Baryonic resonances close to theK¯Nthreshold: The case ofΛ(1405)in

Abstract

We present an analysis of the (1405) resonance produced in the reaction p + p → ± + π ∓ + K + + p at 3.5 GeV kinetic beam energy measured with the High Acceptance Dielectron Spectrometer (HADES) at the Gesellschaft für Schwerionenforschung (GSI). The two charged decay channels (1405) → ± π ∓ have been reconstructed for the first time in p + p collisions. The efficiency and acceptance-corrected spectral shapes show a peak position clearly below 1400 MeV/c 2 . We find a total production cross section of σ (1405) = 9.2 ± 0.9 ± 0.7 +3.3 −1.0 μb. The analysis of its polar angle distribution suggests that the (1405) is produced isotropically in the p − p center-of-mass system (CMS).

Role of the triangle singularity in Λ(1405) production in the π−p→K0πΣBayar1, Pavao2, Sakai3 et al. 2018Phys. Rev. C220170View full textAdd to dashboardCite

“…Yet, the results that we find in the next section, where we show that the triangle mechanism is far more important than the tree-level diagram, give us confidence that the triangle mechanism discussed here is indeed very important and provides a plausible solution to the puzzle of the experimental results of Ref. [65]. At present we would suggest that an experimental exploration is done of the dependence of the cross sections on the K + π invariant mass to see if the predictions tied to the TS studied here hold.…”

“…The work done here could explain why in the experiments of Refs. [65,66] the invariant-mass distribution of π for (1405) are found at lower invariant masses than in other reactions. It would also be interesting to see if the predictions done here concerning the triangle singularity are fulfilled by the experimental data, an issue that has not been investigated so far.…”

“…The production of (1405) from the proton-proton collision is studied in Refs. [64][65][66]. The future observation of the inevitable peak from the triangle mechanism induced by (1405) would give further support for the molecular nature of (1405).…”

“…7, we show the results of d 2 σ pK + π /dM inv dm inv for the pp → pK + π scattering as a functions of m inv (π 0 0 ), m inv (π + − ), and m inv (π − + ), respectively. The total energy of the system √ s is fixed at 3179 MeV which can be accessed experimentally [64][65][66]. The dependence on m inv is similar to that in dσ K 0 π /dm inv .…”

“…[65]. In addition, the small width of the φ makes the TS structure narrower, but the p-wave coupling of φ → KK reduces drastically the strength.…”