arXiv subjects

Ju-Jun Xie

Publications and source records attributed to Ju-Jun Xie.

At least 127 records · Page 7Linked to original sources

arXiv2018

$D Ξ$ and $D^* Ξ$ Molecular States from One Boson Exchange

We explore the existence of $D Ξ$ and $D^* Ξ$ molecular states within the one boson exchange model. We regularize the potential derived in this model with a form factor and a cut-off of the order of $1\,{\rm GeV}$. To determine the cut-off, we use the condition that the $X(3872)$ is reproduced as a pole in the $J^{PC} = 1^{++}$ $D^*\bar{D}$ amplitude. From this we find that the $J^P= {\frac{1}{2}}^{-}$ $D^*\,Ξ$ system is on the verge of binding and has an unnaturally large scattering length. For the $J^P= {\frac{1}{2}}^{-}$ $D\,Ξ$ and the $J^P= {\frac{3}{2}}^{-}$ $D^*\,Ξ$ systems the attraction is not enough to form a bound state. From heavy quark symmetry and the quark model we can extend the previous model to the $P Ξ_{QQ}$ and $P^* Ξ_{QQ}$ systems, with $P = D, \bar{B}$, $P^* = D^*, \bar{B}^*$ and $Ξ_{QQ} = Ξ_{cc}, Ξ_{bb}$. In this case we predict a series of triply heavy pentaquark-like molecules.

hep-ph↗

arXiv2018

Strong decay modes $\bar{K}Ξ$ and $\bar{K}Ξπ$ of the $Ω(2012)$ in the $\bar{K}Ξ(1530)$ and $ηΩ$ molecular scenario

We study the $\bar{K} Ξ$ decay mode of the newly observed $Ω(2012)$ assuming that the $Ω(2012)$ is a dynamically generated state with spin-parity $J^P = 3/2^-$ from the coupled channel $S$-wave interactions of $\bar{K}Ξ(1530)$ and $ηΩ$. In addition we also calculate its $KπΞ$ three-body decay mode. It is shown that the so-obtained total decay width is in fair agreement with the experimental data. We compare our results with those of other recent studies and highlight differences among them.

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arXiv2018

The $X(4140)$ and $X(4160)$ resonances in the $e^+e^-\to γJ/ψϕ$ reaction

We investigate the $J/ψϕ$ invariant mass distribution of the $e^+e^-\to γJ/ψϕ$ reaction at a center of mass energy of $\sqrt{s}=4.6$~GeV measured by the BESIII collaboration, who concludes that no significant signals are observed for $e^+e^- \to γX(4140)$ because of the low statistics. We show, however, that the three bump structures in the $J/ψϕ$ invariant mass distribution, though given only by three data points, are compatible with the existence of the $X(4140)$ state, appearing as a peak, and a strong cusp structure at the $D^*_s\bar{D}^*_s$ threshold, resulting from the molecular nature of the $X(4160)$ state, which also provides a substantial contribution to the reaction. This is consistent with our previous analysis on the $B^+\to J/ψϕK^+$ decay measured by the LHCb collaboration. We strongly call for the measurement of this process with more statistics to further pin down the nature of the $X(4140)$ and $X(4160)$ resonances.

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arXiv2018

Triangle singularity enhancing isospin violation in $\bar B_s^0 \to J/ψπ^0 f_0(980)$

We perform calculations for the $\bar B_s^0 \to J/ψπ^0 f_0(980)$ and $\bar B_s^0 \to J/ψπ^0 a_0(980)$ reactions, showing that the first one is isospin-suppressed while the second one is isospin-allowed. The reaction proceeds via a triangle mechanism, with $\bar B_s^0 \to J/ψK^* \bar K +c.c.$, followed by the decay $K^* \to Kπ$ and a further fusion of $K\bar K$ into the $f_0(980)$ or $a_0(980)$. We show that the mechanism develops a singularity around the $π^0 f_0(980)$ or $π^0 a_0(980)$ invariant mass of 1420 MeV where the $π^0 f_0$ and $π^0 a_0$ decay modes are magnified and also the ratio of $π^0 f_0$ to $π^0 a_0$ production. Using experimental information for the $\bar B_s^0 \to J/ψK^* \bar K +c.c.$ decay, we are able to obtain absolute values for the reactions studied which fall into the experimentally accessible range. The reactions proposed and the observables evaluated, when contrasted with actual experiments should be very valuable to obtain information on the nature of the low lying scalar mesons.

hep-ph↗

arXiv2018

Production and mixing of scalar mesons in $η_c$ and $χ_{c1}$ decays

We briefly discuss how the chiral unitary approach in coupled channels and $SU(3)$ symmetry can be used to describe the production of $f_0(500)$, $f_0(980)$ and $a_0(980)$ in the $χ_{c1} \to ηπ^+ π^-$ reaction, recently measured by the BESIII collaboration. In this reaction a very strong peak for the $a_0(980)$ can be seen in the $ηπ$ invariant mass, while clear signals for the $f_0(500)$ and $f_0(980)$ appear in the one of $π^+π^-$. Next, we show the predictions made with the same model for the analogous decay $η_c \to ηπ^+ π^-$, which could also be measured experimentally. We discuss the differences of these two reactions which are interesting to test the picture where these scalar mesons are dynamically generated from the interaction of pairs of pseudoscalars. Furthermore, we comment on a new recent work where the same model was used to study the $a_0(980) - f_0(980)$ mixing in the $χ_{c1} \to π^0 π^0 η$ and $χ_{c1} \to π^0 π^+ π^-$ reactions, showing that quantitative agreement with the experimental measurement of this mixing, also performed by BESIII, can be obtained, revealing interesting aspects of the dynamics of this process and the importance of coupled channels.

hep-ph↗

arXiv2018

The bottomed strange molecules with isospin 0

Using the local hidden gauge approach, we study the possibility of the existence of bottomed strange molecular states with isospin 0. We find three bound states with spin-parity $0^+$, $1^+$ and $2^+$ generated by the $\bar{K}^*B^*$ and $ωB_s^*$ interaction, among which the state with spin 2 can be identified as $B_{s2}^*(5840)$. In addition, we also study the $\bar{K}^*B$ and $ωB_s$ interaction and find a bound state which can be associated to $B_{s1}(5830)$. Besides, the $\bar{K}B^*$ and $ηB_s^*$ and $\bar{K}B$ and $ηB_s$ systems are studied, and two bound states are predicted. We expect that further experiments can confirm our predictions.

hep-ph↗

arXiv2018

Hidden charm pentaquark and $Λ(1405)$ in the $Λ^0_b \to η_c K^- p (πΣ)$ reaction

We have performed a study of the $Λ^0_b \to η_c K^- p$ and $Λ^0_b \to η_c πΣ$ reactions based on the dominant Cabibbo favored weak decay mechanism. We show that the $K^- p$ produced only couples to $Λ^*$ states, not $Σ^*$ and that the $πΣ$ state is only generated from final state interaction of $\bar{K}N$ and $ηΛ$ channels which are produced in a primary stage. This guarantees that the $πΣ$ state is generated in isospin $I=0$ and we see that the invariant mass produces a clean signal for the $Λ(1405)$ of higher mass at $1420$ MeV. We also study the $η_c p$ final state interaction, which is driven by the excitation of a hidden charm resonance predicted before. We relate the strength of the different invariant mass distributions and find similar strengths that should be clearly visible in an ongoing LHCb experiment. In particular we predict that a clean peak should be seen for a hidden charm resonance that couples to the $η_c p$ channel in the invariant $η_c p$ mass distribution.

hep-ph↗

arXiv2018

$\bar{B}^0$, $\bar{B}^0_s$ and $B^-$ decays into $η_c$ plus a scalar meson

We investigate the decays of $\bar{B}^0_s$, $\bar{B}^0$ and $B^-$ into $η_c$ plus a scalar meson in a theoretical framework by taking into account the dominant process for the weak decay of $\bar{B}$ meson into $η_c$ and a $q\bar{q}$ pair. After hadronization of this $q\bar{q}$ component into pairs of pseudoscalar mesons we obtain certain weights for the pseudoscalar meson-pseudoscalar meson components. The calculation is based on the postulation that the scalar mesons $f_0(500)$, $f_0(980)$ and $a_0(980)$ are dynamically generated states from the pseudoscalar meson-pseudoscalar meson interactions in $S$-wave. Up to a global normalization factor, the $ππ$, $K \bar{K}$ and $πη$ invariant mass distributions for the decays of $\bar B^0_s \to η_c π^+ π^-$, $\bar{B}^0_s \to η_c K^+ K^-$, $\bar B^0 \to η_c π^+ π^-$, $\bar{B}^0 \to η_c K^+ K^-$, $\bar{B}^0 \to η_c π^0 η$, $B^- \to η_c K^0 K^-$ and $B^- \to η_c π^- η$ are predicted. Comparison is made with the limited experimental information available and other theoretical calcualtions. Further comparison of these results with coming LHCb measurements will be very valuable to make progress in our understanding of the nature of the low lying scalar mesons, $f_0(500), f_0(980)$ and $a_0(980)$.

hep-ph↗

arXiv2017

The radiative decay $D^0 \to \bar{K}^{*0} γ$ with vector meson dominance

Motivated by the experimental measurements of $D^0$ radiative decay modes we have proposed a model to study the $D^0\to \bar{K}^{*0}γ$ decay, by establishing a link with $D^0\to \bar{K}^{*0}V$ $(V=ρ^0,\, ω)$ decays through the vector meson dominance hypothesis. In order to do this properly, we have used the Lagrangians from the local hidden gauge symmetry approach to account for $Vγ$ conversion. As a result, we have found the branching ratio $\mathcal{B}[D^0\to \bar{K}^{*0}γ] =(1.55 - 3.44)\times 10^{-4}$, which is in fair agreement with the experimental values reported by Belle and Babar collaborations.

hep-ph↗

arXiv2017

Production of the charmoniumlike state $Y(4220)$ through the $p\bar{p} \to Y(4220) π^0$ reaction

The $Y(4220)$ production in the process of $p\bar{p} \to Y(4220)π^0$ is studied within the effective Lagrangian approach. We first study the $e^+e^-\to Y(4220) \to p\bar{p}π^0$ reaction at center-of-mass energy $4.258$ GeV with the assumption that the $Y(4220)$ is a $ψ(4S)$ state. We show that the inclusion of nucleon and nucleon resonance leads to a quite good description of the experimental data of $π^0 p$ and $π^0 \bar{p}$ invariant mass distributions. Then, the total and angular distributions of the $p\bar{p} \to Y(4220)π^0$ reaction are investigated. It is shown that the nucleon pole is dominant but the contributions from excited nucleon resonances are non-negligible. The $p\bar{p} \to Y(4220)π^0$ reaction is useful for studying the property of $Y(4220)$ and our calculated results may be tested at the forthcoming $\overline{\mbox{P}}$ANDA experiments.

hep-ph↗

arXiv2017

Analysis of the $B^+\to J/ψϕK^+$ data at low $J/ψϕ$ invariant masses and the $X(4140)$ and $X(4160)$ resonances

We have studied the $J/ψϕ$ mass distribution of the $B^+\to J/ψϕK^+$ reaction from threshold to about 4250 MeV, and find that one needs the contribution of the $X(4140)$ with a narrow width, together with the $X(4160)$ which accounts for most of the strength of the distribution in that region. The existence of a clear cusp at the $D_s^* \bar{D}_s^*$ threshold indicates that the $X(4160)$ resonance is strongly tied to the $D_s^* \bar{D}_s^*$ channel, which finds a natural interpretation in the molecular picture of this resonance.

hep-ph↗

arXiv2017

Triangular singularity and a possible $ϕp$ resonance in the $Λ^+_c \to π^0 ϕp$ decay

We study the $Λ^+_c \to π^0 ϕp$ decay by considering a triangle singularity mechanism. In this mechanism, the $Λ^+_c$ decays into the $K^* Σ^*(1385)$, the $Σ^*(1385)$ decays into the $π^0 Σ$ (or $Λ$), and then the $K^* Σ$ (or $Λ$) interact to produce the $ϕp$ in the final state. This mechanism produces a peak structure around $2020$ MeV. In addition, the possibility that there is a hidden-strange pentaquark-like state is also considered by taking into account the final state interactions of $K^* Λ$, $K^* Σ$, and $ϕp$. We conclude that it is difficult to search for the hidden-strange analogue of the $P_c$ states in this decay. However, we do expect nontrivial behavior in the $ϕp$ invariant mass distribution. The predictions can be tested by experiments such as BESIII, LHCb and Belle-II.

hep-ph↗

arXiv2017

Production of $f_0(500)$, $f_0(980)$ and $a_0(980)$ in the $χ_{c1} \to ηπ^+ π^-$ and $η_c \to ηπ^+ π^-$ decays

Using the chiral unitary approach in coupled channels and $SU(3)$ symmetry we describe the production of $f_0(500)$, $f_0(980)$ and $a_0(980)$ in the $χ_{c1} \to ηπ^+ π^-$ reaction, recently performed by the BESIII collaboration. A very strong peak for the $a_0(980)$ can be seen in the $ηπ$ invariant mass, while clear signals for the $f_0(500)$ and $f_0(980)$ appear in the one of $π^+π^-$. Next, we make predictions for the analogous decay $η_c \to ηπ^+ π^-$, which could also be measured experimentally. We discuss the differences of these reactions which are interesting to test the picture where these scalar mesons are dynamically generated from the interaction of pairs of pseudoscalars.

hep-ph↗

arXiv2017

Role of the $N^*(1535)$ in the $Λ^+_c \to \bar{K}^0 ηp$ decay

The nonleptonic weak decay of $Λ^+_c \to \bar{K}^0 ηp$ is analyzed from the viewpoint of probing the $N^*(1535)$ resonance, which has a big decay branching ratio to $ηN$. Up to an arbitrary normalization, the invariant mass distribution of $ηp$ is calculated with both the chiral unitary approach and an effective Lagrangian model. Within the chiral unitary approach, the $N^*(1535)$ resonance is dynamically generated from the final state interaction of mesons and baryons in the strangeness zero sector. For the effective Lagrangian model, we take a Breit-Wigner formula to describe the distribution of the $N^*(1535)$ resonance. It is found that the behavior of the $N^*(1535)$ resonance in the $Λ^+_c \to \bar{K}^0 N^*(1535) \to \bar{K}^0 ηp$ decay within the two approaches is different. The proposed $Λ^+_c$ decay mechanism can provide valuable information on the properties of the $N^*(1535)$ and can in principle be tested by facilities such as BEPC II and SuperKEKB.

hep-ph↗

arXiv2017

$Σ^*_{1/2^-}(1380)$ in the $Λ^+_c \to ηπ^+ Λ$ decay

A $Σ^*$ state with spin-parity $J^P = 1/2^-$ with mass and width around $1380$ MeV and $120$ MeV, refereed to as the $Σ^*_{1/2^-}(1380)$, has been predicted in several pentaquark models and inferred from the analysis of CLAS $γp$ data. In the present work, we discuss how one can employ the $Λ^+_c \to ηπ^+ Λ$ decay to test its existence, as well as to study the $Σ^*(1385)$ state with $J^P = 3/2^+$. Because the final $π^+ Λ$ system is in a pure isospin $I = 1$ combination, the $Λ^+_c \to ηπ^+ Λ$ decay can be an ideal process to study these $Σ^*$ resonances. In particular, we show that the decay angle and energy distributions of the $π^+$ are very different for $Σ^*(1385)$ and $Σ^*_{1/2^-}(1380)$. The proposed decay mechanism as well as the existence of the $Σ^*_{1/2^-}(1380)$ state can be checked by future BESIII and Belle experiments.

hep-ph↗

arXiv2017

Faddeev fixed center approximation to $π\bar{K} K^*$ system and the $π_1(1600)$

We investigate the three-body system of $π\bar{K} K^*$ by using the fixed-center approximation to the Faddeev equation, taking the interaction between $π$ and $\bar{K}$, $π$ and $K^*$, and $\bar{K}$ and $K^*$ from the chiral unitary approach. The study is made assuming scattering of a $π$ on a $\bar{K} K^*$ cluster, which is known to generate the $f_1(1285)$ state. The resonant structure around $1650$ MeV shows up in the modulus squared of the $π$-$(\bar{K} K^*)_{f_1(1285)}$ scattering amplitude and suggests that a $π$-$(\bar{K} K^*)_{f_1(1285)}$ state, with "exotic" quantum numbers $J^{PC} = 1^{-+}$, can be formed. This state can be identified as the observed $π_1(1600)$ resonance. We suggest that this is the origin of the present $π_1(1600)$ resonance and propose to look at the $πf_1(1285)$ mode in future experiments to clarify the issue.

hep-ph↗

arXiv2017

$f_2(1810)$ as a triangle singularity

We perform calculations showing that a source producing $K^* \bar{K}^*$ in $J = 2$ and $L=0$ gives rise to a triangle singularity at $1810$ MeV with a width of about $200$ MeV from the mechanism $K^* \to πK$ and then $K\bar{K}^*$ merging into the $a_1(1260)$ resonance. We suggest that this is the origin of the present $f_2(1810)$ resonance and propose to look at the $πa_1(1260)$ mode in several reactions to clarify the issue.

hep-ph↗

arXiv2017

Role of a triangle singularity in the $γp\rightarrow K^+ Λ(1405)$ reaction

We show the effects of a triangle singularity mechanism for the $γp \to K^+Λ(1405)$ reaction. The mechanism has a $N^*$ resonance around 2030 MeV, which decays into $K^* Σ$. The $K^*$ decays to $K^+ π$, and the $πΣ$ merge to form the $Λ(1405)$. This mechanism produces a peak around $\sqrt{s} = 2110$ MeV, and has its largest contribution around cos$θ=0$. The addition of this mechanism to other conventional ones, leads to a good reproduction of ${\rm d}σ/{\rm dcos}θ$ and the integrated cross section around this energy, providing a solution to a problem encountered in previous theoretical models.

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