Recognition: no theorem link
Constraining magnetic monopoles and multiply charged particles with diphoton events at the LHC
Pith reviewed 2026-05-10 17:53 UTC · model grok-4.3
The pith
LHC diphoton data excludes magnetic monopoles and high-electric-charge objects up to tens of TeV
A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.
Core claim
Measurements of central exclusive photon pair production with proton tagging in LHC Run 2 data are used to constrain the contributions of virtual monopoles and HECOs to light-by-light scattering. In effective field theories and a Born-Infeld scenario, with resummation for large couplings, this leads to the exclusion of masses of up to a few tens of TeV for monopoles and HECOs of various spins and magnetic and electric charges.
What carries the argument
Virtual particle contributions to light-by-light scattering in diphoton events, modeled using effective field theories and the Born-Infeld scenario with resummation techniques.
If this is right
- Monopoles with different spins and magnetic charges are excluded below masses of tens of TeV.
- HECOs with high electric charges are similarly excluded up to tens of TeV.
- This provides complementary constraints to direct searches for these particles.
- The use of resummation enables reliable modeling even for large couplings.
Where Pith is reading between the lines
- These limits could guide searches in future higher-energy colliders.
- Similar techniques might apply to other beyond-Standard-Model particles affecting photon interactions.
- If the exclusions hold, it suggests such particles, if they exist, are very heavy and perhaps not relevant for low-energy phenomena.
Load-bearing premise
The theoretical modeling of virtual monopoles and HECOs in light-by-light scattering using effective theories and Born-Infeld with resummation is accurate enough to derive reliable limits from the diphoton data.
What would settle it
An observation of diphoton production rates or distributions in central exclusive processes that cannot be explained by the Standard Model plus the included virtual contributions from monopoles or HECOs at the excluded mass scales would challenge the derived constraints.
read the original abstract
The LHC is achieving energies never reached before, opening up possibilities for the discovery of exotic particles in the TeV mass range. Such states include magnetic monopoles, which can explain the electric charge quantisation and restore the symmetry in Maxwell's equations with respect to the magnetic and electric fields. Scenarios proposed to shed light to dark matter and neutrino masses introduce high-electric-charge objects (HECOs). The existence of both classes of particles can be probed in precision measurements in a manner complementary to direct searches. We focus on the contributions of such virtual particles to light-by-light scattering in the context of effective field theories and a Born-Infeld scenario. Specifically, measurements of central exclusive production of photon pairs with proton tagging carried out by the CMS-TOTEM Precision Proton Spectrometer with LHC Run 2 proton-proton collision data are used to constrain magnetic monopole and HECOs. Resummation techniques have been employed to deal with the large HECO-photon coupling. Masses of up to a few tens of TeV have been excluded for monopoles and HECOs of various spins and magnetic and electric charges, respectively.
Editorial analysis
A structured set of objections, weighed in public.
Referee Report
Summary. The paper investigates constraints on magnetic monopoles and high-electric-charge objects (HECOs) through their virtual effects on light-by-light scattering in central exclusive diphoton production at the LHC. Utilizing CMS-TOTEM Precision Proton Spectrometer data from Run 2 proton-proton collisions, the authors employ effective field theory frameworks and a Born-Infeld scenario to model these contributions. Resummation techniques are applied to handle large couplings, leading to the exclusion of masses up to several tens of TeV for monopoles and HECOs with various spins, magnetic charges, and electric charges.
Significance. If the theoretical modeling and experimental interpretation are robust, this study provides valuable complementary limits on exotic particles that may address electric charge quantization and dark matter. It demonstrates the power of precision measurements in constraining high-mass states beyond direct production searches, potentially impacting a range of BSM models.
major comments (2)
- The derivation of the mass limits hinges on the resummed amplitudes in the EFT and Born-Infeld approaches for virtual particle contributions to the diphoton cross section. However, the manuscript lacks a clear validation of the resummation procedure for couplings larger than unity, raising concerns about whether higher-order or non-perturbative effects are adequately captured.
- Insufficient information is provided on the implementation details of the EFT, including cutoff choices, matching conditions, and how systematic uncertainties in the theoretical prediction and experimental data are handled. This is essential to substantiate the claimed exclusions up to tens of TeV.
minor comments (1)
- The abstract mentions 'various spins and magnetic and electric charges' but does not specify the exact values considered, which would help readers quickly assess the scope of the results.
Simulated Author's Rebuttal
We thank the referee for the careful reading of our manuscript and the constructive comments, which will help improve the clarity and robustness of our results. We address each major comment below and will revise the manuscript accordingly.
read point-by-point responses
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Referee: The derivation of the mass limits hinges on the resummed amplitudes in the EFT and Born-Infeld approaches for virtual particle contributions to the diphoton cross section. However, the manuscript lacks a clear validation of the resummation procedure for couplings larger than unity, raising concerns about whether higher-order or non-perturbative effects are adequately captured.
Authors: We appreciate the referee's concern on this point. The resummation is performed using standard leading-logarithmic techniques applied to the effective photon couplings, consistent with approaches used in the literature for large-charge scenarios. We agree that explicit validation for couplings exceeding unity would strengthen the presentation. In the revised manuscript, we will add a new subsection (or appendix) providing validation tests, including comparisons of the resummed amplitude against fixed-order perturbative results at moderate couplings and convergence checks of the series. We will also clarify that our limits are derived conservatively by restricting the resummed contribution to the regime where the EFT remains valid, and that unaccounted higher-order or non-perturbative effects would typically only strengthen the exclusions. This addresses the potential limitations while preserving the robustness of the reported mass bounds. revision: yes
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Referee: Insufficient information is provided on the implementation details of the EFT, including cutoff choices, matching conditions, and how systematic uncertainties in the theoretical prediction and experimental data are handled. This is essential to substantiate the claimed exclusions up to tens of TeV.
Authors: We thank the referee for this observation. While the manuscript outlines the overall EFT framework and Born-Infeld scenario, we acknowledge that specific implementation details were not fully elaborated. In the revised version, we will expand the relevant sections to explicitly state: the cutoff scale is chosen as the mass of the heavy particle to ensure proper decoupling; matching conditions are performed by equating the EFT coefficients to the full theory at the particle threshold; and systematic uncertainties are handled by propagating theoretical errors from EFT truncation (via higher-dimensional operators) together with experimental systematics from the CMS-TOTEM diphoton spectrum, proton tagging efficiency, and luminosity. These additions will be accompanied by a brief discussion of how they affect the final mass limits, thereby substantiating the exclusions up to tens of TeV. revision: yes
Circularity Check
No circularity: limits derived by comparing independent EFT predictions to external CMS-TOTEM data
full rationale
The derivation computes virtual-particle contributions to light-by-light scattering in EFT/Born-Infeld frameworks (with resummation for large couplings) and then compares the resulting cross-section predictions against measured central exclusive diphoton data. No step reduces a prediction to a fitted parameter from the same dataset, no self-definition equates input to output, and no load-bearing premise collapses to a self-citation chain. The central claim therefore rests on external experimental input rather than internal re-labeling or construction.
Axiom & Free-Parameter Ledger
free parameters (1)
- spins and charges of monopoles and HECOs
axioms (3)
- domain assumption Effective field theory accurately captures virtual contributions of monopoles and HECOs to light-by-light scattering
- domain assumption Born-Infeld nonlinear electrodynamics provides a valid alternative scenario for strong photon couplings
- ad hoc to paper Resummation techniques correctly handle large HECO-photon couplings
Forward citations
Cited by 1 Pith paper
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Magnetic Monopoles -- From Dirac to the Large Hadron Collider
Magnetic monopoles are theoretically well-motivated but remain unobserved after extensive searches in cosmic rays and at particle colliders such as the LHC.
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discussion (0)
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