arXiv subjects

Shao-Zhou Jiang

Publications and source records attributed to Shao-Zhou Jiang.

At least 19 recordsLinked to original sources

arXiv2026

Higher-order chiral Lagrangians with vector meson nonet in different representations

In this paper, chiral Lagrangians with vector meson nonet are constructed across multiple representations, including those to the next-to-leading order in the vector-field representation, as well as to the next-to-next-to-leading order in the tensor-field and hidden local symmetry representations. For the next-to-leading order octet, redundant terms in the other literature are also identified in both the tensor-field and hidden local symmetry representations. Additionally, the equivalence between the tensor-field and hidden local symmetry representations is examined.

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arXiv2026

Investigating the internal structure of $X(6900)$ in the $2J/ψ$ decay channel

Assuming $X(6900)$ is a tetraquark state, the decay width of $X(6900)\to 2J/ψ$ is calculated in a covariant quark model, with the diquark-antidiquark $[cc][\bar{c}\bar{c}]$ picture. Two possible structures, vector-vector and axial-vector--axial-vector coupling, are investigated. The result indicates that the axial-vector--axial-vector coupling is consistent with the experiments. Additionally, as another application of the covariant quark model, the decay width of $X(6900)\to 2η_c$ is predicted to be $66\sim88$ keV.

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arXiv2026

Study of transition form factors of the lightest pseudoscalars

In this paper, we study the transition form factors of the lightest pseudoscalar mesons, $π^0$, $η$, and $η'$, within the framework of resonance chiral theory. Our analysis is performed based on the data of time-like and space-like singly-virtual and space-like doubly-virtual form factors, as well as the relevant cross sections and latest invariant mass spectra of $e^+e^-$ pair for the process of $P\toγe^+ e^-$. The transition form factors of these pseudoscalars are obtained. Also, we evaluate their contributions to the light-by-light part of the anomalous magnetic moment of the muon. Our two Fits give similar results, where Fit-A gives $a_μ^{π^0 }=(61.6\pm 1.8)\times10^{-11}$, $a_μ^{η}=(15.2\pm1.7)\times10^{-11}$, $a_μ^{η'}=(16.0\pm 1.2)\times10^{-11}$, and the total contribution of neutral pseudo-scalar meson poles is $a_μ^{π^0+η+η'}=(92.8\pm2.9)\times10^{-11}$.

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arXiv2025

An anlaysis on $J/ψ\toπ^0γ^*$ within resonance chiral theory

In this study, we analyze the first measurement of the electron-positron invariant mass spectrum in $J/ψ\to π^0 e^+e^-$ by BESIII, using the framework of resonance chiral theory. Our results indicate that both strong interaction and electromagnetic transition are essential to accurately describe the data. We obtain the $π^0$ transition form factor for $J/ψ\to π^0γ^*$ and the corresponding decay branching ratios for $J/ψ\to π^0 l^+l^-$. The decay process $J/ψ\to π^0 V$ is also examined. It is found that $J/ψ\to π^0 ρ^0$ is dominated by the strong interaction, while the other two channels, $J/ψ\to π^0 ω$ and $π^0 ϕ$, arise primarily from electromagnetic transitions.

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arXiv2024

Bayesian method for fitting the low-energy constants in chiral perturbation theory

The values of the low-energy constants (LECs) are very important in the chiral perturbation theory. This paper adopts a Bayesian method with the truncation errors to globally fit eight next-to-leading order (NLO) LECs $L_i^r$ and next-to-next-leading order (NNLO) LECs $C_i^r$. With the estimation of the truncation errors, the fitting results of $L_i^r$ in the NLO and NNLO are very close. The posterior distributions of $C_i^r$ indicate the boundary-dependent relations of these $C_i^r$. Ten $C_i^r$ are weakly dependent on the boundaries and their values are reliable. The other $C_i^r$ are required more experimental data to constrain their boundaries. Some linear combinations of $C_i^r$ are also fitted with more reliable posterior distributions. If one knows some more precise values of $C_i^r$, some other $C_i^r$ can be obtained by these values. With these fitting LECs, most observables provide a good convergence, except for the $πK$ scattering lengths $a_0^{3/2}$ and $a_0^{1/2}$. An example is also introduced to test the improvement of the method. All the computations indicate that considering the truncation errors can improve the global fit greatly, and more prior information can obtain better fitting results. This fitting method can be extended to the other effective field theories and the perturbation theory.

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arXiv2023

Chiral Lagrangians for singly heavy baryons to $\mathcal{O}(p^{4})$ order

The chiral Lagrangians for singly heavy baryons are constructed up to the $\mathcal{O}(p^{4})$ order. The involved baryons may be in a flavor antitriplet with spin-1/2, a flavor sextet with spin-$1/2$, or a flavor sextet with spin-3/2 when one considers three light flavors. For the relativistic version of Lagrangian, from $\mathcal{O}(p^{2})$ to $\mathcal{O}(p^{4})$, there exist 48, 199, and 1242 independent terms in the $SU(2)$ case and 59, 307, and 2454 independent terms in the $SU(3)$ case, respectively. For the Lagrangian in the heavy quark limit, from $\mathcal{O}(p^{2})$ to $\mathcal{O}(p^{4})$, the numbers of independent terms are reduced to 16, 64, and 412 in the $SU(2)$ case and to 17, 88, and 714 in the $SU(3)$ case, respectively. We obtain the low-energy constant relations between the relativistic case and the heavy-quark case up to the $\mathcal{O}(p^{3})$ order. The relations between low-energy constants of independent relativistic terms are also presented up to this order by using the heavy quark symmetry.

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arXiv2023

Chiral Lagrangians for spin-$\frac{1}{2}$ and spin-$\frac{3}{2}$ doubly charmed baryons

The relativistic chiral Lagrangians for both spin-$\frac{1}{2}$ and spin-$\frac{3}{2}$ doubly charmed baryons are constructed up to the order $\mathcal{O}(p^{4})$. From $\mathcal{O}(p^{2})$ to $\mathcal{O}(p^{4})$, there are 19, 74, and 452 independent terms in the two-flavor case and 25, 112, and 864 independent terms in the three-flavor case. The chiral Lagrangians in the heavy diquark limit are also obtained. From $\mathcal{O}(p^{2})$ to $\mathcal{O}(p^{4})$, there are 7, 23, and 118 independent terms in the two-flavor case and 8, 31, and 189 independent terms in the three-flavor case. We present the low-energy constant relations between the relativistic case and the case in the heavy diquark limit up to the order $\mathcal{O}(p^{3})$. With the heavy diquark-antiquark symmetry, the low-energy constant relations between the doubly charmed baryon case and the heavy-light meson case are also obtained up to the order $\mathcal{O}(p^{3})$.

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arXiv2023

Relations for low-energy constants in baryon chiral perturbation theory with explicit $Δ(1232)$ derived from the chiral quark model

We study the relations between low-energy constants (LECs) in the chiral Lagrangians with $Δ(1232)$ and those in the quark-level description model up to the third chiral order. Ten structure correspondences are involved in getting the relations. This situation is more complicated than the spin-1/2 baryon case. The obtained results may help to further investigations involving the $Δ(1232)$ baryons.

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arXiv2022

Relations for low-energy coupling constants in baryon chiral perturbation theory derived from the chiral quark model

The quark model symmetry can be adopted to establish relations between the low-energy constants (LECs) in the baryon chiral perturbation theory ($χPT$) if one assumes that a baryon-baryon-meson coupling is described equivalently by a quark-quark-meson coupling at the quark level. Through the correspondence between the $SU(2)$ description and the $SU(3)$ description for the same coupling vertex at the quark level, we find some relations between the LECs in $SU(2)_{χPT}$ and $SU(3)_{χPT}$ up to the third chiral order. The $SU(3)_{χPT}$ LEC relations at the same order are also obtained. The numerical analysis roughly supports these relations. In the situation that the available experimental data are not enough, one may employ such constraints to reduce the number of LECs.

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arXiv2022

High order chiral Lagrangians with vector mesons in different approaches

The chiral Lagrangians with vector mesons are constructed in different approaches, including the next-to-leading order Lagrangian in the vector-field approach, the next-to-next-to-leading order Lagrangians in the tensor-field and the hidden local symmetry approaches. Some redundant terms are found at the next-to-leading order in the tensor-field and the hidden local symmetry approaches. The corresponding relations between the next-to-next-to-leading order pseudoscalar mesonic low-energy constants and the ones in the hidden local symmetry approach are obtained at tree level. The equivalence between the tensor-field approach and the hidden local symmetry approach is also discussed.

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arXiv2020

New method for fitting the low-energy constants in chiral perturbation theory

A new set of the next-to-leading order (NLO) and the next-to-next-to-leading order (NNLO) low-energy constants $L_i^r$ and $C_i^r$ in chiral perturbation theory is obtained. These values are computed using the new experimental data with a new calculation method. This method combines the traditional global fit and Monte Carlo method together. The higher order contributions are estimated with this method. The theoretical values of the observables provide good convergence at each chiral dimension, except for the NNLO values of the $πK$ scattering lengths $a_0^{3/2}$ and $a_0^{1/2}$. The fitted values for $L_i^r$ at NLO are close to their results with the new method at NNLO; i.e., these $L_i^r$ are nearly order-independent in this method. The estimated ranges for $C_i^r$ are consistent with those in the literature, and their possible upper or/and lower boundaries are given. The values of some linear combinations of $C_i^r$ are also given, and they are more reliable. If one knows a more exact value $C_i^r$, another $C_i^r$ can be obtained by these values.

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arXiv2019

Chiral Lagrangians for mesons with a single heavy quark

We construct the relativistic chiral Lagrangians for heavy-light mesons $(Q\bar{q})$ to the $\mathcal{O}(p^4)$ order. From $\mathcal{O}(p^2)$ to $\mathcal{O}(p^4)$, there are 17, 67, and 404 independent terms in the flavor $SU(2)$ case and 20, 84, and 655 independent terms in the flavor $SU(3)$ case. The Lagrangians in the heavy quark limit are also obtained. From $\mathcal{O}(p^2)$ to $\mathcal{O}(p^4)$, there are 7, 25, and 136 independent terms in the flavor $SU(2)$ case and 8, 33, and 212 independent terms in the flavor $SU(3)$ case. The relations between low-energy constants based on the heavy quark symmetry are also given up to the $\mathcal{O}(p^3)$ order.

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arXiv2018

Chiral Lagrangians with decuplet baryons to one loop

We construct the relativistic chiral Lagrangians with decuplet baryons up to the order $\mathcal{O}(p^4)$ (one loop). For the meson-decuplet-decuplet couplings, there are 1, 13, 55, and 548 terms in the $\mathcal{O}(p^1)$-$\mathcal{O}(p^4)$ order Lagrangians, respectively. For the meson-octet-decuplet Lagrangians, the number of independent terms from $\mathcal{O}(p^1)$ to $\mathcal{O}(p^4)$ are 1, 5, 67, and 611, respectively. For convenience of applications, the $πΔΔ$ and $πNΔ$ chiral Lagrangians are picked out. This new form of $Δ$ Lagrangians is equivalent to the original isovector-isospinor one and we establish relations between these two forms.

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arXiv2017

Chiral Lagrangians with $Δ(1232)$ to one loop

We construct the Lorentz-invariant chiral Lagrangians up to the order $\mathcal{O}(p^4)$ by including $Δ(1232)$ as an explicit degree of freedom. A full one-loop investigation on processes involving $Δ(1232)$ can be performed with them. For the $πΔΔ$ Lagrangian, one obtains 38 independent terms at the order $\mathcal{O}(p^3)$ and 318 independent terms at the order $\mathcal{O}(p^4)$. For the $πNΔ$ Lagrangian, we get 33 independent terms at the order $\mathcal{O}(p^3)$ and 218 independent terms at the order $\mathcal{O}(p^4)$. The heavy baryon projection is also briefly discussed.

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arXiv2017

Meson-baryon effective chiral Lagrangians at order $p^4$

We construct the three-flavor Lorentz-invariant meson-baryon chiral Lagrangians at the order $p^4$, with which a full one-loop investigation may be performed. One obtains 540 independent terms. The processes with the minimal number of mesons and photons that this order Lagrangians may contribute to are also presented.

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arXiv2015

Computation of the O(p^6) order low-energy constants: an update

We update our original low-energy constants to the O(p6) order, including two and three flavours, the normal and anomalous ones. Following a comparative analysis, the O(p4) results are considered better. In the O(p6) order, most of our results are consistent or better with those we have found in the literature, although several are worse.

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arXiv2014

Full pseudoscalar mesonic chiral Lagrangian at p6 order under the unitary group

We construct the full p6 order chiral Lagrangians for the unitary group and special unitary groups, including nf-, three- and two-flavor cases, all bilinear currents (scalar, pseudoscalar, vector, axial-vector and tensor currents) and theta parameter. The number of independent operators are 1391, 1326 and 969 for each of the flavor unitary groups. From these results, we find one extra linear relation among the traditional p4 order low-energy constants under the U(3) group, and some more linear relations with tensor sources for the p6 order low-energy constants in the special unitary groups. We develop a scheme to obtain the relations for the dependent operators in terms of independent operators.

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arXiv2013

Computation of the $p^6$ order low-energy constants with tensor sources

We present the results of calculations of the $p^4$ and $p^6$ order low-energy constants for the chiral Lagrangian with tensor sources for both two and three flavors of pseudoscalar mesons. This is a generalization of our previous work on similar calculations without tensor sources in terms of the quark self-energy $Σ(p^2)$, based on the first principle derivation of the low-energy effective Lagrangian and computation of the low-energy constants with some rough approximations. With the help of partial integration and some epsilon relations, we find that some $p^6$ order operators with tensor sources appearing in the literature are related to each other. That leaves 98 independent terms for $n$-flavor, 92 terms for three-flavor, and 65 terms for two-flavor cases. We also find that the odd-intrinsic-parity chiral Lagrangian with tensor sources cannot independently exist in any order of low-energy expansion.

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