2020/09/30 by Belle Collaboration, J. Yelton, I. Adachi +235 · 1 citation
Physics and Astronomy · #Baryon #Collider #Excited state #High-Energy Particle Collisions Research #KEKB #Nuclear physics #Particle physics #Particle physics theoretical and experimental studies #Physics #Quantum Chromodynamics and Particle Interactions #hep-ex
paper · pdf · doi:10.1103/physrevd.102.071103
published as Phys. Rev. D 102, 071103 (2020) · Submitted to Phys. Rev. D (Rapid Communications)
openalex created_date 2020/09/14 · openalex publication_date 2020/10/26 · arxiv created 2020/10/27 · arxiv updated 2020/11/04 · openalex updated_date 2026/08/06
Using 980 fb^\ensuremath-1 of data collected with the Belle detector operating at the KEKB asymmetric-energy e+e^\ensuremath- collider, we report a study of the electromagnetic decays of excited charmed baryons \mathrm\ensuremathΞc(2790) and \mathrm\ensuremathΞc(2815). A clear signal (8.6 standard deviations) is observed for \mathrm\ensuremathΞc(2815)0\ensuremath→\mathrm\ensuremathΞc0\ensuremathγ, and we measure: \fracB[\mathrm\ensuremathΞc(2815)0 \ensuremath→ \mathrm\ensuremathΞc0\ensuremathγ]B[\mathrm\ensuremathΞc(2815)0 \ensuremath→ \mathrm\ensuremathΞc(2645)+\ensuremathπ^\ensuremath- \ensuremath→ \mathrm\ensuremathΞc0\ensuremathπ+\ensuremathπ^\ensuremath-]=0.41\ifmmode±\else\textpm\fi0.05\ifmmode±\else\textpm\fi0.03. We also present evidence (3.8 standard deviations) for the similar decay of the \mathrm\ensuremathΞc(2790)0 and measure: \fracB[\mathrm\ensuremathΞc(2790)0 \ensuremath→ \mathrm\ensuremathΞc0\ensuremathγ]B[\mathrm\ensuremathΞc(2790)0 \ensuremath→ \mathrm\ensuremathΞc^\ensuremath'+\ensuremathπ^\ensuremath- \ensuremath→ \mathrm\ensuremathΞc+\ensuremathγ\ensuremathπ^\ensuremath-]=0.13\ifmmode±\else\textpm\fi0.03\ifmmode±\else\textpm\fi0.02. The first quoted uncertainties are statistical and the second systematic. We find no hint of the analogous decays of the \mathrm\ensuremathΞc(2815)+ and \mathrm\ensuremathΞc(2790)+ baryons and set upper limits at the 90% confidence level of: \fracB[\mathrm\ensuremathΞc(2815)+ \ensuremath→ \mathrm\ensuremathΞc+\ensuremathγ]B[\mathrm\ensuremathΞc(2815)+ \ensuremath→ \mathrm\ensuremathΞc(2645)0\ensuremathπ+ \ensuremath→ \mathrm\ensuremathΞc+\ensuremathπ^\ensuremath-\ensuremathπ+]<0.09, and \fracB[\mathrm\ensuremathΞc(2790)+ \ensuremath→ \mathrm\ensuremathΞc+\ensuremathγ]B[\mathrm\ensuremathΞc(2790)+ \ensuremath→ \mathrm\ensuremathΞc^\ensuremath'0\ensuremathπ+ \ensuremath→ \mathrm\ensuremathΞc0\ensuremathγ\ensuremathπ+]<0.06. Approximate values of the partial widths of the decays are extracted, which can be used to discriminate between models of the underlying quark structure of these excited states.