From data to the analytic S-matrix: A Bootstrap fit of the pion scattering amplitude

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Main Authors: Guerrieri, Andrea, Häring, Kelian, Su, Ning
Format: Preprint
Published: 2024
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author Guerrieri, Andrea
Häring, Kelian
Su, Ning
author_facet Guerrieri, Andrea
Häring, Kelian
Su, Ning
contents We propose a novel strategy to fit experimental data using a UV complete amplitude ansatz satisfying the constraints of Analyticity, Crossing, and Unitarity. We focus on $ππ$ scattering combining both experimental and lattice data. The fit strategy requires using S-matrix Bootstrap methods and non-convex Particle Swarm Optimization techniques. Using this procedure, we numerically construct a full-fledged scattering amplitude that fits the data and contains the known QCD spectrum that couples to $ππ$ states below $1.4$ GeV. The amplitude constructed agrees below the two-particle threshold with the two-loop $χ$PT prediction. Moreover, we correctly predict the $D_2$ phase shift, the appearance of a spin three state, and the behavior of the high-energy total cross-section. Finally, we find a genuine tetraquark resonance around 2 GeV, which we argue might be detected by looking into the decays of B mesons.
format Preprint
id arxiv_https___arxiv_org_abs_2410_23333
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle From data to the analytic S-matrix: A Bootstrap fit of the pion scattering amplitude
Guerrieri, Andrea
Häring, Kelian
Su, Ning
High Energy Physics - Theory
High Energy Physics - Lattice
High Energy Physics - Phenomenology
We propose a novel strategy to fit experimental data using a UV complete amplitude ansatz satisfying the constraints of Analyticity, Crossing, and Unitarity. We focus on $ππ$ scattering combining both experimental and lattice data. The fit strategy requires using S-matrix Bootstrap methods and non-convex Particle Swarm Optimization techniques. Using this procedure, we numerically construct a full-fledged scattering amplitude that fits the data and contains the known QCD spectrum that couples to $ππ$ states below $1.4$ GeV. The amplitude constructed agrees below the two-particle threshold with the two-loop $χ$PT prediction. Moreover, we correctly predict the $D_2$ phase shift, the appearance of a spin three state, and the behavior of the high-energy total cross-section. Finally, we find a genuine tetraquark resonance around 2 GeV, which we argue might be detected by looking into the decays of B mesons.
title From data to the analytic S-matrix: A Bootstrap fit of the pion scattering amplitude
topic High Energy Physics - Theory
High Energy Physics - Lattice
High Energy Physics - Phenomenology
url https://arxiv.org/abs/2410.23333