Generalized Dipole Model Offers New Insight Into Proton Collision Entropy

Physicists at the Institute of Nuclear Physics of the Polish Academy of Sciences (IFJ PAN) have introduced a generalized dipole model that extends previous approaches to describe proton collision data more comprehensively. This development addresses behavior at lower collision energies and was recently published in Physical Review D.

The new model incorporates subleading effects that become relevant at lower energies, expanding on existing dipole models. Researchers tested the model using experimental results from the ALICE, ATLAS, CMS, and LHCb experiments at the Large Hadron Collider (LHC), covering a broad energy range from 0.2 TeV to 13 TeV.

According to the published findings, the generalized dipole model provided a more accurate description of the experimental data across a wider range of collision energies than previous models. The research was conducted by Prof. Krzysztof Kutak and Dr. Sándor Lökös, who published their results in Physical Review D.

One of the key results from the study is that entropy measured during the early quark–gluon (parton) stage of proton collisions closely matches the entropy observed in the hadrons produced later. This observation aligns with the prediction of the Kharzeev–Levin formula, which states that entropy remains constant between these two phases.

What the numbers show

• The model was tested with collision energies ranging from 0.2 TeV to 13 TeV
• Data from ALICE, ATLAS, CMS, and LHCb experiments at the LHC were used
• The research was published in Physical Review D in 2025

The constancy of entropy between the parton and hadron phases is consistent with the principle of unitarity in quantum mechanics. This principle requires that probability is conserved and that quantum processes are reversible, supporting the observed results in the study.

The generalized dipole model's ability to match experimental data more closely than earlier models demonstrates its effectiveness across a broad spectrum of collision energies. This approach allows for improved analysis of proton collisions, particularly at lower energies where subleading effects are important.

Further testing of the generalized dipole model is planned. Researchers intend to use data from the upgraded ALICE detector following the next LHC upgrade, as well as from the future Electron–Ion Collider (EIC) at Brookhaven National Laboratory.

The research team at IFJ PAN stated that these additional tests will help confirm the model's applicability and accuracy using new experimental data. The ongoing work aims to refine the understanding of entropy and particle production in high-energy physics.

These findings contribute to the ongoing study of quantum mechanics and particle physics by providing a model that aligns with both theoretical predictions and experimental results. The work demonstrates the value of integrating new theoretical approaches with large-scale experimental data.

* This article is based on publicly available information at the time of writing.