QCD Scattering Amplitudes and Prescriptive Unitarity

Fuente: arXiv
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Autori principali: Carrôlo, Sérgio, Chicherin, Dmitry, Henn, Johannes, Yang, Qinglin, Zhang, Yang
Natura: Preprint
Pubblicazione: 2026
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author Carrôlo, Sérgio
Chicherin, Dmitry
Henn, Johannes
Yang, Qinglin
Zhang, Yang
author_facet Carrôlo, Sérgio
Chicherin, Dmitry
Henn, Johannes
Yang, Qinglin
Zhang, Yang
contents We present a systematic framework for the maximally-transcendental part of planar QCD scattering amplitudes and perform the first bootstrap computation of six-gluon MHV amplitudes in massless QCD at the symbol level. By analyzing the maximal weight projection of amplitudes at the integrand level, we relate their maximally-transcendental parts to prescriptive unitarity integrals. This reveals a novel analytic structure: the prefactors multiplying the functions of maximal transcendentality are identified with the four-dimensional leading singularities of the theory. As a consequence, these prefactors admit a complete classification and can be computed using on-shell diagrams, a formalism originally developed in $\mathcal{N}{=}4$ super Yang-Mills theory. As a concrete application, we determine the two-loop prefactors for planar MHV gluon amplitudes at arbitrary multiplicity. Combining these prefactors with recent advances in the planar two-loop six-point function space and explicit six-point prescriptive-unitarity input, we construct a complete symbol ansatz and uniquely fix the maximally-transcendental part of the two-loop six-gluon MHV QCD amplitudes by imposing physical constraints. The resulting symbols are expressible in a reduced 137-letter alphabet, suggesting that this alphabet is complete for two-loop six-point massless MHV scattering. We also discuss the implications for multi-collinear splitting and multi-soft functions.
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id arxiv_https___arxiv_org_abs_2602_02783
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle QCD Scattering Amplitudes and Prescriptive Unitarity
Carrôlo, Sérgio
Chicherin, Dmitry
Henn, Johannes
Yang, Qinglin
Zhang, Yang
High Energy Physics - Theory
High Energy Physics - Phenomenology
We present a systematic framework for the maximally-transcendental part of planar QCD scattering amplitudes and perform the first bootstrap computation of six-gluon MHV amplitudes in massless QCD at the symbol level. By analyzing the maximal weight projection of amplitudes at the integrand level, we relate their maximally-transcendental parts to prescriptive unitarity integrals. This reveals a novel analytic structure: the prefactors multiplying the functions of maximal transcendentality are identified with the four-dimensional leading singularities of the theory. As a consequence, these prefactors admit a complete classification and can be computed using on-shell diagrams, a formalism originally developed in $\mathcal{N}{=}4$ super Yang-Mills theory. As a concrete application, we determine the two-loop prefactors for planar MHV gluon amplitudes at arbitrary multiplicity. Combining these prefactors with recent advances in the planar two-loop six-point function space and explicit six-point prescriptive-unitarity input, we construct a complete symbol ansatz and uniquely fix the maximally-transcendental part of the two-loop six-gluon MHV QCD amplitudes by imposing physical constraints. The resulting symbols are expressible in a reduced 137-letter alphabet, suggesting that this alphabet is complete for two-loop six-point massless MHV scattering. We also discuss the implications for multi-collinear splitting and multi-soft functions.
title QCD Scattering Amplitudes and Prescriptive Unitarity
topic High Energy Physics - Theory
High Energy Physics - Phenomenology
url https://arxiv.org/abs/2602.02783