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Entropy of a Jet.

Duff Neill¹, Wouter J Waalewijn^2,3

¹Theoretical Division, MS B283, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA.

Physical Review Letters

|November 9, 2019

Summary

This summary is machine-generated.

We calculated the entropy of hard scattering events by analyzing infrared radiation. This entropy increases as resolution scales decrease and relates to subjet multiplicity in jets.

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Area of Science:

High Energy Physics
Quantum Field Theory
Jet Physics

Background:

Scattering processes generate infrared (IR) states, which correlate with hard scattering events and cause decoherence.
The entropy of the hard reduced density matrix, derived by tracing over IR states, quantifies this decoherence.

Purpose of the Study:

To determine the entropy of the hard reduced density matrix for an asymptotically free gauge theory.
To investigate the relationship between entropy, resolution scales, and subjet multiplicity in jets.
To explore potential applications in machine learning and deep-inelastic scattering.

Main Methods:

Separating the Hilbert space into hard and infrared (IR) states.
Calculating entropy in a leading-logarithmic approximation for jets.
Analyzing the behavior of entropy with varying resolution scales.

Main Results:

Entropy increases as the resolution scales defining hard radiation are lowered.
A direct relationship was found between this entropy and the subjet multiplicity.
Connections were explored to machine learning using jet images and parton density matrices.

Conclusions:

The entropy of the hard reduced density matrix provides a quantifiable measure of decoherence in scattering processes.
Jet substructure, quantified by entropy and subjet multiplicity, offers insights into fundamental particle interactions.
This work opens avenues for advanced machine learning applications and understanding nucleon structure.