40 likes | 126 Views
This study explores the disagreement between different experiments' measurements of the Λp invariant mass signals. Analysis of various reactions involving Λp and simulations indicate discrepancies that challenge existing models.*
E N D
[K-pp] search now is a “Λp puzzle” Several experiments measure different (Λp) invariant mass signals: are they indeed in such a disagreement ? E549 vs FINUDA H. Outa, E549 Collaboration, talk given at this workshop S. Piano, FINUDA Collaboration, talk given at this workshop K-4He → Σπ(3N) (ΣN→ΛN) K-4He → ΣN(3N) ? Unlikely due only to ΣN conversion K-4He → ΛN(2N) not acceptance corrected not acceptance corrected
FINUDA: ΣN→ΛN conversion reactions Simulations: Λp Invariant Mass ΣN→ΛN cannot explain the FINUDA Λp bump: Inv Mass Spectra is out of range and/or Angular Distribution has a different shape K-6Li→Σ0,+π0,-4Hgs Σ0p→Λp Σ+n→Λp K-6Li→Σ0p4Hgs Σ0→Λγ K-6Li→Λp4Hgs K-6Li→Σ0,+n4Hgs Σ0p→Λp Σ+n→Λp Simulations: Λp angular distribution K-6Li→Σ0,-p4Hgs Σ0n→Λn Σ-p→Λn
G. Bendiscioli et al., NPA789(2007)222 G. Bendiscioli et al., EPJA40(2009)11 p4He→(pπ-)pK0sX ¯ Λp inv mass: FINUDA vs OBELIX ppπ- invariant mass spectrum T. Buran et al., PL20(1966)318 K-(CF3Br)→ΛpX K-6Li→Σ0p4Hgs Σ0→Λγ S. Piano, FINUDA Collaboration, talk given at this workshop K-6Li→Λp4Hgs K-6Li→Λπ0,+,-p4Hgs not acceptance corrected not acceptance corrected All these reactions are can occur on d only
Λp inv mass: FOPI vs (old) K-d experiments N. Hermann, FOPI Collaboration, talk given at this workshop The signal is compatible with a K-d absorption with pion production K-d→(Σ+n)π-→(Λp)π- D. Eastwood et al., PRD3(1971)2603 K-d→Λp π-X (1.45 GeV/c and 1.65 GeV/c) Signal also compatible with a threshold (ΣN) cusp effect (no resonance needed) D. Cline et al., PRL20(1968)1452 K-d→Λp π-X (400 MeV/c)