第十二届中国 LHC 物理会议（CLHCP2026）

We identify a new spin--flavor entanglement structure in $\Lambda_b\to\Lambda D$ decays, formed by the correlation between the $\Lambda$ spin and the $D$ flavor states ($D=D^0,\overline D^0,D_1,D_2$). The entanglement information is encoded in the decay rates and Lee--Yang parameters of the four neutral-$D$ modes. We then show that the same spin--flavor structure provides a new method to determine the weak phase $\gamma$, a key angle of the Cabibbo--Kobayashi--Maskawa unitarity triangle. We find that the experimental uncertainty scales as $\sigma_\gamma\propto 1/{\cal C}$, where ${\cal C}$ is the Wootters concurrence, thereby quantitatively relating the precision of the weak-phase extraction to the amount of spin--flavor entanglement.