The ${\Lambda }_b^0\to {\Lambda }_c^{+}{K}^{+}{K}^{-}{\pi }^{-}$ decay is observed for the first time using a data sample of proton-proton collisions at centre-of-mass energies of $\sqrt{s}=7$ and $8\text{TeV}$ collected by the LHCb detector, corresponding to an integrated luminosity of $3\mathrm{f}{\mathrm{b}}^{-\mathrm{1}}$. The ratio of branching fractions between the ${\Lambda }_b^0\to {\Lambda }_c^{+}{K}^{+}{K}^{-}{\pi }^{-}$ and the ${\Lambda }_b^0\to {\Lambda }_c^{+}{D}_s^{-}$ decays is measured to be$\frac{\mathcal{B}({\Lambda }_b^0\to {\Lambda }_c^{+}{K}^{+}{K}^{-}{\pi }^{-})}{\mathcal{B}({\Lambda }_b^0\to {\Lambda }_c^{+}{D}_s^{-})}=(9.26\pm 0.29\pm 0.46\pm 0.26)\times {10}^{-2},$ where the first uncertainty is statistical, the second systematic and the third is due to the knowledge of the $D_s^{-}\to K^{+}{K}^{-}{\pi }^{-}$ branching fraction. No structure on the invariant mass distribution of the ${\Lambda }_c^{+}{K}^{+}$ system is found, consistent with no open-charm pentaquark signature.

这 ${\Lambda }_b^0\to {\Lambda }_C^{+}{ķ}^{+}{ķ}^{-}{\pi }^{-}$ 首次使用质子能量中心的质子-质子碰撞数据样本观察到了衰变 $\sqrt{s}=7$ 和 $8\text{电视}$ LHCb检测器收集到的光，对应于 $3\mathrm{F}{\mathrm{b}}^{-\mathrm{1个}}$。两者之间的支化比例之比${\Lambda }_b^0\to {\Lambda }_C^{+}{ķ}^{+}{ķ}^{-}{\pi }^{-}$ 和 ${\Lambda }_b^0\to {\Lambda }_C^{+}{d}_s^{-}$ 衰变被测量为$\frac{\mathcal{乙}（{\Lambda }_b^0\to {\Lambda }_C^{+}{ķ}^{+}{ķ}^{-}{\pi }^{-}）}{\mathcal{乙}（{\Lambda }_b^0\to {\Lambda }_C^{+}{d}_s^{-}）}=（9.26\pm 0.29\pm 0.46\pm 0.26）\times {10}^{-\mathrm{2个}}，$ 第一个不确定性是统计性的，第二个系统性不确定性，第三个不确定性是由于 $d_s^{-}\to {ķ}^{+}{ķ}^{-}{\pi }^{-}$分支分数。没有结构上的不变质量分布${\Lambda }_C^{+}{ķ}^{+}$ 找到的系统与没有开放式的五夸克签名一致。