Pith. sign in

REVIEW 6 minor 1 cited by

Viable secret neutrino interactions with ultralight dark matter

T0 review · 0 major / 6 minor · reviewed 2026-08-14 · deepseek-v4-flash

Pith's one-line read Coupling an eV-scale sterile neutrino to an ultralight scalar dark matter condensate suppresses its early-universe production enough to satisfy CMB and BBN bounds, provided the induced mass exceeds about 160 eV.

desk verdict Cline's short note makes the Farzan ultralight-DM mechanism quantitative and finds a robust lower bound m_s,0 > 160 eV; the core claim survives scrutiny, with the main caveat being the all-DM/coherent-field assumption. read the letter →

arxiv 1908.02278 v2 pith:F5BZLRJP submitted 2019-08-06 hep-ph astro-ph.CO

classification hep-phastro-ph.CO
keywords sterileneutrinoultralightdarkmattersecretinteractionscosmologicalboundseffectivenumberofspeciesmasssumshort-baselineanomaliesfuzzy
topics Dark Matter
open problems Dark Matter
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

Short-baseline reactor and gallium anomalies suggest a ~1 eV sterile neutrino mixing with $\nu_e$ at $U_{e4}\sim0.1$, but such a state would thermalize in the early universe and violate bounds on the extra relativistic species $\delta N_{\rm eff}$ and the neutrino mass sum $\sum_\nu m_\nu$. This paper shows that the obstacle disappears if the sterile neutrino couples to ultralight dark matter $\phi$: before $\phi$ starts oscillating, the condensate gives $\nu_s$ a large effective mass $m_{s,0}=\lambda\phi_0$, suppressing $\nu_e\to\nu_s$ oscillations during BBN and CMB epochs. Mapping the two parameters $m_\phi$ and $m_{s,0}$, the author finds the scenario is allowed by the strongest CMB mass-sum constraint when $m_{s,0}\gtrsim160$ eV, equivalently $\lambda\gtrsim10^{-22}(m_\phi/10^{-15}\ \mathrm{eV})^{1/4}$. A sympathetic reader would care because it offers a concrete, minimal way to reconcile laboratory hints of sterile neutrinos with cosmology, and it ties that reconciliation to the fuzzy-dark-matter proposal for solving small-scale structure problems.

What carries the argument

The central object is the time-dependent sterile-neutrino mass $m_{\rm eff}(t)=m_{ss}+m_{s,0}\hat\varphi(t)$, where $m_{s,0}=\lambda\varphi_0$ is the early-time mass induced by the coupling $\frac12\lambda\bar\nu_s\phi\nu_s$ to a coherent ultralight scalar condensate whose amplitude $\varphi_0$ is fixed by the dark matter relic density (eq. (6)). The argument runs on the condensate being frozen at early times, so the large $m_{s,0}$ suppresses matter-enhanced oscillations, and only turning on once $H\sim m_\phi$, after which the induced mass redshifts away. Production is computed with a two-state Schrodinger equation including an imaginary damping term $-i\Gamma/2$ for $\nu_e$ plasma scattering; the resulting rate (eq. (7)) integrates analytically to the closed-form bound (eq. (12)) when $m_\phi\lesssim10^{-14}$ eV.

What would settle it

Measure the cosmic neutrino mass sum and the extra relativistic species together: the model predicts $\sum m_\nu\simeq0.06\ \mathrm{eV}+(1.1\ \mathrm{eV})\,\delta N_{\rm eff}$. If future CMB data finds a combination that violates this relation by more than the measurement uncertainty---for instance $\delta N_{\rm eff}>0.1$ together with $\sum m_\nu<0.10$ eV---then the $\nu_s$-$\phi$ condensate mechanism cannot be the explanation and the sterile-neutrino interpretation loses its cosmological cover.

Watch

Extended reading notes

Core claim

On the paper's own terms, the central claim is that 'secret interactions' mediated by an ultralight scalar dark matter field provide a reliable suppression of sterile-neutrino production, unlike previously studied sterile-neutrino self-interactions that later convert active neutrinos into $\nu_4$ and violate $\sum m_\nu$. The effective mass of $\nu_s$ is $m_{\rm eff}=m_{ss}+m_{s,0}\hat\varphi(t)$, with $m_{s,0}=\lambda\varphi_0$ and $\hat\varphi(t)\simeq J_{1/4}(m_\phi t)/(m_\phi t)^{1/4}$; while $H\gg m_\phi$ the field is frozen and heavy, and once $H\lesssim m_\phi$ it dilutes as $a^{-3/2}$, restoring the bare $\sim1$ eV mass. Using a simplified but calibrated Schrodinger treatment with an imaginary damping term for $\nu_e$ scattering, the author computes $\delta N_{\rm eff}$ from eq. (7), obtains the closed form (12) when $m_\phi\lesssim10^{-14}$ eV, and numerically maps the $(m_{s,0},m_\phi)$ plane for larger masses. The decisive constraint is the CMB mass sum, $\sum m_\nu\simeq0.06\ \mathrm{eV}+m_4\,\delta N_{\rm eff}<0.145\ \mathrm{eV}$, which requires $\delta N_{\rm eff}\lesssim0.08$ and therefore $m_{s,0}>160$ eV; a separate BBN bound is evaluated using an effective $\delta N^{\rm BBN}_{\rm eff}$ that accounts for $\nu_e$ depletion, and spectral distortion effects are checked to be at the few-percent level.

Load-bearing premise

The calculation assumes the ultralight scalar $\phi$ is all of the dark matter and behaves as a single coherent classical condensate, so its early-universe amplitude---and therefore the early sterile-neutrino mass $m_{s,0}$---is fixed by the measured dark matter density.

Editorial extensions

If this is right

  • The $\nu_e$-$\nu_s$ interpretation of short-baseline anomalies, with $m_4=1.1$ eV and $U_{e4}=0.11$, is compatible with CMB and BBN constraints as long as $m_{s,0}\gtrsim160$ eV, so the mechanism removes the main cosmological objection to that interpretation.
  • For $m_\phi\lesssim10^{-14}$ eV the induced mass is effectively constant through $\nu_e$ freezeout, making the allowed region analytically tractable; for larger $m_\phi$ the required $m_{s,0}$ grows to compensate for oscillations activated before nucleosynthesis.
  • The allowed parameter space includes $m_\phi\sim10^{-22}$ eV, the fuzzy-dark-matter regime that suppresses galactic-scale structure, so the same particle can address both the sterile-neutrino anomaly and the cusp-core problem.
  • If the coupling is large enough (roughly $\lambda\sim10^{-15}$), the induced sterile mass can vary on a timescale of about a year for $m_\phi\sim10^{-22}$ eV, making the effective $\Delta m^2$ in laboratory oscillation experiments time-dependent; the paper notes that the Daya Bay experiment has searched for such a signal.

Reading between the lines

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

  • Beyond the paper: if $\phi$ is only a fraction of the dark matter or its coherence is broken by self-interactions or gravitational substructure, $m_{s,0}=\lambda\varphi_0$ is smaller than assumed and the 160 eV lower bound shifts upward, so the bound is specific to the all-dark-matter, coherent-condensate case.
  • Beyond the paper: the same condensate-mass mechanism could suppress the early-universe production of any other weakly coupled fermion coupled to $\phi$, so the quantitative toolkit in eqs. (7)--(13) transfers to such species with minimal changes.
  • Beyond the paper: the predicted linear relation $\sum m_\nu\simeq0.06\ \mathrm{eV}+m_4\,\delta N_{\rm eff}$ means that independent future measurements of both quantities could test the mechanism even without resolving uncertainties about dark matter substructure.
Share X Bluesky LinkedIn Reddit HN

Editorial analysis

A structured set of objections, weighed in public.

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

Referee Report

0 major / 6 minor

Summary. This manuscript proposes that an eV-scale sterile neutrino ν_s, mixing with ν_e at U_e4 ≈ 0.1, can evade cosmological constraints on δN_eff and the sum of neutrino masses if ν_s couples to an ultralight scalar field φ that constitutes the dark matter. Because φ is frozen at early times, it gives the sterile neutrino a large effective mass m_s,0 = λ φ_0, suppressing sterile-neutrino production through oscillations. The author derives a simplified two-state oscillation treatment, presents an analytic formula for δN_eff in the regime where φ is frozen, and numerically evaluates the production for larger m_φ. The main quantitative result is a lower bound m_s,0 > 160 eV (λ > 10^-22 (m_φ/10^-15 eV)^{1/4}) from the CMB bound on the sum of neutrino masses, which leaves a wide viable region in the (m_s,0, m_φ) plane. The paper also discusses BBN constraints and the possibility of time-dependent signals in laboratory experiments.

Significance. If the mechanism holds, it is significant because it provides a concrete and economical way to reconcile short-baseline neutrino anomalies with cosmological bounds, using only a sterile-neutrino coupling to ultralight dark matter. The paper gives an explicit analytic expression for the suppression, Eq. (12), which makes the parametric dependence transparent, and it provides a conservative estimate of the sum-mass constraint by deliberately neglecting neutrino-number conservation below freezeout. It also checks the validity of the simplified effective-δN_eff treatment by computing the collision terms that would arise from spectral distortions, finding agreement at the 2-3% level. The central bound m_s,0 > 160 eV is robust to the simplifications discussed in the text, including the assumption that φ constitutes all of the dark matter, since a smaller DM fraction only rescales the required coupling. The manuscript is honest about the approximations it uses and cross-validates the oscillation formalism by reference to a recent quantitative comparison with the full quantum-kinetic approach.

minor comments (6)
  1. [Eq. (9)] The MSW denominator in Eq. (9) is written as (m_eff + 2 V_e p / m_eff)^2, while the standard matter effect for a positive ν_e potential would give (m_eff - 2 V_e p / m_eff)^2. Please clarify the sign convention for V_e or correct the displayed expression, and confirm that the analytic integral leading to Eq. (12) and the numerical contours in Fig. 1 were computed with the same convention, since a sign inconsistency in the high-m_φ region could shift the contours in Fig. 1.
  2. [Eqs. (7) and (9)] Eq. (7) uses sin^2 θ_m in the exponent, whereas Eq. (9) defines sin^2 2θ_m; the two differ by a factor of four in the small-angle limit. Please clarify which quantity is intended in the rate equation, since this factor affects the normalization of Eq. (12).
  3. [Eq. (15) and following text] With the adopted values m_4 = 1.1 eV and δN_eff < 0.08, Eq. (15) gives ∑ m_ν ≲ 0.148 eV, which is slightly above the quoted bound of 0.145 eV from Ref. [47]. The precise CMB sum-mass bound would require δN_eff < 0.077; the subsequent lower limit m_s,0 > 160 eV is still conservative, but the numerical statements should be made consistent.
  4. [Eq. (6) and normalization] The amplitude φ_0 is fixed by assuming φ constitutes all of the dark matter. If φ is only a fraction f of the dark matter, φ_0 rescales as √f and the required coupling for a given m_s,0 rescales as 1/√f; stating this scaling explicitly near Eq. (6) would make the dependence on this assumption transparent.
  5. [Derivation of Eq. (12)] The text says that m_es^2 is ignored in the denominator of the mixing angle but does not explicitly state how the matter potential V_e is treated in the analytic integral. Adding one sentence to explain that V_e provides the high-temperature cutoff would help the reader reproduce Eq. (12).
  6. [Fig. 1 and caption] The caption says the figure shows contours of δN_eff, but the figure contains both δN_eff contours (CMB and BBN) and a ∑ m_ν contour. Please clarify the description of the plotted contours and the meaning of the numerical labels.

Circularity Check

0 steps flagged · score 0.0 of 10

No significant circularity: the ms,0 > 160 eV bound follows from external Planck/BBN limits through the standard oscillation formula.

full rationale

The paper does not fit its parameters to the target result. The two free parameters (m_phi, ms,0) are varied and compared against externally measured limits on delta_Neff and sum m_nu from Planck (ref. [44]) and BBN (refs. [45,46]). The headline lower bound ms,0 > 160 eV is obtained by inverting the analytic formula (12) for the externally bounded delta_Neff < 0.08, which itself follows from the published cosmological limit sum m_nu < 0.145 eV (ref. [47]) together with eq. (15). No quantity is redefined in terms of the conclusion. The only self-citations, refs. [20] and [40], supply the simplified oscillation treatment and its validation against the full density-matrix formalism; this is a borrowed tool with independent benchmark support, not a circular input. The paper also explicitly checks the spectral-distortion approximation at the 2-3% level (discussion following eqs. 14 and 15), and notes that neglecting neutrino-number conservation below freezeout makes the sum-mass estimate conservative. The weakest assumption, that phi constitutes all of the dark matter, is a stated simplification rather than a circular one; it rescales the quoted limit without changing the structure of the derivation. Hence no circularity is present.

Assumptions & free parameters 4 free parameters · 5 assumptions · 0 invented entities

The model is borrowed from Farzan (ref [29]); the paper introduces no new particles or forces. The central analysis depends on four adopted quantities (m_4, U_e4, m_phi, m_s,0) and on the domain assumptions of coherent ultralight DM and a reduced two-flavor oscillation treatment.

free parameters (4)
  • m_4 (sterile mass eigenvalue) = 1.1 eV
    Adopted central value from SBL fits (ref [8]); the entire constraint map depends on this choice, but the paper does not fit it.
  • U_e4 (mixing matrix element) = 0.11
    Adopted central value from ref [8]; mes = U_e4 m_4 enters the oscillation amplitude.
  • m_phi (ultralight dark matter mass) = scanned, allowed region shown in Fig. 1
    Free model parameter that sets when the DM condensate begins oscillating; scanned logarithmically from about 10^-16 to 10^-12 eV.
  • m_s,0 (early-time nu_s mass from coupling) = allowed region; lower bound > 160 eV
    Free model parameter equal to lambda phi_0; the paper maps constraints in the (m_phi, m_s,0) plane.
assumptions (5)
  • domain assumption The ultralight scalar phi behaves as a coherent classical condensate and does not thermalize for lambda ~ 10^-23.
    Invoked before eq. (3) and after; required for the large VEV that gives nu_s a mass. Relies on the axion-like DM framework from refs [34,35].
  • domain assumption phi constitutes all of the dark matter, so its present amplitude is fixed by the DM density (eq. 6).
    Load-bearing for the normalization of ms,0; quoted after eq. (6).
  • domain assumption The simplified Schroedinger-equation treatment with an imaginary decoherence term accurately reproduces the full density-matrix Boltzmann result for nu_s-nu_e oscillations.
    Used for eq. (7); the agreement is asserted via ref [40], not proven in this paper.
  • domain assumption Only nu_e-nu_s mixing is relevant; other flavors and full 3+1 mixing are neglected.
    Stated in the introduction: 'I focus on the simpler nu_e-nu_s scenario.' This makes the analysis tractable but ignores nu_mu-nu_s constraints from MINOS and IceCube.
  • domain assumption The mapping sum_m_nu approx 0.06 eV + m4 delta_N_eff (eq. 15) correctly converts the late-time nu_e to nu_s conversion into a mass contribution.
    Used for the strongest constraint; adopted from standard treatments in the section on CMB constraints.

how reviews work

0 comments
Cite this review

Pith. "Pith review of Viable secret neutrino interactions with ultralight dark matter." pith.science (2026). https://pith.science/paper/F5BZLRJP

@misc{pith2026190802278,
  author       = {Pith},
  title        = {Pith review of: Viable secret neutrino interactions with ultralight dark matter},
  year         = {2026},
  howpublished = {\url{https://pith.science/paper/F5BZLRJP}},
  note         = {Machine review of arXiv:1908.02278}
}
abstract

Several anomalies in neutrino oscillation experiments point to the existence of a $\sim 1\,$eV sterile neutrino $\nu_s$ mixing with $\nu_e$ at the level of $U_{e4}\cong 0.1$, but such a neutrino is strongly disfavored by constraints on additional light degrees of freedom ($\delta N_{\rm eff}$) and total neutrino mass ($\sum_\nu m_\nu$) from cosmology. "Secret neutrino interactions" that have been invoked to suppress the cosmological production of $\nu_s$ typically falter, but recently it was pointed out that $\nu_s$ could get a large mass in the early universe by coupling to ultralight dark matter $\phi$, which can robustly suppress its production. The model has essentially two free parameters: $m_\phi$, and $m_{s,0}$, the mass of the sterile neutrino at early times, enhanced by its coupling to $\phi$. I determine the parameter regions allowed by limits on $\delta N_{\rm eff}$ and $\sum_\nu m_\nu$ from the cosmic microwave background and big bang nucleosynthesis, using a simplified yet accurate treatment of neutrino oscillations in the early universe. This mechanism could have an important impact on laboratory experiments that suggest oscillations with sterile neutrinos.

Figures

Figures reproduced from arXiv: 1908.02278 by the authors.

Figure 1
Figure 1. Contours of δNeff (solid blue for CMB and dashed red for BBN) and corresponding to Pmν (solid black) in the ms,0-mφ plane, illustrative of cosmological upper limits as described in the text. CMB constraints. For the CMB constraints, there is an analogous effect from late time νe → νs conversions. Even though oscillations occuring after freezeout of νe should not change δNeff, they can increase the sum of neutrino ma… view at source ↗

Discussion (0). Continue with ORCID to comment.

Forward citations

Cited by 1 Pith paper

Reviewed papers in the Pith corpus that reference this work. Sorted by Pith novelty score. Full citation record

  1. Sterile Neutrino Dark Matter as a Probe of Inflationary Reheating

    hep-ph 2026-01 conditional novelty 5.0 of 10

    Inflaton decays during reheating can produce all of the observed sterile-neutrino dark matter with a branching ratio below 10^-4, evading X-ray bounds and making a future X-ray line a probe of the inflaton mass and re...

Reference graph

Works this paper leans on

47 extracted references · 10 canonical work pages · cited by 1 Pith paper

  1. [40]

    Baryogenesis from neutron-dark matter oscilla- tions,

    T. Bringmann, J. M. Cline and J. M. Cornell, “Baryogenesis from neutron-dark matter oscilla- tions,” Phys. Rev. D 99, no. 3, 035024 (2019) doi:10.1103/PhysRevD.99.035024 [arXiv:1810.08215 [hep-ph]]

  2. [1]

    Update of Short-Baseline Electron Neu- trino and Antineutrino Disappearance,

    C. Giunti, M. Laveder, Y. F. Li, Q. Y. Liu and H. W. Long, “Update of Short-Baseline Electron Neu- trino and Antineutrino Disappearance,” Phys. Rev. D 86, 113014 (2012) doi:10.1103/PhysRevD.86.113014 [arXiv:1210.5715 [hep-ph]]

  3. [2]

    Short-Baseline Electron Neutrino Oscillation Length After Troitsk

    C. Giunti, M. Laveder, Y. F. Li and H. W. Long, “Short-baseline electron neutrino oscillation length af- ter troitsk,” Phys. Rev. D 87, no. 1, 013004 (2013) doi:10.1103/PhysRevD.87.013004 [arXiv:1212.3805 [hep- ph]]

  4. [3]

    Sterile Neutrino Oscillations: The Global Picture,

    J. Kopp, P. A. N. Machado, M. Maltoni and T. Schwetz, “Sterile Neutrino Oscillations: The Global Picture,” JHEP 1305, 050 (2013) doi:10.1007/JHEP05(2013)050 [arXiv:1303.3011 [hep-ph]]

  5. [4]

    Updated Global Analysis of Neutrino Os- cillations in the Presence of eV-Scale Sterile Neutrinos,

    M. Dentler, ´A. Hern´ andez-Cabezudo, J. Kopp, P. A. N. Machado, M. Maltoni, I. Martinez-Soler and T. Schwetz, “Updated Global Analysis of Neutrino Os- cillations in the Presence of eV-Scale Sterile Neutrinos,” JHEP 1808, 010 (2018) doi:10.1007/JHEP08(2018)010 [arXiv:1803.10661 [hep-ph]]

  6. [5]

    Where Are We With Light Sterile Neutrinos?,

    A. Diaz, C. A. Arg¨ uelles, G. H. Collin, J. M. Conrad and M. H. Shaevitz, “Where Are We With Light Sterile Neutrinos?,” arXiv:1906.00045 [hep-ex]

  7. [6]

    Ster- ile Neutrino Search at the NEOS Experiment,

    Y. J. Ko et al. [NEOS Collaboration], “Ster- ile Neutrino Search at the NEOS Experiment,” Phys. Rev. Lett. 118, no. 12, 121802 (2017) doi:10.1103/PhysRevLett.118.121802 [arXiv:1610.05134 [hep-ex]]

  8. [7]

    Search for sterile neutrinos at the DANSS experiment,

    I. Alekseev et al. [DANSS Collaboration], “Search for sterile neutrinos at the DANSS experiment,” Phys. Lett. B 787, 56 (2018) doi:10.1016/j.physletb.2018.10.038 [arXiv:1804.04046 [hep-ex]]

Show all 47 references
  1. [8]

    The gallium anomaly revisited,

    J. Kostensalo, J. Suhonen, C. Giunti and P. C. Sri- vastava, “The gallium anomaly revisited,” Phys. Lett. B 795, 542 (2019) doi:10.1016/j.physletb.2019.06.057 [arXiv:1906.10980 [nucl-th]]

  2. [9]

    Ev- idence for neutrino oscillations from the observa- tion of anti-neutrino(electron) appearance in a anti- neutrino(muon) beam,

    A. Aguilar-Arevalo et al. [LSND Collaboration], “Ev- idence for neutrino oscillations from the observa- tion of anti-neutrino(electron) appearance in a anti- neutrino(muon) beam,” Phys. Rev. D 64, 112007 (2001) doi:10.1103/PhysRevD.64.112007 [hep-ex/0104049]

  3. [10]

    Significant Excess of ElectronLike Events in the MiniBooNE Short-Baseline Neutrino Experi- ment,

    A. A. Aguilar-Arevalo et al. [MiniBooNE Collabo- ration], “Significant Excess of ElectronLike Events in the MiniBooNE Short-Baseline Neutrino Experi- ment,” Phys. Rev. Lett. 121, no. 22, 221801 (2018) doi:10.1103/PhysRevLett.121.221801 [arXiv:1805.12028 [hep-ex]]

  4. [11]

    Adamson et al

    P. Adamson et al. [MINOS+ Collaboration], Phys. Rev. Lett. 122, no. 9, 091803 (2019) doi:10.1103/PhysRevLett.122.091803 [arXiv:1710.06488 [hep-ex]]

  5. [12]

    Search for sterile neutrino mixing using three years of IceCube DeepCore data,

    M. G. Aartsen et al. [IceCube Collaboration], “Search for sterile neutrino mixing using three years of IceCube DeepCore data,” Phys. Rev. D 95, no. 11, 112002 (2017) doi:10.1103/PhysRevD.95.112002 [arXiv:1702.05160 [hep-ex]]

  6. [13]

    IceCube Sterile Neutrino Searches,

    B. J. P. Jones [IceCube Collaboration], “IceCube Sterile Neutrino Searches,” EPJ Web Conf. 207, 04005 (2019) doi:10.1051/epjconf/201920704005 [arXiv:1902.06185 [hep-ex]]

  7. [14]

    KATRIN Sensitiv- ity to Sterile Neutrino Mass in the Shadow of Light- est Neutrino Mass,

    A. Esmaili and O. L. G. Peres, “KATRIN Sensitiv- ity to Sterile Neutrino Mass in the Shadow of Light- est Neutrino Mass,” Phys. Rev. D 85, 117301 (2012) doi:10.1103/PhysRevD.85.117301 [arXiv:1203.2632 [hep- ph]]

  8. [16]

    BBN bounds on active sterile neutrino mixing,

    A. D. Dolgov and F. L. Villante, “BBN bounds on active sterile neutrino mixing,” Nucl. Phys. B 679, 261 (2004) doi:10.1016/j.nuclphysb.2003.11.031 [hep-ph/0308083]

  9. [17]

    Thermali- sation of sterile neutrinos in the early Universe in the 3+1 scheme with full mixing matrix,

    S. Gariazzo, P. F. de Salas and S. Pastor, “Thermali- sation of sterile neutrinos in the early Universe in the 3+1 scheme with full mixing matrix,” JCAP 1907, no. 07, 014 (2019) doi:10.1088/1475-7516/2019/07/014 [arXiv:1905.11290 [astro-ph.CO]]

  10. [18]

    Relaxing nucleosynthe- sis bounds on sterile-neutrinos,

    K. S. Babu and I. Z. Rothstein, “Relaxing nucleosynthe- sis bounds on sterile-neutrinos,” Phys. Lett. B 275, 112 (1992). doi:10.1016/0370-2693(92)90860-7

  11. [19]

    Cosmological bounds on Dirac-Majorana neutrinos,

    K. Enqvist, K. Kainulainen and M. J. Thomson, “Cosmological bounds on Dirac-Majorana neutrinos,” Phys. Lett. B 280, 245 (1992). doi:10.1016/0370- 2693(92)90062-9

  12. [20]

    Constraints on almost Dirac neutrinos from neutrino - anti-neutrino oscillations,

    J. M. Cline, “Constraints on almost Dirac neutrinos from neutrino - anti-neutrino oscillations,” Phys. Rev. Lett. 68, 3137 (1992). doi:10.1103/PhysRevLett.68.3137 5

  13. [21]

    How Self-Interactions can Reconcile Sterile Neutrinos with Cosmology,

    S. Hannestad, R. S. Hansen and T. Tram, “How Self-Interactions can Reconcile Sterile Neutrinos with Cosmology,” Phys. Rev. Lett. 112, no. 3, 031802 (2014) doi:10.1103/PhysRevLett.112.031802 [arXiv:1310.5926 [astro-ph.CO]]

  14. [22]

    Cosmologically Safe eV- Scale Sterile Neutrinos and Improved Dark Matter Structure,

    B. Dasgupta and J. Kopp, “Cosmologically Safe eV- Scale Sterile Neutrinos and Improved Dark Matter Structure,” Phys. Rev. Lett. 112, no. 3, 031803 (2014) doi:10.1103/PhysRevLett.112.031803 [arXiv:1310.6337 [hep-ph]]

  15. [23]

    Unveiling secret interactions among sterile neu- trinos with big-bang nucleosynthesis,

    N. Saviano, O. Pisanti, G. Mangano and A. Mi- rizzi, “Unveiling secret interactions among sterile neu- trinos with big-bang nucleosynthesis,” Phys. Rev. D 90, no. 11, 113009 (2014) doi:10.1103/PhysRevD.90.113009 [arXiv:1409.1680 [astro-ph.CO]]

  16. [24]

    Short- baseline neutrino oscillations, Planck, and IceCube,

    J. F. Cherry, A. Friedland and I. M. Shoemaker, “Short- baseline neutrino oscillations, Planck, and IceCube,” arXiv:1605.06506 [hep-ph]

  17. [25]

    Cosmic mi- crowave background constraints on secret interac- tions among sterile neutrinos,

    F. Forastieri, M. Lattanzi, G. Mangano, A. Mi- rizzi, P. Natoli and N. Saviano, “Cosmic mi- crowave background constraints on secret interac- tions among sterile neutrinos,” JCAP 1707, no. 07, 038 (2017) doi:10.1088/1475-7516/2017/07/038 [arXiv:1704.00626 [astro-ph.CO]]

  18. [26]

    Sterile neutrinos with secret inter- actions—cosmological discord?,

    X. Chu, B. Dasgupta, M. Dentler, J. Kopp and N. Saviano, “Sterile neutrinos with secret inter- actions—cosmological discord?,” JCAP 1811, no. 11, 049 (2018) doi:10.1088/1475-7516/2018/11/049 [arXiv:1806.10629 [hep-ph]]

  19. [27]

    Cos- mological constraints with self-interacting sterile neutri- nos,

    N. Song, M. C. Gonzalez-Garcia and J. Salvado, “Cos- mological constraints with self-interacting sterile neutri- nos,” JCAP 1810, no. 10, 055 (2018) doi:10.1088/1475- 7516/2018/10/055 [arXiv:1805.08218 [astro-ph.CO]]

  20. [28]

    Col- lisional production of sterile neutrinos via secret interac- tions and cosmological implications,

    A. Mirizzi, G. Mangano, O. Pisanti and N. Saviano, “Col- lisional production of sterile neutrinos via secret interac- tions and cosmological implications,” Phys. Rev. D 91, no. 2, 025019 (2015) doi:10.1103/PhysRevD.91.025019 [arXiv:1410.1385 [hep-ph]]

  21. [29]

    Ultra-light scalar saving the 3+1 neutrino scheme from the cosmological bounds,

    Y. Farzan, “Ultra-light scalar saving the 3+1 neutrino scheme from the cosmological bounds,” arXiv:1907.04271 [hep-ph]

  22. [30]

    Berlin, Phys

    A. Berlin, Phys. Rev. Lett. 117, no. 23, 231801 (2016) doi:10.1103/PhysRevLett.117.231801 [arXiv:1608.01307 [hep-ph]]

  23. [31]

    Dis- torted neutrino oscillations from time varying cosmic fields,

    G. Krnjaic, P. A. N. Machado and L. Necib, “Dis- torted neutrino oscillations from time varying cosmic fields,” Phys. Rev. D 97, no. 7, 075017 (2018) doi:10.1103/PhysRevD.97.075017 [arXiv:1705.06740 [hep-ph]]

  24. [32]

    Fuzzy dark matter and nonstandard neutrino in- teractions,

    V. Brdar, J. Kopp, J. Liu, P. Prass and X. P. Wang, “Fuzzy dark matter and nonstandard neutrino in- teractions,” Phys. Rev. D 97, no. 4, 043001 (2018) doi:10.1103/PhysRevD.97.043001 [arXiv:1705.09455 [hep-ph]]

  25. [33]

    Light scalar dark matter at neutrino oscillation experiments,

    J. Liao, D. Marfatia and K. Whisnant, “Light scalar dark matter at neutrino oscillation experiments,” JHEP 1804, 136 (2018) doi:10.1007/JHEP04(2018)136 [arXiv:1803.01773 [hep-ph]]

  26. [34]

    Cold and fuzzy dark matter,

    W. Hu, R. Barkana and A. Gruzinov, “Cold and fuzzy dark matter,” Phys. Rev. Lett. 85, 1158 (2000) doi:10.1103/PhysRevLett.85.1158 [astro-ph/0003365]

  27. [35]

    Ultralight scalars as cosmological dark mat- ter,

    L. Hui, J. P. Ostriker, S. Tremaine and E. Wit- ten, “Ultralight scalars as cosmological dark mat- ter,” Phys. Rev. D 95, no. 4, 043541 (2017) doi:10.1103/PhysRevD.95.043541 [arXiv:1610.08297 [astro-ph.CO]]

  28. [36]

    On the Treatment of Neutrino Oscilla- tions in a Thermal Environment,

    L. Stodolsky, “On the Treatment of Neutrino Oscilla- tions in a Thermal Environment,” Phys. Rev. D 36, 2273 (1987). doi:10.1103/PhysRevD.36.2273

  29. [37]

    Refrac- tion and Oscillations of Neutrinos in the Early Uni- verse,

    K. Enqvist, K. Kainulainen and J. Maalampi, “Refrac- tion and Oscillations of Neutrinos in the Early Uni- verse,” Nucl. Phys. B 349 (1991) 754. doi:10.1016/0550- 3213(91)90397-G

  30. [38]

    General kinetic description of relativistic mixed neutrinos,

    G. Sigl and G. Raffelt, “General kinetic description of relativistic mixed neutrinos,” Nucl. Phys. B 406, 423 (1993). doi:10.1016/0550-3213(93)90175-O

  31. [39]

    Light Singlet Neutrinos and the Pri- mordial Nucleosynthesis,

    K. Kainulainen, “Light Singlet Neutrinos and the Pri- mordial Nucleosynthesis,” Phys. Lett. B 244 (1990) 191. doi:10.1016/0370-2693(90)90054-A

  32. [41]

    Neutrino Dispersion at Fi- nite Temperature and Density,

    D. Notzold and G. Raffelt, “Neutrino Dispersion at Fi- nite Temperature and Density,” Nucl. Phys. B 307, 924 (1988). doi:10.1016/0550-3213(88)90113-7

  33. [42]

    The Early Universe,

    E. W. Kolb and M. S. Turner, “The Early Universe,” Front. Phys. 69, 1 (1990)

  34. [43]

    Cosmologi- cal nucleosynthesis and active sterile neutrino os- cillations with small mass differences: The Non- resonant case,

    D. P. Kirilova and M. V. Chizhov, “Cosmologi- cal nucleosynthesis and active sterile neutrino os- cillations with small mass differences: The Non- resonant case,” Phys. Rev. D 58, 073004 (1998) doi:10.1103/PhysRevD.58.073004 [hep-ph/9707282]

  35. [44]

    Planck 2018 results. VI. Cosmological parameters,

    N. Aghanim et al. [Planck Collaboration], “Planck 2018 results. VI. Cosmological parameters,” arXiv:1807.06209 [astro-ph.CO]

  36. [45]

    BBN constraints on MeV-scale dark sectors. Part I. Ster- ile decays,

    M. Hufnagel, K. Schmidt-Hoberg and S. Wild, “BBN constraints on MeV-scale dark sectors. Part I. Ster- ile decays,” JCAP 1802, 044 (2018) doi:10.1088/1475- 7516/2018/02/044 [arXiv:1712.03972 [hep-ph]]

  37. [46]

    Big Bang Nucleosynthesis: 2015,

    R. H. Cyburt, B. D. Fields, K. A. Olive and T. H. Yeh, “Big Bang Nucleosynthesis: 2015,” Rev. Mod. Phys. 88, 015004 (2016) doi:10.1103/RevModPhys.88.015004 [arXiv:1505.01076 [astro-ph.CO]]

  38. [47]

    Updated results on neutrino mass and mass hierarchy from cosmology,

    S. Roy Choudhury and S. Hannestad, “Updated results on neutrino mass and mass hierarchy from cosmology,” arXiv:1907.12598 [astro-ph.CO]

  39. [48]

    Search for a time-varying electron antineutrino signal at Daya Bay,

    D. Adey et al. [Daya Bay Collaboration], “Search for a time-varying electron antineutrino signal at Daya Bay,” Phys. Rev. D 98, no. 9, 092013 (2018) doi:10.1103/PhysRevD.98.092013 [arXiv:1809.04660 [hep-ex]]

Pith tools

Reviewed August 14, 2026 · model on record in the stance chip above.