arXiv subjects

Ju-Jun Xie

Publications and source records attributed to Ju-Jun Xie.

At least 181 records · Page 10Linked to original sources

arXiv2015

Glueball Physics in QCD

The Abelian decomposition of QCD which decomposes the gluons to the color neutral binding gluons and the colored valence gluons shows that QCD can be viewed as the restricted QCD (RCD) made of the binding gluons which has the valence gluons as colored source, and simplifies the QCD dynamics greatly. In particular, it tells that the gauge covariant valence gluons can be treated as the constituents of hadrons, and generalizes the quark model to the quark and valence gluon model. So it provides a comprehensive picture of glueballs and their mixing with quarkoniums, and predicts new hybrid hadrons made of quarks and valence gluons. We discuss how these predictions could be confirmed experimentally. In particular we present a systematic search for the ground state glueballs and their mixing with quarkoniums below 2 GeV in $0^{++}$, $2^{++}$, and $0^{-+}$ channels within the framework of QCD, and predict the relative branching ratios of the radiative decay of $ψ$ to the physical states.

hep-ph↗

arXiv2014

Role of the $Δ^*(1940)$ in the $π^+ p \to K^+ Σ^+(1385)$ and $pp \to n K^+ Σ^+(1385)$ reactions

The $p p \to n K^+ Σ^+(1385)$ reaction is a very good isospin $3/2$ filter for studying $Δ^{++*}$ resonance decaying to $K^+Σ^+(1385)$. Within the effective Lagrangian method, we investigate the $Σ(1385)$ (spin-parity $J^P = 3/2^+$) hadronic production in the $π^+ p \to K^+ Σ^+(1385)$ and $p p \to n K^+ Σ^+(1385)$ reactions. For $π^+ p \to K^+ Σ^+(1385)$ reaction, in addition to the "background" contributions from $t$-channel $K^{*0}$ exchange, $u$-channel $Λ(1115)$ and $Σ^0(1193)$ exchange, we also consider the contribution from the $s$-channel $Δ^*(1940)$ resonance, which has significant coupling to $KΣ(1385)$ channel. We show that the inclusion of the $Δ^*(1940)$ resonance leads to a fairly good description of the low energy experimental total cross section data of $π^+ p \to K^+ Σ^+(1385)$ reaction. Basing on the study of $π^+ p \to K^+Σ^+(1385)$ reaction and with the assumption that the excitation of $Δ^*(1940)$ resonance dominant the $pp \to n K^+ Σ^+(1385)$ reaction, we calculate the total and differential cross sections of $p p \to n K^+ Σ^+(1385)$ reaction. It is shown that the new experimental data support the important role played by the $Δ^*(1940)$ resonance with a mass in the region of $1940$ MeV and a width of around $200$ MeV. We also demonstrate that the invariant mass distribution and the Dalitz Plot provide direct information of the $Σ^+(1385)$ production, which can be tested by future experiments.

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arXiv2014

The $\bar{p} p \to ϕϕ$ reaction in an effective Lagrangian approach

We investigate the $\bar{p} p \to ϕϕ$ reaction within an effective Lagrangian approach.We show that the inclusion of either a scalar meson $f_0$ or a tensor meson $f_2$ in the $s$-channel can lead to a fairly good description of the bump structure of the total cross section around the invariant $\bar{p} p$ mass $W \simeq 2.2$ GeV, which cannot be reproduced with only the "background" contributions from $t$- and $u$-channel $N^*(1535)$ resonance as studied in a previous work. From the fits, we infer the properties of the involved scalar or tensor resonances.

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arXiv2014

The low lying scalar resonances in the $D^0$ decays into $K^0_s$ and $f_0(500)$, $f_0(980)$, $a_0(980)$

The $D^0$ decay into $K^0_s$ and a scalar resonance, $f_0(500)$, $f_0(980)$, $a_0(980)$, is studied obtaining the scalar resonances from final state interaction of a pair of mesons produced in a first step in the $D^0$ decay into $K^0_s$ and the pair of pseudoscalar mesons. This weak decay is very appropriate for this kind of study because it allows to produce the three resonances in the same decay in a process that is Cabibbo allowed, hence the rates obtained are large compared to those of $\bar{B}^0$ decays into $J/ψ$ and a scalar meson that have at least one Cabibbo suppressed vertex. Concretely the $a_0(980)$ production is Cabibbo allowed here, while it cannot be seen in the $\bar{B}^0_s$ decay into $J/ψa_0(980)$ and is doubly Cabibbo suppressed in the $\bar{B}^0$ decay into $J/ψa_0(980)$ and has not been identified there. The fact that the three resonances can be seen in the same reaction, because there is no isospin conservation in the weak decays, offers a unique opportunity to test the ideas of the chiral unitary approach where these resonances are produced from the interaction of pairs of pseudoscalar mesons.

hep-ph↗

arXiv2014

The nucleon resonances in the $J/ψ\to p\bar{p}η'$ decay

We are aiming to study the $J/ψ\to p\bar{p}η'$ decay in an isobar model and the effective Lagrangian approach. After a careful exploration of the contributions of the $S_{11}(1535)$, $P_{11}(1710)$, $P_{13}(1900)$, $S_{11}(2090)$ and $P_{11}(2100)$ resonances, we conclude that either a subthreshold resonance or a broad $P$-wave state in the near threshold range seems to be indispensable to describe present data of the $πN \to η'N$. Furthermore, at least one broad resonance above $η'N$ threshold is preferred. With this detailed analysis, we could give the invariant mass spectrum and Dalitz plot of the $J/ψ\to p\bar{p}η'$ decay for the purpose of assisting the future detailed partial wave analysis. It is found that the $J/ψ\to p\bar{p}η'$ data are useful for disentangling the above or below threshold resonant contribution, though it still further needs the differential cross section data of $πN \to η'N$ to realize some of the resonant and the non-resonant contribution. Our results are enlightening for the $η'N$ production mechanism and the properties of the nucleon resonances with the mass around 2.0~GeV.

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arXiv2014

Role of the possible $Σ^*(\frac{1}{2}^-)$ state in the $Λp \to Λp π^0$ reaction

The $Λp \to Λp π^0$ reaction near threshold is studied within an effective Lagrangian method. The production process is described by single-pion and single-kaon exchange. In addition to the role played by the $Σ^*(1385)$ resonance of spin-parity $J^P = 3/2^+$, the effects of a newly proposed $Σ^*$ ($J^P = 1/2^-$) state with mass and width around $1380$ MeV and $120$ MeV are investigated. We show that our model leads to a good description of the experimental data on the total cross section of the $Λp \to Λp π^0$ reaction by including the contributions from the possible $Σ^*(\frac{1}{2}^-)$ state. However, the theoretical calculations by considering only the $Σ^*(1385)$ resonance fail to reproduce the experimental data, especially for the enhancement close to the reaction threshold. On the other hand, it is found that the single-pion exchange is dominant. Furthermore, we also demonstrate that the angular distributions provide direct information of this reaction, hence could be useful for the investigation of the existence of the $Σ^*(\frac{1}{2}^-)$ state and may be tested by future experiments.

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arXiv2014

Regge signatures from forward CLAS $Λ(1520)$ photoproduction data

The $γp \to K^+ Λ(1520)$ reaction mechanism is investigated within a Regge--effective Lagrangian hybrid approach based on our previous study of this reaction [Physical Review C89, 015203 (2014)]. Near threshold and for large $K^+$ angles, both the CLAS and LEPS data can be successfully described by considering the contributions from the contact, $t$-channel $\bar K$ exchange, $u$-channel $Λ(1115)$ hyperon pole, and the $s$-channel nucleon pole and $N^*(2120)$ resonance contributions. However, for higher energies and forward $K^+$ angles, systematic discrepancies with data appear, which hint the possible existence of sizable quark-gluon string mechanism effects. We show how the inclusion of a $\bar K$ Regge--trajectory exchange in the $t$-channel leads to an efficient description of the $Λ(1520)$ photoproduction channel over the whole energy and angular ranges accessible in the CLAS experiment.

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arXiv2014

Re-analysis of the $Λ(1520)$ photoproduction reaction

Based on previous studies that support the important role of the $N^*(2120) D_{13}$ resonance in the $γp \to K^+ Λ(1520)$ reaction, we make a re-analysis of this $Λ(1520)$ photoproduction reaction taking into account the recent CLAS differential cross-section data. In addition to the contact, $t-$channel $\bar K$ exchange, $s-$channel nucleon pole and $N^*(2120)$ [previously called $N^*(2080)$] resonance contributions, which have been already considered in previous works, we also study the $u-$channel $Λ(1115)$ hyperon pole term. The latter mechanism has always been ignored in all theoretical analysis, which has mostly relied on the very forward $K^+$ angular LEPS data. It is shown that when the contributions from the $N^*(2120)$ resonance and the $Λ(1115)$ hyperon are taken into account, both the new CLAS and the previous LEPS data can be simultaneously described. We also show that the contribution from the $u-$channel $Λ(1115)$ pole term produces an enhancement for large $K^+$ angles, and it becomes more and more relevant as the photon energy increases, being essential to describe the CLAS differential cross sections at backward angles. Furthermore, we find that the new CLAS data also favor the existence of the $N^*(2120)$ resonance, and that these measurements can be used to further constrain its properties.

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arXiv2013

The near threshold $π^- p \to ηn$ reaction in an effective Lagrangian approach

The near threshold $π^- p \to ηn$ reaction is studied within an effective Lagrangian approach and the isobar model. By considering the contributions from $s$- and $u$-channel nucleon pole and $N^{*}(1535)$ resonance, the total and differential cross sections of the $π^- p \to ηn$ reaction near threshold are calculated. Our theoretical results can fairly reproduce the current experimental data. It is also shown that while the center-of-mass energy lies in the range from the reaction threshold up to $1.65$ GeV, $s$-channel $N^{*}(1535)$ resonance plays the dominant role. The effect from nucleon pole is found to be small but the interference terms between the $N^*(1535)$ resonance and the nucleon pole are significant. The contributions from $t$-channel processes are negligible in the present calculation.

hep-ph↗

arXiv2013

Recent Developments on Hadron Interaction and Dynamically Generated Resonances

In this talk I report on the recent developments in the subject of dynamically generated resonances. In particular I discuss the $γp \to K^0 Σ^+$ and $γn \to K^0 Σ^0$ reactions, with a peculiar behavior around the $K^{*0} Λ$ threshold, due to a $1/2^-$ resonance around 2035 MeV. Similarly, I discuss a BES experiment, $J/ψ\to ηK^{*0} \bar K^{*0}$ decay, which provides evidence for a new $h_1$ resonance around 1830 MeV that was predicted from the vector-vector interaction. A short discussion is then made about recent advances in the charm and beauty sectors.

hep-ph↗

arXiv2013

The role of $N^*(2120)$ nucleon resonance in $KΛ(1520)$ photon and hadronic productions

The associate $KΛ(1520)$ photon and hadronic production in the $γp \to K^+Λ(1520)$, $p p \to p K^+ Λ(1520)$ and $π^- p \to K^0 Λ(1520)$ reactions are investigated within the effective Lagrangian approach and the isobar model. We are interested in the contribution from the $N^*(2120)$ (previously called $N^*(2080)$) resonance, which has a significant coupling to the $KΛ(1520)$ channel. The theoretical results show that the current experimental data for the $γp \to K^+Λ(1520)$ reaction favor the existence of the $N^*(2120)$ resonance, and that these measurements can be used to further constrain its properties. We present results, including the $N^*(2120)$ contribution, for total cross sections of the $γp \to K^+Λ(1520)$, $π^- p \to K^0 Λ(1520)$, and $p p \to p K^+ Λ(1520)$ reactions. For this latter one, we also calculate invariant mass and Dalitz plot distributions.

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arXiv2013

$N^*(1920)(1/2^+)$ state in the $NK\bar{K}$ system

We study the three body $N \bar{K} K$ system by using the fixed center approximation to the Faddeev equations, taking the interaction between $N$ and $\bar{K}$, $N$ and $K$, and $\bar{K}$ and $K$ from the chiral unitary approach. Our results suggest that a $N\bar{K}K$ hadron state, with spin-parity $J^P=1/2^+$, and mass around 1920 MeV, can be formed.

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arXiv2013

The $γp \to n a^+_2(1320) \to n ρ^0 π^+$ reactions within an effective Lagrangian approach

We investigate the $a_2(1320)$ meson photon production in the $γp \to n a^+_2(1320)$ and $γp \to n ρ^0 π^+$ reactions within the effective Lagrangian method. For $γp \to n a^+_2(1320)$ reaction, by considering the contributions only from the $t-$channel $π^+$ exchange, we get a fairly good description of the current experimental total cross section data. We also studied the $γp \to n ρ^0 π^+$ reaction, which mainly contribute to the $γp \to n π^+ π^+ π^-$ reaction. The latter reaction has measured by the CLAS Collaboration. The total cross sections, invariant mass distribution, and the Dalitz Plot of $γp \to n ρ^0 π^+$ reaction are shown, which can be tested by future experiments.

hep-ph↗

arXiv2013

Coupling constant for $Λ(1405)\bar{K}N$

The value of the $Λ(1405){\bar K}N$ coupling constant $g_{Λ(1405)\bar{K}N}$ is obtained by fitting it to the experimental data on the total cross sections of the $K^-p \to π^0Σ^0$ reaction. On the basis of an effective Lagrangian approach and isobar model, we show that the value $|g_{Λ(1405)\bar{K}N}| = 1.51 \pm 0.10$ could be extracted from the available experimental data by assuming that the $s-$channel $Λ(1405)$ resonance plays a dominant role, whereas, the background contributions from the $s-$channel $Λ(1115)$, $t-$channel $K^*$ and $u-$channel nucleon pole processes are small and can be neglected. However, the $u-$channel nucleon pole diagram may also give an important contribution in the present calculations. After the background contributions are taken into account, the above value of $g_{Λ(1405)\bar{K}N}$ is reduced to $|g_{Λ(1405)\bar{K}N}| = 0.77 \pm 0.07$, which is not supported by the previous calculations and the recent CLAS measurements. The theoretical calculations on differential cross sections are also presented, which can be checked by future experiments.

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arXiv2013

Signature of an $h_1$ state in the $J/ψ\to ηh_1 \to ηK^{0}\bar{K}^{0}$ decay

The BES data on the $J/ψ\to ηK^{*0}\bar{K}^{*0}$ reaction show a clear enhancement in the $K^{*0}\bar{K}^{*0}$ mass distribution close to the threshold of this channel. Such an enhancement is usually a signature of a L=0 resonance around threshold, which in this case would correspond to an $h_1$ state with quantum numbers $I^G(J^{PC})=0^-(1^{+-})$. A state around $1800\ \text{MeV}$ results from the interaction of the $K^* \bar{K}^*$ using the local hidden gauge approach. We show that the peak observed in $J/ψ\to ηK^{*0}\bar{K}^{*0}$ naturally comes from the creation of this $h_1$ state with mass and width around $1830\ \text{MeV}$ and $110\ \text{MeV}$, respectively. A second analysis, model independent, corroborates the first result, confirming the relationship of the enhancement in the invariant mass spectrum with the $h_1$ resonance.

hep-ph↗

arXiv2013

Role of the $N^*(2080)$ in $pp \to pK^+ Λ(1520)$ and $π^- p \to K^0 Λ(1520)$ reactions

We investigate the $Λ(1520)$ hadronic production in the $p p \to p K^+ Λ(1520)$ and $π^- p \to K^0 Λ(1520)$ reactions within the effective Lagrangian method. For $π^- p \to K^0 Λ(1520)$ reaction, in addition to the "background" contributions from $t-$channel $K^*$ exchange, $u-$channel $Σ^+$ exchange, and $s-$channel nucleon pole terms, we also consider the contribution from the nucleon resonance $N^*(2080)$ (spin-parity $J^P = 3/2^-$), which has significant coupling to $KΛ(1520)$ channel. We show that the inclusion of the nucleon resonance $N^*(2080)$ leads to a fairly good description of the low energy experimental total cross section data of $π^- p \to K^0 Λ(1520)$ reaction. From fitting to the experimental data, we get the $N^*(2080)Nπ$ coupling constant $g_{N^*(2080)N π} = 0.14 \pm 0.04$. By using this value and with the assumption that the excitation of $N^*(2080)$ is due to the $π^0$-meson exchanges, we calculate the total and differential cross sections of $p p \to p K^+ Λ(1520)$ reaction. We also demonstrate that the invariant mass distribution and the Dalitz Plot provide direct information of the $Λ(1520)$ production, which can be tested by future experiments.

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arXiv2013

Low-lying even parity meson resonances and spin-flavor symmetry revisited

We review and extend the model derived in Phys. Rev. D83 016007 (2011) to address the dynamics of the low-lying even parity meson resonances. This model is based on a coupled channels spin-flavor extension of the chiral Weinberg-Tomozawa Lagrangian. This interaction is then used to study the S-wave meson-meson scattering involving members not only of the π-octet, but also of the ρ-nonet. In this work, we study in detail the structure of the SU(6) symmetry breaking contact terms that respect (or softly break) chiral symmetry. We derive the most general local (without involving derivatives) terms consistent with the chiral symmetry breaking pattern of QCD. After introducing sensible simplifications to reduce the large number of possible operators, we carry out a phenomenological discussion of the effects of these terms. We show how the inclusion of these pieces leads to an improvement of the description of J^P = 2^+ sector, without spoiling the main features of the predictions obtained in the original model in the J^P = 0^+ and J^P = 1^+ sectors. In particular, we find a significantly better description of the I^G(J^{PC})=0^+(2^{++}), 1^-(2^{++}) and the I(J^{P})=\frac{1}{2}(2^{+}) sectors, which correspond to the f_2(1270), a_2(1320) and K^*_2(1430) quantum numbers, respectively.

hep-ph↗

arXiv2012

Mechanism of $K^- p \to ηΛ$ reaction near threshold

Within an effective Lagrangian approach, we investigate the reaction mechanism of $K^- p\to ηΛ$ near threshold. It is found that a new $D_{03}$ resonance, with mass $M=1668.5\pm 0.5$MeV and width $Γ=1.5\pm0.5$MeV, is needed to interpret the experimental data reported by the Crystal Ball collaboration. To verify our results, remeasurements on the differential cross sections and $Λ$ polarization in this reaction will be helpful. Furthermore, we also show that the reaction $p\bar p\to Λ\bar Λη$ is a good place to look for this new resonance if it exists.

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