Modular Features of Superstring Scattering Amplitudes: Generalised Eisenstein Series and Theta Lifts

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Main Authors: Dorigoni, Daniele, Green, Michael B., Wen, Congkao
Format: Preprint
Published: 2025
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_version_ 1866912519224819712
author Dorigoni, Daniele
Green, Michael B.
Wen, Congkao
author_facet Dorigoni, Daniele
Green, Michael B.
Wen, Congkao
contents In previous papers it has been shown that the coefficients of terms in the large-$N$ expansion of a certain integrated four-point correlator of superconformal primary operators in $\mathcal{N}=4$ supersymmetric Yang-Mills theory are rational sums of real-analytic Eisenstein series and "generalised Eisenstein series''. The latter are novel modular functions first encountered in the context of graviton amplitudes in type IIB superstring theory. Similar modular functions, known as two-loop modular graph functions, are also encountered in the low-energy expansion of the integrand of genus-one closed superstring amplitudes. In this paper we further develop the mathematical structure of such generalised Eisenstein series emphasising, in particular, the occurrence of $L$-values of holomorphic cusp forms in their Fourier mode decomposition. We show that both the coefficients in the large-$N$ expansion of the integrated correlator and two-loop modular graph functions admit a unifying description in terms of four-dimensional lattice sums generated by theta lifts of local Maass functions, which generalise the structure of real-analytic Eisenstein series. Through the theta lift representation, we demonstrate that elements belonging to these two families of non-holomorphic modular functions can be expressed as rational linear combinations of generalised Eisenstein series for which all the $L$-values of holomorphic cusp forms precisely cancel.
format Preprint
id arxiv_https___arxiv_org_abs_2501_03996
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Modular Features of Superstring Scattering Amplitudes: Generalised Eisenstein Series and Theta Lifts
Dorigoni, Daniele
Green, Michael B.
Wen, Congkao
High Energy Physics - Theory
Number Theory
In previous papers it has been shown that the coefficients of terms in the large-$N$ expansion of a certain integrated four-point correlator of superconformal primary operators in $\mathcal{N}=4$ supersymmetric Yang-Mills theory are rational sums of real-analytic Eisenstein series and "generalised Eisenstein series''. The latter are novel modular functions first encountered in the context of graviton amplitudes in type IIB superstring theory. Similar modular functions, known as two-loop modular graph functions, are also encountered in the low-energy expansion of the integrand of genus-one closed superstring amplitudes. In this paper we further develop the mathematical structure of such generalised Eisenstein series emphasising, in particular, the occurrence of $L$-values of holomorphic cusp forms in their Fourier mode decomposition. We show that both the coefficients in the large-$N$ expansion of the integrated correlator and two-loop modular graph functions admit a unifying description in terms of four-dimensional lattice sums generated by theta lifts of local Maass functions, which generalise the structure of real-analytic Eisenstein series. Through the theta lift representation, we demonstrate that elements belonging to these two families of non-holomorphic modular functions can be expressed as rational linear combinations of generalised Eisenstein series for which all the $L$-values of holomorphic cusp forms precisely cancel.
title Modular Features of Superstring Scattering Amplitudes: Generalised Eisenstein Series and Theta Lifts
topic High Energy Physics - Theory
Number Theory
url https://arxiv.org/abs/2501.03996