this energy, the measured PL results from a phonon-induced up-convertion process that minimizes intervalley scattering events [@Xiaodong2016]. The difference between PL dispersions obtained with left and right circularly polarized excitations is displayed in Fig. \[fig:4\] (a), showing net flows of chiralitons with spin-determined momenta. This is in agreement with the differential white-light reflectivity map $R_{\sigma^-}-R_{\sigma^+}$ of Fig. \[fig:4\] (b). Considering that this map gives the sorting efficiency of our OSO resonator, such correlations in the PL implies that the effect of the initial spin-momentum determination of the chiralitons (see Fig. \[fig:3\] (e) and (f)) is still observed after $200$ ps at RT. After this PL lifetime, a net chiral flow $\mathcal{F}=I_{\sigma^-}-I_{\sigma^+}$ of $\sim 6\%$ is extracted from Fig. \[fig:4\] (a). This is the signature of a chiralitonic valley polarization, in striking contrast with the absence of valley polarization that we report for a bare WS$_2$ monolayer at RT in the Supporting Information, Sec. G. The extracted net flow is however limited by the finite optical contrast $\mathcal{C}$ of our OSO resonator, which we measure at a $15\%$ level from a cross-cut taken on Fig. \[fig:4\] (b) at $1.98$ eV. It is therefore possible to infer that a chiralitonic valley contrast 