Partial-wave analysis ofK+-nucleon scattering

Abstract

We have performed a partial-wave analysis of K + -nucleon scattering in the momentum range from 0 to 1.5 GeV/c addressing the uncertainties of the results and comparing them with several previous analyses. It is found that the treatment of the reaction threshold behavior is particularly important. We find a T=0 scattering length which is not consistent with zero, as has been claimed by other analyses. The T=0 phase shifts for ℓ > 0 are consistent with a pure spin-orbit potential. Some indications for the production of a T=0 pentaquark with spin-parity D5/2+ are discussed.

Study of theKN−K*Ncoupled system ins-wave

“…[37] where a scattering length of the order of 10 −7 fm was obtained. While a nearly zero scattering length is compatible with the results of some older partial wave analyses [61], some other report values varying between −0.1 fm [20] (which is the most recent one) to −0.4 fm [23]. To reproduce these values and the available data on the S 01 (representing L Isospin, 2×Spin ) partial wave KN phase shifts [20][21][22], it is required to go beyond the KN interaction obtained from the lowest order chiral Lagrangian.…”

“…As can be seen from this figure, the isospin 1 phase shifts data [20][21][22] (shown in the right panel) can be reasonably reproduced by considering KN channel alone and by using the parameter set I (dashed line). The phase shifts in isospin 0 are zero in this case.…”

“…We, thus, make χ 2 -fits to the data [20][21][22] on the s-wave isospin 0 and 1 KN phase shifts to fix the subtraction constants. We treat the subtraction constants as free parameters, with the motivation to obtain KN amplitudes in agreement with the data and, hence, obtain constrained predictions for the K * N amplitudes.…”

“…(1) and obtain the scattering matrix for the KN -K * N system. The subtraction constants b KN and b K * N present in the loop functions of KN and K * N are fixed by fitting the data available from the partial wave analysis groups [20][21][22] on the isospin 0 and 1 KN phase shifts (δ 0 KN and δ 1 KN , respectively), which, in our formalism, are related to the scattering matrix through the relations [43] T I,S = η I,S e 2iδ I,S − 1 2i ,…”

“…Although the KN and K * N thresholds are not as close as the preceding examples, as we shall explain in the next section, it is important to couple them since the KN interaction in the isospin 0, spin 1/2 configuration is null. The coupling to the K * N system, then, is useful to obtain non-zero phase shifts and scattering lengths and compare them with those available from the partial wave analyses of the relevant experimental data [20][21][22][23].…”