Composite nature of the $\Lambda \left(1520\right)$ resonance

Recently, the Weinberg compositeness condition of a bound state was generalized to account for resonant states and higher partial waves. We apply this extension to the case of the $\Lambda \left(1520\right)$ resonance and quantify the weight of the meson-baryon components in contrast to other possible genuine building blocks. This resonance was theoretically obtained from a coupled channels analysis using the $s$-wave $\pi {\Sigma }^{*}$ and $K{\Xi }^{*}$ and the $d$-wave $\overline{K}N$ and $\pi \Sigma$ channels, applying the techniques of the chiral unitary approach. We obtain the result that this resonance is essentially dynamically generated from these meson-baryon channels, leaving room for only $15\%$ weight of other kinds of components in its wave function.

Figure 1

Fit no. 1 to the experimental amplitudes for the transitions $\overline{K}N\to \overline{K}N$ in (a) and (c), and $\overline{K}N\to \pi \Sigma$ in (b) and (d).