arXiv subjects

Peng-Nian Shen

Publications and source records attributed to Peng-Nian Shen.

At least 19 recordsLinked to original sources

arXiv2024

Reveal short range interactions between $u/d$ quarks in the $NN$, $D_{03}$, and $D_{30}$ systems

The dynamic mechanism of short range interactions between $u/d$ quarks remains an open and challenging problem. In order to reveal this quark dynamics, we perform a systematic analysis of $NN$, $D_{03}$, and $D_{30}$ systems in the (extended) chiral SU(3) constituent quark models. By comparing results calculated with different models and different parameter sets, the effects of one gluon exchange and vector meson exchange terms are carefully examined. The results indicate that the vector meson exchange interactions dominate the short range interactions between $u/d$ quarks, whereas the small residual one gluon exchange coupling strength is also allowed.

hep-ph↗

arXiv2018

The opportunity to find $\bar{d}^\ast(2380)$ in the $Υ(nS)$ decay

$d^\ast(2380)$ was observed by WASA-at-COSY collaborations in the nuclear reaction recently. Its particularly narrow width may indicate the new QCD-allowed hadronic structure. To further confirm the existence of this peculiar particle in a totally different kind of reaction, we study the opportunity for searching $\bar{d}^\ast$ in the $Υ(nS)$ (with n=1, 2, 3) decay. As a phenomenological study, our framework is based on SU(3) chiral quark model. By virtue of the unitarity of $S$-matrix and crossing symmetry, we study the imaginary part of the forward scattering amplitudes between $Υ(nS)$ and $d^\ast$. The scattering process is mainly governed by the quark-meson interaction. We examine both the pseudoscalar and vector meson contribution in the intermediate state. Hopefully, our results show that it's quite possible to find $\bar{d}^\ast$ in this decay mode in the future.

hep-ph↗

arXiv2016

Properties of single cluster structure of $d^*(2380)$ in chiral SU(3) quark model

The structure of $d^*(2380)$ is re-studied with the single cluster structure in the chiral SU(3) quark model which has successfully been employed to explain the scattering and binding behaviors of baryonic systems. The mass and width are explicitly calculated with two types of trial wave functions. The result shows that the $(0s)^6 [6]_{orb}$ configuration is easy to convert to the configuration with the same $[6]_{orb}$ symmetry but $2\hbar ω$ excitation back and forth, however, it is seldom to turn into a two-cluster configuration with a (1s) relative motion in between. The resultant mass and width are about $2394$MeV and $25$MeV, respectively, and the stable size is about $0.75fm$, which are consistent with both the results in the two-cluster configuration calculation and the data measured by the COSY collaboration. It seems that the observed $d^*$ is a six-quark dominated exotic state with a spherical shape and breath mode in the coordinate space. Moreover, if $d^*$ does have $2\hbar ω$ excitation, the $d^* \to npπππ$ decay mode might be a good place to distinguish the real structure of the observed phenomenon by COSY. The masses of various isospin-spin states of six-light-quark systems are also computed. It is shown that by considering the coupling with the configurations with $2\hbar ω$ excitations, only the mirror state with $IS$=$30$ will be lower down to the place where whose mass is slightly higher than the value of the $ΔΔ$ threshold.

hep-ph↗

arXiv2013

Baryonium

In the framework of the heavy baryon perturbation theory, in which the two-pion exchange is considered, the physical properties of heavy-baryon-anti-heavy-baryon systems are revisited. The potentials between heavy-baryon and anti-heavy-baryon are extracted in a holonomic form. Based on the extracted potentials, the s-wave scattering phase shifts and scattering lengths of $Λ_c$-$\barΛ_c$ and $Σ_c$-$\barΣ_c$ are calculated. From these scattering features, it is found that the $Λ_c$-$\barΛ_c$ system can be bound only when the value of the coupling constant $g_2$ is larger than that from the decay data of the $Σ_c(Σ_c^*) \to Λ_c π$ process. The binding condition for the $Σ_c$-$\barΣ_c$ system is also examined. The binding possibilities of these systems deduced from the scattering calculations are also checked by the bound state calculation and the binding energies are obtained if the system can be really bound. The binding possibility of the $Λ_b$-$\barΛ_b$ system is investigated as well.

hep-ph↗

arXiv2013

A possible NN*(1440) quasi-molecular state

Inspired by the recent observation of a narrow resonance-like structure around 2360 MeV in the p+n to d + π0 + π0 cross section, the possibility of forming a NN*(1440) quasi-molecular state is investigated by using a meson exchange model in which the π, σ, ρ and ω exchanges in t- and u-channels are considered. By adopting the coupling constants extracted from the relevant NN scattering and N*(1440) decay data, it is found that a deuteron-like quasi-molecular state of NN*(1440) with a binding energy in the range of from 2 to 67MeV can be formed. Therefore, it is speculated that the observed structure around 2360 MeV might be or may have a large component of the NN*(1440) quasi-molecular state.

hep-ph↗

arXiv2009

Testing the Bell Inequality at Experiments of High Energy Physics

Besides using the laser beam, it is very tempting to directly testify the Bell inequality at high energy experiments where the spin correlation is exactly what the original Bell inequality investigates. In this work, we follow the proposal raised in literature and use the successive decays $J/ψ\toγη_c\to Λ\barΛ\to pπ^-\bar pπ^+$ to testify the Bell inequality. Our goal is twofold, namely, we first make a Monte-Carlo simulation of the processes based on the quantum field theory (QFT). Since the underlying theory is QFT, it implies that we pre-admit the validity of quantum picture. Even though the QFT is true, we need to find how big the database should be, so that we can clearly show deviations of the correlation from the Bell inequality determined by the local hidden variable theory. There have been some critiques on the proposed method, so in the second part, we suggest some improvements which may help to remedy the ambiguities indicated by the critiques. It may be realized at an updated facility of high energy physics, such as BES III.

hep-ph↗

arXiv2007

On the structure of the pi pi invariant mass spectra of the Upsilon(4S)-->Upsilon(1S,2S) pi^+ pi^- decays

We perform a model-independent analysis for recently reported data of the $π^+π^-$ invariant mass spectra in the $Υ(4S)\toΥ(1S,2S)π^+π^-$ decays and point out that there does exist a broad peak below 0.6 GeV in the data of the $Υ(4S)\toΥ(1S)π^+π^-$ decay, which is analogous to that in the $Υ(3S)\toΥ(1S)π^+π^-$ decay. With the data of $Υ(4S)$ decays, we further test our model developed for studying the puzzle in the $Υ(3S)\toΥ(1S)π^+π^-$ decay. The result shows that with such a model, all the $π^+π^-$ invariant mass spectra of $Υ(4S)$ decays can be described. We also predict the $\cosθ_π^*$ distributions of $Υ(4S)\toΥ(1S,2S)π^+π^-$ decays, which can be used to justify our model prediction.

hep-ph↗

arXiv2007

Baryon spectra and non-strange baryon strong decays in the chiral SU(3) quark model

In the framework chiral SU(3) quark model, the baryon spectra within the band of $N\leq 2$ are studied, and the effect of the confining potential in different configurations, namely the $Δ$-mode and Y-mode are compared. In the same way, the baryon spectra in the extended chiral SU(3) quark model, in which additional vector meson exchanges are introduced, are also calculated. It is shown that a reasonable baryon spectrum in the chiral SU(3) quark model can be achieved no matter whether the $Δ$-mode or the Y-mode confining potential is employed. In the extended chiral SU(3) quark model, several energy levels are further improved. The resultant binding energies of excited baryon states in different confining modes deviate just by a few to several tens MeV, and it is hard to justify which confining mode is the dominant one. The non-strange baryon strong decay widths are further discussed in the point-like meson emission model by using the wave-function obtained in the spectrum calculation. The resultant widths can generally explain the experimental data but still cannot distinguish which confining mode is more important in this simple decay mode.

hep-ph↗

arXiv2007

Light vector hybrid states via QCD sum rules

Vector hybrid states with light quarks $u,d,s$ are investigated via QCD sum rules. The results show that the masses of the $q{\bar q}g$ $(q=u,d)$, $q{\bar s}g$, and $s{\bar s}g$ states with $J^{PC}=1^{--}$ are about 2.3-2.4, 2.3-2.5, and 2.5-2.6 GeV, respectively. It suggests that the recently discovered Y(2175) could not be a pure $s{\bar s}g$ vector hybrid state.

hep-ph↗

arXiv2007

Dynamically generated 1^+ heavy mesons

By using a heavy chiral unitary approach, we study the $S$ wave interactions between heavy vector meson and light pseudoscalar meson. By searching for poles of the unitary scattering amplitudes in the appropriate Riemann sheets, several $1^+$ heavy states are found. In particular, a $D^*K$ bound state with a mass of $2.462\pm0.010$ GeV which should be associated with the recently observed $D_{s1}(2460)$ state is obtained. In the same way, a $B^*{\bar K}$ bound state ($B_{s1}$) with mass of $5.778\pm0.007$ GeV in the bottom sector is predicted. The spectra of the dynamically generated $D_1$ and $B_1$ states in the $I=1/2$ channel are also calculated. One broad state and one narrow state are found in both the charmed and bottom sectors. The coupling constants and decay widths of the predicted states are further investigated.

hep-ph↗

arXiv2006

Study on the Form Factors at Effective Vertices of Diqarks Interacting with Gauge Bosons

The diquark structure in baryons is commonly accepted as a reasonable approximation which can much simplify the picture and reduce the length of calculations. However, a diquark by no means is a point-like particle, even though it is treated as a whole object. Therefore, to apply the diquark picture to the phenomenological calculations, at the effective vertices for the diquark-gauge boson interactions, suitable form factors must be introduced to compensate the effects caused by the inner structure of the diquark. It is crucial to derive the appropriate form factors for various interactions. In this work, we use the Bethe-Salpeter equation to derive such form factors and numerically evaluate their magnitudes.

hep-ph↗

arXiv2006

Isospin and a possible interpretation of the newly observed X(1576)

Recently, the BES collaboration observed a broad resonant structure X(1576) with a large width being around 800 MeV and assigned its $J^{PC}$ number to $1^{--}$. We show that the isospin of this resonant structure should be assigned to 1. This state might be a molecule state or a tetraquark state. We study the consequences of a possible $K^*(892)$-${\bar κ}$ molecular interpretation. In this scenario, the broad width can easily be understood. By using the data of $B(J/ψ\to Xπ^0)\cdot B(X\to K^+K^-)$, the branching ratios $B(J/ψ\to Xπ^0)\cdot B(X\to π^+π^-)$ and $B(J/ψ\to Xπ^0)\cdot B(X\to K^+K^-π^+π^-)$ are further estimated in this molecular state scenario. It is shown that the $X\to π^+π^-$ decay mode should have a much larger branching ratio than the $X\to K^+K^-$ decay mode has. As a consequence, this resonant structure should also be seen in the $J/ψ\to π^+π^-π^0$ and $J/ψ\to K^+K^-π^+π^-π^0$ processes, especially in the former process. Carefully searching this resonant structure in the $J/ψ\to π^+π^-π^0$ and $J/ψ\to K^+K^-π^+π^-π^0$ decays should be important for understanding the structure of X(1567).

hep-ph↗

arXiv2006

Dynamically generated 0^+ heavy mesons in a heavy chiral unitary approach

In terms of the heavy chiral Lagrangian and the unitarized coupled-channel scattering amplitude, interaction between the heavy meson and the light pseudoscalar meson is studied. By looking for the pole of scattering matrix on an appropriate Riemann sheet, a $DK$ bound state $D_{s0}^*$ with the mass of $2.312\pm0.041$ GeV is found. This state can be associated as the narrow $D_{sJ}^*(2317)$ state found recently. In the same way, a $B{\bar K}$ bound state $B_{s0}^*$ is found, and its mass of $5.725\pm0.039$ GeV is predicted. The spectra of $D_0^*$ and $B_0^*$ with $I=1/2$ are further investigated. One broad and one narrow states are predicted in both charm and bottom sectors. The coupling constants and decay widths of the predicted states are also calculated.

hep-ph↗

arXiv2006

Chromo-polarizability and pipi final state interaction

The chromo-polarizability of a quarkonium state is a measure of the amplitude of the $E1$-$E1$ chromo-electric interaction of the quarkonium with soft gluon fields and can be measured in the heavy quarkonium decays. Based on the chiral unitary approach, formulas with modification caused by the $S$ wave $ππ$ final state interaction (FSI) for measuring the chromo-polarizabilities are given. It is shown that the effect of the $S$ wave $ππ$ FSI is very important in extracting chromo-polarizabilities from the experimental data. The resultant values with the FSI are reduced to about 1/3 of those determined without the FSI. The consequences of the FSI correction in the $J/ψ$-nucleon scattering near the threshold are also discussed. The estimated lower bound of the total cross section is reduced from about 17 mb to 2.9 mb, which agrees with the experimental data point and is compatible with the previously estimated values in the literature. In order to understand the interaction of heavy quarkonia with light hadrons at low energies better and to obtain the chromo-polarizabilities of quarkonia accurately, more data should be accumulated. This can be done in the $J/ψ\to π^+π^-l^+l^-$ decay at BES-III and CLEO-c and in the $Υ\to π^+π^-l^+l^-$ decay at B factories.

hep-ph↗

arXiv2006

The pi pi Phase Shifts from psi' to J/psi pi^+ pi^- Decays

The $ψ'\to J/ψπ^+π^-$ decay process provides a new way to extract the $ππ$ $S$ wave phase shifts up to $0.59GeV$. In this paper we derive the formulae for extracting the $ππ$ $S$ wave phase shifts from the invariant mass spectrum of $ππ$ in the $ψ'\to J/ψπ^+π^-$ decay.

hep-ph↗

arXiv2006

An effective formulation on quantum hadrodynamics at finite temperatures and densities

According to Wick's theorem, the second order self-energy corrections of hadrons in the hot and dense nuclear matter are calculated. Furthermore, the Feynman rules are summarized, and an effective formulation on quantum hadrodynamics at finite temperatures and densities is evaluated. As the strong couplings between nucleons are considered, the self-consistency of this method is discussed in the framework of relativistic mean-field approximation. Debye screening masses of the scalar and vector mesons in the hot and dense nuclear matter are calculated with this method in the relativistic mean-field approximation. The results are different from those of thermofield dynamics and Brown-Rho conjecture. Moreover, the effective masses of the photon and the nucleon in the hot and dense nuclear matter are discussed.

nucl-th↗

arXiv2006

Possible S-wave Bound-States of Two Pseudoscalar Mesons

Using the potentials derived from vector-meson-exchanges, the $K\bar K$, $DK$, $B\bar K$, $D\bar D$, $B\bar B$, $BD$, $\bar D K$, $BK$ and $B\bar D$ systems are studied. Possible S-wave bound-states of two pseudoscalar mesons are discussed. We find that systems of $DB$, $D\bar D$, $B\bar B$ and $DK$ with isospin 0 are likely to form S-wave bound states via strong interactions while the others are unlikely to be bound by the strong interaction sector alone. With the Coulomb potential, the $K^+K^-$ system can form an atomic bound state - the kaonium. The influence of the one-meson-exchange potential on the ground state energy of the kaonium and its decay widths to $ππ$ and $πη$ are evaluated.

hep-ph↗

arXiv2006

S wave Kπscattering and effects of κin J/ψ\to {\bar K}^{*0}(892)K^+π^-

$Kπ$ $S$ wave scattering is studied using a chiral unitary approach (ChUT) taking into account coupled channels. With the amplitudes derived from the lowest order chiral Lagrangian as the kernel of a set of coupled channel Bathe-Salpeter equations, the $I=1/2$ $S$ wave $Kπ$ scattering phase shifts below 1.2 GeV can be fitted by one parameter, a subtraction constant, and a scalar resonance corresponding to the controversial $κ$ ($K^*_0(800)$) can be generated dynamically. A good description of the $I=3/2$ $S$ wave $Kπ$ scattering phase shifts below 1.2 GeV can also be obtained. An artificial singularity in the conventional cut-off method of the 2-meson loop integral of the ChUT is found. The formalism is applied to deal with the $S$ wave $Kπ$ final state interaction (FSI) in the decay $J/ψ\to {\bar K}^{*0}(892)K^+π^-$, and a qualitatively good fit to the data is achieved. The role of $κ$ in the decay is discussed.

hep-ph↗