2003/07/31 by The SAPHIR Collaboration, Wolfgang Braun, J. Barth +20 · 313 citations
Physics and Astronomy · #Baryon #Detector #Electron #High-Energy Particle Collisions Research #Invariant mass #Isoscalar #Nuclear physics #Particle physics #Particle physics theoretical and experimental studies #Pentaquark #Physics #Quantum Chromodynamics and Particle Interactions #Strangeness #hep-ex
paper · pdf · doi:10.1016/j.physletb.2003.08.019
published in Physics Letters B 572(3-4), 127-132 (Elsevier BV) · 9 pages, 4 figures
arxiv created 2003/09/30 · openalex publication_date 2003/10/01 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
The positive-strangeness baryon resonance Θ+ is observed in photoproduction of the nK+K0s final state with the SAPHIR detector at the Bonn ELectron Stretcher Accelerator ELSA. It is seen as a peak in the nK+ invariant mass distribution with a 4.8σ confidence level. We find a mass MΘ+=1540±4±2 MeV and an upper limit of the width ΓΘ+<25 MeV at 90% c.l. The photoproduction cross section for K0Θ+ is in the order of 300 nb. From the absence of a signal in the pK+ invariant mass distribution in γp→pK+K− at the expected strength we conclude that the Θ+ must be isoscalar.