Synopsis: How to Untangle Quark and Gluon Jets

Inspired by a text-mining technique, scientists have developed a more direct way to distinguish quark jets from gluon jets in high-energy particle collisions.
Synopsis figure
E. Metodiev and J. Thaler/MIT

High-energy particle collisions spew forth a mash of different particles, often in the form of collimated streams, or “jets.” Jets are comprised of hadrons (such as protons, neutrons, mesons), but they originate from accelerated quarks and gluons. Eric Metodiev and Jesse Thaler of the Massachusetts Institute of Technology, Cambridge, have now adapted a text-mining technique in order to determine the properties of such quark- and gluon-initiated jets directly from data. Compared with indirect approaches that involve simulations to understand data, their method may lead to more accurate determinations of jet properties, which provide important clues about the behavior of quarks and gluons at high energies.

The researchers rely on a technique called topic modeling, which was originally developed to identify themes in written documents. Say you wanted to analyze how often the subject of dogs appears in a document but not pets in general. Topic modeling would allow you to identify words unique to this topic (e.g., bark, canine) and to then use these identifiers to pinpoint how often and where the topic shows up.

Metodiev and Thaler demonstrated that the same methodology can be applied to jets. The duo compared data from quark-enriched and gluon-enriched samples of jets and showed that it’s possible to eliminate overlapping properties of the two jet types and identify those distinct to each one. These distinct properties include the number of particles in the jet and the jet’s mass, and they can be used to determine the distribution and fraction of each jet type within a sample. The approach could also be applied to high-energy jets initiated by particles other than quarks and gluons.

This research is published in Physical Review Letters.

–Michelle Hampson

Michelle Hampson is a freelance science writer based in Toronto.


Features

More Features »

Announcements

More Announcements »

Subject Areas

Particles and Fields

Previous Synopsis

Next Synopsis

Related Articles

Synopsis: Ion Collisions Reveal Photon-Photon Scattering
Particles and Fields

Synopsis: Ion Collisions Reveal Photon-Photon Scattering

Researchers at the Large Hadron Collider conclusively detect two photons scattering off each other, following initial evidence first published in 2017. Read More »

Viewpoint: Putting Distance Between Collider Events
Particles and Fields

Viewpoint: Putting Distance Between Collider Events

A new way to measure the “distance” between high-energy particle collision events can help researchers interpret events involving, for example, the production of Higgs bosons or of top quarks. Read More »

Synopsis: How a Pentaquark is Put Together
Particles and Fields

Synopsis: How a Pentaquark is Put Together

New Large Hadron Collider data reveal that exotic quark quintets, discovered in 2016, are composites of quark-antiquark mesons and three-quark baryons.   Read More »

More Articles