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Search for B̄0 → Λ + cΛ ̄̄ cdecay at Belle

Abe K., Adachi I., Aihara H., Arinstein K., Aso T., Aulchenko V., Aushev T., Aziz T., Bahinipati S., Bakich A. M., Balagura V., Ban Y., Banerjee S., Barberio E., Bay A., Bedny I., Belous K., Bhardwaj V., Bitenc U., Blyth S., Bondar A., Bozek A., Bracko M., Brodzicka J., Browder T. E., Chang M. C., Chang P., Chao Y., Chen A., Chen K. F., Chen W. T., Cheon B. G., Chiang C. C., Chistov R., Cho I. S., Choi S. K., Choi Y., Choi Y. K., Cole S., Dalseno J., Danilov M., Das A., Dash M., Dragic J., Drutskoy A., Eidelman S., Epifanov D., Fratina S., Fujii H., Fujikawa M., Gabyshev N., Garmash A., Go A., Gokhroo G., Goldenzweig P., Golob B., Grosse Perdekamp M., Guler H., Ha H., Haba J., Hara K., Hara T., Hasegawa Y., Hastings N. C., Hayasaka K., Hayashii H., Hazumi M., Heffernan D., Higuchi T., Hinz L., Hoedlmoser H., Hokuue T., Horii Y., Hoshi Y., Hoshina K., Hou S., Hou W. S., Hsiung Y. B., Hyun H. J., Igarashi Y., Iijima T., Ikado K., Inami K., Ishikawa A., Ishino H., Itoh R., Iwabuchi M., Iwasaki M., Iwasaki Y., Jacoby C., Joshi N. J., Kaga M., Kah D. H., Kaji H., Kajiwara S., Kakuno H.

We search for the doubly charmed baryonic decay B̄0 → Λ + cΛ ̄̄ cin a data sample of 520 × 106 B ̄B events accumulated at the γ(4S) resonance with the Belle detector at the KEKB asymmetricenergy e+e- collider. We find no significant signal and set an upper limit of B B̄0 → Λ + cΛ ̄̄ c) 6.2 × 10-5 at 90% confidence level. The result is significantly below a naive extrapolation fromB(B̄→ Ε0 c̄ Λc ) assuming a simple Cabibbo-suppression factor of |Vcd/Vcs|2. The small branching fraction could be attributed to a suppression due to the large momentum of the baryonic decay products, which has been observed in other charmed baryonic two-body B decays.