Event Shocks and Partisan Affect Asymmetry During the Black Lives Matter (BLM) Protests

Does affective polarization respond symmetrically to major political shocks? Using139,064 tweets from political elites and public users in a ±100-day window around George Floyd's killing on May 25, 2020, this paper estimates interrupted time-series models of moral-foundations density, sentiment, and destructive toxicity by source and party. Democratic discourse moves immediately into moralized language with a sustained post-event slope and a parallel turn toward more solidaristic sentiment, activating moralization as a sub-dimension of partisan animus. Republican discourse first disengages from the dominant moral framing of the event and then re-engages on a different moral grammar, with destructive toxicity rising slowly afterward, consistent with a value-protection mechanism under threat. Elite signals concentrate at the moment of the shock, while public expression carries the post-event trajectories. Asymmetric affective polarization therefore takes a structural form, with each coalition activating a different sub-dimension of partisan animus through which the event is publicly enacted and reinforced.