A plethora of long-range neutrino interactions probed by DUNE and T2HK

Masoom Singh; Mauricio Bustamante; Pragyanprasu Swain; Sanjib Kumar Agarwalla

REVIEW 3 major objections 4 minor 13 references

A plethora of long-range neutrino interactions probed by DUNE and T2HK

T0 review · 3 major / 4 minor · reviewed 2026-08-10 · deepseek-v4-flash

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Pith's one-line read DUNE and T2HK can constrain long-range neutrino-matter interactions to potentials of order 10^-14 to 10^-13 eV, and their combination can identify the underlying U(1)' symmetry in favorable cases.

desk verdict A useful proceedings digest of the authors' JHEP long-range neutrino interaction forecasts, but the abstract's 'identify the symmetry' claim overreaches what the per-texture sensitivity curves show. read the letter →

arxiv 2501.14835 v1 pith:ZE6OSNXI submitted 2025-01-23 hep-ph hep-exphysics.ins-det

Sanjib Kumar Agarwalla , Mauricio Bustamante , Masoom Singh , Pragyanprasu Swain This is my paper · ORCID

classification hep-phhep-exphysics.ins-det

keywords long-rangeneutrinointeractionsDUNET2HKU(1)'symmetriesoscillationsbeyondStandardModelflavor-dependentmatterpotentialZ'boson

verification ladder T0 review T1 audit T2 compute T3 formal

The pith

A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.

The reading

This paper forecasts how well the next-generation long-baseline neutrino oscillation experiments DUNE and T2HK could detect or rule out new long-range neutrino-matter interactions. It considers fourteen anomaly-free $U(1)^\prime$ gauge symmetries built from lepton and baryon numbers, each of which would give a distinct flavor-dependent neutrino potential in matter. The central claim is that, regardless of which symmetry is realized, ten years of data from these experiments could constrain the long-range potential to roughly $10^{-14}$ to $10^{-13}$ eV, provided that potential is comparable to the standard oscillation scale. In favorable cases, the pattern of appearance and disappearance signals could single out the $U(1)^\prime$ symmetry responsible. The tightest projected limits come from muon-neutrino disappearance, while electron-neutrino appearance gives the weakest ones, and this short report defers the full statistical treatment to a companion paper.

What carries the argument

The load-bearing object is the long-range matter potential $V_{\mathrm{LRI}} = \mathrm{diag}(V_{\mathrm{LRI},e}, V_{\mathrm{LRI},\mu}, V_{\mathrm{LRI},\tau})$, added to the standard vacuum and matter terms in the neutrino propagation Hamiltonian $H = H_{\mathrm{vac}} + V_{\mathrm{mat}} + V_{\mathrm{LRI}}$. A new neutral gauge boson $Z^\prime$ with mass between $10^{-35}$ and $10^{-10}$ eV mediates the interaction, and because its range is so long, neutrinos feel coherent contributions from matter in the Earth, Moon, Sun, Milky Way, and local Universe. The charges of the $U(1)^\prime$ symmetry fix the texture of $V_{\mathrm{LRI}}$; that texture determines which oscillation channel carries the signal and therefore how tight the resulting bound is.

What would settle it

Take early real data from DUNE and T2HK, fit each $V_{\mathrm{LRI}}$ texture from Fig. 2 to the observed $\nu_\mu$ disappearance and $\nu_e$ appearance rates, and check whether the 2-$\sigma$ upper limit on $V_{\mathrm{LRI}}$ falls at or below $10^{-13}$ eV; if the real-data limits are weaker by more than the quoted systematic uncertainties, the forecast is falsified.

Watch

Extended reading notes

Core claim

The paper establishes that next-generation long-baseline oscillation experiments can act as a generic probe of long-range neutrino interactions. For each of fourteen $U(1)^\prime$ symmetries, the new matter potential $V_{\mathrm{LRI}}$ enters the neutrino propagation Hamiltonian as a diagonal matrix, and the projected $2\sigma$ sensitivity of DUNE and T2HK, especially in combination, reaches $V_{\mathrm{LRI}} \sim 10^{-14}$--$10^{-13}$ eV, comparable to the standard oscillation terms. The texture of $V_{\mathrm{LRI}}$ determines whether the $\nu_\mu \to \nu_\mu$ disappearance channel or the $\nu_\mu \to \nu_e$ appearance channel is affected, so the pattern of deviations can, in favorable cases, identify the underlying $U(1)^\prime$ symmetry. The projected limits convert into constraints on the effective coupling $G^\prime$ of the new mediator versus its mass, and for mediators lighter than roughly $10^{-18}$ eV the projected constraints improve on existing limits.

Load-bearing premise

The projections assume that the way DUNE and T2HK data would be analyzed, including background rates and systematic uncertainties, is realistic; if those systematic errors are underestimated, the quoted limits would be stronger than the experiments can actually achieve.

Editorial extensions

If this is right

A combined DUNE+T2HK analysis removes degeneracies between $V_{\mathrm{LRI}}$, $\theta_{23}$, $\delta_{\mathrm{CP}}$, and the neutrino mass ordering that weaken each experiment's standalone limits.
For all fourteen candidate symmetries, a null result would place upper limits on $V_{\mathrm{LRI}}$ in the $10^{-14}$--$10^{-13}$ eV range, ruling out long-range interactions with potentials above that scale.
Symmetries whose texture has nonzero entries in the $\mu$--$\tau$ sector are constrained most strongly, through $\nu_\mu \to \nu_\mu$ disappearance, while textures with a nonzero first diagonal entry are constrained least, through $\nu_\mu \to \nu_e$ appearance.
If a signal appears, the channel pattern, including which flavors are involved, can distinguish among the candidate $U(1)^\prime$ symmetries in favorable cases.

Reading between the lines

Editorial extensions of the paper, not claims the author makes directly.

Beyond this paper's explicit forecasts, the same Hamiltonian treatment could be applied to atmospheric neutrinos or neutrino telescopes, whose much longer baselines through the Earth would sample different matter densities and might extend sensitivity to mediator masses outside the range considered here.
The paper's caveat that the new potential must be comparable to the standard oscillation scale implies that optimizing the analysis to the highest-energy bins, where the relevant vacuum Hamiltonian entry scales as $1/E$, could sharpen the projected limits further than the quoted energy-integrated numbers.
A testable extension is to remove individual celestial sources, such as the Earth, Moon, Sun, Milky Way, and local Universe, one at a time from $V_{\mathrm{LRI}}$ and check which object contributes most of the projected sensitivity; this would tell future analyses where uncertainty in the matter distribution matters most.

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Editorial analysis

A structured set of objections, weighed in public.

Desk editor's note, referee report, and a circularity audit.

Desk Editor's Note

read the letter

Quick take: this is a conference proceedings that restates the authors' own JHEP 09 (2024) 055 analysis. If you want the actual results, read Ref [1]; this text gives the summary figures and the 14-symmetry catalog but no statistical machinery, no detector simulation details, and no source-density modeling. The one new claim that is not in the original paper is in the abstract: DUNE and T2HK 'may identify the new U(1)' symmetry.' That claim is unsupported by anything in this text. The test statistics shown are upper limits on each VLRI texture separately, not a model-selection comparison between textures. The authors themselves mention degeneracies with θ23, δCP, and mass ordering in Section III, which make cross-symmetry identification even less obvious. Unless there is a confusion-matrix or likelihood-ratio analysis somewhere, the 'identify' wording should be cut.

What the paper does well: it is honest about being a summary. It states in the introduction and again in the conclusions that it is based on Ref [1]. The Figures 1 and 2 give a compact view of the projected VLRI constraints for all 14 charge assignments, and Figure 3 translates them to coupling limits. For a reader who wants the broad-brush numbers without wading through JHEP, this is a useful digest.

The soft spots are exactly what the reader notes. The central quantitative results — the 10^-14 to 10^-13 eV sensitivity band and the per-symmetry limits — are not derivable from this text alone. They live in Ref [1]. The conversion from VLRI limits to coupling limits in Figure 3 is not documented here. No code or data are included. For a proceedings that is normal, but the arXiv posting is a standalone document; a reader landing here without Ref [1] cannot check the numbers. The circularity concern is minor: these are forecasts against the standard-oscillation null hypothesis, not fits to real data, so the constraints are not forced by construction. The heavy reliance on the authors' own earlier paper is a citation-pattern fact, not a flaw.

Bottom line: this is a proceedings summary, not a new result. If it is meant as a citable paper, the abstract overclaim must be fixed. If it is just a NuFact contribution, it is acceptable. As a regular journal submission, I would not send it to a full referee because it is not self-contained and adds nothing beyond Ref [1]. The underlying JHEP paper is the thing to cite.

Referee Report

3 major / 4 minor

Summary. This proceedings contribution summarizes sensitivity forecasts for long-range neutrino interactions (LRI) at DUNE and T2HK, based on the authors' earlier detailed study in JHEP 09 (2024) 055. The paper considers 14 U(1)' gauge symmetries built from combinations of lepton and baryon numbers, each inducing a flavor-dependent long-range matter potential VLRI. Using a Poissonian chi-square statistic that is marginalized over the uncertain oscillation parameters θ23, δCP, and the mass ordering, the authors present projected upper limits on VLRI for each texture (Fig. 2) and convert them to constraints on the effective coupling G' vs mediator mass m_Z' (Fig. 3). The central quantitative claim is that the combined DUNE+T2HK dataset can constrain VLRI at roughly 10^-14 to 10^-13 eV for all candidate symmetries, with the tightest limits in channels that primarily affect ν_μ→ν_μ disappearance. The abstract additionally claims that the experiments may 'identify the new U(1)' symmetry' in favorable cases.

Significance. If the forecasts are reliable, the paper provides a useful systematic survey of long-range neutrino interaction models and identifies the oscillation channels that give the strongest sensitivity. The observation that a long-range potential comparable to the standard oscillation Hamiltonian can be probed is well taken, and the comprehensive treatment of U(1)' symmetries is a strength. The paper also clearly points to the underlying JHEP publication for the full statistical machinery, which is appropriate for a proceedings. However, the abstract's identification claim is not supported by the per-texture limit-setting analysis, and the conversion to coupling limits in Fig. 3 is not documented in this manuscript. These issues affect the strength of the advertised conclusions.

major comments (3)

[Abstract; Section IV] The abstract and conclusions claim that DUNE and T2HK 'may identify the new U(1)' symmetry' in favorable cases, but the analysis in Section III only computes, for each candidate texture, a Poissonian Delta-chi^2 against the null hypothesis of standard oscillations. No model-selection test is presented that compares different U(1)' charge assignments after marginalizing over theta23, deltaCP, and the mass ordering. In fact, the degeneracies acknowledged after Fig. 1—between VLRI and theta23, deltaCP, and the mass ordering—make it plausible that different textures produce overlapping signatures. The identification claim is therefore not derivable from the material shown. Please either remove the claim from the abstract and conclusions or add an explicit identifiability/confusion-matrix analysis.
[Section III, Fig. 3] The conversion from the VLRI limits of Fig. 2 to the effective-coupling limits G' vs m_Z' shown in Fig. 3 is not documented in this manuscript. The caption states that the limits are 'converted' from the VLRI limits, and the text refers to Ref. [1] for details, but the reader cannot reproduce or assess the result without knowing the definition of G', the relation between G' and VLRI (including the U(1)' charges of matter fermions), and the celestial source densities used. Since the claim that DUNE and T2HK may outperform existing limits for light mediators rests on this conversion, please include at least the defining equation and a brief description of the source model.
[Section III] The projected sensitivities depend entirely on the statistical treatment defined in Ref. [1], including the Poissonian chi-square, nuisance parameters for detector systematics, backgrounds, and efficiencies. None of these are described here, yet the central quantitative claim that 'in all cases' DUNE and T2HK can constrain VLRI at the level of the standard-oscillation terms presupposes that the assumed systematic uncertainties are realistic. Please state explicitly which systematic errors are included and how they are implemented, or provide a more detailed pointer to the exact sections of Ref. [1], so that a reader cannot inadvertently over-interpret the projected limits.

minor comments (4)

[Header] There is a typo in the workshop name: 'W orkshop' should be 'Workshop'.
[Throughout] Many numbers have missing spaces, e.g., '10 −10 eV' and '10 −35 − 10−10 eV' in the Introduction; these should be formatted consistently as '10^{-10} eV' etc.
[Introduction] The phrase 'For the first time, we explore a plethora of U(1)' symmetries' is misleading because the same authors have already explored these symmetries in Ref. [1], on which this contribution is based. Please rephrase to avoid a novelty claim that this proceedings does not carry.
[Fig. 1 caption] The arrows in the caption, e.g., 'E = 18 GeV →' and '≤ 0.2 (Hvac)ττ', are unclear. Please explain in the caption what these annotations mean, or remove them if they are only decorative.

Circularity Check

0 steps flagged · score 0.0 of 10

No circularity: the sensitivity forecasts are genuine simulations against standard oscillations, with the target limits not used as inputs.

full rationale

The paper's derivation chain is a standard sensitivity forecast: it takes the U(1)' charge assignments and VLRI textures from Ref. [1], adopts NuFIT 5.1 oscillation parameters (Table I), defines the Hamiltonian H = Hvac + Vmat + VLRI (Eqs. 1-4), and computes Poissonian Δχ² curves versus an assumed VLRI to derive upper limits (Figs. 1-3). No step fits VLRI to real data and then re-predicts it; the projected limits are outputs of the simulation, not inputs. The heavy reliance on the authors' own Ref. [1] for the statistical treatment, texture table, and existing limits is self-citation, but under the review rules that is not circularity because Ref. [1] contains independent, code-based simulations whose stated assumptions (detector response, systematics, oscillation parameters) do not include the forecasted limits. The abstract's claim that DUNE and T2HK 'may identify the new U(1)' symmetry' is not demonstrated by the per-texture upper-limit curves shown in Figs. 1-2, since no model-selection or confusion-matrix analysis is presented; however, that is an unsupported/overclaim issue, not a circular reduction. The explicit deferrals ('see Ref. [1]', 'for details on the statistical methods... Ref. [1]') are completeness limitations of a proceedings summary, not circular steps.

Assumptions & free parameters 0 free parameters · 5 assumptions · 0 invented entities

The paper rests on a model hypothesis (anomaly-free U(1)' extensions with a light Z'), on the standard effective-Hamiltonian description of neutrino propagation, on assumed celestial matter distributions, and on a statistical procedure defined in the authors' earlier JHEP paper. No additional free parameters are introduced in this proceedings; the oscillation parameters are inputs from NuFIT 5.1, and the y parameter in By is stated to be irrelevant because only first-generation quarks are used. No new particles are invented beyond the already-studied light Z' gauge boson.

assumptions (5)

domain assumption The Standard Model is extended by an anomaly-free U(1)' = U(1)_{B-L} x U(1)_{Lmu-Ltau} x U(1)_{Lmu-Le} with three right-handed neutrinos.
Used in Section II to define the charge assignments that produce the candidate symmetries; this is an input model assumption, not derived in the paper.
domain assumption Neutrino propagation is governed by H = Hvac + Vmat + VLRI, with VLRI diagonal in the flavor basis.
Written in Section II, Eqs. (1)-(4). The entire forecast assumes the new interaction affects propagation only and is flavor-diagonal in the chosen basis.
domain assumption The new Z' boson is light enough (10^-35 to 10^-10 eV) that matter in the Earth, Moon, Sun, Milky Way, and local Universe contributes coherently to VLRI.
Stated in the abstract and Section I; the whole sensitivity study depends on this mass window and on combining distant sources.
domain assumption The matter distributions of the Earth, Moon, Sun, Milky Way, and local Universe are known well enough to compute the long-range potential.
Implicit in the conversion from VLRI limits to coupling limits in Figure 3; the source abundances are not given in this proceedings but are drawn from Ref [1].
domain assumption The projected sensitivity is computed with a Poissonian chi-square minimized over theta23, deltaCP, and the mass ordering, as defined in Ref [1].
Stated in Section III and Table I; this is a methodological assumption from prior work and is not justified or described in this proceedings.

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Cite this review

Pith. "Pith review of A plethora of long-range neutrino interactions probed by DUNE and T2HK." pith.science (2026). https://pith.science/paper/ZE6OSNXI

@misc{pith2026250114835,
  author       = {Pith},
  title        = {Pith review of: A plethora of long-range neutrino interactions probed by DUNE and T2HK},
  year         = {2026},
  howpublished = {\url{https://pith.science/paper/ZE6OSNXI}},
  note         = {Machine review of arXiv:2501.14835}
}

abstract

The next-generation neutrino oscillation experiments would be sensitive to the new neutrino interactions that would strengthen the search for physics beyond the Standard Model. In this context, we explore the capabilities of the two leading future long-baseline neutrino oscillation experiments, DUNE and T2HK, to search for new flavor-dependent neutrino interactions with electrons, protons, and neutrons that could potentially modify neutrino flavor transitions. We forecast their sensitivities in the context of long-range neutrino interactions mediated by a neutral vector boson lighter than $10^{-10}$ eV and sourced by the vast amount of nearby and distant matter in the Earth, Moon, Sun, Milky Way, and local Universe. For the first time, we explore a plethora of $U(1)^\prime$ symmetries inducing the new interactions built from the combination of lepton and baryon numbers. We find that in all cases, DUNE and T2HK may constrain or discover the existence of new long-range neutrino interaction, and in some favorable cases, may identify the new $U(1)^\prime$ symmetry responsible for it. In this short proceeding, we only summarize the prospects of constraining the new interaction in case of all our candidate $U(1)^\prime$ symmetries, which have been discussed in JHEP 09 (2024) 055.

Figures

Figures reproduced from arXiv: 2501.14835 by the authors.

**Figure 2.** shows the projected constraints for all the candidate symmetries considered in this work. We find that regardless of which symmetry is responsible for inducing the new interaction, DUNE and T2HK are able to constrain the new interaction to a level comparable to standard-oscillation terms in the Hamiltonian (∼ 10−14 − 10−13 eV). The symmetries with new matter potential containing non-zero entries in the µ − τ sect… view at source ↗

**Figure 3.** shows the constraints on the coupling vs. mass plane of the new neutral gauge boson, Z ′ . These constraints are derived from the upper limits on VLRI (for the detailed procedure, see Ref. [1]). Because different celestial objects have a different abundance of electrons, protons, and neutrons, the tightest constraints on the LRI potential in [PITH_FULL_IMAGE:figures/full_fig_p004_3.png] view at source ↗

Discussion (0). Continue with ORCID to comment.

Reference graph

Works this paper leans on

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Pith tools

Reviewed August 10, 2026 · model on record in the stance chip above.

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S. K. Agarwalla, M. Bustamante, M. Singh, and P. Swain, JHEP 09, 055 (2024), arXiv:2404.02775 [hep- ph]

arXiv 2024

[2] [2]

Abi et al

B. Abi et al. (DUNE), (2021), arXiv:2103.04797 [hep-ex]

arXiv 2021

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Abe et al

K. Abe et al. (Hyper-Kamiokande), PTEP 2018, 063C01 (2018), arXiv:1611.06118 [hep-ex]

arXiv 2018

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Abe et al

K. Abe et al. (Hyper-Kamiokande), (2018), arXiv:1805.04163 [physics.ins-det]

arXiv 2018

[5] [5]

Araki, J

T. Araki, J. Heeck, and J. Kubo, JHEP 07, 083 (2012), arXiv:1203.4951 [hep-ph]

arXiv 2012

[6] [6]

Heeck, M

J. Heeck, M. Lindner, W. Rodejohann, and S. Vogl, SciPost Phys. 6, 038 (2019), arXiv:1812.04067 [hep-ph]

arXiv 2019

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B. C. Allanach, J. Davighi, and S. Melville, JHEP 02, 082 (2019), [Erratum: JHEP 08, 064 (2019)], arXiv:1812.04602 [hep-ph]

arXiv 2019

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Coloma, M

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