate
dependence; (b) in model III, the prediction of the branching ratio ranges from one third to three times of the standard
model prediction, but is highly correlated with that of ; (c) the new physics enhancement to the branching ratio in model II can be as large as ; (d) the
contribution from 1PR diagrams is dominant and hence four normalized
differential distributions are insensitive to the variation of scale and
possible new physics corrections; (e) due to the smallness of its decay rate
and the long-distance background, the decay is not a
better process in detecting new physics than the decay.Comment: Latex file, 27 pages with 17 ps and eps figures. Accepted for
publication in Phys.Rev.
Study on the rare radiative decay in the standard model and multiscale walking technicolor model
Applying the perturbative QCD ( PQCD ) method, we study the decay
in the standard model and multiscale walking
technicolor model. In the SM, we find that the contribution of weak
annihilation is more important than that of the electromagnetic penguin. The
presence of Pseudo-Goldstone-Bosons in the MWTCM leads to a large enhancement
in the rate of , but this model is in conflict with
the branching ratio of ( ) and the CLEO data
on the branching ratio BR ( ). If topcolor is further
introduced, the calculated results in the topcolor assisted MWTCM can be
suppressed and be in agreement with the CLEO data for a certain range of the
parameters.Comment: 16 pages, Latex, no macros, 1 figure(in Latex), hard copy is
available upon request. to appear in Phys. Rev.
Combination of Chinese Herbal Medicines and Conventional Treatment versus Conventional Treatment Alone in Patients with Acute Coronary Syndrome after Percutaneous Coronary Intervention (5C Trial): An Open-Label Randomized Controlled, Multicenter Study
Aims. To evaluate the efficacy of Chinese herbal medicines (CHMs) plus conventional treatment in patients with acute coronary syndrome (ACS) after percutaneous coronary intervention (PCI). Methods and Results. Participants (n=808) with ACS who underwent PCI from thirteen hospitals of mainland China were randomized into two groups: CHMs plus conventional treatment group (treatment group) or conventional treatment alone group (control group). All participants received conventional treatment, and participants in treatment group additionally received CHMs for six months. The primary endpoint was the composite of cardiac death, nonfatal recurrent MI, and ischemia-driven revascularization. Secondary endpoint was the composite of readmission for ACS, stroke, or congestive heart failure. The safety endpoint involved occurrence of major bleeding events. The incidence of primary endpoint was 2.7% in treatment group versus 6.2% in control group (HR, 0.43; 95% CI, 0.21 to 0.87; P=0.015). The incidence of secondary endpoint was 3.5% in treatment group versus 8.7% in control group (HR, 0.39; 95% CI, 0.21 to 0.72; P=0.002). No major bleeding events were observed in any participant. Conclusion. Treatment with CHMs plus conventional treatment further reduced the occurrence of cardiovascular events in patients with ACS after PCI without increasing risk of major bleeding
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