arXiv subjects

Ju-Jun Xie

Publications and source records attributed to Ju-Jun Xie.

At least 109 records · Page 6Linked to original sources

arXiv2020

Role of the low-lying nucleon resonances in the $p\bar{p} \to ψη$ reaction

Within the effective Lagrangian approach, we study the $p\bar{p} \rightarrow ψη$ [$ψ\equivψ(3686)$, $J/ψ$] reaction at the low energy where the contributions from nucleon pole and low-lying nucleon resonances, $N(1520)$, $N(1535)$ and $N(1650)$ are considered. All the model parameters are determined with the help of current experimental data on the decay of $ψ\to p \bar{p} η$. Within the model parameters, the total and differential cross sections of the $p\bar{p} \rightarrow ψη$ reaction are predicted. We show that the relative phases between different amplitudes of different nucleon resonance will change significantly the angular distributions of the $\bar{p} p \to ψη$ reaction. Therefore, we conclude that these reactions are suitable to study experimentally the properties of the low-lying nucleon resonance and the reaction mechanisms. We hope that these theoretical calculations can be tested by future experiments.

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arXiv2020

Evasion of HSR in the charmless decays of excited $P$-wave charmonia

We investigate the charmless decays of excited $P$-wave charmonia $χ_{c1}^\prime \to VV$ and $χ_{c2}^\prime \to VP$ via intermediate charmed meson loops, where $V$ and $P$ denote the light vector and pseudoscalar mesons, respectively. Within the model parameters, the charmed meson loop contributions are evaluated by using the effective Lagrangian approach. For $χ_{c1}^\prime \to VV$, the partial widths of the $ρρ$, $ωω$, and $K^*{\bar K}^*$ channels can reach to the order of MeV, while the partial width of the $ϕϕ$ channel is very small and in the order of keV. For $χ_{c2}^\prime \to V P$, the partial widths of $χ_{c2}^{\prime} \to K^\ast \bar{K}+c.c$ turns out to be sizeable, while the partial widths of $χ_{c2}^{\prime} \to ρ^+π^- +c.c$ is found to be much smaller than the $K^\ast \bar{K}+c.c$ channel. Our calculations may be examined by the future BESIII experiments.

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arXiv2020

Prediction of possible exotic states in the $η\bar{K}K^*$ system

We investigate the $η\bar{K}K^*$ three body system in order to look for possible $I^G(J^{PC})=0^+(1^{-+})$ exotic states in the framework of the fixed center approximation to the Faddeev equation. We assume the scattering of $η$ on a clusterized system $\bar{K}K^*$, which is known to generate the $f_1(1285)$, or a $\bar{K}$ on a clusterized system $ηK^*$, which is shown to generate the $K_1(1270)$. In the case of the $η$-$(\bar{K}K^*)_{f_1(1285)}$ scattering, we find evidence of a bound state $I^G(J^{PC})=0^+(1^{-+})$ below the $η{f_1(1285)}$ threshold with mass around 1700 MeV and width about 180 MeV. Considering the $\bar{K}$-$(ηK^*)_{K_1(1270)}$ scattering, we obtain a bound state $I(J^{P})=0(1^{-})$ just below the $\bar{K}{K_1(1270)}$ threshold with a mass around 1680 MeV and a width about 160 MeV.

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arXiv2020

Photoproduction of hidden-bottom pentaquark and related topics

Due to the discovery of the hidden-charm pentaquark $P_c$ states by the LHCb collaboration, the interests on the candidates of hidden-bottom pentaquark $P_b$ states are increasing. They are anticipated to exist as the analogues of the $P_c$ states in the bottom sector and predicted by many models. We give an exploration of searching for a typical $P_b$ in the $γp \to Υp$ reaction, which shows a promising potential to observe it at an electron-ion collider. The possibility of searching for $P_b$ in open-bottom channels are also briefly discussed. Meanwhile, the $t$-channel non-resonant contribution, which in fact covers several interesting topics at low energies, is systematically investigated.

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arXiv2020

Role of the $Λ(1600)$ in the $K^-p \to Λπ^0π^0$ reaction

Role of the $Λ(1600)$ is studied in the $K^- p \to Λπ^0 π^0$ reaction by using the effective Lagrangian approach near the threshold. We perform a calculation for the total and differential cross sections by considering the contributions from the $Λ(1600)$ and $Λ(1670)$ intermediate resonances decaying into $π^0 Σ^{*0}(1385)$ with $Σ^{*0}(1385)$ decaying into $π^0 Λ$. Besides, the non-resonance process from $u$-channel nucleon pole is also taken into account. With our model parameters, the current experimental data on the total cross sections of the $K^- p \to Λπ^0 π^0$ reaction can be well reproduced. It is shown that we really need the contribution from the $Λ(1600)$ with spin-parity $J^P = 1/2^+$, and that these measurements can be used to determine some of the properties of the $Λ(1600)$ resonance. Furthermore, we also plot the $π^0 Λ$ invariant mass distributions which could be tested by the future experimental measurements.

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arXiv2020

$Ξ_{bb}$ and $Ω_{bbb}$ molecular states

Using the vector-exchange interaction in the local hidden gauge approach, which in the light quark sector generates the chiral Lagrangian, and has produced realistic results for $Ω_c, Ξ_c, Ξ_b$ and the hidden charm pentaquark states, we study the meson-baryon interactions in the coupled channels that lead to the $Ξ_{bb}$ and $Ω_{bbb}$ excited states of the molecular type. We obtain seven states of the $Ξ_{bb}$ type with energies between $10408$ and $10869$ MeV and one $Ω_{bbb}$ state at $15212$ MeV.

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arXiv2020

Theoretical interpretation of the $D^+_s \to π^+ π^0 η$ decay and the nature of $a_0(980)$

In a recent paper \cite{Ablikim:2019pit}, the BESIII collaboration reported the so-called first observation of pure $W$-annihilation decays $D^+_s \to a^+_0(980) π^0$ and $D_s^+ \to a^0_0(980)π^+$. The measured absolute branching fractions are, however, puzzlingly larger than those of other measured pure $W$-annihilation decays by at least one order of magnitude. In addition, the relative phase between the two decay modes is found to be about 180 degrees. In this letter, we show that all these can be easily understood if the $a_0(980)$ is a dynamically generated state from $\bar{K} K$ and $πη$ interactions in coupled channels. In such a scenario, the $D^+_s$ decay proceeds via internal $W$ emission instead of $W$-annihilation, which has a larger decay rate than $W$-annihilation. The proposed decay mechanism and the molecular nature of the $a_0(980)$ also provide a natural explanation to the measured negative interference between the two decay modes.

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arXiv2019

Radiative decays of $f_1(1285)$ as the $ K^*\bar K$ molecular state

Within a picture of the $f_1(1285)$ being a dynamically generated resonance from the $ K^*\bar K$ interactions, we estimate the rates for the radiative transitions of the $f_1(1285)$ meson to the vector mesons $ρ^0$,$ω$ and $ϕ$. These radiative decays proceed via the kaon loop diagrams. The calculated results are in fair agreement with the experimental measurements. Some predictions can be tested by experiments and their implementation and comparison with these predictions will be valuable to decode the nature of the $f_1(1285)$ state.

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arXiv2019

Visible narrow cusp structure in $Λ_c^+\to p K^- π^+$ enhanced by triangle singularity

A resonance-like structure as narrow as 10 MeV is observed in the $K^-p$ invariant mass distributions in $Λ_c^+\to p K^- π^+$ at Belle. Based on the large data sample of about 1.5 million events and the small bin width of just 1 MeV for the $K^-p$ invariant mass spectrum, the narrow peak is found precisely lying at the $Λη$ threshold. While lacking evidence for a quark model state with such a narrow width at this mass region, we find that this narrow structure can be naturally identified as a threshold cusp but enhanced by the nearby triangle singularity via the $Λ$-$a_0(980)^+$ or $η$-$Σ(1660)^+$ rescatterings.

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arXiv2019

Heavy-quark spin and flavour symmetry partners of the X(3872) revisited: what can we learn from the one boson exchange model?

Heavy-quark symmetry as applied to heavy hadron systems implies that their interactions are independent of their heavy-quark spin (heavy-quark spin symmetry) and heavy flavour contents (heavy flavour symmetry). In the molecular hypothesis the $X(3872)$ resonance is a $1^{++}$ $D^*\bar{D}$ bound state. If this is the case, the application of heavy-quark symmetry to a molecular $X(3872)$ suggests the existence of a series of partner states, the most obvious of which is a possible $2^{++}$ $D^*\bar{D}^*$ bound state for which the two-body potential is identical to that of the $1^{++}$ $D^*\bar{D}$ system, the reason being that these two heavy hadron-antihadron states have identical light-spin content. As already discussed in the literature this leads to the prediction of a partner state at $4012\,{\rm MeV}$, at least in the absence of other dynamical effects which might affect the location of this molecule. However the prediction of further heavy-quark symmetry partners cannot be done solely on the basis of symmetry and requires additional information. We propose to use the one boson exchange model to fill this gap, in which case we will be able to predict or discard the existence of other partner states. Besides the isoscalar $2^{++}$ $D^*\bar{D}^*$ bound state, we correctly reproduce the location and quantum numbers of the isovector hidden-bottom $Z_b(10610)$ and $Z_b(10650)$ molecular candidates. We also predict the hidden-bottom $1^{++}$ $B^*\bar{B}^*$ and $2^{++}$ $B^*\bar{B}^*$ partners of the $X(3872)$, in agreement with previous theoretical speculations, plus a series of other states. The isoscalar, doubly charmed $1^+$ $D D^*$ and $D^* D^*$ molecules and their doubly bottomed counterparts are likely to bind, providing a few instances of explicitly exotic systems.

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arXiv2019

Search for the $Σ^*$ state in $Λ^+_c \to π^+ π^0 π^-Σ^+$ decay by triangle singularity

A $Σ^*$ resonance with spin-parity $J^P = 1/2^-$ and mass in the vicinity of the $\bar{K}N$ threshold has been predicted in the unitary chiral approach and inferred from the analysis of CLAS data on the $γp \to K^+ π^0 Σ^0$ reaction. In this work, based on the dominant Cabibbo favored weak decay mechanism, we perform a study of $Λ_c^+ \to π^+ π^0 Σ^*$ with the possible $Σ^*$ state decaying into $π^- Σ^+$ through a triangle diagram. This process is initiated by $ Λ_c^+ \to π^+ \bar{K}^*N $, then the $\bar{K}^*$ decays into $\bar{K} π$ and $\bar{K} N$ produce the $Σ^*$ through a triangle loop containing $\bar{K}^* N \bar{K}$ which develops a triangle singularity. We show that the $π^- Σ^+$ state is generated from final state interaction of $\bar{K}N$ in $S$-wave and isospin $I=1$, and the $Λ_c^+ \to π^+ π^0 π^- Σ^+$ decay can be used to study the possible $Σ^*$ state around the $\bar{K}N$ threshold. The proposed decay mechanism can provide valuable information on the nature of the $Σ^*$ resonance and can in principle be tested by facilities such as LHCb, BelleII and BESIII.

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arXiv2018

Study of $a_1(1260)$ in the $γp \to π^+π^+π^- n$ reaction

We investigate the discovery potential of the $a_1(1260)$ photoproduction in the $γp \to a_1(1260)^+ n$ and $γp \to π^+π^+π^- n$ reactions via the $π$-exchange mechanism. For the $γp \to π^+π^+π^- n$ reaction, we perform a calculation for the differential and total cross sections by including the contributions from the $a_1(1260)$ intermediate resonance decaying into $ρπ$ then into $π^+π^+π^-$. Besides, the non-resonance process is also considered. With a lower mass of $a_1(1260)$, we get a fairly good description of the experimental data for the invariant $π^+π^+π^-$ mass distributions. For the $γp \to a_1(1260)^+ n$ reaction, with our model parameters, the total cross section is of the order of 10 $μ$b at photon beam energy $E_γ \sim$ 2.5 GeV. It is expected that our model calculations could be tested by future experiments.

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arXiv2018

$Λ(1405)$ production in the process $χ_{c0}(1P)\to \barΛΣπ$

We have performed a theoretical study on the process $χ_{c0}(1P)\to \barΛΣπ$, by taking into account the final state interactions of $πΣ$ and $π\barΛ$ based on the chiral unitary approach. As the isospin filters of $I=0$ in the $πΣ$ channel and $I=1$ in the $π\barΛ$ channel, this process can be used to study the molecular structure of the $Λ(1405)$ resonance, and to test the existence of the predicted states $Σ(1380)$ and $Σ(1430)$ with spin-parity $J^P=1/2^-$. Our results show that there is a peak around $1350 \sim 1400$~MeV, and a cusp around the $\bar{K}N$ threshold in the $πΣ$ invariant mass distribution, which should be the important feature of the molecular state $Λ(1405)$. We also find a peak around $1380$~MeV, and a cusp around $\bar{K}N$ threshold in the $π\barΛ$ invariant mass distribution, which are associated to the $Σ(1380)$ and $Σ(1430)$ resonances.

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arXiv2018

Decay patterns of low-lying $N_{s\bar{s}}$ states to the strangeness channels

Here we investigate the decay patterns of the low-lying hidden strangeness nucleon resonances ($\equiv N_{s\bar{s}}$) to the strangeness channels by employing the chiral Lagrangian approach, where the $N_{s\bar{s}}$ states are treated as compact pentaquark states. The $S$-wave decays of these states to the $PB$ (pseudoscalar meson and baryon) and $VB$ (vector meson and baryon) channels are studied. According to the obtained masses and decay properties, we find four states, namely, $N_{s\bar{s}}(1874)$ with quantum numbers $I(J^{P})=1/2(1/2^{-})$, $N_{s\bar{s}}(1885)$ with $I(J^{P})=1/2(3/2^{-})$, $N_{s\bar{s}}(2327)$ with $I(J^{P})=1/2(1/2^{-})$, and $N_{s\bar{s}}(2252)$ with $I(J^{P})=1/2(3/2^{-})$, may be associated to the well established nucleon resonances $N^*(1895)$, $N^{*}(1875)$, and the newly predicted $N^{*}(2355)$ and $N^{*}(2250)$ by CLAS collaboration, respectively. In addition, several other obtained hidden strangeness nucleon resonances may be expected to be dominant components of the predicted missing resonances in the literatures.

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arXiv2018

$\boldsymbolη$-$\boldsymbol{^4{\rm He}}$ interaction from the $\boldsymbol{d d \to η^4{\rm He}}$ reaction near threshold

We analyze the data on the total cross sections for the $dd \to η^4{\rm He}$ reaction close to threshold and look for possible $η^4 {\rm He}$ bound states. We develop a framework in which the $η^4{\rm He}$ optical potential is the key ingredient, rather than parameterizing the scattering matrix, as is usually done. The strength of this potential, together with some production parameters, are fitted to the available experimental data. The relationship of the scattering matrix to the optical potential is established using the Bethe-Salpeter equation and the $η^4{\rm He}$ loop function incorporates the range of the interaction given by the experimental $^4 {\rm He}$ density. However, when we look for poles of the scattering matrix, we get poles in the bound region, poles in the positive energy region or no poles at all. If we further restrict the results with constraints from a theoretical model with all its uncertainties the bound states are not allowed. However, we find a bump structure in $|T|^2$ of the $η^4{\rm He} \to η^4{\rm He}$ amplitude below threshold for the remaining solutions.

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arXiv2018

The three-pion decays of the $a_1(1260)$

We investigate the decay of $a^+_1(1260) \to π^+ π^+ π^-$ with the assumption that the $a_1(1260)$ is dynamically generated from the coupled channel $ρπ$ and $\bar{K}K^*$ interactions. In addition to the tree level diagrams that proceed via $a^+_1(1260) \to ρ^0 π^+ \to π^+π^+ π^-$, we take into account also the final state interactions of $ππ\to ππ$ and $K \bar{K} \to ππ$. We calculate the invariant $π^+ π^-$ mass distribution and also the total decay width of $a^+_1(1260) \to π^+ π^+ π^-$ as a function of the mass of $a_1(1260)$. The calculated total decay width of $a_1(1260)$ is significantly different from other model calculations and tied to the dynamical nature of the $a_1(1260)$ resonance. The future experimental observations could test of model calculations and would provide vary valuable information on the relevance of the $ρπ$ component in the $a_1(1260)$ wave function.

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arXiv2018

Photoproduction of $f_0(980)$ and $f_0(1500)$ resonances off a proton target

We study the $γp \to p f_0$ [$f_0(980)$ and $f_0(1500)$] reaction close to threshold within an effective Lagrangian approach. The production process is described by $s$-channel nucleon pole or $t$-channel $ρ$ and $ω$ exchange. The $K^0 \bar{K}^0$ invariant mass distributions of the $γp\to f_0(980)p \to K^0 \bar{K}^0$ and $γp\to f_0(1500)p \to K^0 \bar{K}^0 p$ reactions are investigated, where the two kaons have been separated in $S$ wave decaying from $f_0(980)$ and $f_0(1500)$. It is shown that the $s$-channel process is favored for the production of $f_0(980)$, while for the $f_0(1500)$ production, the experimental measurements can be described quite well by the $t$-channel process. It is expected that the theoretical results can be tested by further experiments at CLAS.

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arXiv2018

$Ξ$(2030) and $Ξ$(2120) as $\bar{K}^*Σ$ molecular states

In this work, the molecular states from the \bar{K}^{*}Σinteraction are studied in a quasipotential Bethe-Salpeter equation approach with the one-boson-exchange potentials. We consider the exchanges of vector (ρ,ωand ϕ) mesons and pseudoscalar (πand η) mesons to describe the \bar{K}^{*}Σinteraction with the coupling constants determined by the SU(3) symmetry, The poles of the scattering amplitude are searched for to find the molecular states dynamically generated from the \bar{K}^{*}Σinteraction. A bound state with quantum number I(J^{p})=1/2(5/2^{+}) is produced, which can be associated to the Ξ(2030) baryon. Other bound states with J\le{}5/2 are also searched for and it is found that there exist bound states with quantum numbers I(J^P)=1/2(1/2^-), 1/2(3/2^{-}), and 1/2(3/2^+). The Ξ(2120) may be a candidate for one of these three bound states. In addition, we also find two bound states with isospin 3/2 and spin parities 1/2^- and 1/2^+.

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