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Xiao-Song Yang

Publications and source records attributed to Xiao-Song Yang.

34 records · Page 2Linked to original sources
arXiv2025

Strong decays of the fully-charm tetraquark states with explicit P-waves via the QCD sum rules

We introduce a relative P-wave to construct the vector doubly-charm diquark $(\widetilde{V})$, therefore, the scalar and tensor four-quark currents to investigate the decay widths of the fully-charm tetraquark states with the $J^{PC}=0^{++}$, $1^{+-}$ and $2^{++}$ via the QCD sum rules. We observe that the total width of the ground state $\widetilde{V}\overline{\widetilde{V}}$-type scalar tetraquark state is compatible with that of the $X(6552)$ within the uncertainties, and the branching ratios are quite different from that of the first radial excitation of the $A\bar{A}$-type scalar tetraquark state. Other predictions can be verified in the future experiments to shed light on the nature of the fully-charm tetraquark states.

hep-ph↗
arXiv2025

Incomplete crossing and semi-topological horseshoes

This paper enriches the topological horseshoe theory using finite subshift theory in symbolic dynamical systems, and develops an elementary framework addressing incomplete crossing and semi-horseshoes. Two illustrative examples are provided: one from the perturbed Duffing system and another from a polynomial system proposed by Chen, demonstrating the prevalence of semi-horseshoes in chaotic systems. Moreover, the semi-topological horseshoe theory enhances the detection of chaos and improves the accuracy of topological entropy estimation.

math.DS↗
arXiv2024

Probability of constructing prediction model for observable of a dynamical process via time series

One fundamental problem in studying dynamical process is whether it is possible and how to construct prediction model for an unknown system via sampled time series, especially in the modern big data era. The research in this area is beneficial to experimentalists in physics, chemistry, especially, in biological science, where it is hard to construct a prediction models by first principles. Therefore constructing prediction model for the observable of a complex system is of great practical significance in various areas of science and engineering. In the present paper, we show in terms of Lebesgue measure that, at least in the linear case, one can almost surely construct by linear algebra approach the prediction model about observable of unknown systems only via observed time series in the settings of discrete time and continuous time linear systems, even in the situation that one has no information about the underlying dynamical process and output function that generates the observed time series. Interestingly, we can obtain the characteristic polynomial of the unknown matrices for both of discrete time and continuous time linear systems with probability 1.

math.DS↗
arXiv2023

The two-body strong decays of the fully-charm tetraquark states

We study the hadronic coupling constants in the two-body strong decays of the fully-charm tetraquark states with the $J^{PC}=0^{++}$, $1^{+-}$ and $2^{++}$ via the QCD sum rules based on rigorous quark-hadron duality. Then we obtain the hadronic coupling constants and partial decay widths therefore total decay widths, which support assigning the $X(6552)$ as the first radial excitation of the scalar tetraquark state. And other predictions can be used to diagnose exotic states in the future.

hep-ph↗
arXiv2023

The singly-charmed pentaquark molecular states via the QCD sum rules

In this work, we systematically investigate the singly-charmed pentaquark molecular states $D^{(*)}N$, $D^{(*)}Ξ^{(*)}$ and $D_s^{(*)}Ξ^{(*)}$ with the QCD sum rules by carrying out the operator product expansion up to the vacuum condensates of dimension 13 and taking fully account of the light-flavor $SU(3)$ breaking effects. The numerical results favor assigning the $Ω_c(3185)$ as the $DΞ$ molecular state with the $J^P=\frac{1}{2}^-$ and $| I,I_3 \rangle=| 0,0 \rangle$, assigning the $Ω_c(3327)$ as the $D^*Ξ$ molecular state with the $J^P=\frac{3}{2}^-$ and $|I,I_3 \rangle=| 0,0 \rangle$, assigning the $Σ_c(2800)$ as the $DN$ molecular state with the $J^P=\frac{1}{2}^-$ and $| I,I_3 \rangle=| 1,0 \rangle$, and assigning the $Λ_c(2940)/Λ_c(2910)$ as the $D^*N$ molecular state with the $J^P=\frac{3}{2}^-$ and $| I,I_3 \rangle=| 0,0 \rangle$. Other potential molecule candidates are also predicted, which may be observed in future experiments. For example, we can search for the $DΞ$ and $D^*Ξ$ molecular states with the isospin $| I,I_3 \rangle=| 1,\pm1 \,\rangle$ in the $Ξ_c^+\bar{K}^0$ and $Ξ_c^0\bar{K}^-$ mass spectrum respectively in the future, which could shed light on the nature of the $Ω_c(3185/3327)$.

hep-ph↗
arXiv2023

Analysis of the $T_{c\bar{s}}(2900)$ and related tetraquark states with the QCD sum rules

In this research, we tentatively assign the $T_{c\bar{s}}(2900)$ as the $A\bar{A}$-type tetraquark state, and study the mass spectrum of the tetraquark states with strange and doubly strange, which have the spin-parity $J^P = 0^+$, $1^+$ and $2^+$, in the framework of the QCD sum rules in details, where the $A$ denotes the axialvector diquark state. The predicted mass $M=2.92\pm0.12\,\rm{GeV}$ is in consistent with the experimental values $M=2.892\pm0.014\pm0.015\,\rm{GeV}$ and $2.921\pm0.017\pm0.020\,\rm{GeV}$ from the LHCb collaboration and supports assigning the $T_{c\bar{s}}(2900)$ to be the $A\bar{A}$-type scalar $c\bar{s}q\bar{q}$ tetraquark state. The predictions for other tetraquark states can be confronted to the experimental data in the future to diagnose the nature of the fully open flavor exotic states.

hep-ph↗
arXiv2022

Analysis of the $X(3960)$ and related tetraquark molecular states via the QCD sum rules

In this work, we study the $D\bar{D}$, $DD$, $D\bar{D}_s$, $DD_s$, $D_s\bar{D}_s$ and $D_sD_s$ tetraquark molecular states with the $J^{PC}=0^{++}$ via the QCD sum rules. The prediction $M_{D_s\bar {D}_s} = 3.98\pm0.10\, \rm{GeV}$ is in very good agreement with the experimental value $M_{X(3960)} = 3956 \pm 5\pm 10 \,\rm{MeV}$ from the LHCb collaboration and supports assigning the $X(3960)$ as the $D_s^+D_s^-$ molecular state with the $J^{PC}=0^{++}$. We take account of our previous works on the four-quark states consisting of two color-neutral clusters, and acquire the mass spectrum of the ground state hidden-charm and doubly-charm tetraquark molecular states.

hep-ph↗
arXiv2021

Tetraquark molecular states in the $D_s\bar{D}_{s1}$ and $D_s^*\bar{D}_{s0}^*$ mass spectrum

In the present work, we construct the color-singlet-color-singlet type four-quark currents to investigate the $D_s\bar{D}_{s1}$ and $D_s^*\bar{D}_{s0}^*$ tetraquark molecular states with the $J^{PC}=1^{--}$ and $1^{-+}$ via the QCD sum rules, and obtain satisfactory results. We can search for the $D_s\bar{D}_{s1}$ and $D_s^*\bar{D}_{s0}^*$ tetraquark molecular states with the $J^{PC}=1^{--}$ and $1^{-+}$ at the BESIII and Belle II in the future.

hep-ph↗
arXiv2021

Indices of equilibrium points of linear control systems with saturated state feedback

In this paper we investigate some properties of equilibrium points in n-dimensional linear control systems with saturated state feedback. We provide an index formula for equilibrium points and discuss its relation to boundaries of attraction basins in feedback systems with single input. In addition, we also touch upon convexity of attraction basin.

math.OC↗
arXiv2018

Singular cycles connecting saddle periodic orbit and saddle equilibrium in piecewise smooth systems

For flows, the singular cycles connecting saddle periodic orbit and saddle equilibrium can poten- tially result in the so-called singular horseshoe, which means the existence of a non-uniformly hyperbolic chaotic invariant set. However, it is very hard to find a specific dynamical system that exhibits such singular cycles in general. In this paper, the existence of the singular cycles involved in saddle periodic orbits is studied by two types of piecewise affine systems: one is the piecewise affine system having an admissible saddle point with only real eigenvalues and an admissible saddle periodic orbit, and the other is the piecewise affine system having an admissible saddle- focus and an admissible saddle periodic orbit. Precisely, several kinds of sufficient conditions are obtained for the existence of only one heteroclinic cycle or only two heteroclinic cycles in the two types of piecewise affine systems, respectively. In addition, some examples are presented to illustrate the results.

math.DS↗
arXiv2015

The invariant tori of knot type and the interlinked invariant tori in the Nosé-Hoover system

We revisit the famous Nosé-Hoover system in this paper and show the existence of some averagely conservative regions which are filled with an infinite sequence of nested tori. Depending on initial conditions, some invariant tori are of trefoil knot type, while the others are of trivial knot type. Moreover, we present a variety of interlinked invariant tori whose initial conditions are chosen from different averagely conservative regions and give all the interlinking numbers of those interlinked tori, showing that this quadratic system possesses so rich dynamic properties.

nlin.CD↗
arXiv2010

Targetability of chaotic sets with small parameter perturbations

In this paper targetability of chaotic sets with small controls is discussed by virtue of some results of geometric control theory. It is proved that given a chaotic set Λ, it is possible to steer a orbit in to every final state in some neighborhood of the chaotic set by suitable small perturbations to the parameters of the system under the Lie rank condition.

nlin.CD↗
arXiv2010

Existence of periodic orbits in three-dimensional piecewise linear systems

Based on the results about the invariant cones appeared in the literature this paper analyses the existence of periodic orbits in three-dimensional continuous piecewise linear homogeneous systems with two zones, and a necessary and sufficient condition for the existence of periodic orbits of such systems is given.

math.DS↗
arXiv2010

Nonstandard Hopf bifurcation in switched

This paper presents an analysis on nonstandard generalized Hopf bifurcation in a class of switched systems where the lost of stability of linearized systems is not due to the crossing of their complex conjugate eigenvalues but relevant to the switching laws between the subslystems. Thus is remarkably different from the mechanism of the Hopf bifurcation and the generalized Hopf bifurcation studied in the literature.

math.DS↗
arXiv2009

Existence and bifurcation of homoclinic orbits in planar piecewise linear systems

The existence and bifurcation of homoclinic orbits in planar piecewise linear homogeneous systems with two regions separated by a discontinuity boundary are investigated in this paper. In addition, existence of periodic orbits and stability of the origin are also discussed without the assumption of continuity for the planar piecewise linear homogeneous systems.

math.DS↗