10,446 research outputs found
Charm-strange baryon strong decays in a chiral quark model
The strong decays of charm-strange baryons up to N=2 shell are studied in a
chiral quark model. The theoretical predictions for the well determined
charm-strange baryons, , and , are in
good agreement with the experimental data. This model is also extended to
analyze the strong decays of the other newly observed charm-strange baryons
, , , and .
Our predictions are given as follows. (i) might be the first
-wave excitation of with , favors the $|\Xi_c'\
^2P_\lambda 1/2^->|\Xi_c'\ ^4P_\lambda 1/2^->\Xi_c(2980)P|\Xi_c'\ ^2P_\rho 1/2^->|\Xi_c'\ ^2P_\rho 3/2^->\Xi_c(2980)\Lambda_c^+\bar{K}\pi|\Xi_c'\ ^2P_\rho
1/2^->m\simeq 2.97\Xi_c^*(2645)\pi|\Xi_c'\ ^2P_\rho 3/2^->\Xi_c(3080)|\Xi_c\ S_{\rho\rho} 1/2^+>\Xi_c\Xi_c(3055)D\Xi_cJ^P=3/2^+|\Xi_c\
^2D_{\lambda\lambda} 3/2^+>\Xi_c(3123)|\Xi_c'\ ^4D_{\lambda\lambda} 3/2^+>|\Xi_c'\ ^4D_{\lambda\lambda} 5/2^+>|\Xi_c\ ^2D_{\rho\rho} 5/2^+>\Sigma_b^{\pm}\Sigma_b^{*\pm}\Xi_b^*$, which are in good agreement with the recent observations as well.Comment: 15 pages, 9 figure
Semiparametric Estimation of the Covariate-Specific ROC Curve in Presence of Ignorable Verification Bias
Covariate-specific ROC curves are often used to evaluate the classification accuracy of a medical diagnostic test or a biomarker, when the accuracy of the test is associated with certain covariates. In many large-scale screening tests, the gold standard is subject to missingness due to high cost or harmfulness to the patient. In this paper, we propose a semiparametric estimation method for the covariate-specific ROC curves with a partial missing gold standard. A location-scale model is constructed for the test result to model the covariates\u27 effect, but the residual distributions are left unspecified. Thus the baseline and link functions of the ROC curve both have flexible shapes. With the gold standard missing at random (MAR) assumption, we consider weighted estimating equations for the location-scale parameters, and weighted kernel estimating equations for the residual distributions. Three ROC curve estimators are proposed and compared, namely, imputation-based, inverse probability weighted and doubly robust estimators. We derive the asymptotic normality of the estimated ROC curve, as well as the analytical form the standard error estimator. The proposed method is motivated and applied to the data in an Alzheimer\u27s disease study
The edge engineering of topological Bi(111) bilayer
A topological insulator is a novel quantum state, characterized by
symmetry-protected non-trivial edge/surface states. Our first-principle
simulations show the significant effects of the chemical decoration on edge
states of topological Bi(111) bilayer nanoribbon, which remove the trivial edge
state and recover the Dirac linear dispersion of topological edge state. By
comparing the edge states with and without chemical decoration, the Bi(111)
bilayer nanoribbon offers a simple system for assessing conductance fluctuation
of edge states. The chemical decoration can also modify the penetration depth
and the spin texture of edge states. A low-energy effective model is proposed
to explain the distinctive spin texture of Bi(111) bilayer nanoribbon, which
breaks the spin-momentum orthogonality along the armchair edge.Comment: 5 pages, 5 figure
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