Cutoff dependence of the thrust peak position in the dipole shower

Robin Baumeister,Stefan Weinzierl

doi:10.1140/epjc/s10052-020-8425-5

Robin Baumeister, Stefan Weinzierl

Open Access

https://doi.org/10.1140/epjc/s10052-020-8425-5

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Abstract

We analyse the dependence of the peak position of the thrust distribution on the cutoff value in the Nagy–Soper dipole shower. We compare the outcome of the parton shower simulations to a relation of the dependence from an analytic computation, derived within soft-collinear effective theory. We show that the result of the parton shower simulations and the analytic computation are in good agreement.

Highlights

MMSR (R = 0) = mpole, mMSR (R = m ) = m . (1)Here, mdenotes the MS-mass
We show that the theoretical prediction is valid for angular ordered parton showers but holds for Nagy-Soper dipole showers as well
This paper is organised as follows: we review the analytic computations for the cutoff dependence and give the essential relation

Summary

Introduction

Mass can be understood in the context of effective theories, which separates the various relevant scales (the centre-ofmass energy Q, the top mass mt , the top width t and QCD). In order to understand the situation better, it is helpful to consider a related problem: The dependence of the peak position of the thrust distribution in electron–positron annihilation on the shower cutoff [38]. The second derivation in [29] based on soft-collinear effective theory uses just the condition on the transverse momentum and is not tied to any particular shower algorithm. We expect these results to hold for any shower algorithm whose shower evolution variable reduces in the singular limit to p⊥.

Analytic results

The massless case

The massive case

Dipole shower results

Conclusions