Abstract

In the framework of soft-collinear effective theory (SCET), we show how to formulate the resummation for a broad family of final-state, global observables in high-energy collisions in a general way that is suitable for a numerical calculation. Contrary to the standard SCET approach, this results in a method that does not require an observable-specific factorization theorem. We present a complete formulation at next-to-next-to-leading logarithmic order for e+e− observables, and show how to systematically extend the framework to higher orders. This work paves the way to automated resummation in SCET for several physical observables within a single framework.

Highlights

  • Perturbation theory is one of the most widely used techniques to make predictions for interacting quantum field theories

  • In the framework of soft-collinear effective theory (SCET), we show how to formulate the resummation for a broad family of final-state, global observables in high-energy collisions in a general way that is suitable for a numerical calculation

  • In fixed order (FO) perturbation theory, one expands the physical observables in powers of the coupling constants of the theory, where leading order (LO) predictions describe a given process to lowest order, while higher order corrections are suppressed by additional powers of αi = gi2/4π

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Summary

Introduction

Perturbation theory is one of the most widely used techniques to make predictions for interacting quantum field theories. Using the thrust observable as a case study, in [48] it was shown how these two formulations of resummation can be combined into a hybrid method This approach proceeds by defining a simpler version of thrust, defined in order to obey a simple factorization theorem that can be handled using the standard SCET formalism. We briefly touch on all aspects of the derivation: we introduce a generic and fully differential factorization approach derived from SCET, from which any observable can be calculated, define the simple observable and how it can be resummed using SCET and finish by an SCET definition of the transfer function.

Remarks on the counting of logarithms
Kinematics and notation
Basic idea of numerical resummation for rIRC safe observables
Decompose the resummed cumulative distribution as
Factorization of the fully differential energy distribution
Definition of the simple observable
The SCET Lagrangian and resummation of the simple observable
Definition of the transfer function
General expressions for the fully differential transfer function
Numerical treatment of the UV and rapidity divergences
Numerical treatment of the IRC divergences
General expression for the transfer function at NLL
General expression for the transfer function at NNLL
The soft transfer function
The collinear transfer function
Explicit results for transfer function
Details of the observable used in the final combination
Explicit expressions at NLL
Explicit expressions at NNLL
Dealing with the observable
The soft sector
The collinear sector and the zero-bin subtraction
Conclusions
A Kinematics and phase space parametrization
B SCET amplitudes
C Numerical algorithms
Results at NLL
Results at NNLL
Compute
Full Text
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