Measurement of $σ(Λ_b)/σ(B^0) \times BR(Λ_b\toΛ_cπ^-) / BR(B^0\to D^+π^-)$ in $p\bar{p}$ Collisions at $\sqrt{s}=1.96$ TeV

Abstract

We present the first observation of the baryon decay $Λ_b\toΛ_cπ^-$ followed by $Λ_c\to p K^-π^+$ in 106 pb-1 of $p\bar{p}$ collisions at $\sqrt{s} = 1.96$ TeV in the CDF experiment. In order to reduce systematic error, the measured rate for $Λ_b$ decay is normalized to the kinematically similar meson decay $B^0\to D^+π^-$ followed by $D^+\toπ^+K^-π^+$. We report the ratio of production cross sections ($σ$) times the ratio of branching fractions (BR) for the momentum region integrated above $p_T > 6$ GeV/c and pseudorapidity range $|η| < 1.3$: $σ(p\bar{p}\to Λ_b X) / σ(p\bar{p}\to B^0 X) \times BR(Λ_b\toΛ_cπ^-) / BR(B^0\to D^+π^-) = 0.82 \pm 0.08(stat) \pm 0.11(syst) \pm 0.22 (BR(Λ_c\to p K^-π^+))$.