Observation of Λ[over ¯]p→K^{+}π^{+}π^{-}π^{0} and Λ[over ¯]p→K^{+}π^{+}π^{-}2π^{0}

Area of Science:

• Particle Physics
• High Energy Physics
• Nuclear Physics

Background:

• Antihyperon-nucleon interactions are fundamental to understanding nuclear matter.
• Previous studies have limited data on multi-pion final states in these interactions.

Purpose of the Study:

• To investigate antihyperon-nucleon annihilation processes, specifically Λ-bar p → K+π+π- + kπ0 (k=1, 2, 3).
• To measure cross sections for newly observed reactions and search for resonances.

Main Methods:

• Analysis of J/ψ events collected with the BESIII detector.
• Study of antihyperon-nucleon annihilation at a center-of-mass energy of 3.097 GeV.
• Measurement of cross sections and invariant mass spectra.

Main Results:

• Observed Λ-bar p → K+π+π-π0 and Λ-bar p → K+π+π-2π0 for the first time with measured cross sections.
• Set an upper limit for Λ-bar p → K+π+π-3π0.
• Observed evidence for the K*(892)+ resonance in the K+π0 invariant mass spectrum.

Conclusions:

• The study provides the first measurements of specific antihyperon-nucleon annihilation channels involving multiple pions.
• The findings contribute essential data for theoretical models of antihyperon-nucleon interactions.
• The observation of the K*(892)+ resonance offers insights into intermediate states.