pith. sign in

arxiv: 2603.24677 · v2 · pith:32F6S7WDnew · submitted 2026-03-25 · ✦ hep-ph

Constraints on Light Sterile Neutrinos and Scalar Non-Standard Interactions Using the First Reactor Antineutrino Oscillation Results at JUNO

L. J. Flores , R. Pacheco-Ak\'e , Eduardo Peinado , G. Sanchez Garcia , E. V\'azquez-J\'auregui This is my paper

Pith reviewed 2026-05-21 09:27 UTC · model grok-4.3

classification ✦ hep-ph
keywords sterile neutrinosnon-standard interactionsJUNOreactor antineutrinosneutrino oscillationssolar parametersnew physics
0
0 comments X

The pith

JUNO's first 59 days of reactor data already constrain light sterile neutrinos and scalar NSI parameters.

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

The paper analyzes the initial reactor antineutrino data collected by JUNO to look for small departures from the standard three-neutrino picture. It extends the usual oscillation analysis to include a possible fourth light sterile neutrino and effective scalar non-standard interactions, then performs a spectral fit to the observed prompt-energy distribution. The fit shows that the present dataset already has reach into sterile-neutrino mixing amplitudes of order 0.1 for mass splittings between 10^{-5} and 10^{-2} eV squared, while also bounding the scalar interaction strength at the percent level. These early limits illustrate how a high-precision reactor experiment can begin testing new-physics scenarios well before its full statistics are accumulated.

Core claim

A spectral chi-squared fit to the prompt-energy spectrum from 59.1 days of JUNO data, using the Daya Bay-measured reactor flux and nuisance parameters for systematics, is performed in a 3+1 framework that incorporates scalar NSI. The analysis establishes sensitivity to light sterile neutrinos for Delta m squared 41 in the interval from roughly 10^{-5} to 10^{-2} eV squared, reaching sin squared 2 theta 14 values of order 0.1, and yields a bound on the scalar NSI parameter absolute value eta ee of order 0.01 that correlates with solar oscillation parameters.

What carries the argument

Spectral chi-squared fit to the prompt-energy distribution in an extended 3+1 neutrino framework that includes effective scalar NSI contributions.

Load-bearing premise

The reactor antineutrino flux spectrum is correctly given by the Daya Bay measurement and that the chosen nuisance parameters fully capture the relevant systematic uncertainties in flux normalization, spectral shape, backgrounds, and detector response.

What would settle it

A statistically significant oscillatory distortion in the JUNO prompt-energy spectrum at a frequency corresponding to a mass splitting near 10^{-3} eV squared that cannot be absorbed by adjustments to the nuisance parameters or standard three-flavor oscillations.

Figures

Figures reproduced from arXiv: 2603.24677 by Eduardo Peinado, E. V\'azquez-J\'auregui, G. Sanchez Garcia, L. J. Flores, R. Pacheco-Ak\'e.

Figure 1
Figure 1. Figure 1: FIG. 1. 95% CL exclusion contour for the neutrino oscillation [PITH_FULL_IMAGE:figures/full_fig_p005_1.png] view at source ↗
Figure 2
Figure 2. Figure 2: FIG. 2 [PITH_FULL_IMAGE:figures/full_fig_p005_2.png] view at source ↗
Figure 3
Figure 3. Figure 3: Allowed region in the sin2 θ12–ηee parameter space. The filled contour corresponds to the JUNO-only fit performed in this work, while the line contours include the solar prior on sin2 θ12 and ∆m2 21 [52]. Contours indicate the 1σ, 2σ, and 3σ confidence regions. 6.5 7.0 7.5 8.0 8.5 ∆m2 21 [10−5 eV2 ] −0.03 −0.02 −0.01 0.00 0.01 0.02 0.03 0.04 0.05 ηee 1σ 2σ 3σ JUNO (this work) JUNO + Solar [PITH_FULL_IMAGE… view at source ↗
Figure 4
Figure 4. Figure 4: Allowed region in the ∆m2 21–ηee parameter space. The filled contour corresponds to the JUNO-only fit performed in this work, while the line contours include the solar prior on sin2 θ12 and ∆m2 21 [52]. Contours indicate the 1σ, 2σ, and 3σ confidence regions. CONCLUSIONS The results of this work show that the first JUNO re￾actor antineutrino data already provide meaningful sen￾sitivity to oscillatory featu… view at source ↗
read the original abstract

Constraints on light sterile neutrinos and scalar non-standard neutrino interactions are obtained from the first reactor antineutrino results reported by JUNO. The analysis is based on a spectral $\chi^2$ fit to the prompt-energy distribution corresponding to 59.1 days of data, including full three-flavor oscillations extended to a $3+1$ framework and effective scalar NSI contributions. The reactor flux is modeled using the Daya Bay measured spectrum, and systematic uncertainties are accounted for through a set of nuisance parameters describing reactor flux normalization, spectral shape, background normalization, and detector response. It is found that JUNO is already sensitive to light sterile neutrinos in the mass-splitting range $10^{-5} \lesssim \Delta m^2_{41}/\text{eV}^2 \lesssim 10^{-2}$, probing mixing amplitudes down to $\sin^2 2\theta_{14} \sim \mathcal{O}(10^{-1})$. In addition, a constraint on the scalar NSI parameter $|\eta_{ee}| < \mathcal{O}(10^{-2})$ is obtained, with correlations with solar oscillation parameters. These results demonstrate the potential of JUNO to probe small deviations from the Standard Model resulting from new physics through precision measurements, with significant improvements expected as statistics and systematic control improve.

Editorial analysis

A structured set of objections, weighed in public.

Desk editor's note, referee report, simulated authors' rebuttal, and a circularity audit. Tearing a paper down is the easy half of reading it; the pith above is the substance, this is the friction.

Referee Report

2 major / 2 minor

Summary. The manuscript reports constraints on light sterile neutrinos and scalar non-standard interactions (NSI) derived from the first 59.1 days of reactor antineutrino data at JUNO. It performs a spectral χ² fit to the prompt-energy distribution, extending the standard three-flavor oscillation framework to a 3+1 sterile neutrino model and incorporating effective scalar NSI contributions. The reactor flux is modeled using the Daya Bay measured spectrum, with systematic uncertainties handled via nuisance parameters for flux normalization, spectral shape, background normalization, and detector response. The analysis finds sensitivity to sterile neutrinos for mass splittings 10^{-5} ≲ Δm²₄₁/eV² ≲ 10^{-2} with sin²2θ₁₄ down to O(10^{-1}), and obtains a bound |η_ee| < O(10^{-2}) correlated with solar oscillation parameters.

Significance. If the central results hold after addressing the flux modeling, the work demonstrates JUNO's early reach for new-physics searches in the neutrino sector using real data. Credit is due for employing the full three-flavor plus sterile framework on actual experimental spectra and for including a standard set of nuisance parameters. The findings provide a useful benchmark for the experiment's potential as statistics and systematic control improve.

major comments (2)
  1. [Section 3 (Analysis Method)] Section 3 (Analysis Method) and associated flux-model description: the adoption of the Daya Bay measured spectrum as baseline, combined with only a single overall normalization and a generic spectral-shape nuisance parameter, does not demonstrably absorb site-specific differences in fission fractions, plutonium buildup, and off-equilibrium corrections between the Taishan/Yangjiang cores observed by JUNO and the Daya Bay cores. These differences produce energy-dependent flux variations at the few-percent level that can mimic or dilute the low-frequency spectral distortions expected from the quoted sterile-neutrino mass range or the scalar NSI term; the central sensitivity claims therefore rest on an unverified assumption that residuals are negligible in the 59.1-day sample.
  2. [Results section] Results section, sterile-neutrino sensitivity contours: the reported reach to sin²2θ₁₄ ∼ O(10^{-1}) for 10^{-5} ≲ Δm²₄₁ ≲ 10^{-2} eV² is presented without explicit quantification of how the fit χ² changes when the spectral-shape nuisance is allowed to vary more freely or when an additional reactor-specific shape uncertainty is introduced; this leaves open whether the claimed sensitivity is robust against plausible flux mismodeling.
minor comments (2)
  1. [Abstract] Abstract and throughout: the notation Δm²₄₁/eV² mixes the symbol with the unit; adopt a consistent style such as Δm²₄₁ (eV²) for clarity.
  2. [Figure captions] Figure captions (presumed): ensure that all nuisance-parameter pull values and their correlations with the sterile and NSI parameters are tabulated or shown in supplementary material for reproducibility.

Simulated Author's Rebuttal

2 responses · 0 unresolved

We thank the referee for the detailed and constructive feedback on our manuscript. We have carefully considered the major comments and provide point-by-point responses below. Where appropriate, we will revise the manuscript to address the concerns raised.

read point-by-point responses

  1. Referee: Section 3 (Analysis Method) and associated flux-model description: the adoption of the Daya Bay measured spectrum as baseline, combined with only a single overall normalization and a generic spectral-shape nuisance parameter, does not demonstrably absorb site-specific differences in fission fractions, plutonium buildup, and off-equilibrium corrections between the Taishan/Yangjiang cores observed by JUNO and the Daya Bay cores. These differences produce energy-dependent flux variations at the few-percent level that can mimic or dilute the low-frequency spectral distortions expected from the quoted sterile-neutrino mass range or the scalar NSI term; the central sensitivity claims therefore rest on an unverified assumption that residuals are negligible in the 59.1-day sample.

    Authors: We agree that site-specific differences in reactor fuel composition between the JUNO (Taishan/Yangjiang) and Daya Bay cores warrant careful consideration. The Daya Bay spectrum was chosen as the baseline because it provides the most precise empirical determination of the reactor antineutrino spectrum to date. Our generic spectral-shape nuisance parameter is designed to accommodate energy-dependent uncertainties at the few-percent level, which should cover the variations due to differences in fission fractions and plutonium buildup as reported in the literature. To make this explicit, we will revise Section 3 to include a quantitative assessment of the expected flux differences based on published core composition data, showing that any residual effects are smaller than the current systematic uncertainties and do not significantly impact the reported sensitivities for the 59.1-day dataset. revision: yes

  2. Referee: Results section, sterile-neutrino sensitivity contours: the reported reach to sin²2θ₁₄ ∼ O(10^{-1}) for 10^{-5} ≲ Δm²₄₁ ≲ 10^{-2} eV² is presented without explicit quantification of how the fit χ² changes when the spectral-shape nuisance is allowed to vary more freely or when an additional reactor-specific shape uncertainty is introduced; this leaves open whether the claimed sensitivity is robust against plausible flux mismodeling.

    Authors: The sensitivity contours presented are already obtained after marginalizing over the full set of nuisance parameters, including the spectral shape. To further demonstrate robustness, we will perform and report additional fits in the revised manuscript where the spectral-shape nuisance is allowed to vary with a wider prior (e.g., doubled uncertainty) and where an extra reactor-specific shape uncertainty is added. Preliminary checks indicate that the sensitivity to sin²2θ₁₄ remains of order 10^{-1} with only modest degradation. These results will be included in the Results section or as a supplementary figure to address the referee's concern directly. revision: yes

Circularity Check

0 steps flagged

No circularity: constraints obtained from direct spectral fit to JUNO data with external flux model

full rationale

The paper performs a standard chi-squared spectral fit to the observed prompt-energy distribution from 59.1 days of JUNO data. The model incorporates three-flavor oscillations extended to 3+1 sterile neutrinos plus effective scalar NSI terms. Reactor flux is taken from the external Daya Bay measured spectrum, with nuisance parameters for normalization, shape, backgrounds, and detector response. No equation or step reduces the reported sensitivity ranges or |eta_ee| bound to a fitted parameter by construction, nor does any load-bearing premise rest on a self-citation chain. The derivation remains self-contained against the external data and standard nuisance treatment.

Axiom & Free-Parameter Ledger

4 free parameters · 2 axioms · 0 invented entities

Ledger extracted from abstract only: the analysis rests on use of an external flux model and standard nuisance parameters for systematics.

free parameters (4)
  • reactor flux normalization nuisance parameter
    Included to account for systematic uncertainty in the spectral fit.
  • spectral shape nuisance parameters
    Used to model uncertainties in the reactor flux shape.
  • background normalization nuisance parameter
    Accounts for background uncertainties in the data.
  • detector response nuisance parameters
    Handles uncertainties in detector effects.
axioms (2)
  • domain assumption The Daya Bay measured spectrum provides an accurate model of the reactor antineutrino flux at JUNO.
    Explicitly stated as the flux input for the analysis.
  • domain assumption Extension of three-flavor oscillations to a 3+1 framework plus effective scalar NSI is a valid description for the data.
    Basis for the fit model described in the abstract.

pith-pipeline@v0.9.0 · 5799 in / 1543 out tokens · 42462 ms · 2026-05-21T09:27:05.130091+00:00 · methodology

discussion (0)

Sign in with ORCID, Apple, or X to comment. Anyone can read and Pith papers without signing in.

Lean theorems connected to this paper

Citations machine-checked in the Pith Canon. Every link opens the source theorem in the public Lean library.

What do these tags mean?
matches
The paper's claim is directly supported by a theorem in the formal canon.
supports
The theorem supports part of the paper's argument, but the paper may add assumptions or extra steps.
extends
The paper goes beyond the formal theorem; the theorem is a base layer rather than the whole result.
uses
The paper appears to rely on the theorem as machinery.
contradicts
The paper's claim conflicts with a theorem or certificate in the canon.
unclear
Pith found a possible connection, but the passage is too broad, indirect, or ambiguous to say the theorem truly supports the claim.

Reference graph

Works this paper leans on

53 extracted references · 53 canonical work pages · 12 internal anchors

  1. [1]

    (4) where∆ ′ ij = ∆m 2′ ij L/4E

    sin2 ∆′ 21 −sin 2(2θ13) cos2 θ′ 12 sin2 ∆′ 31 + sin2 θ′ 12 sin2 ∆′ 32 . (4) where∆ ′ ij = ∆m 2′ ij L/4E. The modified solar mixing angle and mass splittings are given by tan 2θ′ 12 = sin 2θ12 ∆m2 21 +ϵ 3 cos2 θ13 ∆m2 21 cos 2θ12 −ϵ 2 , ∆m2′ 21 = ∆m2 21 cos 2(θ12 −θ ′ 12) + cos2 θ13 sin 2θ12 sin 2θ′ 12 ϵ3 −cos 2θ ′ 12 ϵ2, and ∆m2′ 31 = ∆m2 31 −∆m 2 21 sin2...

    work page 2025

  2. [2]

    Evidence for oscillation of atmospheric neutrinos

    Y. Fukudaet al. (Super-Kamiokande), Phys. Rev. Lett. 81, 1562 (1998), hep-ex/9807003

    work page internal anchor Pith review Pith/arXiv arXiv 1998

  3. [3]

    Q. R. Ahmadet al. (SNO), Phys. Rev. Lett.89, 011301 (2002)

    work page 2002

  4. [4]

    Eguchi et al

    K. Eguchi et al. (KamLAND), Phys. Rev. Lett.90, 021802 (2003)

    work page 2003

  5. [5]

    Pontecorvo, Sov

    B. Pontecorvo, Sov. Phys. JETP6, 429 (1957)

    work page 1957

  6. [6]

    Z. Maki, M. Nakagawa, and S. Sakata, Prog. Theor. Phys.28, 870 (1962)

    work page 1962

  7. [7]

    Abeet al

    S. Abeet al. (KamLAND), Phys. Rev. Lett.100, 221803 (2008)

    work page 2008

  8. [8]

    Abe et al

    K. Abe et al. (Super-Kamiokande), Phys. Rev. D97, 072001 (2018)

    work page 2018

  9. [9]

    Abeet al

    K. Abeet al. (T2K), Nature580, 339 (2020)

    work page 2020

  10. [10]

    M. A. Aceroet al. (NovA Collaboration), Physical Re- view D106(2022), 10.1103/physrevd.106.032004

    work page doi:10.1103/physrevd.106.032004 2022

  11. [11]

    F. P. An et al. (Daya Bay Collaboration), Phys. Rev. Lett.129, 041801 (2022)

    work page 2022

  12. [12]

    Navas et al

    S. Navas et al. (Particle Data Group Collaboration), Phys. Rev. D110, 030001 (2024)

    work page 2024

  13. [13]

    Bak et al

    G. Bak et al. (RENO Collaboration), Phys. Rev. Lett. 121, 201801 (2018)

    work page 2018

  14. [14]

    Abeet al

    Y. Abeet al. (Double Chooz Collaboration), Phys. Rev. D86, 052008 (2012)

    work page 2012

  15. [15]

    2016, Journal of Physics G Nuclear Physics, 43, 030401, doi: 10.1088/0954-3899/43/3/030401

    F. Anet al., Journal of Physics G: Nuclear and Particle Physics43(2016), 10.1088/0954-3899/43/3/030401

    work page doi:10.1088/0954-3899/43/3/030401 2016

  16. [16]

    Abusleme et al

    A. Abusleme et al. (JUNO Collaboration), Progress in Particle and Nuclear Physics123, 103927 (2022)

    work page 2022

  17. [17]

    Girardi, D

    I. Girardi, D. Meloni, T. Ohlsson, H. Zhang, and S. Zhou, Journal of High Energy Physics2014(2014), 7 10.1007/jhep08(2014)057

    work page doi:10.1007/jhep08(2014)057 2014

  18. [18]

    Wolfenstein, Phys

    L. Wolfenstein, Phys. Rev. D17, 2369 (1978)

    work page 1978

  19. [19]

    Status of non-standard neutrino interactions

    T. Ohlsson, Rept. Prog. Phys.76, 044201 (2013), arXiv:1209.2710 [hep-ph]

    work page internal anchor Pith review Pith/arXiv arXiv 2013

  20. [20]

    Neutrino oscillations and Non-Standard Interactions

    Y. Farzan and M. Tortola, Front. in Phys.6, 10 (2018), arXiv:1710.09360 [hep-ph]

    work page internal anchor Pith review Pith/arXiv arXiv 2018

  21. [21]

    Ge and S

    S.-F. Ge and S. J. Parke, Physical Review Letters122 (2019), 10.1103/physrevlett.122.211801

    work page doi:10.1103/physrevlett.122.211801 2019

  22. [22]

    K. S. Babu, G. Chauhan, and P. S. B. Dev, Phys. Rev. D101, 095029 (2020)

    work page 2020

  23. [23]

    P. B. Dev et al., SciPost Phys. Proc.2, 001 (2019), arXiv:1907.00991 [hep-ph]

    work page arXiv 2019

  24. [24]

    D. K. Singha, R. Majhi, L. Panda, M. Ghosh, and R. Mohanta, Phys. Rev. D109, 095038 (2024), arXiv:2308.10789 [hep-ph]

    work page arXiv 2024

  25. [25]

    P. B. Denton, A. Giarnetti, and D. Meloni, JHEP01, 097 (2025), arXiv:2409.15411 [hep-ph]

    work page arXiv 2025

  26. [26]

    Choubey and A

    S. Choubey and A. Lund, arXiv (2026), arXiv:2602.05564 [hep-ph]

    work page arXiv 2026

  27. [27]

    JUNO Collaboration, arXiv (2025), arXiv:2511.14593 [hep-ex]

    work page arXiv 2025

  28. [28]

    F. P. An and others (Daya Bay Collaboration), Phys. Rev. Lett.134, 201802 (2025)

    work page 2025

  29. [29]

    P. F. de Salas, D. V. Forero, S. Gariazzo, P. Martínez- Miravé, O. Mena, C. A. Ternes, M. Tórtola, and J. W. F. Valle, JHEP02, 071 (2021), arXiv:2006.11237 [hep-ph]

    work page internal anchor Pith review Pith/arXiv arXiv 2021

  30. [30]

    NuFit-6.0: Updated global analysis of three-flavor neutrino oscillations

    I. Esteban, M. C. Gonzalez-Garcia, M. Maltoni, I. Martinez-Soler, J. P. Pinheiro, and T. Schwetz, JHEP 12, 216 (2024), arXiv:2410.05380 [hep-ph]

    work page internal anchor Pith review Pith/arXiv arXiv 2024

  31. [31]

    Capozzi, W

    F. Capozzi, W. Giarè, E. Lisi, A. Marrone, A. Mel- chiorri, and A. Palazzo, Phys. Rev. D111, 093006 (2025), arXiv:2503.07752 [hep-ph]

    work page arXiv 2025

  32. [32]

    M. A. Acero et al., J. Phys. G51, 120501 (2024), arXiv:2203.07323 [hep-ex]

    work page arXiv 2024

  33. [33]

    Minkowski, Phys

    P. Minkowski, Phys. Lett. B67, 421 (1977)

    work page 1977

  34. [34]

    Yanagida, Progress of Theoretical Physics64, 1103 (1980)

    T. Yanagida, Progress of Theoretical Physics64, 1103 (1980)

    work page 1980

  35. [35]

    S. L. Glashow, NATO Sci. Ser. B61, 687 (1980)

    work page 1980

  36. [36]

    Complex Spinors and Unified Theories

    M. Gell-Mann, P. Ramond, and R. Slansky, Conf. Proc. C790927, 315 (1979), arXiv:1306.4669 [hep-th]

    work page internal anchor Pith review Pith/arXiv arXiv 1979

  37. [37]

    R. N. Mohapatra and G. Senjanovic, Phys. Rev. D23, 165 (1981)

    work page 1981

  38. [38]

    Schechter and J

    J. Schechter and J. W. F. Valle, Phys. Rev. D22, 2227 (1980)

    work page 1980

  39. [39]

    Sterile neutrinos: the dark side of the light fermions

    A. Kusenko, Phys. Rept.481, 1 (2009), arXiv:0906.2968 [hep-ph]

    work page internal anchor Pith review Pith/arXiv arXiv 2009

  40. [40]

    Evidence for Neutrino Oscillations from the Observation of Electron Anti-neutrinos in a Muon Anti-Neutrino Beam

    A. Aguilar et al. (LSND), Phys. Rev. D64, 112007 (2001), arXiv:hep-ex/0104049

    work page internal anchor Pith review Pith/arXiv arXiv 2001

  41. [41]

    A. A. Aguilar-Arevaloet al. (MiniBooNE), Phys. Rev. Lett.105, 181801 (2010), arXiv:1007.1150 [hep-ex]

    work page internal anchor Pith review Pith/arXiv arXiv 2010

  42. [42]

    Statistical Significance of the Gallium Anomaly

    C. Giunti and M. Laveder, Phys. Rev. C83, 065504 (2011), arXiv:1006.3244 [hep-ph]

    work page internal anchor Pith review Pith/arXiv arXiv 2011

  43. [43]

    Abratenko et al

    P. Abratenko et al. (MicroBooNE), Nature648, 64 (2025), arXiv:2512.07159 [hep-ex]

    work page arXiv 2025

  44. [44]

    S. F. King, Rept. Prog. Phys.67, 107 (2004), arXiv:hep- ph/0310204

    work page arXiv 2004

  45. [45]

    Ma, Phys

    E. Ma, Phys. Rev. D73, 077301 (2006), arXiv:hep- ph/0601225

    work page arXiv 2006

  46. [46]

    Bischer and W

    I. Bischer and W. Rodejohann, Nucl. Phys. B947, 114746 (2019), arXiv:1905.08699 [hep-ph]

    work page arXiv 2019

  47. [47]

    L. J. Flores, O. G. Miranda, and G. Sanchez Garcia, arXiv (2026), arXiv:2602.02688 [hep-ph]

    work page internal anchor Pith review Pith/arXiv arXiv 2026

  48. [48]

    Abusleme et al

    A. Abusleme et al. (JUNO), arXiv (2025), arXiv:2511.14590 [hep-ex]

    work page arXiv 2025

  49. [49]

    The angular distribution of the reaction $\bar{\nu}_e + p \to e^+ + n$

    P. Vogel and J. F. Beacom, Phys. Rev. D60, 053003 (1999), arXiv:hep-ph/9903554

    work page internal anchor Pith review Pith/arXiv arXiv 1999

  50. [50]

    Chenet al., Journal of High Energy Physics2022(2022), 10.1007/jhep09(2022)004

    work page doi:10.1007/jhep09(2022)004 2022

  51. [51]

    An et al., Physical Review Letters113(2014), 10.1103/physrevlett.113.141802

    F. An et al., Physical Review Letters113(2014), 10.1103/physrevlett.113.141802

    work page doi:10.1103/physrevlett.113.141802 2014

  52. [52]

    Choi et al., Physical Review Letters125(2020), 10.1103/physrevlett.125.191801

    J. Choi et al., Physical Review Letters125(2020), 10.1103/physrevlett.125.191801

    work page doi:10.1103/physrevlett.125.191801 2020

  53. [53]

    Abe et al

    K. Abe et al. (Super-Kamiokande), Phys. Rev. D109, 092001 (2024), arXiv:2312.12907 [hep-ex]

    work page arXiv 2024