K-theoretic McKay conjecture for tautological exterior powers

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Let XX be a scheme of dimension at least 22, let K,LK,L be line bundles on XX, and let pi:Xn→Xp_i:X^n\to X be the projections. Set

U=⨁i=1npi∗K,V=⨁i=1npi∗L.U=\bigoplus_{i=1}^n p_i^*K,\qquad V=\bigoplus_{i=1}^n p_i^*L.

Let ρ:X[n]→X(n)\rho:X^{[n]}\to X^{(n)} be the Hilbert–Chow morphism, and let π:[Xn/Sn]→X(n)\pi:[X^n/\mathfrak{S}_n]\to X^{(n)} be the projection from the quotient stack. Tautological McKay conjecture. The K-theoretical pushforward satisfies

ρ∗(Λ−u((K[n])∗)⊗Λ−v(L[n]))≅π∗[(Λ−uU∗⊗Λ−vV)/Sn].\rho_*\left(\Lambda_{-u}\big((K^{[n]})^*\big)\otimes\Lambda_{-v}\big(L^{[n]}\big)\right) \cong \pi_*\left[(\Lambda_{-u}U^*\otimes\Lambda_{-v}V)/\mathfrak{S}_n\right].

This extends the structure-sheaf pushforward to exterior powers of tautological bundles. It is presented as a conjectural higher-dimensional McKay-type identity; the paper does not establish it in general.

References

Primary source

Xiaowen Hu, “On singular Hilbert schemes of points: Local structures and tautological sheaves”, arXiv:2101.05236 (2025).

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