arXiv subjects

Aditya Srivastav

Publications and source records attributed to Aditya Srivastav.

6 recordsLinked to original sources

arXiv2025

CWebGen -- A tool to study colour structure of scattering amplitudes in IR limit

Infrared singularities in perturbative Quantum Chromodynamics (QCD) are captured by the Soft function, which can be calculated efficiently using Feynman diagrams known as webs. The starting point for calculating Soft function using webs is to compute the web mixing matrices using a well known replica trick algorithm. We present a package implemented in Mathematica to calculate these mixing matrices. Along with the package, we provide several state-of-the art computations.

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arXiv2025

Colour structure of next-to-eikonal correlator webs at three loops

Correlators of Wilson-line, which capture eikonal contributions, are known to exponentiate in non-abelian gauge theories, and their logarithms can be organised in terms of collections of Feynman diagrams called webs. In~\cite{Agarwal:2020nyc} the concept of correlator web (Cweb), which is a set of skeleton diagrams built with connected gluon correlators and provides a generalisation of webs was introduced. The part of next-to-eikonal contributions to the scattering amplitude which exponentiates is given in terms of next-to-eikonal Cwebs~\cite{Gardi:2010rn,Laenen:2008gt}. In the present article we study next-to-eikonal Cwebs at three loop order, the order at which non trivial Cweb mixing matrices appear for the first time. The methods developed in~\cite{Agarwal:2022wyk} to construct mixing matrices directly without use of replica trick are used in this article to obtain the mixing matrices for next-to-eikonal Cwebs after we establish a relationship between next-to-eikonal and eikonal Cwebs.

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arXiv2024

Multiparton Cwebs at five loops

Scattering amplitudes involving multiple partons are plagued with infrared singularities. The soft singularities of the amplitude are captured by the soft function which is defined as the vacuum expectation value of Wilson line correlators. Renormalization properties of soft function allows us to write it as an exponential of the finite soft anomalous dimension. An efficient way to study the soft function is through a set of Feynman diagrams known as Cwebs (webs). We present the mixing matrices and exponentiated colour factors (ECFs) for the Cwebs at five loops that connect six Wilson lines, except those that are related by relabeling of Wilson lines. Further, we express these ECFs in terms of 29 basis colour factors. We also find that this basis can be categorized into two colour structures. Our results are the first key ingredients for the calculation of the soft anomalous dimension at five loops.

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arXiv2024

Correlator webs of massive multiparton amplitudes at four loops: A study of boomerang webs

Logarithm of the soft function can be organized into sets of Feynman diagrams known as Cwebs. We introduced a new formalism in~\cite{Agarwal:2022wyk}, that allows to determine several of the building blocks of Cweb mixing matrices without explicit computations. In~\cite{Agarwal:2022xec} we used this formalism to obtain the diagonal blocks of four general classes of Cwebs to all orders in perturbation theory which also covered all the four loop Boomerang Cwebs connecting four Wilson lines. In this work we present complete mixing matrices and exponentiated colour factors for Boomerang Cwebs at four loops that connect three and four Wilson lines. Also, we present a more efficient version of the algorithm of generating Cwebs that was presented in~\cite{Agarwal:2020nyc}. This new algorithm has been used to generate the Cwebs in the present work.

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arXiv2023

Deciphering Colour Building Blocks of Massive Multiparton Amplitudes at 4-loops and beyond

The soft function in non-abelian gauge theories exponentiate, and their logarithms can be organised in terms of the collections of Feynman diagrams called Cwebs. The colour factors that appear in the logarithm are controlled by the web mixing matrices. Direct construction of the diagonal blocks of Cwebs using the new concepts of Normal ordering, basis Cweb and Fused-Web was recently carried out in~\cite{Agarwal:2022wyk}. In this article we establish correspondence between the boomerang webs introduced in ~\cite{Gardi:2021gzz} and non-boomerang Cwebs. We use this correspondence together with Uniqueness theorem and Fused web formalism introduced in ~\cite{Agarwal:2022wyk} to obtain the diagonal blocks of four general classes of Cwebs to all orders in perturbation theory which also cover all the four loop Boomerang Cwebs connecting four Wilson lines. We also fully construct the mixing matrix of a special Cweb to all orders in perturbation theory.

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arXiv2022

Building blocks of Cwebs in multiparton scattering amplitudes

The correlators of Wilson-line operators in non-abelian gauge theories are known to exponentiate, and their logarithms can be organised in terms of the collections of Feynman diagrams called Cwebs. The colour factors that appear in the logarithm correspond to completely connected diagrams and are determined by the web mixing matrices. In this article we introduce several new concepts: (a) Normal ordering of the diagrams of a Cweb, (b) Fused-Webs (c) Basis and Family of Cwebs. We use these ideas together with a Uniqueness theorem that we prove to arrive at an understanding of the diagonal blocks, and several null matrices that appear in the mixing matrices. We demonstrate using our formalism that, once the basis Cwebs present upto order $α_{s}^{n}$ are determined, the number of exponentiated colour factors for several classes of Cwebs starting at order $α_{s}^{n+1}$ can be predicted. We further provide complete results for the mixing matrices, to all orders in perturbation theory, for two special classes of Cwebs using our framework.

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