arXiv subjects

Ju-Jun Xie

Publications and source records attributed to Ju-Jun Xie.

At least 163 records · Page 9Linked to original sources

arXiv2015

$B^0 \to D^0 \bar D^0 K^0$, $B^+ \to D^0 \bar D^0 K^+$ and the scalar $D \bar D$ bound state

We study the $B^0$ decay to $D^0 \bar D^0 K^0$ based on the chiral unitary model that generates the X(3720) resonance, and make predictions for the $D^0 \bar D^0$ invariant mass distribution. From the shape of the distribution, the existence of the resonance below threshold could be induced. We also predict the rate of production of the X(3720) resonance to the $D^0 \bar D^0$ mass distribution with no free parameters.

hep-ph↗

arXiv2015

The $K \bar K π$ decay of the $f_1(1285)$ and its nature as a $K^* \bar K -cc$ molecule

We investigate the decay of $f_1(1285) \to πK \bar K$ with the assumption that the $f_1(1285)$ is dynamically generated from the $K^* \bar{K} - cc$ interaction. In addition to the tree level diagrams that proceed via $f_1(1285) \to K^* \bar{K} - cc \to πK \bar K$, we take into account also the final state interactions of $K \bar K \to K \bar K$ and $πK \to πK$. The partial decay width and mass distributions of $f_1(1285) \to πK \bar K$ are evaluated. We get a value for the partial decay width which, within errors, is in fair agreement with the experimental result. The contribution from the tree level diagrams is dominant, but the final state interactions have effects in the mass distributions. The predicted mass distributions are significantly different from phase space and tied to the $K^* \bar{K} - cc$ nature of the $f_1(1285)$ state.

hep-ph↗

arXiv2015

$\bar K$ induced formation of the $f_0(980)$ and $a_0(980)$ resonances on proton targets

We perform a calculation of the cross section for nine reactions induced by $\bar K$ scattering on protons. The reactions studied are $K^-p \to Λπ^+ π^-$, $K^-p \to Σ^0 π^+ π^-$, $K^-p \to Λπ^0 η$, $K^-p \to Σ^0 π^0 η$, $K^-p \to Σ^+ π^- η$, $\bar K^0 p \to Λπ^+ η$, $\bar K^0 p \to Σ^0 π^+ η$, $\bar K^0 p \to Σ^+ π^+ π^-$, $\bar K^0 p \to Σ^+ π^0 η$. We find that in the reactions producing $π^+ π^-$ a clear peak for the $f_0(980)$ resonance is found, while no trace of $f_0(500)$ appears. Similarly, in the cases of $πη$ production a strong peak is found for the $a_0(980)$ resonance, with the characteristic strong cusp shape. Cross sections and invariant mass distributions are evaluated which should serve, comparing with future data, to test the dynamics of the chiral unitary approach used for the evaluations and the nature of these resonances.

nucl-th↗

arXiv2015

Role of $Λ(1670)$ in the $γp \to K^+ ηΛ$ reaction near threshold

The role of the $Λ(1670)$ resonance in the $γp \to K^+ ηΛ$ reaction near threshold is studied within an effective Lagrangian approach. We perform a calculation for the total and differential cross section of the $γp \to K^+ ηΛ$ reaction by including the contributions from the $Λ(1670)$ intermediate state decaying into $ηΛ$ dominated by $K^-$ and $K^{*-}$ mesons exchanges, the nucleon pole and $N^*(1535)$ resonance decaying into $K^+ Λ$ dominated by exchanges of $ω$ and $K^-$ mesons. Besides, the non-resonance process and contact terms to keep the total scattering amplitude gauge invariant are also considered. With our model parameters, the total cross section of this reaction is of the order of $1$ nanobarn at photon beam energy $E_γ \sim 2.5$ GeV. It is expected that our model predictions could be tested by future experiments.

nucl-th↗

arXiv2015

Nucleon resonances in the $π^- p \to K^0 Λ$ reaction near threshold

We investigate the two-body reaction $π^- p \to K^{0} Λ$ within the effective Lagrangian approach and the isobar model. In addition to the "background" contributions from $t$-channel $K^*$ exchange, $u$-channel $Σ(1192)$ and $Σ^*(1385)$ exchanges, and $s$-channel nucleon pole terms, the contributions from the nucleon resonances $N^*(1535)$, $N^*(1650)$, and $N^*(1720)$ are investigated. It is shown that the inclusion of these nucleon resonances contributions leads to a good description of the experimental total and differential cross sections data at low energy region. The $s$-channel $N^*(1535)$, $N^*(1650)$, and $N^*(1720)$ resonances and the $t$-channel $K^*$ exchange give the dominant contributions below $W = 1.76$ GeV, while the $u$-channel $Σ(1192)$ and $Σ^*(1385)$ exchanges give the minor contributions.

nucl-th↗

arXiv2015

Nucleon resonances in the $γp \to ϕK^+ Λ$ reaction near threshold

We investigate the $γp \to ϕK^+ Λ$ reaction near threshold within an effective Lagrangian approach and the isobar model. Various nucleon resonances caused by the $π$ and $η$ meson exchanges and background contributions are considered. It is shown that the contribution from the $N^*(1535)$ resonance caused by the $η$ meson exchange plays the predominant role. Hence, this reaction provides a good new platform to study the $N^*(1535)$ resonance. The predicted total cross section and specific features of angular distributions can be tested by future experiments.

nucl-th↗

arXiv2015

Study of the $f_2(1270)$, $f'_2(1525)$, $\bar{K}^*_{2}(1430)$, $f_0(1370)$ and $f_0(1710)$ production from $ψ(nS)$ and $Υ(nS)$ decays

Based on previous studies that support the important role of the $f_2(1270)$, $f'_2(1525)$, and $\bar{K}^{*}_{2}(1430)$ resonances in the $J/ψ[ψ(2S)] \to ϕ(ω) VV$ decays, we make an analysis of the analogous decays of $Υ(1S)$ and $Υ(2S)$, taking into account recent experimental data. In addition, we study the $J/ψ$ and $ψ(2S)$ radiative decays and we also made predictions for the radiative decay of $Υ(1S)$ and $Υ(2S)$ into $γf_2(1270)$, $γf'_2(1525)$, $γf_0(1370)$ and $γf_0(1710)$, comparing with the recent results of a CLEO experiment. We can compare our results for ratios of decay rates with eight experimental ratios and find agreement in all but one case, where experimental problems are discussed.

hep-ph↗

arXiv2015

Effects of a $N^*$ resonance with hidden charm in the $π^- p \to D^- Σ_c^+$ reaction near threshold

We study the effect of a hidden charm nuclear excited state $N^*_{c\bar{c}}$ in the $π^- p \to D^- Σ_c^+$ reaction near threshold using an effective Lagrangian approach. We calculate the background contribution of the $t$ and $u$ channels by the $D^{*0}$ vector meson exchange and $Σ_c^{++}$ intermediate state, respectively. We show that the consideration of a $N^*_{c\bar{c}}$ resonance provides an enhancement of the total cross section close to the reaction threshold. We also evaluate the differential cross section for different energies and we study the angle dependence. It is expected that our model calculations will be tested in future experiments.

hep-ph↗

arXiv2015

Role of the $Λ^+_c(2940)$ in the $π^- p \to D^- D^0 p$ reaction close to threshold

We report on a theoretical study of the $π^- p \to D^- D^0 p$ reaction near threshold within an effective Lagrangian approach. The production process is described by $t$ channel $D^{*0}$ meson exchange, $s$-channel nucleon pole, and $u$ channel $Σ^{++}_{c}$ exchange. In our work, the final $D^0 p$ results from the ground $Λ^+_c(2286)$ state and also dominantly from the excited $Λ^+_c(2940)$ state which is assumed as a $D^{*0} p$ molecular state with spin parity $J^P = \frac{1}{2}^+$ or $\frac{1}{2}^-$. We calculate the total cross section of the $π^- p \to D^- D^0 p$ reaction. It is shown that the spin parity assignment of $\frac{1}{2}^-$ for $Λ^+_c(2940)$ gives a sizable enhancement for the total cross section in comparison with a choice of $J^p = \frac{1}{2}^+$. However, our theoretical result of the total cross section is sensitive to the value of the cutoff parameter involved in the form factor of the exchanged off-shell particles. Moreover, we also calculate the second order differential cross section and find it can be used to determine the parity of the $Λ^+_c(2940)$. It is expected that our model calculations can be tested by future experiments at J-PARC in Japan.

hep-ph↗

arXiv2015

Photoproduction of the $f_2(1270)$ resonance

We have performed a calculation of the $γp \to π^+ π^- p$ reaction, where the two pions have been separated in $D$-wave producing the $f_2(1270)$ resonance. We use elements of the local hidden gauge approach that provides the interaction of vector mesons in which the $f_2(1270)$ resonance appears as a $ρ$-$ρ$ molecular state in $L=0$ and spin 2. The vector meson dominance, incorporated in the local hidden gauge approach converts a photon into a $ρ^0$ meson and the other meson connects the photon with the proton. The picture is simple and has no free parameters, since the parameters of the theory have been constrained in the previous study of the vector-vector states. In a second step we introduce new elements, not present in the local hidden gauge approach, adapting the $ρ$ propagator to Regge phenomenology and introducing the $ρNN$ tensor coupling. We find that both the differential cross section as well as the $t$ dependence of the cross section are in good agreement with the experimental results and provide support for the molecular picture of the $f_2(1270)$ in the first baryonic reaction where it has been tested.

nucl-th↗

arXiv2015

Reexamination of the role of the $Δ^{\ast}$ resonances in the $pp\rightarrow nK^{+}Σ^{+}$ reaction

In this work, the role of the $Δ^{\ast }$ resonances in the process of $pp\rightarrow nK^{+}Σ^{+}$ are systematically investigated with the effective Lagrangian approach and the isobar model. We find that a $P_{31}$ state, either $Δ^{\ast }(1750)$ or $Δ^{\ast }(1910)$, is favored by the data while the $P_{33}$ state, namely $Δ^{\ast }(1920)$, has small contribution. Besides, either sub-threshold $S_{31}$ $Δ^{\ast }(1620)$ resonance or strong $nΣ$ final state interaction or both have possible contribution at near threshold region, depending on the measured cross sections. We demonstrate the invariant mass distributions and the Dalitz Plots in order to investigate whether it is possible to distinguish the controversial $KΣ$ production mechanism in these observables.

nucl-th↗

arXiv2015

Baryon resonances in the strangeness production

We have studied the $N^*(2120)$, $Δ^*(1940)$, and the possible $Σ^*(1380)$ resonances in the $γp \to K^+ Λ(1520)$, $pp \to n K^+ Σ(1385)$, and $Λp \to Λp π^0$ reactions within the resonance model and the effective Lagrangian approach. It is shown that when the contributions from these baryonic states were considered, the current experimental measurement could be well reproduced. In addition, we also demonstrate that the angular distributions provide direct information of these reactions, which could be useful for the investigation of those states and may be tested by future experiments.

nucl-th↗

arXiv2015

Looking for a hidden-charm pentaquark state with strangeness $S=-1$ from $Ξ^-_b$ decay into $J/ψK^- Λ$

Assuming that the recently observed hidden-charm pentaquark state, $P_c(4450)$, is of molecular nature as predicted in the unitary approach, we propose to study the decay of $Ξ^-_b\rightarrow J/ψK^- Λ$ to search for the strangeness counterpart of the $P_c(4450)$. There are three ingredients in the decay mechanism: the weak decay mechanism, the hadronization mechanism, and the finite state interactions in the meson-baryon system of strangeness $S=-2$ and isospin $I=1/2$ and of the $J/ψΛ$. All these have been tested extensively. As a result, we provide a genuine prediction of the differential cross section where a strangeness hidden-charm pentaquark state, the counterpart of the $P_c(4450)$, can be clearly seen. The decay rate is estimated to be of similar magnitude as the $Λ_b^0\rightarrow J/ψK^- p$ observed by the LHCb collaboration.

hep-ph↗

arXiv2015

Photoproduction of the $f'_2(1525)$ and $K^*_2(1430)$

Assuming that the $f'_2(1525)$ and $K^*_2(1430)$ resonances are dynamically generated states from the vector meson-vector meson interactions in $S$-wave with spin $S=2$, we study the $γp \to f'_2(1525) p$ and $γp \to K^*_2(1430) Λ(Σ)$ reactions. These reactions proceed in the following way: the incoming photon first mutates into a $ρ^0$, $ω$, or $ϕ$ meson via vector meson dominance, which then interacts with the $ρ^0$, $ω$ or $K^*$ emitted by the incoming proton to form the tensor mesons $f'_2(1525)$ and $K^*_2(1430)$. The picture is simple and has no free parameters, as all the parameters of the mechanism have been fixed in previous studies. We predict the differential and total cross sections of these reactions. The results can be tested in future experiments and therefore offer new clues on the nature of these tensor states.

nucl-th↗

arXiv2015

$\bar{B}^0$ and $\bar{B}^0_s$ decays into $J/ψ$ and $f_0(1370),~f_0(1710),~f_2(1270),~f'_2(1525),~K^*_2(1430)$

We make predictions for the ratios of branching fractions of ${\bar B}^0$ and ${\bar B}^0_s$ decays into $J/ψ$ and the scalar mesons $f_0(1370),~f_0(1710)$ or tensor mesons $f_2(1270),~f'_2(1525),~K^*_2(1430)$. The theoretical approach is based on results of chiral unitary theory where these resonances are shown to be generated from the vector meson-vector meson interaction. Eight independent ratios can be predicted and comparison is made with the recent data on $\bar{B}^0_s$ decay into $J/ψf'_2(1525)$ versus the $\bar{B}^0_s$ decay into $J/ψf_2(1270)$.

hep-ph↗

arXiv2015

$\bar B^0$ decay into $D^0$ and $f_0(500)$, $f_0(980)$, $a_0(980)$, $ρ$ and $\bar B^0_s$ decay into $D^0$ and $κ(800)$, $K^{*0}$

We make predictions for ratios of branching fractions of $\bar B^0$ decays into $D^0$ and the scalar mesons $f_0(500)$, $f_0(980)$, $a_0(980)$, plus $\bar B^0_s$ decay into $D^0$ and $κ(800)$. We also compare the $π^+ π^-$ production in the scalar channel with that observed in the $ρ$ channel and make predictions for the $\bar B^0_s$ decay into $D^0$ and $K^*(892)$, comparing the strength of this channel with that of $κ(800)$ production. The work is based on results of the chiral unitary approach where the scalar resonances are generated from the pseudoscalar-pseudoscalar interaction. Up to an arbitrary normalization, the mass distributions and rates for decays into the scalar resonances are predicted with no free parameters. Comparison with experimental data is done when available.

hep-ph↗

arXiv2015

Dynamically generated $J^P=1/2^-(3/2^-)$ singly charmed and bottom heavy baryons

Approximate heavy-quark spin and flavor symmetry and chiral symmetry play an important role in our understanding of the nonperturbative regime of strong interactions. In this work, utilizing the unitarized chiral perturbation theory, we explore the consequences of these symmetries in the description of the interactions between the ground-state singly charmed (bottom) baryons and the pseudo-Nambu-Goldstone bosons. In particular, at leading order in the chiral expansion, by fixing the only parameter in the theory to reproduce the $Λ_b(5912)$ [$Λ_b^*(5920)$] or the $Λ_c(2595)$ [$Λ_c^*(2625)$], we predict a number of dynamically generated states, which are contrasted with those of other approaches and available experimental data. In anticipation of future lattice QCD simulations, we calculate the corresponding scattering lengths and compare them to the existing predictions from a $\mathcal{O}(p^3)$ chiral perturbation theory study. In addition, we estimate the effects of the next-to-leading-order potentials by adopting heavy-meson Lagrangians and fixing the relevant low-energy constants using either symmetry or naturalness arguments. It is shown that higher-order potentials play a relatively important role in many channels, indicating that further studies are needed once more experimental or lattice QCD data become available.

hep-ph↗

arXiv2015

Predictions for the $\bar B^0 \to \bar K^{*0} X (YZ)$ and $\bar B^0_s \to ϕX (YZ)$ with $X(4160), Y(3940), Z(3930)$

We investigate the decay of $\bar B^0 \to \bar K^{*0} R$ and $\bar B^0_s \to ϕR$ with $R$ being the $X(4160)$, $Y(3940)$, $Z(3930)$ resonances. Under the assumption that these states are dynamically generated from the vector-vector interaction, as has been concluded from several theoretical studies, we use a reaction mechanism of quark production at the elementary level, followed by hadronization of one final $q \bar q$ pair into two vectors and posterior final state interaction of this pair of vector mesons to produce the resonances. With this procedure we are able to predict five ratios for these decays, which are closely linked to the dynamical nature of these states, and also predict the order of magnitude of the branching ratios which we find of the order of $10^{-4}$, well within the present measurable range. In order to further test the dynamical nature of these resonances we study the $\bar B^0_s \to ϕD^* \bar D^*$ and $\bar B^0_s \to ϕD_s^* \bar D_s^*$ decays close to the $D^* \bar D^*$ and $D_s^* \bar D_s^*$ thresholds and make predictions for the ratio of the mass distributions in these decays and the $\bar B^0_s \to ϕR$ decay widths. The measurement of these decays rates can help unravel the nature of these resonances.

hep-ph↗