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Regular version of the site

Article

Study of Electromagnetic Decays of Orbitally Excited Ξc Baryons

Aushev T., Mizuk R., Pakhlov P., Pakhlova G., Popov V., Uglov T.

Using 980 fb−1 of data collected with the Belle detector operating at the KEKB asymmetric-energy e^+e^- collider, we report a study of the electromagnetic decays of excited {charmed baryons} Ξc(2790) and Ξc(2815). A clear signal (8.6 standard deviations) is observed for Ξc(2815)0→Ξ0cγ, and we measure:
Bc(2815)0→Ξ0cγ]/Bc(2815)0→Ξc(2645)+π−→Ξ0cπ+π−]=0.41±0.05±0.03.
We also present evidence (3.8 standard deviations) for the similar decay of the Ξc(2790)0 and measure:
Bc(2790)0→Ξ0cγ]/Bc(2790)0→Ξ′+cπ−→Ξ+cγπ−]=0.13±0.03±0.02.
The first quoted uncertainties are statistical and the second systematic. We find no hint of the analogous decays of the Ξc(2815)+ and Ξc(2790)+ baryons and set upper limits at the 90% confidence level of: Bc(2815)+→Ξ+cγ]/Bc(2815)+→Ξc(2645)0π+→Ξ+cππ+]<0.09, and Bc(2790)+→Ξ+cγ]/Bc(2790)+→Ξ′0cπ+→Ξ0cγπ+]<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.