The WA3 data and the two $K_1(1270)$ resonances

Abstract

Recent studies based on unitary chiral perturbation theory (U$\chi$PT) found that the low-lying axial vector mesons can be dynamically generated due to the interaction of the pseudoscalar octet of the pion and the vector nonet of the rho. In particular, two poles in the second Riemann sheet have been associated to the nominal $K_1(1270)$ resonance. In this talk, we present a recent analysis of the WA3 data on $K^-p\to K^-\pi^+\pi^- p$ at 63 GeV using the U$\chi$PT amplitudes, and show that it is in favor of the existence of two $K_1(1270)$'s [Phys. Rev. D 75, 014017 (2007)].