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Register a new user$Xi(1690)^-$ resonance production via $K^-p to K^+K^-Lambda$
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In this talk, we investigate $Xi(1690)^-$ production from the $K^-pto K^+K^-Lambda$ reaction wit the effective Lagrangian method and consider the $s$- and $u$-channel $Sigma/Lambda$ ground states and resonances for the $Xi$-pole contributions, in addition to the $s$-channel $Lambda$, $u$-channel nucleon pole, and $t$-channel $K^-$-exchange for the $phi$-pole contributions. The $Xi$-pole includes $Xi(1320)$, $Xi(1535)$, $Xi(1690)(J^p=1/2^-)$, and $Xi(1820)(J^p=3/2^-)$. We compute the Dalitz plot density of $(d^2sigma/dM_{K^+K^-}dM_{K^-Lambda}$ at 4.2 GeV$/c$) and the total cross sections for the $K^-pto K^+K^-Lambda$. Employing the parameters from the fit, we present the cross sections for the two-body $K^-pto K^+Xi(1690)^-$ reaction near the threshold. We also demonstrate that the Dalitz plot analysis for $p_{K^-}=1.915 sim2.065$ GeV/c makes us to explore direct information for $Xi(1690)^-$ production, which can be done by future $K^-$ beam experiments.
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In the present work, we investigate the hidden-strangeness production process in the $S=+1$ channel via $K^+pto K^+phi,p$, focussing on the exotic textit{pentaquark} molecular $K^*Sigma$ bound state, assigned by $P^+_s(2071,3/2^-)$. For this purpose, we employ the effective Lagrangian approach in the tree-level Born approximation. Using the experimental and theoretical inputs for the exotic state and for the ground-state hadron interactions, the numerical results show a small but obvious peak structure from $P^+_s$ with the signal-to-background ratio $approx1.7,%$, and it is enhanced in the backward-scattering region of the outgoing $K^+$ in the center-of-mass frame. We also find that the contribution from the $K^*(1680,1^-)$ meson plays an important role to reproduce the data. The proton-spin polarizations are taken into account to find a way to reduce the background. The effects of the possible $27$-plet pentaquark $Theta^{++}_{27}$ is discussed as well.
Various model-independent aspects of the $bar{K} N to K Xi$ reaction are investigated, starting from the determination of the most general structure of the reaction amplitude for $Xi$ baryons with $J^P=frac12^pm$ and $frac32^pm$ and the observables that allow a complete determination of these amplitudes. Polarization observables are constructed in terms of spin-density matrix elements. Reflection symmetry about the reaction plane is exploited, in particular, to determine the parity of the produced $Xi$ in a model-independent way. In addition, extending the work of Biagi $mathrm{textit{et al. } [Z. Phys. C textbf{34}, 175 (1987)]}$, a way is presented of determining simultaneously the spin and parity of the ground state of $Xi$ baryon as well as those of the excited $Xi$ states.
We study the $bar K p to Y Kbar K pi$ reactions with $bar K = bar K^0, K^-$ and $Y=Sigma^0, Sigma^+, Lambda$, in the region of $Kbar K pi$ invariant masses of $1200-1550$ MeV. The strong coupling of the $f_1(1285)$ resonance to $K^* bar K$ makes the mechanism based on $K^*$ exchange very efficient to produce this resonance observed in the $Kbar K pi$ invariant mass distribution. In addition, in all the reactions one observes an associated peak at $1420$ MeV which comes from the $K^* bar K$ decay mode of the $f_1(1285)$ when the $K^*$ is placed off shell at higher invariant masses. We claim this to be the reason for the peak of the $K^* bar K$ distribution seen in the experiments which has been associated to the $f_1(1420)$ resonance.
We investigate $S=-2$ production from the $Lambda pto K^+X$ reactions within the effective Lagrangian approach. The $Lambda pto K^+LambdaLambda$ and $Lambda pto K^+Xi^-p$ reactions are considered to find the lightest $S=-2$ system, which is $H$-dibaryon. We assume that the $H(2250)toLambdaLambda$, and $H(2270)toXi^-p$ decays with the intrinsic decay width of 1 MeV. According to our calculations, the total cross-sections for $Lambda pto K^+LambdaLambda$ and $Lambda pto K^+Xi^-p$ reactions were found to be of the order of a few $mu$b in the $Lambda$ beam momentum range of up to 5 GeV$/c$. Furthermore, the direct access of information regarding the interference patterns between the $H$-dibaryon and non-resonant contributions was demonstrated.
We investigate $S=-1$ hyperon production from the $Lambda_c^+to K^-ppi^+$ and $Lambda_c^+to K^0_Sppi^0$ decays within the effective Lagrangian approach. We consider the $Sigma/Lambda$ ground states, $Lambda(1520)$, $Lambda(1670)(J^p=1/2^-)$, $Lambda(1890)(J^p=3/2^+)$; $Lambda/Sigma$-pole contributions from the combined resonances between 1800 MeV and 2100 MeV; and $N/Delta$-pole and $K^ast$-pole contributions, which include the proton, $Delta(1232)$, and $K(892)$. We calculate the Dalitz plot density $(d^2Gamma/dM_{K^-p}dM_{K^-pi^+}$) for the $Lambda_c^+to K^-ppi^+$ decay. The calculated result is in good agreement with experimental data from the Belle Collaboration. Using the parameters from the fit, we present the Dalitz plot density for the $Lambda_c^+to K^0_Sppi^0$ decay. In our calculation, a sharp peak-like structure near 1665 MeV is predicted in the $Lambda_c^+to K^-ppi^+$ decay because of the interference effects between the $Lambda(1670)$ resonance and $eta$-$Lambda$ loop channels. We also demonstrate that we can access direct information regarding the weak couplings of $Lambda(1670)$ and $Sigma(1670)$ from the $Lambda_c^+to K^0_Sppi^0$ decay. Finally, a possible interpretation for the 1665 MeV structure beyond our prediction is briefly discussed.
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