# Measurements of ${\cal B}(\bar{B}^0 \to \Lambda_{c}^{+} \bar{p})$ and ${\cal B}(B^- \to \Lambda_{c}^{+} \bar{p} \pi^-)$ and Studies of $\Lambda_{c}^{+}\pi^-$ Resonances

Abstract : We present an investigation of the decays $\bar{B}^0 \to \Lambda_{c}^{+} \bar{p}$ and $B^- \to \Lambda_{c}^{+} \bar{p} \pi^-$ based on $383\times10^6$ $\Upsilon(4S) \to B\bar{B}$ decays recorded with the BABAR detector. We measure the branching fractions of these decays; their ratio is ${\cal B}(B^- \to \Lambda_{c}^{+} \bar{p} \pi^-) / {\cal B}(\bar{B}^0 \to \Lambda_{c}^{+} \bar{p}) = 15.4 \pm 1.8 \pm 0.3$. The $B^- \to \Lambda_{c}^{+} \bar{p} \pi^-$ process exhibits an enhancement at the $\Lambda_{c}^{+} \bar{p}$ threshold and is a laboratory for searches for excited charm baryon states. We observe the resonant decays $\bar{B}^- \to \Sigma_{c}(2455)^{0} \bar{p}$ and $B^- \to \Sigma_{c}(2800)^{0} \bar{p}$ but see no evidence for $B^- \to \Sigma_{c}(2520)^{0} \baver{p}$. This is the first observation of the decay $B^- \to \Sigma_{c}(2800)^{0} \bar{p}$; however, the mass of the observed excited $\Sigma_{c}^{0}$ state is $(2846\pm8\pm10)MeV/c^2$, which is somewhat inconsistent with previous measurements. Finally, we examine the angular distribution of the $B^- \to \Sigma_{c}(2455)^{0} \bar{p}$ decays and measure the spin of the $\Sigma_{c}(2455)^{0}$ baryon to be 1/2, as predicted by the quark model.
Document type :
Journal articles

http://hal.in2p3.fr/in2p3-00315894
Contributor : Claudine Bombar <>
Submitted on : Monday, September 1, 2008 - 3:28:41 PM
Last modification on : Wednesday, September 16, 2020 - 4:14:40 PM

### Citation

B. Aubert, M. Bona, Y. Karyotakis, J. P. Lees, V. Poireau, et al.. Measurements of ${\cal B}(\bar{B}^0 \to \Lambda_{c}^{+} \bar{p})$ and ${\cal B}(B^- \to \Lambda_{c}^{+} \bar{p} \pi^-)$ and Studies of $\Lambda_{c}^{+}\pi^-$ Resonances. Physical Review D, American Physical Society, 2008, 78, pp.112003. ⟨10.1103/PhysRevD.78.112003⟩. ⟨in2p3-00315894⟩

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