arXiv subjects

Y. D. Yang

Publications and source records attributed to Y. D. Yang.

5 recordsLinked to original sources

arXiv2022

A posteriori error estimates of mixed discontinuous Galerkin method for the Stokes eigenvalue problem

In this paper, for the Stokes eigenvalue problem in $d$-dimensional case $(d=2,3)$, we present an a posteriori error estimate of residual type of the mixed discontinuous Galerkin finite element method using $P_{k}-P_{k-1}$ element $(k\geq 1)$. We give the a posteriori error estimators for approximate eigenpairs, prove their reliability and efficiency for eigenfunctions, and also analyze their reliability for eigenvalues. We implement adaptive calculation, and the numerical results confirm our theoretical predictions and show that our method can achieve the optimal convergence order $O(dof^{-2k/d})$.

math.NA↗

arXiv2012

A study of thinner-THGEM, with some applications

THGEMs (THick Gas Electron Multiplier) of varying thickness, hole diameter and hole pitch have been studied. For a thinner-THGEM of thickness 0.2 mm, with hole diameter 0.2 mm, pitch 0.2 mm and narrow (5-10 μm) rim, the performance of gain versus high voltage with different gas mixtures have been studied using 5.9 keV X-rays. In general, a gain of around 3\times10^3 was obtained with a single board in Ar/iC4H10, and gains higher than 10^4 were obtained in Ne mixture at lower voltage. The dependence of the energy resolution on the drift and induction electric fields was measured and an energy resolution of 15.9% was obtained. A curved thinner-THGEM chamber with one-dimensional readout has been assembled for use in the diffraction studies at the Beijing Synchrotron Radiation Facility (BSRF). A cosmic-ray muon hodoscope based on thinner-THGEM was developed as a teaching experiment for the Graduate University of the Chinese Academy of Sciences (GUCAS).

hep-ex↗

arXiv2008

Physics at BES-III

This physics book provides detailed discussions on important topics in $τ$-charm physics that will be explored during the next few years at \bes3 . Both theoretical and experimental issues are covered, including extensive reviews of recent theoretical developments and experimental techniques. Among the subjects covered are: innovations in Partial Wave Analysis (PWA), theoretical and experimental techniques for Dalitz-plot analyses, analysis tools to extract absolute branching fractions and measurements of decay constants, form factors, and CP-violation and \DzDzb-oscillation parameters. Programs of QCD studies and near-threshold tau-lepton physics measurements are also discussed.

hep-ex↗

arXiv2003

The rare $\bar{B}^0_{d} \to ϕγ$ decays in Standard Model and as a probe of R-parity violation

We present the first study of the rare annihilation decay $\bar{B}^0_d \to ϕγ$ in the Standard Model. Using QCD factorization formalism, we find ${\cal B}(\bar{B}^0_d \toϕγ)=3.6\times 10^{-12}$. The smallness of the decay rate in the Standard Model make the decay a sensitive probe of new physics contributions. As an example, we calculate the effects of R-parity violating couplings. Within the available upper bounds for $|λ^{''}_{i23}λ^{''}_{i12}|$ and $|λ^{'}_{i32}λ^{'*}_{i12}|$, ${\cal B}(\bar{B}^0_d \toϕγ)$ could be enhanced to order of $10^{-9}\sim 10^{-8}$, which might be accessible at LHCB, B-TeV and the planning super high luminosity B factories at KEK and SLAC.

hep-ph↗

arXiv2001

Semileptonic and nonleptonic B decays to three charm quarks: B->J/psi (eta_c) D l nu and J/psi (eta_c) D pi

We evaluate the form factors describing the semileptonic decays $\bar{B^0}\to J/ψ(η_c) D^+ \ell^- \bar ν_\ell$, within the framework of a QCD relativistic potential model. This decay is complementary to $\bar{B^0}\to J/ψ(η_c) D^+ π^-$ in a phase space region where a pion factors out.We estimate the branching ratio for these semileptonic and nonleptonic channels, finding $\mathcal{BR}(\bar{B^0} \to J/ψ(η_c) D^+ \ell ν_\ell) \simeq 10^{-13}$, $\mathcal{BR}(\bar{B^0} \to J/ψD^+ π^-) = 3.1 \times 10^{-8}$ and $\mathcal{BR}(\bar{B^0} \to η_c D^+ π^-) = 3.5 \times 10^{-8}$.

hep-ph↗