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ISSN - 15507998, Physical Review D - Particles, Fields, Gravitation and Cosmology, 2013, vol. 87, p. -

Measurements of the branching fractions for J/ψ and ψ′→ΛΛ̄π0 and ΛΛ̄η

Ablikim M., Achasov M. N., Albayrak O., Ambrose D. J., An F. F., An Q., Bai J. Z., Ban Y., Becker J., Bennett J. V., Bertani M., Bian J. M., Boger E., Bondarenko O., Boyko I., Briere R. A., Bytev V., Cai X., Cakir O., Calcaterra A., Cao G. F., Cetin S. A., Chang J. F., Chelkov G., Chen G., Chen H. S., Chen J. C., Chen M. L., Chen S. J., Chen X., Chen Y. B., Cheng H. P., Chu Y. P., Cronin-Hennessy D., Dai H. L., Dai J. P., Dedovich D., Deng Z. Y., Denig A., Denysenko I., Destefanis M., Ding W. M., Ding Y., Dong L. Y., Dong M. Y., Du S. X., Fang J., Fang S. S., Fava L., Feng C. Q., Ferroli R. B., Friedel P., Fu C. D., Gao Y., Geng C., Goetzen K., Gong W. X., Gradl W., Greco M., Gu M. H., Gu Y. T., Guan Y. H., Guo A. Q., Guo L. B., Guo T., Guo Y. P., Han Y. L., Harris F. A., He K. L., He M., He Z. Y., Held T., Heng Y. K., Hou Z. L., Hu C., Hu H. M., Hu J. F., Hu T., Huang G. M., Huang G. S., Huang J. S., Huang L., Huang X. T., Huang Y., Huang Y. P., Hussain T., Ji C. S., Ji Q., Ji Q. P., Ji X. B., Ji X. L., Jiang L. L., Jiang X. S., Jiao J. B., Jiao Z., Jin D. P., Jin S.

We report on a study of the isospin-violating and isospin-conserving decays of the J/ψ and ψ′ charmonium state to ΛΛ̄π0 and ΛΛ̄η, respectively. The data are based on 225 million J/ψ and 106 million ψ′ events that were collected with the BESIII detector. The most accurate measurement of the branching fraction of the isospin-violating process J/ψ→ΛΛ̄π0 is obtained, and the isospin-conserving processes J/ψ→ΛΛ̄η and ψ ′→ΛΛ̄η are observed for the first time. The branching fractions are measured to be B(J/ ψ→ΛΛ̄π0)=(3.78±0.27stat± 0.30sys)×10-5, B(J/ ψ→ΛΛ̄η)=(15.7±0.80stat± 1.54sys)×10-5 and B(ψ ′→ΛΛ̄η)=(2.48±0.34 stat±0.19sys)×10-5. No significant signal events are observed for ψ ′→ΛΛ̄π0 decay resulting in an upper limit of the branching fraction of B(ψ ′→ΛΛ̄π0)<0.29×10 -5 at the 90% confidence level. The two-body decay of J/ψ→Σ(1385)0Λ̄+c.c. is searched for, and the upper limit is B(J/ψ→Σ(1385)0Λ̄+c.c.)<0.82×10 -5 at the 90% confidence level. © 2013 American Physical Society.