Multiexciton states in monolayer transition metal dichalcogenides represent fertile ground for uncovering emergent many-body quantum behaviors, particularly in the context of valley polarization and coherence. Understanding how complex excitonic correlations influence valley-resolved optical properties is essential for both fundamental valleytronic science and potential quantum applications. Here, we investigate the valley-selective polarization characteristics of hexcitons—six-body bound states—in monolayer ${\mathrm{WSe}}_2$. Surprisingly, we observe that hexciton photoluminescence exhibits strong circular polarization but negligible linear polarization, indicating that valley polarization is well preserved, while valley coherence is entirely lost. This decoupling behavior stands in stark contrast to neutral excitons, which typically exhibit both forms of polarization, and points to fundamentally different valley dynamics in higher-order excitonic complexes. Our analysis reveals that, despite nominally symmetric excitation and emission configurations at the +$K$ and $-K$ valleys, the exchange interactions and spins in the many-body final states subtly break the conditions required for intervalley coherence, suppressing any linear polarization signature. These findings shed light on the intrinsic decoherence mechanisms in multiexciton systems and highlight the critical role of many-body effects in shaping the valley quantum dynamics of two-dimensional semiconductors.

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• Excitons
• 2-dimensional systems
• Transition metal dichalcogenides
• Photoluminescence