1,467 research outputs found
A phase-field model of relaxor ferroelectrics based on random field theory
A mechanically coupled phase-field model is proposed for the first time to
simulate the peculiar behavior of relaxor ferroelectrics. Based on the random
field theory for relaxors, local random fields are introduced to characterize
the effect of chemical disorder. This generic model is developed from a
thermodynamic framework and the microforce theory and is implemented by a
nonlinear finite element method. Simulation results show that the model can
reproduce relaxor features, such as domain miniaturization, small remnant
polarization and large piezoelectric response. In particular, the influence of
random field strength on these features are revealed. Simulation results on
domain structure and hysteresis behavior are discussed and compared with
related experimental results.Comment: 8 figure
Angular distribution of the FCNC process
In this work, we study the flavor-changing neutral-current process
(= , ,
). The relevant weak transition form factors are obtained by using the
covariant light-front quark model, in which, the main inputs, i.e., the meson
wave functions of and , are adopted as the numerical wave
functions from the solution of the Schr\"{o}dinger equation with the modified
Godfrey-Isgur model. With the obtained form factors, we further investigate the
relevant branching fractions and their ratios, and some angular observables,
i.e., the forward-backward asymmetry , the polarization fractions
, and the -averaged angular coefficients and the
asymmetry coefficients . We also present our results of the clean
angular observables and , which can reduce
the uncertainties from the form factors. Our results show that the
corresponding branching fractions of the electron or muon channels can reach up
to . With more data being accumulated in the LHCb experiment, our
results are helpful for exploring this process, and deepen our understanding of
the physics around the process.Comment: 25 pages, 8 tables and 9 figure
Isoprenaline: A Potential Contributor in Sick Sinus SyndromeβInsights from a Mathematical Model of the Rabbit Sinoatrial Node
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