CMB Signals of Neutrino Mass Generation

Lawrence J. Hall; Steven J. Oliver; Takemichi Okui; Z.Chacko

REVIEW

CMB Signals of Neutrino Mass Generation

Z.Chacko, Lawrence J. Hall, Takemichi Okui, Steven J. Oliver

High Energy Physics - Phenomenology · Submitted 18 Dec 2003 · 18 references

Pith's verdict: A clean, falsifiable CMB signature of low-scale lepton flavor breaking; the headline Δl ≈ +8 n_S number leans on a formula derived for free-streaming neutrinos, which is a quantitative caveat rather than a refutation.

T0 · AI review

How this review was made: An AI referee (selfhosted/deepseek-v4.1-flash) read the paper on November 11, 2026 and answered a fixed list of questions about it. T0 is the starting level every paper gets. The levels describe how deeply Pith has checked the paper, never the authors.

T0 AI review An AI read the paper and answered a fixed list of questions.
T1 Audit Automatic checks that the references and files the paper relies on exist and match.
T2 Compute The paper's code or calculations re-run with the same results.
T3 Formal statement The claims written out in a formal math language a computer can read.
T4 Proof Those claims proved, and the proof checked by computer.

How Pith checks papers →

· 3 major objections · 7 minor · Ask about this paper · The compiled record · Read the full review →

Challenge this review Comment (0) Read on arXiv ↗

Cite ▾

arXiv IDhep-ph/0312267 (version 1)

Pith ID6MJP5VBN, Pith's permanent record of this paper and its review

CitationLawrence J. Hall, Steven J. Oliver, Takemichi Okui, Z.Chacko. "CMB Signals of Neutrino Mass Generation." arXiv:hep-ph/0312267 (2003). https://pith.science/paper/6MJP5VBN

Cite this reviewBibTeX for Pith's review of this paper

Claim paper

Why Pith says this

Highlight any text to comment on it.

Editor's note

read the letter

Worth your time, with one caveat you should carry in your head while reading it. The genuinely new thing here is not Majoron-neutrino cosmology, which is 1980s material and properly cited. It is the mapping of pseudo-Goldstone recoupling onto CMB acoustic peak positions: the claim that a uniform shift of the high-n peaks to larger l, Δl_n ≈ +7.8 n_S (Δl_peak/300), is a signature of reduced neutrino free-streaming that other new physics cannot mimic for adiabatic perturbations. That is a good idea, cleanly stated, and it turns a class of models that had no laboratory probe into something Planck or CMBPOL could in principle see. The ΔNν tables for one, two, three, eight and sixteen PGBs are a useful deliverable, and the paper is upfront that ΔNν is model dependent (abstract:s6) while the scattering signal is not. The parameter-space maps in Figs. 1–4 are the right way to present this kind of proposal, and the supersymmetric section showing f can naturally land at 30 MeV is more than decoration — it answers the obvious objection that the required symmetry breaking scale is tuned. The soft spot is the one the stress test names, and it lands. Eq. 20 substitutes N_ν^FS = 3 − n_S into the Bashinsky-Seljak phase shift, which was derived for freely streaming species sourcing an anisotropic stress. A scattering species has its quadrupole damped, so the shift shrinks — qualitatively right, but the paper's own isotropization criterion is Γ ~ H·N with N = (T/m_G)², a marginal condition, not tight coupling. The residual quadrupole reduces the coefficient by O(1/N), which is small for m_G ≪ T_* and O(1) near m_G ~ T_*. That matters for the claim that a measurement counts n_S and hence reads off the neutrino spectrum; it does not threaten detectability, since 8 per species against Planck's ±2 has room. Note also that the f1–f4 boundaries come from rate formulas with prefactors explicitly dropped (footnote 2), so the region edges are fuzzy anyway — the two caveats partly overlap rather than compound. The entropy-dilution assumption in Sec. II.A is asserted, not derived, but it is a model-building choice and stated as one. For whom: anyone working on neutrino cosmology, light scalars, or CMB constraints on dark radiation. Send it out.

Referee report

Major objections (3)

[III.B, Eqs. (19)-(20)] The substitution N_nu^FS = 3 - n_S into the Bashinsky-Seljak phase shift (Eq. 15) is asserted rather than derived. That formula was obtained for freely streaming neutrinos, where the shift is sourced by the anisotropic stress pi_nu; a species that scatters has its quadrupole damped, and the residual is O(H/Gamma). The paper's own isotropization criterion (Sec. IV.A, below Eq. 25) is Gamma > H N with N = (T_*/m_G)^2, which is marginal at the boundary m_G ~ T_*. Near that boundary the effective R_nu^FS lies between 3 - n_S and 3, and the coefficient in Delta l_n is reduced by an O(1/N) factor. Since the claimed Planck reach is Delta l ~ +/-2 and the signal is about 8 per species, this matters for the claim that a measurement counts n_S and hence reflects the neutrino spectrum. A concrete test would be a Boltzmann code with an explicit nu-G scattering term, or at least a quantitative estimate of the residual quadrupole as a function of Gamma/H.
[IV.A, Eq. (22) and Eq. (25)] The rate formula (22) is derived for T >> m_G > 2 m_nu, but the scattering region of interest is m_G < 1 eV with T_* ~ eV, i.e. T ~ m_G. In this regime the 2-to-1 rate is Boltzmann-suppressed and the temperature dependence differs from Eq. (22); the f_2 boundary and the shape of region II near m_G ~ eV should be re-derived or explicitly qualified. This affects the claimed size of the scattering region in Figures 1-4 and the statement that the signal region extends to m_G < 1 eV.
[VI, Tables III-IV and Eq. (41)] The Delta N_nu values assume a specific ordering of the thermal history: that all Goldstone bosons equilibrate prior to any decaying, and that all heavy Goldstone bosons have decayed or annihilated prior to the equilibration of any light PGBs. These orderings are stated but not justified from the model, and the abstract's range 0.03 < Delta N_nu < 1 depends on them. The paper should either justify the ordering or show how the predictions change under different orderings.

Minor objections (7)

[VI, Eq. (39)] The analytic expression and the numerical conversion are mutually inconsistent by roughly three orders of magnitude: for m_G' = 1 keV and f = 1 GeV the analytic form gives about 6 MeV, not 1 keV. The conclusion T_rec > m_G' is unaffected, but the numerical form should be corrected.
[Abstract and Sec. V] The claim that the signal varies as the spectrum of neutrinos is changed is technically true, but the variation is small for a single PGB (Table I gives 3.16, 3.17, 3.18 for Majorana). The abstract should make clear that the spectrum sensitivity is significant mainly in the multi-PGB case of Tables III-IV.
[Figure 1 caption] The caption says the area below f3 and f4 is excluded by BBN; since both f3 and f4 are lower bounds, the excluded region is f < max(f3, f4), and the caption should say so.
[Notation] The symbol g is used both for the PGB-neutrino coupling g_i and for spin degeneracy (g, g_H, g_G, g_nu). This is a genuine notational clash that could confuse readers, and a different symbol should be used for one of them.
[VI, Eq. (41)] The definition of N_nu^FS assumes that all scattering neutrinos and light Goldstones were heated by the heavy PGBs; the paper should state explicitly the assumption that the light PGBs were in equilibrium with the scattering neutrinos.
[IV.A, footnote 2] The approximations are acknowledged, but the paper should state explicitly that the boundaries in Figures 1-4 are order-of-magnitude and could shift by factors of a few.
[III.A] The coefficient 3.7 in delta N_nu = 3.7 g should be checked against a simple energy-conservation estimate, which gives delta N_nu about 1.5 g for a cold bosonic sector of degeneracy g; if the 3.7 figure includes additional effects, the text should say so.

How Pith checks papers → · Full audit of this paper →

The paper

The paper claims

Light Goldstone bosons from broken lepton symmetry would make neutrinos scatter in the eV era, shifting the high CMB peaks by about eight multipoles per scattering species and changing the radiation density by a computable amount.

The reading

The paper asks how cosmology alone could tell whether neutrino masses come from a symmetry broken at or below the weak scale, rather than from the conventional high-scale seesaw. Its answer is that such a symmetry leaves behind light pseudo-Goldstone bosons coupled only to neutrinos, with strength $g = m_ν/f$, and that these bosons recouple to the cosmic neutrinos after nucleosynthesis. Once recoupled they do two things during the eV era: they change the total relativistic energy density, and they stop some neutrino species from free-streaming. The second effect is the centrepiece, because a uniform shift of the high-multipole acoustic peaks to larger $ℓ$ is hard to produce any other way. If the authors are right, a future CMB map counts the neutrino species that scattered, and since the coupling tracks mass, that count reads off the neutrino mass spectrum and separates Majorana from Dirac.

What carries the argument

The engine is the recoupling rate for $νν ↔ G$, which scales as $Γ ≈ m_ν^2 m_G^2/(16π f^2 T)$ and therefore grows relative to the Hubble rate as the universe cools, so a decoupled sector re-equilibrates rather than decouples. Setting $Γ = H$ defines a recoupling temperature $T_{rec} ≈ (m_ν^2 m_G^2 M_{pl}/16π f^2)^{1/3}$; requiring $T_{rec} > m_G$ but below the weak-decoupling temperature gives the window in $(f, m_G)$ where signals exist, and requiring no recoupling before nucleosynthesis gives the lower bound on $f$. When a Goldstone boson becomes non-relativistic and disappears, its entropy heats the remaining neutrino fluid at constant comoving entropy, giving $N_ν = 3 - n_R + n_R((n_R + 4g/7)/(n_R + 4(g-g_H)/7))^{1/3}$ for vanishing chemical potential, with a modified version when a conserved charge forces a chemical potential. The scattering signal is built by taking the analytic free-streaming phase shift of Bashinsky and Seljak, $δφ = 0.19π R_ν$, and replacing $R_ν$ with the free-streaming fraction $ρ_{FS}/ρ_{rel} = 0.23 N_ν^{FS}/(1 + 0.23 N_ν)$, which converts the standard shift into $Δℓ_n ≈ -57(0.23 N_ν^{FS}/(1+0.23 N_ν))(Δℓ_{peak}/300)$.

Extended reading notes

Core claim

The central claim is that in theories where approximate lepton flavor symmetries break spontaneously at or below the weak scale, the resulting pseudo-Goldstone bosons recouple to neutrinos at low temperature and leave two distinct marks on the cosmic microwave background. The first is a change in the relativistic energy density during the eV era, expressed as a deviation $ΔN_ν$ from the standard value of three; for a single Goldstone boson the shift is small (about 0.03 to 0.1 depending on chemical potential and on whether neutrinos are Majorana or Dirac), but with the eight or so Goldstones of a broken $SU(3)$ flavor symmetry it rises to order unity. The second, and in the authors' view the decisive one, is a shift in the position of the $n$th acoustic peak at large $n$: where standard free-streaming neutrinos move the peaks to lower multipoles by about 23, a species that scatters instead of free-streaming moves them back by roughly $Δℓ_n ≈ +7.8 n_S (Δℓ_{peak}/300)$. Because the Goldstone coupling is proportional to the neutrino mass, which species recouple — one, two or three — depends on whether the mass spectrum is hierarchical, inverted or degenerate, so the size of the shift carries spectral information. The authors stress that the energy-density signal is model dependent and can be mimicked by other new physics, while the uniform peak shift cannot.

Load-bearing premise

The quantitative scattering prediction substitutes a reduced free-streaming fraction into a phase-shift formula derived for freely streaming neutrinos, and the paper asserts rather than numerically verifies that the shift stays linear in that fraction once some neutrinos are scattering.

Editorial extensions

If this is right

A measured uniform shift of the high-$n$ peaks toward larger $ℓ$ would count how many neutrino species scattered during the eV era, and hence, through $g = m_ν/f$, discriminate hierarchical, inverted and degenerate neutrino mass spectra.
Because the energy-density shift is systematically larger for Majorana than for Dirac neutrinos at fixed number of recoupled species, a precise $ΔN_ν$ would separate the two mass types even where the scattering signal alone cannot.
The number of pseudo-Goldstone bosons, set by the lepton flavor symmetry group, controls the size of $ΔN_ν$; maximal flavor symmetry with eight or more Goldstones pushes the signal to $ΔN_ν$ of order 0.5 to 1, within reach of Planck and well within reach of a CMBPOL-class satellite.
Lepton flavor symmetry breaking scales in the range 10 MeV to a TeV, including radiatively generated scales in supersymmetry as low as about 30 MeV, become cosmologically testable without a collider.
Theories in which several Goldstones interact via $G' ↔ GG$ have their chemical potentials driven to zero, generically enlarging $ΔN_ν$ relative to the single-Goldstone case.

Reading between the lines

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

The peak-shift signal is a counting experiment for neutrino scattering, so it could in principle be inverted: a measured $Δℓ_n$ that is not an integer multiple of the per-species shift would indicate either a non-standard free-streaming fraction from some other source or a breakdown of the linear substitution used here.
If the shift survives numerical scrutiny, the same logic applies to any light boson that couples derivatively or non-derivatively to neutrinos at late times, so the CMB peak positions become a general probe of secret neutrino interactions, not only of low-scale mass generation.
The authors' own machinery suggests a cross-check with big bang nucleosynthesis: the same $(f, m_G)$ window that yields a CMB signal is bounded below by requiring no recoupling before weak decoupling, so a future tightening of the BBN limit on extra radiation would squeeze the signal region from the same side that Planck squeezes it from above.
Because the coupling is fixed by the mass that a given symmetry-breaking scale generates, a detection of the scattering signal at a known $n_S$ would set a relation between $f$ and the absolute neutrino mass scale, offering a cosmological handle on the lightest neutrino mass that oscillation experiments cannot supply.

Original abstract

We propose signals in the cosmic microwave background to probe the type and spectrum of neutrino masses. In theories that have spontaneous breaking of approximate lepton flavor symmetries at or below the weak scale, light pseudo-Goldstone bosons recouple to the cosmic neutrinos after nucleosynthesis and affect the acoustic oscillations of the electron-photon fluid during the eV era. Deviations from the Standard Model are predicted for both the total energy density in radiation during this epoch, \Delta N_nu, and for the multipole of the n'th CMB peak at large n, \Delta l_n. The latter signal is difficult to reproduce other than by scattering of the known neutrinos, and is therefore an ideal test of our class of theories. In many models, the large shift, \Delta l_n \approx 8 n_S, depends on the number of neutrino species that scatter via the pseudo-Goldstone boson interaction. This interaction is proportional to the neutrino masses, so that the signal reflects the neutrino spectrum. The prediction for \Delta N_nu is highly model dependent, but can be accurately computed within any given model. It is very sensitive to the number of pseudo-Goldstone bosons, and therefore to the underlying symmetries of the leptons, and is typically in the region of 0.03 < \Delta N_nu < 1. This signal is significantly larger for Majorana neutrinos than for Dirac neutrinos, and, like the scattering signal, varies as the spectrum of neutrinos is changed from hierarchical to inverse hierarchical to degenerate.

The compiled record

The paper's own sentences, arranged, kept beside the review and separate from it. Each label is drawn from a closed vocabulary; the number beside it is the probability the classifier gave that label. Numbers in the tables are the authors', checked by code. No sentence in this record was written by a model.

Compiled by classifier-1.13-20260917 via OpenRouter, question bank abstract-p1-20260923, 2026-09-23: 1 request, 7,119 input tokens, $0.0003 reported.

What the abstract itself states, as probabilities: claims first 0.04 · states limitation 0.76 · human participants 0.01 · controlled comparison 0.17 · randomized assignment 0.01 · states quantitative result 0.95 · compares with prior results 0.28 · mentions code or data availability 0.02.

The abstract, sentence by sentence

arXiv listing abstract v1. Results and the main claim are underlined; show every role.

We propose signals in the cosmic microwave background to probe the type and spectrum of neutrino masses. In theories that have spontaneous breaking of approximate lepton flavor symmetries at or below the weak scale, light pseudo-Goldstone bosons recouple to the cosmic neutrinos after nucleosynthesis and affect the acoustic oscillations of the electron-photon fluid during the eV era. Deviations from the Standard Model are predicted for both the total energy density in radiation during this epoch, \Delta N_nu, and for the multipole of the n'th CMB peak at large n, \Delta l_n. The latter signal is difficult to reproduce other than by scattering of the known neutrinos, and is therefore an ideal test of our class of theories. In many models, the large shift, \Delta l_n \approx 8 n_S, depends on the number of neutrino species that scatter via the pseudo-Goldstone boson interaction. This interaction is proportional to the neutrino masses, so that the signal reflects the neutrino spectrum. The prediction for \Delta N_nu is highly model dependent, but can be accurately computed within any given model. It is very sensitive to the number of pseudo-Goldstone bosons, and therefore to the underlying symmetries of the leptons, and is typically in the region of 0.03 < \Delta N_nu < 1. This signal is significantly larger for Majorana neutrinos than for Dirac neutrinos, and, like the scattering signal, varies as the spectrum of neutrinos is changed from hierarchical to inverse hierarchical to degenerate.

background contribution method result interpretation main claim

What the classifier reports for each sentence. The number is the probability it gave the label.
#	sentence	role	the authors' own work	states the main conclusion	strength
s0	We propose signals in the cosmic microwave background to probe the type and spectrum of neutrino masses.	contribution 1.00	0.71	0.29	asserted 0.49
s1	In theories that have spontaneous breaking of approximate lepton flavor symmetries at or below the weak scale, light pseudo-Goldstone bosons recouple to the cosmic neutrinos after nucleosynthesis and affect the acoustic oscillations of the electron-photon fluid during the eV era.	background 0.52	0.11	0.08	asserted 0.98
s2	Deviations from the Standard Model are predicted for both the total energy density in radiation during this epoch, \Delta N_nu, and for the multipole of the n'th CMB peak at large n, \Delta l_n.	result 0.87	0.54	0.18	asserted 0.94
s3	The latter signal is difficult to reproduce other than by scattering of the known neutrinos, and is therefore an ideal test of our class of theories.	interpretation 0.98	0.24	0.17	asserted 0.99
s4	In many models, the large shift, \Delta l_n \approx 8 n_S, depends on the number of neutrino species that scatter via the pseudo-Goldstone boson interaction.	result 0.94	0.55	0.13	asserted 0.59
s5	This interaction is proportional to the neutrino masses, so that the signal reflects the neutrino spectrum.	interpretation 0.85	0.48	0.11	asserted 1.00
s6	The prediction for \Delta N_nu is highly model dependent, but can be accurately computed within any given model.	limitation 0.70	0.38	0.05	asserted 0.93
s7	It is very sensitive to the number of pseudo-Goldstone bosons, and therefore to the underlying symmetries of the leptons, and is typically in the region of 0.03 < \Delta N_nu < 1.	result 0.91	0.53	0.07	asserted 0.80
s8	This signal is significantly larger for Majorana neutrinos than for Dirac neutrinos, and, like the scattering signal, varies as the spectrum of neutrinos is changed from hierarchical to inverse hierarchical to degenerate.	result 0.88	0.64	0.15	asserted 0.99

What kind of paper the classifier reports this is: theoretical result 0.94 · evidence from argument 0.52.

What was examined, and what was not

sources read

arXiv listing abstract v1

not examined

full text
figures and tables
references and citing sentences
relations to other papers

levels run

P abstract

not run

S sections
T body sentences
C citations
R cross-paper relations

Every quoted sentence on this record is the authors'. Every label is from Pith's closed vocabulary, with the probability shown beside it. Every number in the measurements table is the authors', checked by code. Record as JSON

Figures

**Figure 1.** FIG. 1: Signal regions and cosmological bounds for a single M

**Figure 2.** FIG. 2: Signal regions and cosmological bounds for a single D

**Figure 3.** FIG. 3: The signal regions and bounds for three Majorana neut

**Figure 4.** FIG. 4: The signal regions and bounds for three Dirac neutrin

Figures reproduced from arXiv:hep-ph/0312267 by the authors.

References

Works cited (18)

[1]

Y. Fukuda et al. [Super-Kamiokande Collaboration], Phys. Rev. Lett. 81, 1562 (1998) [arXiv:hep-ex/9807003]; Q. R. Ahmad et al. [SNO Collaboration], Phys. Rev. Lett. 89, 011301 (2002) [arXiv:nucl-ex/0204008]; K. Eguchi et al. [KamLAND Collaboration], Phys. Rev. Lett. 90, 021802 (2003) [arXiv:hep-ex/0212021]. 38

View on Pith Pith review arXiv 1998
[2]

M. Gell-Mann, P. Ramond and R. Slansky, in Supergravity (North-Holland, Amsterdam, 1979); T. Yanagida, in Proc. Workshop on Uniﬁed Theories and Baryon Number in the Uni verse; R.N. Mohapatra and G. Senjanovic, Phys. Rev. 44 (1980) 912

View on Pith 1980
[3]

The various regions in this plot are generically labeled by an integer w hich lies between 1 and 3. If the region lies in the mG > 1 eV portion of the plot this number indicates the number of neutrinos in equilibrium with the heavy pseudo-Goldsto ne boson when it disappeared, nR. If it lies in the mG < 1 eV region of the plot it indicates the number of ne...

View on Pith 2000
[4]

Y. Chikashige, R.N. Mohapatra and R.D. Peccei, Phys. Let t B 98 (1981) 265

View on Pith 1981
[5]

G. Gelmini and M. Roncadelli, Phys. Lett B 99 (1981) 411; H. Georgi, S. Glashow, and S. Nussinov, Nucl. Phys. B 193 (1981) 297

View on Pith 1981
[6]

V. Barger, J. P. Kneller, H. S. Lee, D. Marfatia and G. Stei gman, Phys. Lett. B 566, 8 (2003) [arXiv:hep-ph/0305075]

View on Pith Pith review arXiv 2003
[7]

J. M. Cline, K. Kainulainen and K. A. Olive, Astropart. Ph ys. 1, 387 (1993) [arXiv:hep-ph/9304229]

View on Pith Pith review arXiv 1993
[8]

E. K. Akhmedov, Z. G. Berezhiani, R. N. Mohapatra and G. Se njanovic, Phys. Lett. B 299, 90 (1993) [arXiv:hep-ph/9209285]. I. Z. Rothstein, K. S. Babu and D. Seckel, Nucl. Phys. B 403, 725 (1993) [arXiv:hep-ph/9301213]

View on Pith Pith review arXiv 1993
[9]

W. Hu, D. Scott, N. Sugiyama and M. J. White, Phys. Rev. D 52, 5498 (1995) [arXiv:astro-ph/9505043]

View on Pith Pith review arXiv 1995
[10]

S. Bashinsky and U. Seljak, astro-ph/0310198

View on Pith Pith review arXiv
[11]

J. Bartlett and L. Hall, Phys. Rev. Lett. 66 541 (1991); M. White, G. Gelmini and J. Silk, Phys. Rev. D51 2669 (1995); R. Bean, S. Hansen and A. Melchiorri, Phys.Rev. D64 (2001) 103508, astro-ph/0104162; R. Bowen, S. Hansen, A. Me lchiorri, J. Silk and R. Trotta, Mon.Not.Roy.Astron.Soc. 334 (2002) 760, astro-ph/011063 6

View on Pith Pith review arXiv 1991
[12]

C. L. Bennett et al. , Astrophys. J. Suppl. 148, 1 (2003) [arXiv:astro-ph/0302207]

View on Pith Pith review arXiv 2003
[13]

P. Crotty, J. Lesgourgues and S. Pastor, Phys. Rev. D67, 123005 (2003) [arXiv:astro-ph/0302337], E. Pierpaoli, Mon. Not. R. Astr on. Soc. 342, L63 (2003) [arXiv:astro-ph/0302465], S. Hannestad, JCAP 0305, 004 (2003) [arXiv:astro-ph/0303076]

View on Pith Pith review arXiv 2003
[14]

Y. Farzan, Phys. Rev. D 67, 073015 (2003) [arXiv:hep-ph/0211375]

View on Pith Pith review arXiv 2003
[15]

M. Kachelriess, R. Tomas and J. W. F. Valle, Phys. Rev. D 62, 023004 (2000) [arXiv:hep-ph/0001039]

View on Pith Pith review arXiv 2000
[16]

K. Choi and A. Santamaria, Phys Rev D 42 (1990) 293; K. Choi, C.W. Kim, J. Kim and W.P. Lam, Phys. Rev. D 37 (1988) 3325; 39 J.A. Grifols, E. Masso and S. Peris, Phys. Lett B 215 (1988) 593

View on Pith 1990
[17]

J. Schechter and J. W. F. Valle, Phys. Rev. D 25, 774 (1982); J. M. Cline, K. Kainulainen and S. Paban, Phys. Lett. B 319, 513 (1993) [arXiv:hep-ph/9309316]; J. T. Peltoniemi, Phys. Rev. D 57, 5509 (1998)

View on Pith Pith review arXiv 1982
[18]

R. Lopez, S. Dodelson, A. Heckler and M. Turner, astro-p h/9803095, Phys. Rev. Lett. 82, 3952 (1999). 40

View on Pith 1999

Forward citations

Cited by 38 Pith papers

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

Enabling Strong Neutrino Self-interaction with an Unparticle Mediator
hep-ph 2025-01 conditional novelty 7.0 of 10

An unparticle mediator with a continuous mass spectrum can realize strong neutrino self-interactions while evading BBN/CMB and IceCube constraints.
Invisible neutrino decay in precision cosmology
astro-ph.CO 2020-11 conditional novelty 7.0 of 10

The cosmological damping rate for invisible neutrino decay scales as (m/E)^5, not (m/E)^3, relaxing the neutrino lifetime bound by three to four orders of magnitude.
Sensitivity of Next-Generation CMB Surveys to Neutrinos and Other Light Relics
astro-ph.CO 2026-08 conditional novelty 6.0 of 10

CMB-S4 forecasts: the two-site design reaches sigma(Neff)=0.029 in seven years, the Chile-only revised design reaches 0.030 in nine, and a cosmic-variance-limited survey would reach 0.0073.
Neutrino masses from large-scale structures: future sensitivity and theory dependence
astro-ph.CO 2024-12 conditional novelty 6.0 of 10

Forecasted 1-sigma sensitivity to the sum of neutrino masses is 15 meV for Planck+DESI and 7 meV for CMB-S4+MegaMapper, with the one-loop bispectrum providing 10% and 30% of the constraining power.
Atomic Dark Matter, Interacting Dark Radiation, and the Hubble Tension
hep-ph 2024-11 conditional novelty 6.0 of 10

nuADaM, a model of atomic dark matter plus self-interacting dark radiation, improves cosmological fits and raises the inferred Hubble constant to about 72.6 km/s/Mpc.

Show 33 more citing papers

No $\nu$s is Good News
astro-ph.CO 2024-05 conditional novelty 6.0 of 10

DESI plus CMB data, reanalyzed without a positivity prior, prefer a sum of neutrino masses of -160 +/- 90 meV, excluding the minimum 58 meV sum at about 3 sigma.
Redshift Effects in Particle Production from Kerr Primordial Black Holes
astro-ph.CO 2022-07 accept novelty 6.0 of 10

Tracking spin and mass depletion together with cosmic expansion shows that dark radiation from Kerr primordial black holes is diluted by an extra redshift, reducing Delta N_eff by about an order of magnitude relative ...
Towards Powerful Probes of Neutrino Self-Interactions in Supernovae
hep-ph 2022-06 conditional novelty 6.0 of 10

Neutrino self-interactions can turn a supernova neutrino burst into a slowly decoupling fluid ball, and the resulting signal lengthening lets SN 1987A data constrain the coupling strength.
Long Range Interactions in Cosmology: Implications for Neutrinos
hep-ph 2021-01 conditional novelty 6.0 of 10

Scalar-mediated long-range neutrino self-interactions keep cosmic neutrinos relativistic at recombination, erasing the cosmological neutrino mass bound for interaction strengths above roughly 100 eV^-1.
Cosmological Limits on the Neutrino Mass and Lifetime
hep-ph 2019-09 conditional novelty 6.0 of 10

If neutrinos decay into dark radiation after becoming non-relativistic, current CMB and large-scale-structure data allow a summed neutrino mass as large as 0.9 eV instead of 0.25 eV.
A CMB Search for the Neutrino Mass Mechanism and its Relation to the $H_0$ Tension
astro-ph.CO 2019-09 conditional novelty 6.0 of 10

Planck 2018 CMB data exclude neutrino-majoron couplings above about 1e-13, and majoron interactions plus extra dark radiation can reduce the Hubble tension from 4.4 to 2.5 sigma.
Dark Sector Equilibration During Nucleosynthesis
hep-ph 2019-04 accept novelty 6.0 of 10

Time-varying contributions to the effective number of neutrino species during Big Bang nucleosynthesis are consistent with observed helium and deuterium abundances if the deviation occurs between neutron-proton freeze...
A Thermal Neutrino Portal to Sub-MeV Dark Matter
hep-ph 2018-07 accept novelty 6.0 of 10

A sub-MeV thermal dark sector that equilibrates with Standard Model neutrinos after neutrino-photon decoupling evades Neff bounds, and a lepton-number-breaking majoron model realizes this with dark matter near the MeV scale.
Neutrinoless double-beta decay with massive scalar emission
hep-ph 2018-02 accept novelty 6.0 of 10

For a scalar of mass near the double-beta Q-value, the estimated 0ν2βφ limit on the scalar-neutrino coupling weakens by up to an order of magnitude, driven by phase space suppression and a degraded signal-to-background ratio.
Thermal Dark Matter Below an MeV
hep-ph 2017-06 conditional novelty 6.0 of 10

Dark matter that thermalizes with Standard Model neutrinos after neutrino-photon decoupling can be as light as a few keV without spoiling Big Bang nucleosynthesis or the cosmic microwave background.
A New Target for Cosmic Axion Searches
astro-ph.CO 2016-04 conditional novelty 6.0 of 10

If a future CMB experiment can resolve one extra relativistic species at the 0.027 level, it will either detect thermal axions, familons and majorons or bound their couplings to Standard Model fields by up to six orde...
Self-Interacting Dark Matter through the Higgs Portal
hep-ph 2014-11 conditional novelty 6.0 of 10

Coupling the light mediator of Higgs-portal self-interacting dark matter to sterile or active neutrinos lets it decay before Big Bang nucleosynthesis without a large Higgs mixing, removing the direct detection tension.
High energy neutrino telescopes as a probe of the neutrino mass mechanism
hep-ph 2014-08 conditional novelty 6.0 of 10

A light scalar that mediates lepton-number violation generates Majorana neutrino masses and, at the same time, a neutrino self-interaction whose resonant absorption feature IceCube could detect in about ten years.
Cosmic neutrino cascades from secret neutrino interactions
astro-ph.HE 2014-04 accept novelty 6.0 of 10

IceCube's high-energy neutrino data should be sensitive to secret neutrino-neutrino interactions at a level competitive with cosmic-microwave-background and laboratory constraints, and such interactions could imprint ...
Constraining Unparticle Physics with Cosmology and Astrophysics
hep-ph 2007-05 accept novelty 6.0 of 10

Big Bang Nucleosynthesis and SN 1987A cooling place order-of-magnitude upper bounds on unparticle-Standard Model couplings, with the strongest limits at unparticle dimension d_U = 1.
Constraining invisible neutrino decays with the cosmic microwave background
hep-ph 2005-09 accept novelty 6.0 of 10

Requiring free-streaming neutrinos at photon decoupling bounds neutrino couplings to light pseudoscalars at g < 1e-7 (diagonal) and g < 1e-11 (0.05 eV/m)^2 (off-diagonal), ruling out Majoron decays as a cause of alter...
Neutrinoless Universe
astro-ph 2004-04 conditional novelty 6.0 of 10

Relic neutrinos that annihilate into a light boson with coupling above roughly 10^-5 leave a negligible density today, so large-scale structure no longer constrains neutrino mass.
Probing Physics Beyond the Standard Model: Limits from BBN and the CMB Independently and Combined
astro-ph.CO 2022-07 accept novelty 5.0 of 10

Independent BBN and CMB measurements of the relativistic energy density now agree closely enough to bound any change in Nν or η between nucleosynthesis and recombination, with the joint value Nν = 2.898 ± 0.141.
Cosmological Implications of Axion-Matter Couplings
astro-ph.CO 2021-09 accept novelty 5.0 of 10

A full quantum-statistics recalculation of thermal axion production tightens cosmological bounds on axion-fermion couplings and shows they complement SN 1987A limits.
Gravitational waves from first-order phase transitions in Majoron models of neutrino mass
hep-ph 2021-05 accept novelty 5.0 of 10

First-order phase transitions in Majoron models of neutrino mass can produce gravitational waves detectable at planned interferometers, and the sub-100 keV case connects to Hubble-tension solutions involving neutrino-...
The Hubble Tension as a Hint of Leptogenesis and Neutrino Mass Generation
hep-ph 2021-03 conditional novelty 5.0 of 10

GeV-scale sterile neutrinos in a singlet majoron model generate Delta N_eff around 0.4 at BBN, which raises the CMB-inferred H0 to 70.2 +/- 0.6 km/s/Mpc and makes the SH0ES value about ten times more likely than in La...
Self-interacting neutrinos, the Hubble parameter tension, and the Cosmic Microwave Background
astro-ph.CO 2020-12 accept novelty 5.0 of 10

Neutrino self-interactions are not favored by Planck 2018 CMB plus BAO data, and they relieve the Hubble tension only if high-multipole polarization data are removed.
Warm Decaying Dark Matter and the Hubble Tension
astro-ph.CO 2020-04 conditional novelty 5.0 of 10

Decaying warm dark matter with mass 1 to 40 eV and lifetime 10^3 to 10^6 years lowers the Hubble tension from 4.0 sigma to 2.9 sigma, at the cost of two extra parameters.
Interacting radiation after Planck and its implications for the Hubble Tension
astro-ph.CO 2020-03 accept novelty 5.0 of 10

Planck 2018 temperature, polarization and BAO data require at least 80% of the pre-recombination radiation density to be free-streaming, capping any new interacting radiation component at Nfld < 0.6 at 95% CL.
Precision Early Universe Thermodynamics made simple: $N_{\rm eff}$ and Neutrino Decoupling in the Standard Model and beyond
hep-ph 2020-01 accept novelty 5.0 of 10

Replacing full kinetic theory with equilibrium distributions carrying evolving temperatures and chemical potentials reproduces the Standard Model N_eff = 3.045 and matches exact Liouville solutions for a light neutrin...
Signatures of Dark Radiation in Neutrino and Dark Matter Detectors
hep-ph 2017-11 conditional novelty 5.0 of 10

Dark radiation from late dark matter decays with weak-scale couplings to nucleons or electrons is already constrained by Super-Kamiokande, LUX, XENON1T and Borexino, and can raise the neutrino floor for dark matter searches.
A Hidden Dark Matter Sector, Dark Radiation, and the CMB
hep-ph 2015-05 conditional novelty 5.0 of 10

Dark matter annihilating into a light hidden sector yields extra CMB radiation whose free-streaming fraction shifts acoustic peak positions in opposite directions for scattering versus free-streaming dark radiation, g...
Constraining Models of Neutrino Mass and Neutrino Interactions with the Planck Satellite
astro-ph 2007-04 conditional novelty 5.0 of 10

Mock Planck data show the satellite can exclude a single self-coupled neutrino at 4.2 sigma and pin the radiation density at the CMB epoch to +0.5/-0.3 effective neutrino species.
The split majoron model confronts the NANOGrav signal and cosmological tensions
hep-ph 2023-07 conditional novelty 4.0 of 10

The split majoron model's low-scale phase transition yields a nanohertz gravitational-wave background near h²Ω ~ 10⁻¹¹ that can supplement, not replace, the black-hole-binary interpretation of NANOGrav, and the same d...
Cosmological Constraints on Interacting Light Particles
astro-ph.CO 2017-03 conditional novelty 4.0 of 10

Allowing both free-streaming and interacting dark radiation in Planck 2015 plus BAO data caps extra relativistic species at Delta N_tot < 0.39 (2 sigma), with a mild, prior-driven preference for interacting species on...
Feebly Interacting Particles: FIPs 2022 workshop report
hep-ph 2023-05 accept novelty 3.0 of 10

The FIPs 2022 workshop report surveys the theory, astrophysical bounds, and planned experiments for feebly interacting particles below the GeV scale, and argues for a diversified multi-laboratory program over the next decade.
Synergy between cosmological and laboratory searches in neutrino physics
hep-ph 2022-03 accept novelty 3.0 of 10

Cosmology and laboratory neutrino experiments probe different combinations of neutrino properties, and the paper argues that combining them is the sharpest available test of physics beyond the Standard Model.
The Physics of Light Relics
hep-ph 2022-03 accept novelty 2.0 of 10

A community review of how measurements of the cosmic radiation density and of light relic masses constrain or reveal new particles beyond the Standard Model, with forecasts for upcoming surveys.

How the literature uses it

52 arXiv papers cite this in 84 sentences

Each citing sentence is taken from the citing paper's LaTeX source and typed by Pith's classifier. A label appears at probability 0.8 or more (0.95 for support), a contest at 0.7 or more; the quoted words are the citing authors'. How each label was checked · JSON

Papers citing it · 60 sentences without a confident label

Contests it 1 paper

Our results also reveal that the original argument of near-collinearity of the decay products used in [ref] to establish the anisotropic stress damping rate ultimately tells only half of the story, as in its present form the argument is incompatible with detailed balance.

Invisible neutrino decay in precision cosmology · Final remarks · contest 0.85

Compares with it 2 papers

Similar phenomenology is obtained with the models studied in e.g. [ref] .

Constraining dynamical neutrino mass generation with cosmological data · Introduction · 0.85
By following this procedure we find that after the $ϕ$ particles decay, the temperature and neutrino chemical potentials are: [equation] which implies [equation] This is in excellent agreement with the results of [ref] .

Precision Early Universe Thermodynamics made simple: $N_{\rm eff}$ and Neutrino Decoupling in the Standard Model and beyond · Thermodynamics in the strongly interacting regime · 0.99

Cites it as support 1 paper

In particular, $b= 0$ would correspond to the rate controlling the background evolution of such a system [ref] , $b=2$ represents the heuristic rate suppressing neutrino freestreaming assuming a random walk [ref] , and $b =4$ represents the best motivated scenario and roughly matches the temperature dependence of the neutrino freestreaming suppression rate in scenarios with decays and inverse decays [ref] .

Global view of neutrino interactions in cosmology: The freestreaming window as seen by Planck · Rates suppressing neutrino freestreaming · 0.96

Cites it as background 18 papers

Contributions to $ΔN_eff$ at CMB have been considered before in the literature, but only in two contexts: (1) the visible and hidden sectors were initially in thermal contact and decouple later at a temperature $T_d$ causing the temperature of the hidden sector to vary as [ref] [equation] and (2) the sectors were not in thermal equilibrium but eventually become thermalized [ref] where a hidden sector particle decays to neutrinos after it becomes non-relativistic [ref] .

Analyzing the Hubble tension through hidden sector dynamics in the early universe · Reheating of the dark sector bath prior to recombination · 0.95
The idea of identifying features in the CMB arising from the majoron, and thus providing an indirect probe of the neutrino mass mechanism, was proposed at the start of the century [ref] .

A CMB Search for the Neutrino Mass Mechanism and its Relation to the $H_0$ Tension · Introduction · 0.80
The impact of exotic neutrino interactions in cosmology, and in particular in the CMB, have been studied in various contexts, including scenarios in which: neutrinos have self-interactions that arise from heavy mediators [ref] , neutrinos annihilate into massless scalars [ref] , neutrinos decay into light particles [ref] , and neutrinos temporarily thermalize with $eV-$scale neutrino-philic scalars [ref] .

Precision CMB constraints on eV-scale bosons coupled to neutrinos · Introduction · 0.98

Discussion

Disagree with the review, or know something it missed? Leave a comment, highlight any passage above to comment on it, or challenge this review formally.

[1] [1]

Y. Fukuda et al. [Super-Kamiokande Collaboration], Phys. Rev. Lett. 81, 1562 (1998) [arXiv:hep-ex/9807003]; Q. R. Ahmad et al. [SNO Collaboration], Phys. Rev. Lett. 89, 011301 (2002) [arXiv:nucl-ex/0204008]; K. Eguchi et al. [KamLAND Collaboration], Phys. Rev. Lett. 90, 021802 (2003) [arXiv:hep-ex/0212021]. 38

View on Pith Pith review arXiv 1998

[2] [2]

M. Gell-Mann, P. Ramond and R. Slansky, in Supergravity (North-Holland, Amsterdam, 1979); T. Yanagida, in Proc. Workshop on Uniﬁed Theories and Baryon Number in the Uni verse; R.N. Mohapatra and G. Senjanovic, Phys. Rev. 44 (1980) 912

View on Pith 1980

[3] [3]

The various regions in this plot are generically labeled by an integer w hich lies between 1 and 3. If the region lies in the mG > 1 eV portion of the plot this number indicates the number of neutrinos in equilibrium with the heavy pseudo-Goldsto ne boson when it disappeared, nR. If it lies in the mG < 1 eV region of the plot it indicates the number of ne...

View on Pith 2000

[4] [4]

Y. Chikashige, R.N. Mohapatra and R.D. Peccei, Phys. Let t B 98 (1981) 265

View on Pith 1981

[5] [5]

G. Gelmini and M. Roncadelli, Phys. Lett B 99 (1981) 411; H. Georgi, S. Glashow, and S. Nussinov, Nucl. Phys. B 193 (1981) 297

View on Pith 1981

[6] [6]

V. Barger, J. P. Kneller, H. S. Lee, D. Marfatia and G. Stei gman, Phys. Lett. B 566, 8 (2003) [arXiv:hep-ph/0305075]

View on Pith Pith review arXiv 2003

[7] [7]

J. M. Cline, K. Kainulainen and K. A. Olive, Astropart. Ph ys. 1, 387 (1993) [arXiv:hep-ph/9304229]

View on Pith Pith review arXiv 1993

[8] [8]

E. K. Akhmedov, Z. G. Berezhiani, R. N. Mohapatra and G. Se njanovic, Phys. Lett. B 299, 90 (1993) [arXiv:hep-ph/9209285]. I. Z. Rothstein, K. S. Babu and D. Seckel, Nucl. Phys. B 403, 725 (1993) [arXiv:hep-ph/9301213]

View on Pith Pith review arXiv 1993

[9] [9]

W. Hu, D. Scott, N. Sugiyama and M. J. White, Phys. Rev. D 52, 5498 (1995) [arXiv:astro-ph/9505043]

View on Pith Pith review arXiv 1995

[10] [10]

S. Bashinsky and U. Seljak, astro-ph/0310198

View on Pith Pith review arXiv

[11] [11]

J. Bartlett and L. Hall, Phys. Rev. Lett. 66 541 (1991); M. White, G. Gelmini and J. Silk, Phys. Rev. D51 2669 (1995); R. Bean, S. Hansen and A. Melchiorri, Phys.Rev. D64 (2001) 103508, astro-ph/0104162; R. Bowen, S. Hansen, A. Me lchiorri, J. Silk and R. Trotta, Mon.Not.Roy.Astron.Soc. 334 (2002) 760, astro-ph/011063 6

View on Pith Pith review arXiv 1991

[12] [12]

C. L. Bennett et al. , Astrophys. J. Suppl. 148, 1 (2003) [arXiv:astro-ph/0302207]

View on Pith Pith review arXiv 2003

[13] [13]

P. Crotty, J. Lesgourgues and S. Pastor, Phys. Rev. D67, 123005 (2003) [arXiv:astro-ph/0302337], E. Pierpaoli, Mon. Not. R. Astr on. Soc. 342, L63 (2003) [arXiv:astro-ph/0302465], S. Hannestad, JCAP 0305, 004 (2003) [arXiv:astro-ph/0303076]

View on Pith Pith review arXiv 2003

[14] [14]

Y. Farzan, Phys. Rev. D 67, 073015 (2003) [arXiv:hep-ph/0211375]

View on Pith Pith review arXiv 2003

[15] [15]

M. Kachelriess, R. Tomas and J. W. F. Valle, Phys. Rev. D 62, 023004 (2000) [arXiv:hep-ph/0001039]

View on Pith Pith review arXiv 2000

[16] [16]

K. Choi and A. Santamaria, Phys Rev D 42 (1990) 293; K. Choi, C.W. Kim, J. Kim and W.P. Lam, Phys. Rev. D 37 (1988) 3325; 39 J.A. Grifols, E. Masso and S. Peris, Phys. Lett B 215 (1988) 593

View on Pith 1990

[17] [17]

J. Schechter and J. W. F. Valle, Phys. Rev. D 25, 774 (1982); J. M. Cline, K. Kainulainen and S. Paban, Phys. Lett. B 319, 513 (1993) [arXiv:hep-ph/9309316]; J. T. Peltoniemi, Phys. Rev. D 57, 5509 (1998)

View on Pith Pith review arXiv 1982

[18] [18]

R. Lopez, S. Dodelson, A. Heckler and M. Turner, astro-p h/9803095, Phys. Rev. Lett. 82, 3952 (1999). 40

View on Pith 1999