arXiv subjects

Yu-Fei Wang

Publications and source records attributed to Yu-Fei Wang.

22 records · Page 2Linked to original sources

arXiv2017

Unitarity Analyses of $πN$ Elastic Scattering Amplitudes

The pion - nucleon scattering phase shifts in $s$ and $p$ waves are analyzed using PKU unitarization approach that can separate the phase shifts into different contributions from poles and branch cuts. It is found that in $S_{11}$ and $P_{11}$ channels, there exist large and positive missing contributions when one compares the phase shift from known resonances plus branch cuts with the experimental data, which indicates that those two channels may contain sizable effects from $N^*(1535)$ and $N^*(1440)$ shadow poles. Those results are obtained using tree level results of the $πN$ amplitude.

hep-ph↗

arXiv2017

The $Z_c(3900)$ peak does not come from the "triangle singularity"

We compare contributions from the triangle diagram and the $D\bar D^*$ bubble chain to the processes of $e^{+}e^{-}\rightarrow J/ψπ^{+}π^{-}$ and $e^{+}e^{-}\rightarrow (D\bar D^*)^\mpπ^{\pm}$. By fitting the $J/ψπ$ maximum spectrum and the $D\bar D^*$ spectrum, we find that the triangle diagram cannot explain the new data from BESIII Collaboration at center of mass at 4.23GeV and 4.26GeV, simultaneously. On the contrary, the molecular assignment of $Z_c(3900)$ gives a much better description.

hep-ph↗

arXiv2017

On Equivalence of Likelihood Maximization of Stochastic Block Model and Constrained Nonnegative Matrix Factorization

Community structures detection in complex network is important for understanding not only the topological structures of the network, but also the functions of it. Stochastic block model and nonnegative matrix factorization are two widely used methods for community detection, which are proposed from different perspectives. In this paper, the relations between them are studied. The logarithm of likelihood function for stochastic block model can be reformulated under the framework of nonnegative matrix factorization. Besides the model equivalence, the algorithms employed by the two methods are different. Preliminary numerical experiments are carried out to compare the behaviors of the algorithms.

cs.SI↗

arXiv2016

$Z_c(3900)$ as a $D\bar{D}^*$ molecule from the pole counting rule

A comprehensive study on the nature of the $Z_c(3900)$ resonant structure is carried out in this work. By constructing the pertinent effective Lagrangians and considering the important final-state-interaction effects, we first give a unified description to all the relevant experimental data available, including the $J/ψπ$ and $ππ$ invariant mass distributions from the $e^+e^-\to J/ψππ$ process, the $h_cπ$ distribution from $e^+e^-\to h_cππ$ and also the $D\bar D^{*}$ spectrum in the $e^+e^-\to D\bar D^{*}π$ process. After fitting the unknown parameters to the previous data, we search the pole in the complex energy plane and find only one pole in the nearby energy region in different Riemann sheets. Therefore we conclude that $Z_c(3900)$ is of $D\bar D^*$ molecular nature, according to the pole counting rule method~[Nucl.~Phys.~A543, 632 (1992); Phys.~Rev.~D 35,~1633 (1987)]. We emphasize that the conclusion based upon the pole counting method is not trivial, since both the $D\bar D^{*}$ contact interactions and the explicit $Z_c$ exchanges are introduced in our analyses and they lead to the same conclusion.

hep-ph↗