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arXiv · 1704.03878

Systematics of quark/gluon tagging

Philippe Gras·Stefan Höche·Deepak Kar·Andrew Larkoski·Leif Lönnblad·Simon Plätzer·Andrzej Siódmok·Peter Skands·Gregory Soyez·Jesse Thaler
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Abstract

By measuring the substructure of a jet, one can assign it a "quark" or "gluon" tag. In the eikonal (double-logarithmic) limit, quark/gluon discrimination is determined solely by the color factor of the initiating parton (C_F versus C_A). In this paper, we confront the challenges faced when going beyond this leading-order understanding, using both parton-shower generators and first-principles calculations to assess the impact of higher-order perturbative and nonperturbative physics. Working in the idealized context of electron-positron collisions, where one can define a proxy for quark and gluon jets based on the Lorentz structure of the production vertex, we find a fascinating interplay between perturbative shower effects and nonperturbative hadronization effects. Turning to proton-proton collisions, we highlight a core set of measurements that would constrain current uncertainties in quark/gluon tagging and improve the overall modeling of jets at the Large Hadron Collider.

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Philippe Gras, Stefan Höche, Deepak Kar, Andrew Larkoski, Leif Lönnblad, Simon Plätzer, Andrzej Siódmok, Peter Skands, Gregory Soyez, Jesse Thaler. 2017-08-08. Systematics of quark/gluon tagging. https://doi.org/10.1007/jhep07(2017)091

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