CERN Accelerating science

Article
Report number	arXiv:2311.13631 ; CERN-TH-2023-214
Title	The Stringy S-matrix Bootstrap: Maximal Spin and Superpolynomial Softness
Author(s)	Häring, Kelian (CERN ; Ecole Polytechnique, Lausanne) ; Zhiboedov, Alexander (CERN)
Publication	2024-10-09
Imprint	2023-11-22
Number of pages	56
In:	JHEP 2410 (2024) 075
DOI	10.1007/JHEP10(2024)075 (publication)
Subject category	hep-th ; Particle Physics - Theory
Abstract	We explore the space of meromorphic amplitudes with extra constraints coming from the shape of the leading Regge trajectory. This information comes in two guises: it bounds the maximal spin of exchanged particles of a given mass; it leads to sum rules obeyed by the discontinuity of the amplitude, which express the softness of scattering at high energies. We assume that the leading Regge trajectory is linear, and we derive bounds on the low-energy Wilson coefficients using the dual and primal approaches. For the graviton-graviton scattering in four dimensions, the maximal spin constraint leads to slightly more stringent bounds than those that follow from general constraints of analyticity, crossing, and unitarity. The exponential softness at high energies is manifest in our primal approach and is not used in our implementation of the dual approach. Nevertheless, we observe the agreement between the bounds obtained from both. We conclude that high-energy superpolynomial softness does not leave an obvious imprint on the low-energy observables. We exhibit a unitary three-parameter deformation of the Veneziano amplitude for the open string case. It has a novel, exponentially soft behavior at high energies and fixed angles. We generalize the previous analysis of this regime and present a stringy version of the lower bound on high-energy, fixed-angle scattering by Cerulus and Martin.
Copyright/License	preprint: (License: CC BY 4.0) publication: © 2024-2025 The Authors (License: CC-BY-4.0), sponsored by SCOAP³

Corresponding record in: Inspire