Arithmetic Hirzebruch-Zagier divisors and central derivative values of Rankin-Selberg $L$-functions
Jeanine Van Order
TL;DR
This work develops two distinct proofs of the Gross–Zagier formula using sums of automorphic Green's functions realized as regularized theta lifts, including a construction on the Hilbert modular surface $X_0(N)\times X_0(N)$ via arithmetic Hirzebruch–Zagier divisors. It presents a comprehensive framework for rational quadratic spaces of signature $(n,2)$ and the associated $\operatorname{GSpin}$ Shimura varieties, producing explicit summation formulas along CM cycles and geodesic sets that relate Green's function sums to derivatives of Rankin–Selberg $L$-functions. A key part of the paper identifies spaces of signature $(2,2)$ tied to quadratic fields with exceptional isomorphisms $\operatorname{GSpin}(V_A)\cong GL_2^2$, enabling integral presentations of standard Rankin–Selberg $L$-functions via lifts like the Doi–Naganuma correspondence and the Shimura correspondence. The authors connect these analytic constructions to arithmetic geometry through arithmetic Hirzebruch–Zagier divisors on Hilbert modular surfaces, deriving BSD-type height formulas and linking central derivatives to arithmetic heights and periods, with extensions to the (1,2) signature and conjectural relations to half-integral weight Fourier coefficients. They also spell out a robust web of equivalences among $L$-functions arising from different realizations and lifts, providing a unifying perspective that incorporates Langlands–Siegel–Weil theory, base change, and vector-valued lifts, with implications for understanding special values and derivatives in the BSD program. Overall, the work deepens the interaction between automorphic forms, arithmetic geometry, and $L$-functions, offering new tools to express central derivatives as geometric/arithmetic data on modular surfaces and Hilbert modular varieties.
Abstract
We give two distinct proofs of the Gross-Zagier formula in terms of sums of automorphic Green's functions realized as regularized theta lifts, including one involving arithmetic Hirzebruch-Zagier divisors on the Hilbert modular surface $X_0(N) \times X_0(N)$. We then describe applications to the refined conjecture of Birch and Swinnerton-Dyer. Through these calculations, we also describe known and conjectural relations of the central derivative values of Rankin-Selberg $L$-functions that appear to Fourier coefficients of certain half-integral weight forms.
