arXiv subjects

Ju-Jun Xie

Publications and source records attributed to Ju-Jun Xie.

At least 199 records · Page 11Linked to original sources

arXiv2012

Evidence for a narrow $D_{03}$ state in $K^- p \rightarrow ηΛ$ near threshold

Recently, we reported a theoretical study on the $K^- p \to ηΛ$ reaction near threshold by using an effective Lagrangian approach. It was found that the description of angular distribution data measured by the Crystal Ball Collaboration needs a $D_{03}$ resonance with mass $M=1668.5\pm 0.5$ MeV and total decay width $Γ=1.5\pm 0.5$ MeV, which is not the conventional $Λ$(1690) or other $Λ$ state listed in the Particle Data Group book. In the present work, we study the $Λ$ polarization in the $K^- p \to ηΛ$ reaction within the same framework. The results show that the existence of this narrow $D_{03}$ state is also compatible with current $Λ$ polarization data and that the more accurate $Λ$ polarization data at $P_{K^-}=735$MeV can offer further evidence for the existence of this resonance. Furthermore, the role of the $Λ(1690)$ resonance in this reaction is also discussed.

hep-ph↗

arXiv2012

The $K^- p \rightarrow ηΛ$ reaction in an effective Lagrangian model

We report on a theoretical study of the $K^- p \to ηΛ$ reaction near threshold by using an effective Lagrangian approach. The role of $s-$channel $Λ(1670)$, $t-$channel $K^*$ and $u-$channel proton pole diagrams are considered. We show that the total cross sections data are well reproduced. However, only including the $s-$wave $Λ(1670)$ state and the background contribution from $t-$ and $u-$channel are not enough to describe the bowl structures in the angular distribution of $K^- p \to ηΛ$ reaction, which indicates that there should be higher partial waves contributing to this reaction in some energy region. Indeed, if we considered the contributions from a $D_{03}$ resonance, we can describe the bowl structures, however, a rather small width ($\sim 2$ MeV) of this resonance is needed.

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arXiv2012

The $DN$, $πΣ_c$ interaction in finite volume and the $Λ_c(2595)$ resonance

In this work the interaction of the coupled channels $DN$ and $πΣ_c$ in an SU(4) extrapolation of the chiral unitary theory, where the $Λ_c(2595)$ resonance appears as dynamically generated from that interaction, is extended to produce results in finite volume. Energy levels in the finite box are evaluated and, assuming that they would correspond to lattice results, the inverse problem of determining the phase shifts in the infinite volume from the lattice results is solved. We observe that it is possible to obtain accurate $πΣ_c$ phase shifts and the position of the $Λ_c(2595)$ resonance, but it requires the explicit consideration of the two coupled channels. We also observe that some of the energy levels in the box are attached to the closed $DN$ channel, such that their use to induce the $πΣ_c$ phase shifts via Lüscher's formula leads to incorrect results.

hep-ph↗

arXiv2012

Are there three Xi(1950) states?

Different experiments on hadron spectroscopy have long suspected the existence of several cascade states in the $1900-2000 {\rm MeV}$ region. They are usually labeled under the common name of $Ξ(1950)$. As we argue here, there are also theoretical reasons supporting the idea of several $Ξ(1950)$ resonances. In particular, we propose the existence of three $Ξ(1950)$ states: one of these states would be part of a spin-parity $(1/2)^{-}$ decuplet and the other two probably would belong to the $(5/2)^{+}$ and $(5/2)^{-}$ octets. We also identify which decay channels are the more appropriate for the detection of each of the previous states.

hep-ph↗

arXiv2011

The pp->p Lambda K+ and pp->p Sigma0 K+ reactions with chiral dynamics

We report on a theoretical study of the pp->p Lambda K+ and pp->p Sigma0 K+ reactions near threshold using a chiral dynamical approach. The production process is described by single-pion and single-kaon exchange. The final state interactions of nucleon-hyperon, K-hyperon and K-nucleon systems are also taken into account. We show that our model leads to a fair description of the experimental data on the total cross section of the pp->p Lambda K+ and pp->p Sigma0 K+ reactions. We find that the experimental observed strong suppression of Sigma0 production compared to Lambda production at the same excess energy can be explained. However, ignorance of phases between some amplitudes does not allow to properly account for the nucleon-hyperon final state interaction for the pp->p Sigma0 K+ reaction. We also demonstrate that the invariant mass distribution and the Dalitz plot provide direct information about the Lambda and Sigma0 production mechanism, and can be tested by experiments at COSY or HIRFL-CSR.

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arXiv2011

The pp -> p Lambda K+ and pp -> p Sigma0 K+ Reactions in the Chiral Unitary Approach

We study the pp -> p Lambda K+ and pp -> p Sigma0 K+ reactions near threshold by using a chiral unitary approach. We consider the single-pion and single-kaon exchange as well as the final state interactions of nucleon-hyperon, K-hyperon and K-nucleon systems. Our results on the total cross section of the pp -> p Lambda K+ reaction is consistent with the experimental data, and the experimental observed strong suppression of Sigma0 production compared to Lambda production at the same excess energy can also be explained in our model.

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arXiv2011

A new perspective on the $Δ_{5/2^{+}}(2000)$ puzzle

We argue that $Δ_{5/2^{+}}(2000)(\ast\ast),$ cataloged as a resonance in the Particle Data Book Review (PDG), should be interpreted instead as two distinctive resonances, $Δ_{5/2^{+}}(\sim1740)$ and $Δ_{5/2^{+}}(\sim2200)$. Our argument is based on a solution of the $πΔρ$ problem in a Fixed Center Approximation (FCA) to the Fadeev equations. $Δ_{5/2^{+}}(\sim1740)$ can then be interpreted as a $π-(Δρ)_{N(1675)}$ bound state. As a corollary $Δ_{1/2^{+}}(1750)(\ast)$ can be understood as a $πN_{1/2^{-}}(1650)$ bound state.

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arXiv2011

Resonance interpretation of the bump structure in the $γp \to K^+ Λ(1520)$ differential cross section

We investigate the $Λ(1520)$ photoproduction in the $\vecγ p \to K^+ Λ(1520)$ reaction within the effective Lagrangian method near threshold. In addition to the "background" contributions from the contact, $t-$channel $K$ exchange, and $s-$channel nucleon pole terms, which were already considered in previous works, the contribution from the nucleon resonance $N^*(2080)$ (spin-parity $J^P = 3/2^-$) is also considered. We show that the inclusion of the nucleon resonance $N^*(2080)$ leads to a fairly good description of the new LEPS differential cross-section data, and that these measurements can be used to determine some of the properties of this latter resonance.

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arXiv2011

A resonance interpretation for the nonmonotonic behavior of the phi-photoproduction cross section near threshold

We study whether the nonmonotonic behavior found in the differential cross section of the phi-meson photoproduction near threshold can be described by a resonance. The resonant contribution is evaluated by using an effective Lagrangian approach. We find that, with the assumption of a J^P=3/2^- resonance with mass of 2.10 \pm 0.03 GeV and width of 0.465 \pm 0.141 GeV, LEPS data can indeed be well described. The ratio of the helicity amplitudes A_1/2/A_3/2 calculated from the resulting coupling constants differs in sign from that of the known D13(2080). We further find that the addition of this postulated resonance can substantially improve the agreement between the existing theoretical predictions and the recent omega photoproduction data if a large value of the OZI evading parameter x_OZI = 12 is assumed for the resonance.

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arXiv2011

Faddeev fixed-center approximation to the $N\bar{K}K$ system and the signature of a $N^*(1920)(1/2^+)$ state

We perform a calculation for the three body $N \bar{K} K$ scattering amplitude 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. The resonant structures show up in the modulus squared of the three body scattering amplitude and suggest that a $N\bar{K}K$ hadron state can be formed. Our results are in agreement with others obtained in previous theoretical works, which claim a new $N^*$ resonance around 1920 MeV with spin-parity $J^P=1/2^+$. The existence of these previous works allows us to test the accuracy of the fixed center approximation in the present problem and sets the grounds for possible application in similar problems, as an explorative tool to determine bound or quasibound three hadron systems.

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arXiv2011

Delta rho pi interaction leading to N* and Delta* resonances

We have performed a calculation for the three body $Δρπ$ system by using the fixed center approximation to Faddeev equations, taking the interaction between $Δ$ and $ρ$, $Δ$ and$π$, and $ρ$ and $π$ from the chiral unitary approach. We find several peaks in the modulus squared of the three-body scattering amplitude, indicating the existence of resonances, which can be associated to known $I=1/2, 3/2$ and $J^P=1/2^+, 3/2^+$ and $5/2^+$ baryon states.

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arXiv2011

Plausible explanation of the $Δ_{5/2^{+}}(2000)$ puzzle

From a Faddeev calculation for the $π-(Δρ)_{N_{5/2^{-}}(1675)}$ system we show the plausible existence of three dynamically generated $I(J^{P})=3/2 (5/2^{+})$ baryon states below 2.3 GeV whereas only two resonances, $Δ_{5/2^{+}}(1905)(\ast\ast\ast\ast)$ and $Δ_{5/2^{+}}(2000)(\ast\ast),$ are cataloged in the Particle Data Book Review. Our results give theoretical support to data analyses extracting two distinctive resonances, $Δ_{5/2^{+}}(\sim1740)$ and $Δ_{5/2^{+}}(\sim2200),$ from which the mass of $Δ_{5/2^{+}}(2000)(\ast\ast)$ is estimated. We propose that these two resonances should be cataloged instead of $Δ_{5/2^{+}}(2000).$ This proposal gets further support from the possible assignment of the other baryon states found in the approach in the $I=1/2,3/2$ with $J^{P}=1/2^{+},3/2^{+},5/2^+$ sectors to known baryonic resonances. In particular, $Δ_{1/2^{+}}(1750)(\ast)$ is naturally interpreted as a $πN_{1/2^{-}}(1650)$ bound state.

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arXiv2010

The role of the $N^*(2080)$ resonance in the $\vecγ p \to K^+ Λ(1520)$ reaction

We investigate the $Λ(1520)$ photo-production in the $\vecγ p \to K^+ Λ(1520)$ reaction within the effective Lagrangian method near threshold. In addition to the "background" contributions from the contact, $t-$channel $K$ exchange, and $s-$channel nucleon pole terms, which were already considered in previous works, the contribution from the nucleon resonance $N^*(2080)$ (spin-parity $J^P = 3/2^-$) is also considered. We show that the inclusion of the nucleon resonance $N^*(2080)$ leads to a fairly good description of the new LEPS differential cross section data, and that these measurements can be used to determine some of the properties of this latter resonance. However, serious discrepancies appear when the predictions of the model are compared to the photon-beam asymmetry also measured by the LEPS Collaboration.

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arXiv2010

Associated strangeness production in the pp to pK^+K^-p and pp to pK^+ pi^0 Sigma^0 reactions

The total and differential cross sections for associated strangeness production in the $pp \to pK^+K^-p$ and $pp \to pK^+π^0Σ^0$ reactions have been studied in a unified approach using an effective Lagrangian model. It is assumed that both the $K^-p$ and $π^0Σ^0$ final states originate from the decay of the $Λ(1405)$ resonance which was formed in the production chain $pp\to p(N^*(1535)\to K^+Λ(1405))$. The available experimental data are well reproduced, especially the ratio of the two total cross sections, which is much less sensitive to the particular model of the entrance channel. The significant coupling of the $N^*(1535)$ resonance to $Λ(1405) K$ is further evidence for large $s \bar{s}$ components in the quark wave function of the $N^*(1535)$ resonance.

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arXiv2010

Is the nonmonotonic behavior in the cross section of phi photoproduction near threshold a signature of a resonance?

We study whether the nonmonotonic behavior found in the differential cross section of the phi-meson photoproduction near threshold can be described by a resonance. Namely, we add a resonance to a model consisting of Pomeron and (pi,eta) exchange by fiat and see if, with a suitable assignment of spin and parity, mass and width, as well as the coupling constants, one would be able to obtain a good description to all the data reported by the LEPS collaboration in the low-energy region. The resonant contribution is evaluated by using an effective Lagrangian approach. We find that, with the assumption of a J^P=3/2^- resonance with mass of 2.10 +- 0.03 GeV and width of 0.465 +- 0.141 GeV, LEPS data can indeed be well described. The ratio of the helicity amplitudes A_(1/2)/A_(3/2) calculated from the resulting coupling constants differs in sign from that of the known D13(2080). We further find that the addition of this postulated resonance can substantially improve the agreement between the existing theoretical predictions and the recent omega photoproduction data if a large value of the OZI evading parameter x_OZI = 12 is assumed for the resonance.

hep-ph↗

arXiv2009

Strangeness production from pp collisions

The study of the strangeness production from pp collisions plays important roles in two aspects: exploring the properties of baryon resonances involved and understanding the strangeness production from heavy ion collisions to explore the properties of high energy and high density nuclear matter. Here we review our recent studies on several most important channels for the strangeness production from pp collisions. The previously ignored contributions from Delta*(1620) and N*(1535) resonances are found to play dominant role for the pp --> n K+ Sigma+, pp --> pK+ Lambda and pp --> pp phi reactions near-thresholds. These contributions should be included for further studies on the strangeness production from both pp collisions and heavy ion collisions.

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arXiv2009

Evidence of N*(1535) resonance contribution in the pn->dϕreaction

The N*(1535) resonance contributions to the pn->dϕreaction are evaluated in an effective Lagrangian model. The π-, η-, and ρ-meson exchange are considered. It is shown that the contributions from π- and ρ-meson exchange are dominant, while the contribution from η-meson exchange is negligibly small. Our theoretical results reproduce the experimental data of both total cross section and angular distribution well. This is another evidence that the N*(1535) resonance has large s\bar{s} component leading to a large coupling to Nϕ, which may be the real origin of the OZI rule violation in the \piN and pN reactions.

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arXiv2009

Role of the N*(1440) resonance in the pp->pnpi+ reaction

New measurement by CELSIUS-WASA Collaboration on the pp->pn pi+ reaction reveals clear evidence for the presence of the Roper resonance N*(1440) which has been ignored in previous theoretical calculations. In this article, based on an effective Lagrangian approach and available knowledge on the Roper resonance, we investigate the role of the Roper resonance for the pp->pn pi+ reaction. It is found that the contribution from the Roper resonance N*(1440) becomes significant for kinetic energy above 1.1 GeV, consistent with the new experimental observation. The t-channel sigma-meson exchange is dominant for the production of the Roper resonance.

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