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arXiv · 2007.14700

First Determination of the Spin and Parity of a Charmed-Strange Baryon, $\Xi_{c}(2970)^+$

Belle Collaboration·T. J. Moon·K. Tanida·Y. Kato·S. K. Kim·I. Adachi·J. K. Ahn·H. Aihara·S. Al Said·D. M. Asner·V. Aulchenko·T. Aushev·R. Ayad·V. Babu·S. Bahinipati·P. Behera·C. Beleño·J. Bennett·M. Bessner·B. Bhuyan·T. Bilka·J. Biswal·G. Bonvicini·A. Bozek·M. Bračko·T. E. Browder·M. Campajola·L. Cao·D. Červenkov·M. -C. Chang·P. Chang·A. Chen·B. G. Cheon·K. Chilikin·K. Cho·S. -K. Choi·Y. Choi·S. Choudhury·D. Cinabro·S. Cunliffe·N. Dash·G. De Nardo·F. Di Capua·Z. Doležal·T. V. Dong·D. Dossett·S. Dubey·S. Eidelman·D. Epifanov·T. Ferber·B. G. Fulsom·R. Garg·V. Gaur·N. Gabyshev·A. Garmash·A. Giri·P. Goldenzweig·B. Golob·C. Hadjivasiliou·O. Hartbrich·K. Hayasaka·H. Hayashii·M. T. Hedges·W. -S. Hou·C. -L. Hsu·K. Inami·G. Inguglia·A. Ishikawa·R. Itoh·M. Iwasaki·Y. Iwasaki·W. W. Jacobs·S. Jia·Y. Jin·K. K. Joo·K. H. Kang·G. Karyan·T. Kawasaki·H. Kichimi·C. Kiesling·B. H. Kim·D. Y. Kim·K. T. Kim·S. H. Kim·Y. J. Kim·Y. -K. Kim·T. D. Kimmel·K. Kinoshita·P. Kodyš·S. Korpar·D. Kotchetkov·P. Križan·R. Kroeger·P. Krokovny·T. Kuhr·R. Kumar·K. Kumara·A. Kuzmin·I. S. Lee·J. Y. Lee
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Abstract

We report results from a study of the spin and parity of $\Xi_{c}(2970)^+$ using a $980~\mathrm{fb^{-1}}$ data sample collected by the Belle detector at the KEKB asymmetric-energy $e^{+}e^{-}$ collider. The decay angle distributions in the chain $\Xi_{c}(2970)^+ \to \Xi_c(2645)^{0}\pi^{+} \to \Xi_c^{+}\pi^{-}\pi^{+}$ are analyzed to determine the spin of this charmed-strange baryon. The angular distributions strongly favor the $\Xi_{c}(2970)^+$ spin $J =1/2$ over $3/2$ or $5/2$, under an assumption that the lowest partial wave dominates in the decay. We also measure the ratio of $\Xi_{c}(2970)^+$ decay branching fractions $R={\mathcal{B}[ \Xi_{c}(2970)^+ \to \Xi_c(2645)^{0}\pi^{+} ]} / { \mathcal{B}[ \Xi_{c}(2970)^+ \to \Xi_c^{\prime0}\pi^{+} ]} =1.67 \pm 0.29\mathrm{(stat.)}^{ +0.15}_{ -0.09}\mathrm{(syst.)} \pm 0.25\mathrm{(IS)}$, where the last uncertainty is due to possible isospin-symmetry-breaking effects. This $R$ value favors the spin-parity $J^P=1/2^+$ with the spin of the light-quark degrees of freedom $s_{l}=0$. This is the first determination of the spin and parity of a charmed-strange baryon.

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Belle Collaboration, T. J. Moon, K. Tanida, Y. Kato, S. K. Kim, I. Adachi, J. K. Ahn, H. Aihara, S. Al Said, D. M. Asner, V. Aulchenko, T. Aushev, R. Ayad, V. Babu, S. Bahinipati, P. Behera, C. Beleño, J. Bennett, M. Bessner, B. Bhuyan, T. Bilka, J. Biswal, G. Bonvicini, A. Bozek, M. Bračko, T. E. Browder, M. Campajola, L. Cao, D. Červenkov, M. -C. Chang, P. Chang, A. Chen, B. G. Cheon, K. Chilikin, K. Cho, S. -K. Choi, Y. Choi, S. Choudhury, D. Cinabro, S. Cunliffe, N. Dash, G. De Nardo, F. Di Capua, Z. Doležal, T. V. Dong, D. Dossett, S. Dubey, S. Eidelman, D. Epifanov, T. Ferber, B. G. Fulsom, R. Garg, V. Gaur, N. Gabyshev, A. Garmash, A. Giri, P. Goldenzweig, B. Golob, C. Hadjivasiliou, O. Hartbrich, K. Hayasaka, H. Hayashii, M. T. Hedges, W. -S. Hou, C. -L. Hsu, K. Inami, G. Inguglia, A. Ishikawa, R. Itoh, M. Iwasaki, Y. Iwasaki, W. W. Jacobs, S. Jia, Y. Jin, K. K. Joo, K. H. Kang, G. Karyan, T. Kawasaki, H. Kichimi, C. Kiesling, B. H. Kim, D. Y. Kim, K. T. Kim, S. H. Kim, Y. J. Kim, Y. -K. Kim, T. D. Kimmel, K. Kinoshita, P. Kodyš, S. Korpar, D. Kotchetkov, P. Križan, R. Kroeger, P. Krokovny, T. Kuhr, R. Kumar, K. Kumara, A. Kuzmin, I. S. Lee, J. Y. Lee. 2020-07-29. First Determination of the Spin and Parity of a Charmed-Strange Baryon, $\Xi_{c}(2970)^+$. https://doi.org/10.1103/physrevd.103.l111101

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