SciPost Submission Page
Universality of entanglement in gluon dynamics
by Claudia Nuñez Garrido, Alba Cervera-Lierta, José Ignacio Latorre
This is not the latest submitted version.
Submission summary
| Authors (as registered SciPost users): | Claudia Nuñez Garrido |
| Submission information | |
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| Preprint Link: | scipost_202512_00009v1 (pdf) |
| Date submitted: | Dec. 3, 2025, 11:18 a.m. |
| Submitted by: | Claudia Nuñez Garrido |
| Submitted to: | SciPost Physics |
| Ontological classification | |
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| Academic field: | Physics |
| Specialties: |
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| Approach: | Theoretical |
Abstract
Entanglement of fundamental degrees of freedom in particle physics is generated ab initio in scattering processes. We find that in the case of a pure SU(N) gauge theory, two gluons in a product state can become maximally entangled in their polarizations as the result of three- and four-gluon vertex interactions. Remarkably, the amount of entanglement among gluon polarizations is independent of the color degree of freedom. We also find that a small deviation of the relative weight between three- and four-gluon vertices would prevent the generation of maximal entanglement. This can be seen as a small piece of a possible it from qubit principle underlying fundamental interactions.
Author indications on fulfilling journal expectations
- Provide a novel and synergetic link between different research areas.
- Open a new pathway in an existing or a new research direction, with clear potential for multi-pronged follow-up work
- Detail a groundbreaking theoretical/experimental/computational discovery
- Present a breakthrough on a previously-identified and long-standing research stumbling block
Current status:
Reports on this Submission
Strengths
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Casts a new light on fundamental interactions by advocating a heuristic principle based on entanglement constraining them, in the it from bit philosophy
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Clear, concise and very readable
Weaknesses
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The reach, significance and the very formulation of the principle may be questioned (see below)
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All the calculations are at tree-level
Report
These are interesting remarks per se, regardless of the overarching principle that they may inform.
May main issue with this study concerns the maximal entanglement principle itself. What is shown here is that, for a certain value of the 4-gluon mixing already convincingly enforced by gauge symmetry, the entanglement in polarization at tree-level for a certain initial product state and a certain final scattering angle is maximal. This looks like very circumstantial evidence in favour of the principle in question (so that gauge symmetry is still much more compelling in setting such values).
I think this whole line of work would benefit from an attempt to state the maxent principle in clear terms: on such grounds one would be able to form a sharper appreciation of how strongly certain dynamical behaviours may relate to the principle.
Also, this should also involve a discussion of why evidence at the lowest perturbative order should be enough to point to the principle.
Requested changes
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The u-channel in the figure has one loop and it doesn’t look like a u-channel to me.
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Statement of the principle and discussion as to why it works at tree-level and for helicity (one may beat classical correlation thresholds even with other degrees of freedom)
Recommendation
Ask for minor revision
Strengths
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Highly non-trivial extension of the maximal entanglement principle, previously only studies in Abelian theories, to the pure Yang-Mills theories.
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Demonstration that the connection between MaxEnt and gauge symmetry is also present for QCD.
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Clear, up to the point text and discussion.
Weaknesses
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the parametrisation of the deviation from gauge symmetry is a bit simplistic and model-dependent
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the quality of the graphics could be improved a bit
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The authors do not provide details about the availability of their numerical code, which could be useful for other researchers or to reproduce the results.
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The connections with possible measurements at the LHC could be discussed a bit more.
Report
In the present manuscript, the researchers explore whether maximal entanglement principles can also be applied to more complex gauge theories, in particular to SU(N) gauge theories such as quantum chromodynamics, where the structure of the scattering amplitudes quickly becomes much more complex than in QED and where in particular one has gluon self-interactions which are completely absent in the case of the Abelian theory. Hence establishing whether the same principles apply to QCD would represent a highly non-trivial validation that the maximal entanglement principles represent a solid guiding strategy for theory building in particle physics. The authors demonstrate, following a calculation of pure yang-mills scattering amplitudes, that MaxEnt would not be satisfied should the amplitudes of three-gluon and four-gluon scattering be related in exactly the same way as required by SU(N) gauge symmetry. This very interesting result confirms previous studies relating maximal entanglement principles with fundamental symmetries in particle physics, specially with gauge symmetry.
Requested changes
The paper is detailed, complete, and clearly written. It is well suited to a journal like SciPost. However, before I can recommend this paper for publication, I would like the authors to address a number of points in the revised version of the manuscript.
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While gluons are not asymptotically free and one cannot really construct Bell-type relations for gluon scattering (at least if the goal is to test them experimentally) the LHC is a prodigious source of gluon collisions. In particular, multijet production receives large contributions from gluon-only scattering. At the light of the findings of the paper, the authors should comment on whether there are observables at the LHC, such as multijet production, which can be used as experimental probes of entanglement in gluon scattering (in the same way as it has been done in the top quark sectors in recent measurements from ATLAS and CMS).
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One of the Feynman diagrams in Figure 1 does not seem to be correct. The u-channel diagram shown in actually part of the one-loop correction to the tree level amplitude.
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When computing the scattering amplitudes, do the author assume gauge symmetry when deriving the Feynman rules? And if the calculation carried out analytically or with the help of numerical tools?
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I am intrigued by the statement from the authors that "As far as a would be violation of a Bell inequality is concerned, color degrees of freedom are neutral witnesses". This is a bit unclear since without colour there are no gluon-only scattering amplitudes right? Maybe it would be good to rewrite this to avoid possible confusions.
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The introduction of the 4-gluon weight k of course violates gauge symmetry. There are other ways in which the authors could implement a violation of gauge symmetry in pure YM scattering amplitudes, such as via a modification in the SU(N) matrices or structure constants. Can the author discuss how robust their results are if one chooses some other way to violate gauge symmetry in their analysis (to then check that it is recovered by the MaxEnt principle?)
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As a related point, Figure 2 shows that there are unphysical solutions for k that lead to MaxEnt. These solutions violate gauge invariance. I wonder to which extent these unphysical solutions go away if one chooses a different way to parametrise the deviations from gauge invariance? I would also in this plot add a vertical line to indicate the physical k=1 solution.
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A recent related study https://arxiv.org/abs/2410.23343 proposes instead a Minimum Entanglement principle, and shows that it can be used to approximately reproduce numerical values of some of the SM parameters in the neutrino sector. What makes, conceptually, a MinEnt principle better (or worse) than a MaxEnt principle? Maybe it depends on the process, or it is part of a bigger, more fundamental principle?
Recommendation
Ask for minor revision
Dear referee,
we attach a file with the answers to your questions. Thank you very much for your report. You can also find there the questions formulated by the other referee, as well as our answers to them.
Author: Claudia Nuñez Garrido on 2026-02-03 [id 6300]
(in reply to Report 2 on 2026-01-21)Dear referee,
We attach a file with the answers to your comments. Thank you very much for your report. You can also find there the questions of the other referee, as well as our answers to them.
Attachment:
referee_response_eCIb3qT.pdf