No Arabic abstract
We show that the $Xi (1690)$ resonance can be dynamically generated in the $s$-wave $bar{K} Sigma$-$bar{K} Lambda$-$pi Xi$-$eta Xi$ coupled-channels chiral unitary approach. In our model, the $Xi (1690)$ resonance appears near the $bar{K} Sigma$ threshold as a $bar{K} Sigma$ molecular state and the experimental data are reproduced well. We discuss properties of the dynamically generated $Xi (1690)$.
The $rhorho$ interaction and the corresponding dynamically generated bound states are revisited. We demonstrate that an improved unitarization method is necessary to study the pole structures of amplitudes outside the near-threshold region. In this work, we extend the study of the covariant $rhorho$ scattering in a unitarized chiral theory to the $S$-wave interactions for the whole vector-meson nonet. We demonstrate that there are unphysical left-hand cuts in the on-shell factorization approach of the Bethe-Salpeter equation. This is in conflict with the correct analytic behavior and makes the so-obtained poles, corresponding to possible bound states or resonances, unreliable. To avoid this difficulty, we employ the first iterated solution of the $N/D$ method and investigate the possible dynamically generated resonances from vector-vector interactions. A comparison with the results from the nonrelativistic calculation is provided as well.
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.
We report the first observation of the doubly-strange baryon $Xi(1620)^0$ in its decay to $Xi^-pi^+$ via $Xi_c^+ rightarrow Xi^- pi^+ pi^+$ decays based on a $980,{rm fb}^{-1}$ data sample collected with the Belle detector at the KEKB asymmetric-energy $e^+ e^-$ collider. The mass and width are measured to be 1610.4 $pm$ 6.0 (stat) $^{+5.9}_{-3.5}$ (syst)~MeV$/c^2$ and 59.9 $pm$ 4.8 (stat) $^{+2.8}_{-3.0}$ (syst)~MeV, respectively. We obtain 4.0$sigma$ evidence of the $Xi(1690)^0$ with the same data sample. These results shed light on the structure of hyperon resonances with strangeness $S=-2$.
Recently, the compositeness, defined as the norm of a two-body wave function for bound and resonance states, has been investigated to discuss the internal structure of hadrons in terms of hadronic molecular components. From the studies of the compositeness, it has been clarified that the two-body wave function of a bound state can be extracted from the residue of the scattering amplitude at the bound state pole. Of special interest is that the two-body wave function from the scattering amplitude is automatically normalized. In particular, while the compositeness is unity for energy-independent interactions, it deviates from unity for energy-dependent interactions, which can be interpreted as a missing-channel contribution. In this manuscript, we show the formulation of the two-body wave function from the scattering amplitude, evaluate the compositeness for several dynamically generated resonances such as $f_{0} (980)$, $Lambda (1405)$, and $Xi (1690)$, and investigate their internal structure in terms of the hadronic molecular components.
We present a quantum error correcting code with dynamically generated logical qubits. When viewed as a subsystem code, the code has no logical qubits. Nevertheless, our measurement patterns generate logical qubits, allowing the code to act as a fault-tolerant quantum memory. Our particular code gives a model very similar to the two-dimensional toric code, but each measurement is a two-qubit Pauli measurement.