171,762 research outputs found
CP violation in in the model III 2HDM
We have calculated the Wilson coefficients (i=1,2) in the
renormalization scheme in the model III 2HDM. Using the obtained
Wilson coefficients, we have analyzed the CP violation in decays (q=d,s) in the model. The CP asymmetry, , depends on the
parameters of models and in can be as large as 40% and
35% for and respectively. It can reach 4% for decays.
Because in SM CP violation is smaller than or equal to O() which is
unobservably small, an observation of CP asymmetry in the decays would unambiguously signal the existence of new physics.Comment: revtex4, 16 pages, 7 figure
Control of tetrahedral coordination and superconductivity in FeSe0.5Te0.5 thin films
We demonstrate a close relationship between superconductivity and the
dimensions of the Fe-Se(Te) tetrahedron in FeSe0.5Te0.5. This is done by
exploiting thin film epitaxy, which provides controlled biaxial stress, both
compressive and tensile, to distort the tetrahedron. The Se/Te height within
the tetrahedron is found to be of crucial importance to superconductivity, in
agreement with the theoretical proposal that (pi,pi) spin fluctuations promote
superconductivity in Fe superconductors
Matrix Elements of Four-quark Operators Relevant to Lifetime Difference \Delta \Gamma_{B_s} from QCD Sum Rules
We extract the matrix elements of four quark operators O_{L,S} relevant to
the B_s and \bar B_s life time difference from QCD sum rules. We find the
vacuum saturation approximation works reasonably well, i.e., within 10%. We
discuss the implications of our results and compare them with the recent
lattice QCD determination.Comment: 11 pages, 4 eps figures, Latex. Some reference renewe
Convective flow during dendritic growth
A review is presented of the major experimental findings obtained from recent ground-based research conducted under the SPAR program. Measurements of dendritic growth at small supercoolings indicate that below approximately 1.5 K a transition occurs from diffusive control to convective control in succinonitrile, a model system chosen for this study. The key theoretical ideas concerning diffusive and convective heat transport during dendritic growth are discussed, and it is shown that a transition in the transport control should occur when the characteristic length for diffusion becomes larger than the characteristic length for convection. The experimental findings and the theoretical ideas discussed suggest that the Fluid Experiment System could provide appropriate experimental diagnostics for flow field visualization and quantification of the fluid dynamical effects presented here
Decay of weak turbulence
Weak turbulence fields generated by single and multiple stage grids covering Reynolds numbers between 7 and 70 showing decay of energy spectr
- …