One-loop four-graviton string amplitude at finite $\alpha'$, by Marco Maria Baccianti, Lorenz Eberhardt, Sebastian Mizera

SciPost Physics Home Authoring Refereeing Submit a manuscript About One-loop four-graviton string amplitude at finite $\alpha'$ Marco Maria Baccianti, Lorenz Eberhardt, Sebastian Mizera SciPost Phys. 20, 052 (2026) · published 23 February 2026 doi: 10.21468/SciPostPhys.20.2.052 pdf BiBTeX RIS Submissions/Reports Abstract We evaluate the one-loop four-graviton scattering amplitude in type-II superstring theory exactly in $\alpha'$. This result is achieved by combining physical insights into the $i\varepsilon$ prescription in string theory with a new technical application of the Rademacher expansion of modular integrals. We provide an implementation of our formula in $\texttt{C++}$ and use it to study the behavior of the amplitude at finite $\alpha'$ and in different kinematic regimes. Our analysis reveals a tension between explicit computations and the saddle point analysis of Gross and Mende in the high-energy limit and suggests the presence of additional saddle points. × TY - JOURPB - SciPost FoundationDO - 10.21468/SciPostPhys.20.2.052TI - One-loop four-graviton string amplitude at finite $\alpha'$PY - 2026/02/23UR - https://scipost.org/SciPostPhys.20.2.052JF - SciPost PhysicsJA - SciPost Phys.VL - 20IS - 2SP - 052A1 - Baccianti, Marco MariaAU - Eberhardt, LorenzAU - Mizera, SebastianAB - We evaluate the one-loop four-graviton scattering amplitude in type-II superstring theory exactly in $\alpha'$. This result is achieved by combining physical insights into the $i\varepsilon$ prescription in string theory with a new technical application of the Rademacher expansion of modular integrals. We provide an implementation of our formula in $\texttt{C++}$ and use it to study the behavior of the amplitude at finite $\alpha'$ and in different kinematic regimes. Our analysis reveals a tension between explicit computations and the saddle point analysis of Gross and Mende in the high-energy limit and suggests the presence of additional saddle points.ER - × @Article{10.21468/SciPostPhys.20.2.052, title={{One-loop four-graviton string amplitude at finite $\alpha'$}}, author={Marco Maria Baccianti and Lorenz Eberhardt and Sebastian Mizera}, journal={SciPost Phys.}, volume={20}, pages={052}, year={2026}, publisher={SciPost}, doi={10.21468/SciPostPhys.20.2.052}, url={https://scipost.org/10.21468/SciPostPhys.20.2.052},} Ontology / Topics See full Ontology or Topics database. String theory Supergravity Authors / Affiliations: mappings to Contributors and Organizations See all Organizations. 1 Marco Maria Baccianti, 1 Lorenz Eberhardt, 2 Sebastian Mizera 1 Institute for Theoretical Physics Amsterdam [ITFA] 2 Columbia University [CU] Funder for the research work leading to this publication Horizon 2020 (through Organization: European Commission [EC])