Isospin 0 and 1 resonances fromπΣphotoproduction data

Abstract

Recently we presented a successful strategy to extract the position of the two (1405) poles from experimental photoproduction data on the γp → K + π 0 0 reaction at Jefferson Lab. Following a similar strategy, we extend the previous method to incorporate also the isospin 1 component which allows us to consider in addition the experimental data on γp → K + π ± ∓ . The idea is based on considering a production mechanism as model independent as possible and implementing the final state interaction of the final meson-baryon pair based on small modifications of the unitary chiral perturbation theory amplitudes. Good fits to the data are obtained with this procedure, by means of which we can also predict the cross sections for the K − p →KN, π , and π reactions for the different charge channels. Besides the two poles found for the (1405) resonance, we discuss the possible existence of an isospin 1 resonance in the vicinity of theKN threshold.

LHCb pentaquark as aD¯*Σc−<

“…(1), G i represents the meson-baryon loop function and t ij stands for the s-wave meson-baryon unitarized scattering amplitudes from ref. [28]. Note that the Λ(1405) is not included as an explicit degree of freedom but it appears dynamically in the highly non-linear dynamics involved in the unitarization procedure leading to the t ij amplitudes.…”

The two Λ(1405) poles from photoproduction data

“…We will refer the b, c and d coefficients by initial production (IP) parameters in the following. In [30,31] it is shown that already good results are obtained fitting only the IP parameters and keeping the chiral parameters like in the original works. But since we want to extract information from photoproduction, we can try to get results with better χ 2 /dof by allowing the basic chiral unitary model to vary slightly.…”

“…The potential parameters obtained are shown in table 1. In [31] we also discuss that no pole is found for I = 1 in the ordinary Riemann sheet, but there is a pole located at 1522 − 14i MeV in another unphysical Riemann sheet which does not produce a Breit-Wigner shape in the real axis but has instead the appearance of a pronounced cusp at theKN threshold.…”

Predictions for pentaquark states of hidden charm molecular nature and comparison with experiment

“…These amplitudes contain two poles for the Λ(1405) resonance at 1352−48i MeV and 1419−29i MeV [16]. The highest mass Λ(1405), couples mostly toKN, and is the one relevant in the present work.…”

“…In the chiral unitary scheme of [16] the Λ(1405) appears dynamically in the highly non-linear dynamics involved in the unitarization procedure showing up in the t i j amplitudes. These amplitudes contain two poles for the Λ(1405) resonance at 1352−48i MeV and 1419−29i MeV [16].…”