In this paper, we study the polarization of the $Λ(1405)$ in the $γp \rightarrow K^+ πΣ$ reaction within an effective Lagrangian approach and isobar model. In our model, the $Λ(1405)$ is excited through the t-channel $K/K^*$ exchanges and u-channel hyperon exchange. Compared to previous studies, we also include the contribution from a contact term, which is necessary for our model to interpret the polarization of the $Λ(1405)$. In addition, we also discuss the possibility to verify the proposed two-pole structure of the $Λ(1405)$ using the polarization data. We find that the polarization of the $Λ(1405)$ or the polarization of the final $Σ$ in this reaction is sensitive to the invariant mass $M_{πΣ}$. Thus the measurement of the dependence of the $Λ(1405)$ polarization on the $M_{πΣ}$ can offer valuable information about the pole structure of the $Λ(1405)$.
In this work, we make a theoretical study on the $p \bar p \rightarrow Λ\barΛη$ reaction for antiproton beam energy from threshold to 4GeV within an effective Lagrangian approach and isobar model. By assuming this reaction is dominated by the excitation of $Λ$ and $\bar Λ$ resonances in intermediate states, we calculate the total cross sections and give the predictions of the angular distribution and invariant mass spectrum of final particles. In particular, we discuss the possibility to verify the existence of a narrow $Λ$ resonance found in the process of $K^- p\to ηΛ$ in the present reactio…
Resonance model study on $K^+ N \rightarrow K N η$ near threshold
利用共振模型研究了$K^+ N \rightarrow K N η$反应,假定这些反应在阈值附近受$N^*(1535)$的激发控制.发现超子交换图和$ρ$交换图对这些反应的贡献最大。因此,这些反应可能是研究$N^*(1535)$与$KΛ$、$KΣ$和$Nρ$通道偶联的好地方。我们表明,最终粒子的角分布提供了有用的信息有关的不同机制的$N^*(1535)$激发,这可能是有用的,为未来的实验分析这些反应。
The $\bar{K} N \rightarrow K Ξ$ reaction in coupled channel chiral models up to next-to-leading order
本文采用次领先阶的手征SU(3)拉格朗日量,在耦合道中实现么正化,研究了奇异度S=-1扇区中s波中的介子-重子相互作用.拉格朗日的参数已被安装到一个大的实验数据在不同的两体通道,特别注意的$\bar{K} N \rightarrow K Ξ$反应,这是特别敏感的非线性光学条款。为了改进$KΞ$产生通道中的模型,唯象地考虑了高自旋超子共振$Σ(2030)$和$Σ(2250)$的影响.
The determination of the Argonne National Laboratory-Osaka University (ANL-Osaka) Partial-Wave Amplitudes (PWA) of $πN$ and $γN$ Reactions is reviewed. The predicted PWA are presented on a web page (https://www.phy.anl.gov/theory/research/anl-osaka-pwa). The formulas are given for using the predicted PWA to calculate the cross sections of (1) meson-baryon ($MB$) scattering $MB \rightarrow M'B'$ with $MB, M'B'= πN, ηN, KΛ, KΣ$, (2) two-pion production $πN \rightarrow πΔ, ρN, σN \rightarrow ππN$, (3) Meson photoproduction $γN \rightarrow πN, ηN, KΛ, KΣ$, (4) Pion electroproduction $N(e,e'π)N$, (…
Partial-wave analysis of $\bar K N$ scattering reactions
我们通过单能分波分析研究了两体反应$\bar K N\rightarrow \bar K N$、$\bar K N\rightarrow πΛ$和$\bar K N\rightarrow πΣ$。能量范围1480 - 2100 MeV。因此,提取的这些反应的分波振幅的多通道能量依赖模型满足的分波$S$矩阵的么正性的约束。我们得到了很好的预测微分截面,极化,极化截面,和截面这些反应从一个全球性的能量依赖的解决方案。
The $K^- p \rightarrow ηΛ$ reaction in an effective Lagrangian model
我们报告的理论研究的$K^- p \to ηΛ$反应阈值附近使用有效的拉格朗日方法。考虑了$s-$通道$Λ(1670)$、$t-$通道$K^*$和$u-$通道质子极图的作用。我们表明,总的截面数据是很好地再现。然而,仅考虑$s-$波$Λ(1670)$态以及$t-$和$u-$通道的背景贡献并不足以描述$K^- p \to ηΛ$反应角分布中的碗状结构,这表明在某些能量区域应该存在对该反应有贡献的较高分波.事实上,如果我们考虑来自$D_{03}$共振的贡献,我们可以描述碗结构,然而,需要相当小的宽度($\sim 2$ MeV)的这种共振。
In present work, we investigated $K^{-}+\, ^{3}\mathrm{He}$ reaction at low energies. The coupled-channel Faddeev AGS equations were solved for $\bar{K}Nd-πΣ{d}$ three-body system in momentum representation to extract the scattering amplitudes. To trace the signature of the $Λ$(1405) resonance in the $πΣ$ invariant mass, the deuteron energy spectrum for $K^{-}+\,^{3}\mathrm{He}\rightarrowπΣ{d}$ reaction was obtained. Different types of $\bar{K}N-πΣ$ potentials based on phenomenological and chiral SU(3) approaches were used. As a remarkable result of this investigation, it was found that the de…
Three-body calculations of $K\bar{K}N$ system with quantum numbers $I=1/2$, $J^π=(\frac{1}{2})^{+}$ were performed. Using separable potentials for two-body interactions, we calculated the $πΣ$ mass spectra for the $(\bar{K}N)_{I=0}+K^{+}\rightarrow(πΣ)^{0}K^{+}$ reaction on the basis of three-body Alt-Grassberger-Sandhas equations in the momentum representation. In this regard, different types of $\bar{K}N-πΣ$ potentials based on phenomenological and chiral SU(3) approach are used. The possibility to observe the trace of $Λ(1405)$ resonance in $(πΣ)^{0}$ mass spectra was studied. Using the $χ^…
Inspired by the observation of the pentaquark states $P_{c}(4312),P_{c}(4440)$ and $P_{c}(4457)$ at LHCb, photoproduction of these three $P_{c}$ states via the interaction $γp\rightarrow J/ψp$ is investigated in an effective Lagrangian approach. The $t$-channel Pomeron exchange diffractive process is considered as the main background for the $J/ψ$ photoproduction. The numerical results show that the theoretical cross section, which is calculated by assuming a branching ratio $Br[P_{c}\rightarrow J/ψp]\simeq 3\%$, is consistent with the existing experimental data of the $ γp\rightarrow J/ψp$ pr…
The ratio of di-lepton production cross sections on a proton, using the $γp\rightarrow l^+ l^- p$ process, above and below di-muon production threshold allows to extract the effective lepton-proton interaction, which is required to be identical for electrons and muons if lepton universality is exact. To test for a scenario of broken universality at the percent level, of the size which could explain the different proton charge radii extracted from electron scattering and from muonic hydrogen spectroscopy, we evaluate all one-loop QED corrections to this process, including the full lepton mass d…
The $f_{1}(1420)$ productions via pion and kaon induced reactions on a proton target are investigated in an effective Lagrangian approach. Two treatments of the $t$-channel Born term, the Feynman model and the Regge model, are introduced to calculate the total and differential cross sections of the $π^{-}p\rightarrow f_{1}(1420)n$ and $K^{-}p\rightarrow f_{1}(1420)Λ$ reactions. The numerical results indicate that the experimental data of the total cross section of the $π^{-}p\rightarrow f_{1}(1420)n$ reaction can be reproduced in both the Feynman and the Regge models. Based on the parameters d…
The dependence of the nucleon polarization in the reaction $e^+ + e^- \to N + \bar{N} +π^0 $ over different invariant variables in frame of the non-resonant mechanism, has been derived. The nucleon polarization is expressed in terms of six invariant complex amplitudes, assuming the conservation of the hadron electromagnetic currents and the P-invariance of the hadron electromagnetic interaction. An inclusive experimental setup when the proton (or the antiproton) and the pion are detected in coincidence is considered. Numerical estimations were performed for the so called normal polarization in…