The crepant-resolution conjecture for DT4 invariants of [C4/Zr][\mathbb C^4/\mathbb Z_r]

Let rr be a positive integer, let [[200 C4/Zr][[200~\mathbb C^4/\mathbb Z_r] be the quotient Calabi–Yau 44-orbifold considered in the source, and let q0,,qr1q_0,\ldots,q_{r-1} be variables. Write

q[i,j]:=qiqi+1qj(ij),Q:=q[0,r1].q_{[i,j]}:=q_iq_{i+1}\cdots q_j\quad (i\leq j),\qquad Q:=q_{[0,r-1]}.

Let M(a,b):=n=1(1abn)nM(a,b):=\prod_{n=1}^{\infty}(1-ab^n)^{-n} be the refined MacMahon series and let M~(a,b):=M(a,b)M(a1,b)\widetilde M(a,b):=M(a,b)M(a^{-1},b). The series DT[C4/Zr],O(m,q0,,qr1)\mathsf{DT}_{[\mathbb C^4/\mathbb Z_r],\mathscr O}(m,q_0,\ldots,q_{r-1}) is defined analogously to the toric case. Cao–Kool–Monavari's crepant-resolution conjecture. There exists a choice of orientation such that

DT[C4/Zr],O(m,q0,,qr1)=M(1,Q)ms4(r(s1+s2)s3+(s1+s2)(s1+s2+s3)rs1s2)0<ij<rM~(q[i,j],Q)m(s1+s2)s3s4.\begin{aligned} \mathsf{DT}_{[\mathbb C^4/\mathbb Z_r],\mathscr O}(m,q_0,\ldots,q_{r-1})={}&M(1,-Q)^{-\frac{m}{s_4}\left(\frac{r(s_1+s_2)}{s_3}+\frac{(s_1+s_2)(s_1+s_2+s_3)}{rs_1s_2}\right)}\\\\ &\cdot\prod_{0<i\leq j<r}\widetilde M(q_{[i,j]},-Q)^{-\frac{m(s_1+s_2)}{s_3s_4}}. \end{aligned}

This conjecture gives the predicted refined MacMahon product for the DT4 theory of the quotient orbifold and is motivated by the crepant resolution correspondence. Its general status is left open in the supplied text; the surrounding paper studies this orbifold case in the context of toric Calabi–Yau 44-orbifolds.

Sources & referencesView supporting material

Primary source

Xiaolong Liu, “Donaldson-Thomas invariants of [C^4/Z_r]”, arXiv:2507.21582 (2026).

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