Deligne's period conjecture for motives of odd weight

Let MM be a Q\mathbb{Q}-motive with coefficients in a number field FF and odd weight. Let HB+(M)H_B^+(M) be the +1+1-eigenspace of complex conjugation, let αM+\alpha_M^+ be the comparison map from HB+(M)CH_B^+(M)\otimes\mathbb{C} to HdR+(M)CH_{\operatorname{dR}}^+(M)\otimes\mathbb{C}, and let c+(M,s0)c^+(M,s_0) denote the Deligne period of MM at s0s_0. If s0Zs_0\in\mathbb{Z} is critical for MM, meaning that neither L(M,s)L_\infty(M,s) nor L(M(1),s)L_\infty(M^*(1),s) has a pole at s0s_0, then Deligne's period conjecture. The map αM+\alpha_M^+ is an isomorphism and there exists L(M,s0)F\mathcal{L}(M,s_0)\in F such that

L(M,s0)=c+(M,s0)L(M,s0).L(M,s_0)=c^+(M,s_0)\cdot\mathcal{L}(M,s_0).

The conjecture predicts that Deligne periods give the irrational parts of critical motivic LL-values. The paper applies this prediction to motivic pieces of superelliptic curves and numerically verifies instances, but the general statement remains open.

Sources & referencesView supporting material

Primary source

Harry Spencer, “Motivic pieces of curves: L-functions and periods”, arXiv:2601.21934 (2026).

Additional references

17 papers in this index state this conjecture (2000–2026). The statement above is taken from the most recent of them; the others are arXiv:2512.02348, arXiv:2509.17007, arXiv:2207.03393, arXiv:2205.15382, arXiv:2008.13375, arXiv:1711.06669, arXiv:1612.09590, arXiv:1608.07527, arXiv:1608.07643, arXiv:1512.03867, arXiv:1511.03517, arXiv:1511.03519, and 4 more.

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