Nonmonotonic rotation imprint on time-integrated neutrino spectral moments in a 15,M_⊙ core-collapse supernova sequence

We study the early postbounce neutrino signal of the published Garching 15,M_⊙ rotating core-collapse supernova (CCSN) sequence consisting of nonrotating (NR), slowly rotating (SR, Ω_0=0.5 -1 ), and fast-rotating (FR, Ω_0=150 rad,s -1 $, artificially boosted $∼300 ) 3D models. We present a new analysis of these publicly available simulation data; no new simulations were performed. Our central result, for this specific model sequence, is that SR and FR shift the integrated spectral moments in opposite directions relative to NR: FR drives the spectra toward softer, more-pinched states, while SR moves them weakly toward harder, less-pinched states. Placed in a spectral-shift plane ( =0.05--0.30,s, where the rotation imprint is strongest. Quantitatively, fast rotation produces Deltałangle E_ E̊angleL,,ΔαL), NR sits at the origin, and SR and FR occupy diagonally opposite quadrants, making the nonmonotonic response immediately visible as an anti-correlation in two spectral dimensions simultaneously. The focus is the accretion interval t_ pb ν_e ̊angle_L=-0.513,MeV and Δα_ ν_e =+0.161, with corresponding shifts Deltałangle E_ ̊angle_L=-0.440,MeV and Δα_ =+0.173; the SR shifts are an order of magnitude smaller and in the opposite sense. The fast-rotation signature is coherent across all 15,488 lines of sight and is established during early accretion. With only three models from a single progenitor family, this result is a phenomenological characterization of one published sequence and a suggestive indication of a nonmonotonic, possibly strongly nonlinear, rotational response within this sequence; the functional form and generality of the dependence on Ω_0 remain unconstrained. Fast rotation widens the integrated flavor hierarchies while leaving the net electron-lepton-number excess nearly unchanged (0.3%), indicating spectral reorganization rather than gross suppression. Under strongly idealized assumptions, the FR-NR spectral difference maps to nonnegligible model-to-model event-count differences in Hyper-Kamiokande, DUNE, and JUNO at Galactic distances; these represent conditional model-separability estimates within this one sequence, not observational detection significances of rotation.