Measurement of Event Shape Variables in Deep Inelastic e^+ Scattering

TL;DR

This paper analyzes event shape variables in deep inelastic e^+ scattering data from HERA, comparing results with e^+e^- experiments, and uses QCD calculations to determine strong coupling and power corrections without relying on fragmentation models.

Contribution

It presents a novel analysis of event shape variables in deep inelastic scattering, extracting power corrections and the strong coupling constant independently of fragmentation assumptions.

Findings

Power corrections follow a 1/Q behavior.

A common parameter alpha_0 describes all event shape variables.

Determined the strong coupling constant from data.

Abstract

Deep inelastic e^+ scattering data, taken with the H1 detector at HERA, are used to study the event shape variables thrust, jet broadening and jet mass in the current hemisphere of the Breit frame over a large range of momentum transfers Q between 7 GeV and 100 GeV. The data are compared with results from e^+e^- experiments. Using second order QCD calculations and an approach to relate hadronisation effects to power corrections an analysis of the Q dependences of the means of the event shape parameters is presented, from which both the power corrections and the strong coupling constant are determined without any assumption on fragmentation models. The power corrections of all event shape variables investigated follow a 1/Q behaviour and can be described by a common parameter alpha_0.