TY - JOUR

T1 - First Study of Antihyperon-Nucleon Scattering Λ¯p→Λ¯p and Measurement of Λp→Λp Cross Section

AU - BESIII Collaboration

AU - Ablikim, M.

AU - Achasov, M. n.

AU - Николаев, Иван Борисович

AU - Мучной, Николай Юрьевич

PY - 2024/6/4

Y1 - 2024/6/4

N2 - Using (10.087±0.044)×109 J/ψ events collected with the BESIII detector at the BEPCII storage ring, the processes Λp→Λp and Λ¯p→Λ¯p are studied, where the Λ/Λ¯ baryons are produced in the process J/ψ→ΛΛ¯ and the protons are the hydrogen nuclei in the cooling oil of the beam pipe. Clear signals are observed for the two reactions. The cross sections in -0.9≤cosθΛ/Λ¯≤0.9 are measured to be σ(Λp→Λp)=(12.2±1.6stat±1.1syst) and σ(Λ¯p→Λ¯p)=(17.5±2.1stat±1.6syst) mb at the Λ/Λ¯ momentum of 1.074 GeV/c within a range of ±0.017 GeV/c, where the θΛ/Λ¯ are the scattering angles of the Λ/Λ¯ in the Λp/Λ¯p rest frames. Furthermore, the differential cross sections of the two reactions are also measured, where there is a slight tendency of forward scattering for Λp→Λp, and a strong forward peak for Λ¯p→Λ¯p. We present an approach to extract the total elastic cross sections by extrapolation. The study of Λ¯p→Λ¯p represents the first study of antihyperon-nucleon scattering, and these new measurements will serve as important inputs for the theoretical understanding of the (anti)hyperon-nucleon interaction.

AB - Using (10.087±0.044)×109 J/ψ events collected with the BESIII detector at the BEPCII storage ring, the processes Λp→Λp and Λ¯p→Λ¯p are studied, where the Λ/Λ¯ baryons are produced in the process J/ψ→ΛΛ¯ and the protons are the hydrogen nuclei in the cooling oil of the beam pipe. Clear signals are observed for the two reactions. The cross sections in -0.9≤cosθΛ/Λ¯≤0.9 are measured to be σ(Λp→Λp)=(12.2±1.6stat±1.1syst) and σ(Λ¯p→Λ¯p)=(17.5±2.1stat±1.6syst) mb at the Λ/Λ¯ momentum of 1.074 GeV/c within a range of ±0.017 GeV/c, where the θΛ/Λ¯ are the scattering angles of the Λ/Λ¯ in the Λp/Λ¯p rest frames. Furthermore, the differential cross sections of the two reactions are also measured, where there is a slight tendency of forward scattering for Λp→Λp, and a strong forward peak for Λ¯p→Λ¯p. We present an approach to extract the total elastic cross sections by extrapolation. The study of Λ¯p→Λ¯p represents the first study of antihyperon-nucleon scattering, and these new measurements will serve as important inputs for the theoretical understanding of the (anti)hyperon-nucleon interaction.

UR - https://www.scopus.com/record/display.uri?eid=2-s2.0-85196148480&origin=inward&txGid=03ce5afc433a77f467cb546038a075d5

UR - https://pubmed.ncbi.nlm.nih.gov/38905649/

U2 - 10.1103/PhysRevLett.132.231902

DO - 10.1103/PhysRevLett.132.231902

M3 - Article

C2 - 38905649

VL - 132

SP - 231902

JO - Physical Review Letters

JF - Physical Review Letters

SN - 0031-9007

IS - 23

M1 - 231902

ER -