Adding subtractions: Comparing the impact of different Regge behaviors, by Brian McPeak, Marco Venuti, Alessandro Vichi

SciPost Physics Home Authoring Refereeing Submit a manuscript About Adding subtractions: Comparing the impact of different Regge behaviors Brian McPeak, Marco Venuti, Alessandro Vichi SciPost Phys. 20, 085 (2026) · published 18 March 2026 doi: 10.21468/SciPostPhys.20.3.085 pdf BiBTeX RIS Submissions/Reports Abstract Dispersion relations let us leverage the analytic structure of scattering amplitudes to derive constraints such as bounds on EFT coefficients. An important input is the large-energy behavior of the amplitude. In this paper, we systematically study how different large-energy behavior affects EFT bounds for the $2 \to 2$ amplitude of complex scalars coupled to photons, gravity, both, or neither. In many cases we find that singly-subtracted dispersion relations yield exactly the same bounds as doubly subtracted relations. However, we identify another assumption, which we call "$t$-channel dominance," that significantly strengthens the EFT bounds. This assumption, which amounts to the requirement that the $++ \to ++$ amplitude has no $s$-channel exchange, is justified in certain cases and is analogous to the condition that the isospin-2 channel does not contribute to the pion amplitude. Using this assumption in the absence of massless exchanges, we find that the allowed region for the complex scalar EFT is identical to one recently discussed for pion scattering at large-$N$. We also study gravity, where we consider smeared dispersion relations to handle the $t$-channel pole. In the case of a gauge field, we are able to derive a number of interesting bounds. These include an upper bound for $G$ in terms of the gauge coupling $e^2$ and the leading dispersive EFT coefficient, which is reminiscent of the weak gravity conjecture. In the $e \to 0$ limit, we find that assuming smeared 1SDRs plus $t$-channel dominance restores positivity on the leading EFT coefficient whose positivity was spoiled by the inclusion of gravity. We interpret this to mean that the negativity of that coefficient in the presence of gravity would imply that the global $U(1)$ symmetry must be gauged. × TY - JOURPB - SciPost FoundationDO - 10.21468/SciPostPhys.20.3.085TI - Adding subtractions: Comparing the impact of different Regge behaviorsPY - 2026/03/18UR - https://scipost.org/SciPostPhys.20.3.085JF - SciPost PhysicsJA - SciPost Phys.VL - 20IS - 3SP - 085A1 - McPeak, BrianAU - Venuti, MarcoAU - Vichi, AlessandroAB - Dispersion relations let us leverage the analytic structure of scattering amplitudes to derive constraints such as bounds on EFT coefficients. An important input is the large-energy behavior of the amplitude. In this paper, we systematically study how different large-energy behavior affects EFT bounds for the $2 \to 2$ amplitude of complex scalars coupled to photons, gravity, both, or neither. In many cases we find that singly-subtracted dispersion relations yield exactly the same bounds as doubly subtracted relations. However, we identify another assumption, which we call "$t$-channel dominance," that significantly strengthens the EFT bounds. This assumption, which amounts to the requirement that the $++ \to ++$ amplitude has no $s$-channel exchange, is justified in certain cases and is analogous to the condition that the isospin-2 channel does not contribute to the pion amplitude. Using this assumption in the absence of massless exchanges, we find that the allowed region for the complex scalar EFT is identical to one recently discussed for pion scattering at large-$N$. We also study gravity, where we consider smeared dispersion relations to handle the $t$-channel pole. In the case of a gauge field, we are able to derive a number of interesting bounds. These include an upper bound for $G$ in terms of the gauge coupling $e^2$ and the leading dispersive EFT coefficient, which is reminiscent of the weak gravity conjecture. In the $e \to 0$ limit, we find that assuming smeared 1SDRs plus $t$-channel dominance restores positivity on the leading EFT coefficient whose positivity was spoiled by the inclusion of gravity. We interpret this to mean that the negativity of that coefficient in the presence of gravity would imply that the global $U(1)$ symmetry must be gauged.ER - × @Article{10.21468/SciPostPhys.20.3.085, title={{Adding subtractions: Comparing the impact of different Regge behaviors}}, author={Brian McPeak and Marco Venuti and Alessandro Vichi}, journal={SciPost Phys.}, volume={20}, pages={085}, year={2026}, publisher={SciPost}, doi={10.21468/SciPostPhys.20.3.085}, url={https://scipost.org/10.21468/SciPostPhys.20.3.085},} Ontology / Topics See full Ontology or Topics database. Bootstrap program Quantum field theory (QFT) Authors / Affiliations: mappings to Contributors and Organizations See all Organizations. 1 2 3 Brian McPeak, 2 3 4 5 Marco Venuti, 2 3 Alessandro Vichi 1 McGill University 2 Università di Pisa / University of Pisa [UniPi] 3 INFN Sezione di Pisa 4 Scuola Internazionale Superiore di Studi Avanzati / International School for Advanced Studies [SISSA] 5 Scuola Normale Superiore di Pisa Funder for the research work leading to this publication European Research Council [ERC]