Speaker
Description
Recent work has proposed sequential hadronization of open-charm hadrons in the quark-gluon plasma, wherein more tightly bound species such as Ds+ form earlier near 1.2Tc and D0 forms later at Tc. That work showed that this mechanism naturally reverses the sign of the D0 − Ds+ elliptic-flow splitting ∆v2 ≡ v2(D0) − v2(Ds+) relative to the conventional simultaneous baseline. In this work, we demonstrate that event-shape engineering (ESE) provides a sharper discrimination between the two pictures than inclusive measurements alone. By selecting large-q2 and small-q2 events in 0–10% and 30–50% centrality classes in Pb–Pb collisions at √sNN = 5.02 TeV, we show that the geometry-driven enhancement of charm-meson v2 can be separated from the hadronization-time response: the positive ∆v2(D0 − Ds+) in the sequential scenario grows systematically with q2,while the corresponding response slope χ reveals a species-dependent hierarchy χ(D0) > χ(Ds+) that is robust against the overall flow normalization and absent in the simultaneous baseline. In the simultaneous case, the splitting is near zero or negative and does not follow the same geometry scaling. Notably, the semi-central 30–50% class emerges as the optimal window, because the non-monotonic interplay between QGP lifetime and initial eccentricity maximizes the late-stage flow conversion. The Ds+/D0 yield ratio and its q2 double ratio remain close to unity, confirming that the splitting is a dynamical flow effect rather than a chemical yield modification. These results establish ∆v2(D0 − Ds+) and the response slope χ under ESE as complementary differential probes of the space-time structure of charm hadronization near the QCD transition temperature.
