arXiv subjects

Zhan-Wei Liu

Publications and source records attributed to Zhan-Wei Liu.

At least 37 records · Page 2Linked to original sources

arXiv2023

Toy model to understand oscillatory behavior in timelike nucleon form factors

To understand the oscillatory behavior exhibited in the timelike electromagnetic form factors of nucleons, we propose a toy model based on the Jost function of the $N\bar N$ pair into the timelike form factors with the help of the distorted-wave Born approximation. By constructing a simple square-well potential reflecting the final-state interaction of $N\bar N$, we naturally represent the damped oscillatory phenomenon in the timelike electromagnetic form factors of nucleons. Especially, our study reveals that the ``period" of the oscillation is approximately determined by the Yukawa interaction range $1/m_π$. Other possible potentials are also discussed. The threshold enhancements of the cross sections for $e^+e^-\to n\bar n$, $Λ\barΛ$, and $Λ_c\barΛ_c$ can also be understand within this scenario.

nucl-th↗

arXiv2023

New type of hydrogenlike charm-pion or charm-kaon matter

Borrowing the structures of the hydrogen atom, molecular ion, and diatomic molecule, we predict the nature of a new type of hydrogenlike charm-pion or charm-kaon matter that could be obtained by replacing the proton and electron in hydrogen matter with a charmed meson and a pion or a kaon, respectively. We find that the spectra of the atom, molecular ion, and diatomic molecule can be obtained simultaneously with the Coulomb potential for the hydrogen, the charm-pion, and the charm-kaon systems. The predicted charm-pion matter also allows us to explore the mass shift mediated by the strong interaction. For the charm-pion and charm-kaon systems, the strong interactions could lead to binding energy shifts. Our calculations suggests that the binding energy shifts in charm-pion systems are in the order of several to tens of eV. For the charm-kaon systems, the results are in the order of tens to hundreds of eV. Exploring hydrogenlike charm-pion matter must lead to new demands for high-precision experiments.

hep-ph↗

arXiv2023

$Λ_c(2910)$ and $Λ_c(2940)$ as the conventional baryons dressed with the $D^*N$ channel

In this work, we treat $Λ_c(2910)^+$ and $Λ_c(2940)^+$ as the conventional $udc$ cores dressed with the $D^*N$ channel. We provide a possible interpretation to both $Λ_c(2910)^+$ and $Λ_c(2940)^+$ within the same framework. In the study, we consider not only the effects between the conventional triquark core and the $D^*N$ channel but also the $D^*N$-$D^*N$ interactions. The mass of $Λ_c$ state with $J^P=1/2^-$ is larger than that with $J^P=3/2^-$ in this unquenched picture, which is very different from the prediction of the conventional quenched quark model. Based on the mass spectrum, the spin-parity of $Λ_c(2940)^+$ is more likely to be $1/2^-$ while $Λ_c(2910)^+$ prefers $3/2^-$. We look forward to the future experiments can test our results with more precise experimental data.

hep-ph↗

arXiv2022

Discovery of $T_{c\bar s 0}^a(2900)^{0,++}$ implies new charmed-strange pentaquark system

Inspired by the very recently discovered tetraquark states $T_{c\bar s 0}^a(2900)^{0,++}$ from the LHCb Collaboration, we predict the existence of a new charmed-strange pentaquark system, $c\bar s nnn$, which is closely connected to $c\bar s n\bar n$ by exchanging $\bar n$ into $nn$ with $n=u,d$. Especially, it is suggested to experimentally search for the predicted new pentaquark system via the weak decays of $B$ mesons or $b$-baryons, with the support from the study of the mass spectrum and the decay properties. The predicted new pentaquark system must attract extensive attention from experimentalists and theorists when it constructs the ``particle zoo 2.0" in the near future.

hep-ph↗

arXiv2022

What can we learn from the electromagnetic properties of hidden-charm molecular pentaquarks with single strangeness?

Inspired by the observation of the $P_{cs}(4459)$ and $P_{ψs}^Λ(4338)$, we systematically investigate the magnetic moments, the transition magnetic moments, and the radiative decay behaviors of the $S$-wave isoscalar $Ξ_c^{(\prime)}\bar D^{(*)}$ molecular pentaquark states in this work. Our quantitative investigation shows that their electromagnetic properties can provide important hint to decode the inner structure of these discussed isoscalar $Ξ_c^{(\prime)}\bar D^{*}$ molecular pentaquarks. As the potential research issue, we suggest future experiment to focus on the electromagnetic properties of these isoscalar $Ξ_c^{(\prime)}\bar D^{(*)}$ molecular pentaquarks, which are a typical hidden-charm molecular pentaquark system with single strangeness.

hep-ph↗

arXiv2022

Probing the electromagnetic properties of the $Σ_c^{()}D^{()}$-type doubly charmed molecular pentaquarks

In this work, we discuss the electromagnetic properties of the $S$-wave $Σ_c^{(*)}D^{(*)}$-type doubly charmed molecular pentaquarks, which have close relation to their inner structures. Both the $S$-$D$ wave mixing effect and the coupled channel effect are taken into account. We analyze the magnetic moments for the $S$-wave $Σ_c^{(*)}D^{(*)}$ molecular states, and extend our theoretical framework to study the transition magnetic moments and the radiative decay widths between the $S$-wave $Σ_c^{(*)}D^{(*)}$ molecules. We discuss the relations between the magnetic moments and the transition magnetic moments for the $S$-wave $Σ_c^{(*)}D^{(*)}$-type doubly charmed molecular pentaquarks, which can be regarded as an indirect way to measure their magnetic moments experimentally. The present study may inspire experimentalist's interest in measuring the electromagnetic properties of the hadronic molecular states.

hep-ph↗

arXiv2022

Induced fission-like process of hadronic molecular states

In this work, we predict a new physical phenomenon, induced fission-like process and chain reaction of hadronic molecular states. As a molecular state, if induced by a $D$ meson, the $X(3872)$ can split into $D\bar{D}$ final state which is forbidden due to the spin-parity conservation. The breeding of the $D$ meson of the reaction, such as $D^0X(3872)\to D^0\bar{D}^0D^0$, makes the chain reaction of $X(3872)$ matter possible. We estimate the cross section of the $D$ meson induced fission-like process of $X(3872)$ into two $D$ mesons. With very small $D^0$ beam momentum of 1 eV, the total cross section reaches an order of 1000 b, and decreases rapidly with the increasing of beam momentum. With the transition of $D^*$ meson in molecular states to a $D$ meson, the $X(3872)$ can release large energy, which is acquired by the final mesons. The momentum distributions of the final $D$ mesons are analyzed. In the laboratory frame, the spectator $D$ meson in molecular state concentrates in the low momentum area. The energy from the transition frim $D^*$ to $D$ meson is mainly acquired by two scattered $D$ mesons. The results suggest that the $D$ meson environment will lead to the induced fission-like process and chain reaction of the $X(3827)$. Such phenomenon can be extended to other hadronic molecular states.

hep-ph↗

arXiv2022

Pion Photoproduction off Nucleon with Hamiltonian Effective Field Theory

We analyze the $γN\toπN$ process in the negative parity channel with Hamiltonian effective filed theory which is successful in studying the nucleon resonances associated with the meson-nucleon scattering and lattice QCD simulations. We provide the scattering amplitude of pion photoproduction and extract the electric dipole amplitudes $E_{0+}$. The triquark component in $N^*(1535)$ is important for improving the consistence between our results and the experimental data.

hep-ph↗

arXiv2022

Fully heavy pentaquark states in constituent quark model

The LHCb collaboration reported a fully charmed tetraquark state X(6900) in the invariant mass spectrum of $J/ψ$ pairs in 2020. This discovery inspires us to further study the fully heavy pentaquark system. In this work, we investigate systematically all possible configurations for ground fully heavy pentaquark system via the variational method in the constituent quark model. According to our calculations, we further analyze the relative lengths between quarks and the contributions to the pentaquark masses from different terms of the Hamiltonian. We think no stable states exist in fully heavy pentaquark system. We hope that our study will be helpful to explore for fully heavy pentaquark states.

hep-ph↗

arXiv2022

Where are the hidden-charm hexaquarks?

In this work, we carry out the study of hidden-charm hexaquark states with the typical configurations $qqc\bar{q}\bar{q}\bar{c}$ ($q=u, d, s$). The mass spectra of hidden-charm hexaquark states are obtained within the chromo-magnetic interaction model. In addition to the mass spectra analysis, we further illustrate their two-body strong decay behaviors. There exist some compact bound states which cannot decay through the strong interaction. Hopefully our results will help to search for such types of the exotic states in the future experiments.

hep-ph↗

arXiv2021

$D D^{*}$ potentials in chiral perturbation theory and possible molecular states

The $DD^{*}$ potentials are studied within the framework of heavy meson chiral effective field theory. We obtain the effective potentials of the $DD^{*}$ system up to $O(ε^2)$ at the one-loop level. In addition to the one-pion exchange contribution, the contact and two-pion exchange interactions are also investigated in detail. Furthermore, we search for the possible molecular states by solving the Schrödinger equation with the potentials. We notice that the contact and two-pion exchange potentials are numerically non-negligible and important for the existence of a bound state. In our results, no bound state is found in the $I=1$ channel within a wide range of cutoff parameter, while there exists a bound state in the $I=0$ channel as the cutoff is near $m_ρ$ in our approach.

hep-ph↗

arXiv2021

Magnetic moments and transition magnetic moments of $P_c$ and $P_{cs}$ states

We study the magnetic moments and transition magnetic moments of $P_c$ and $P_{cs}$ states in the molecular picture. We first revisit the magnetic moments of $P_c$ states as the $S$ wave molecular states without coupled channel effects. The coupled channel effects and the $D$ wave contributions are then investigated carefully. The coupled channel effects contribute to the change of $0.1\sim 0.4$ nuclear magneton $μ_N$ for most cases while the $D$ wave only induces the variation of less than $0.03 ~μ_N$. In addition, we obtain the transition magnetic moments between different $P_c$ states and the related electromagnetic decay widths of $P_c'\to P_cγ$. The magnetic moments of $P_{cs}$ are much different for the assumption of spin being 1/2 and 3/2. The study of electromagnetic properties will help us disclose further the structure of these unconventional states.

hep-ph↗

arXiv2021

Newly observed $X(4630)$: a new charmoniumlike molecule

Very recently, the LHCb Collaboration at the Large Hadron Collider at CERN observed new resonance $X(4630)$. The $X(4630)$ is decoded as a charmoniumlike molecule with hidden-strange quantum number well in the one boson exchange mechanism. Especially, the study of its hidden-charmed decays explicitly shows the dominant role of $J/ψϕ$ among all allowed hidden-charmed decays of $X(4630)$, which enforces the conclusion of $X(4630)$ as a charmoniumlike molecule. The discovery of the $X(4630)$ is a crucial step of constructing charmoniumlike molecule zoo.

hep-ph↗

arXiv2021

Heavy flavor pentaquarks with four heavy quarks

In this work, we carry out the study of heavy flavor pentatuarks with four heavy quarks, which have typical $QQQQ\bar q$ configuration. Within the Chromomagnetic Interaction model, the mass spectrum of these discussed $QQQQ\bar q$ pentaquarks is given. In addition to the mass spectrum analysis, we also illustrate their two-body strong decay behavior by estimating some ratios of decay channels. By these effort, we suggest that future experiment should pay attention to this kind of pentaquark.

hep-ph↗

arXiv2021

Fully heavy pentaquarks

Very recently, the LHCb Collaboration reported a fully charmed tetraquark state $X(6900)$ in the invariant mass spectrum of $J/ψ$ pairs. If one $J/ψ$ meson is replaced with a fully charmed baryon, we obtain a fully charmed pentaquark candidate. In this work, we perform a systematic study on the mass spectra of the S-wave fully heavy pentaquark $QQQQ\bar{Q}$ in the framework of the chromomagnetic interaction model. Based on our results in two different schemes, we further investigate the decay behaviors for them. We hope that our study will be helpful in searching for such types of exotic pentaquark states in experiments in the future.

hep-ph↗

arXiv2021

The magnetic moments and electromagnetic form factors of the decuplet baryons in chiral perturbation theory

We have systematically investigated the magnetic moments and magnetic form factors of the decuplet baryons to the next-to-next-leading order in the framework of the heavy baryon chiral perturbation theory. Our calculation includes the contributions from both the intermediate decuplet and octet baryon states in the loops. We also calculate the charge and magnetic dipole form factors of the decuplet baryons. Our results may be useful to the chiral extrapolation of the lattice simulations of the decuplet electromagnetic properties.

hep-ph↗

arXiv2020

Kaonic Hydrogen and Deuterium in Hamiltonian Effective Field Theory

The anti-kaon nucleon scattering lengths resulting from a Hamiltonian effective field theory analysis of experimental data and lattice QCD studies are presented. The same Hamiltonian is then used to compute the scattering length for the $K^- d$ system, taking careful account of the effects of recoil on the energy at which the $\bar{K}N$ T-matrices are evaluated. These results are then used to estimate the shift and width of the $1S$ levels of anti-kaonic hydrogen and deuterium. The $K^- p$ result is in excellent agreement with the SIDDHARTA measurement. In the $K^- d$ case the imaginary part of the scattering length and consequently the width of the $1S$ state are considerably larger than found in earlier work. This is a consequence of the effect of recoil on the energy of the $\bar{K}N$ energy, which enhances the role of the $Λ(1405)$ resonance.

hep-ph↗

arXiv2020

Resolving the low mass puzzle of $Λ_c(2940)^+$

For the long standing low mass puzzle of $Λ_c(2940)^+$, we propose an unquenched picture. Our calculation explicitly shows that the mass of the $Λ_c(2P,3/2^-)$ state can be lowered down to be consistent with the experimental data of $Λ_c(2940)^+$ by introducing the $D^*N$ channel contribution. Additionally, we give a semi-quantitative analysis to illustrate why the $Λ_c(2940)^+$ state has a narrow width. It means that the low mass puzzle of $Λ_c(2940)^+$ can be solved. What is more important is that we predict a mass inversion relation for the $2P$ $Λ_{c}^+$ states, i.e., the $Λ_c(2P,1/2^-)$ state is higher than the $Λ_c(2P,3/2^-)$, which is totally different from the result of conventional quenched quark model. It provides a criterion to test such an unquenched scenario for $Λ_c(2940)^+$. We expect the future experimental progress from the LHCb and Belle II.

hep-ph↗