Accelerating LHC phenomenology with analytic one-loop amplitudes

John M Campbell,Christian T Preuss,Stefan Höche

doi:10.1140/epjc/s10052-021-09885-0

John M Campbell, Christian T Preuss + Show 1 more

Open Access

https://doi.org/10.1140/epjc/s10052-021-09885-0

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Abstract

The evaluation of one-loop matrix elements is one of the main bottlenecks in precision calculations for the high-luminosity phase of the Large Hadron Collider. To alleviate this problem, a new C++ interface to the parton-level Monte Carlo is introduced, giving access to an extensive library of analytic results for one-loop amplitudes. Timing comparisons are presented for a large set of Standard Model processes. These are relevant for high-statistics event simulation in the context of experimental analyses and precision fixed-order computations.

Highlights

Many measurements at particle colliders can only be made with the help of precise Standard Model predictions, which are typically derived using fixed-order perturbation theory at the next-to-leading order (NLO) or next-to-next-toleading order (NNLO) in the strong and/or electroweak coupling
The algorithmic appeal and comparable simplicity of the novel approaches has led to the partial automation of the computation of one-loop matrix elements in arbitrary theories, including effective field theories that encapsulate the phenomenology of a broad range of additions to the Standard Model [20,21]
We report on an extension of the well-known NLO parton-level program MCFM [27,28,29,30], which allows the one-loop matrix elements in MCFM to be accessed using the Binoth Les Houches Accord (BLHA) [31,32] via a direct C++ interface

Summary

Introduction

Many measurements at particle colliders can only be made with the help of precise Standard Model predictions, which are typically derived using fixed-order perturbation theory at the next-to-leading order (NLO) or next-to-next-toleading order (NNLO) in the strong and/or electroweak coupling. The algorithmic appeal and comparable simplicity of the novel approaches has led to the partial automation of the computation of one-loop matrix elements in arbitrary theories, including effective field theories that encapsulate the phenomenology of a broad range of additions to the Standard Model [20,21]. With this “NLO revolution” precision phenomenology has entered a new era. C (2021) 81:1117 a typical setup of the SHERPA event generator, and summarize the speed gains in comparison to automated one-loop programs

Timing benchmarks

Numerical stability

Conclusions