Positive Geometry for Stringy Scalar Amplitudes

Fuente: arXiv
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Main Authors: Bartsch, Christoph, Kampf, Karol, Podivin, David, Stalknecht, Jonah
Format: Preprint
Published: 2025
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author Bartsch, Christoph
Kampf, Karol
Podivin, David
Stalknecht, Jonah
author_facet Bartsch, Christoph
Kampf, Karol
Podivin, David
Stalknecht, Jonah
contents We introduce a new positive geometry, the associahedral grid, which provides a geometric realization of the inverse string theory KLT kernel. It captures the full $α'$-dependence of stringified amplitudes for bi-adjoint scalar $ϕ^3$ theory, pions in the NLSM, and their mixed $ϕ$/$π$ amplitudes, reducing to the corresponding field theory amplitudes in the $α'\to 0$ limit. Our results demonstrate how positive geometries can be utilized beyond rational functions to capture stringy features of amplitudes, such as an infinite resonance structure. The kinematic $δ$-shift, recently proposed to relate field theory $\mathrm{Tr}(ϕ^3)$ and NLSM pion amplitudes, naturally emerges as the leading contribution to the stringy geometry. We show how the connection between $\mathrm{Tr}(ϕ^3)$ and NLSM can be geometrized using the associahedral grid.
format Preprint
id arxiv_https___arxiv_org_abs_2508_20161
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Positive Geometry for Stringy Scalar Amplitudes
Bartsch, Christoph
Kampf, Karol
Podivin, David
Stalknecht, Jonah
High Energy Physics - Theory
We introduce a new positive geometry, the associahedral grid, which provides a geometric realization of the inverse string theory KLT kernel. It captures the full $α'$-dependence of stringified amplitudes for bi-adjoint scalar $ϕ^3$ theory, pions in the NLSM, and their mixed $ϕ$/$π$ amplitudes, reducing to the corresponding field theory amplitudes in the $α'\to 0$ limit. Our results demonstrate how positive geometries can be utilized beyond rational functions to capture stringy features of amplitudes, such as an infinite resonance structure. The kinematic $δ$-shift, recently proposed to relate field theory $\mathrm{Tr}(ϕ^3)$ and NLSM pion amplitudes, naturally emerges as the leading contribution to the stringy geometry. We show how the connection between $\mathrm{Tr}(ϕ^3)$ and NLSM can be geometrized using the associahedral grid.
title Positive Geometry for Stringy Scalar Amplitudes
topic High Energy Physics - Theory
url https://arxiv.org/abs/2508.20161