The role of $Δ^{++*}(1620)$ resonances in $pp \to nK^+Σ^+$ reaction and its important implications
Abstract
Description
The $pp \to nK^+Σ^+$ reaction is a very good isospin 3/2 filter for studying $Δ^{++*}$ decaying to $K^+Σ^+$. With an effective Lagrangian approach, contributions from a previous ignored sub-$K^+Σ^+$-threshold resonance $Δ^{++*}(1620)1/2^-$ are fully included in addition to those already considered in previous calculations. It is found that the $Δ^{++*}(1620)1/2^-$ resonance gives an overwhelmingly dominant contribution for energies very close to threshold, with a very important contribution from the t-channel $ρ$ exchange. This solves the problem that all previous calculations seriously underestimate the near-threshold cross section by order(s) of magnitude. Many important implications of the results are discussed.
11 pages, 3 figures
11 pages, 3 figures