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Supernovae and Light Neutralinos: SN1987A Bounds on Supersymmetry Revisited

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H. K. Dreiner (Bonn U.), C. Hanhart (FZ-Julich), U. Langenfeld (Bonn U.), D. R. Phillips (Ohio U.)

High Energy Physics - Phenomenology · Submitted 30 Apr 2003 · 45 references

Pith's verdict: A careful and useful recomputation of SN1987A bounds on a light bino; the qualitative reversal on squark masses holds, but the specific 'window around 300 GeV' is contingent on one choice of Δq and vanishes under the other.

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arXiv IDhep-ph/0304289 (version 1)
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CitationC. Hanhart (FZ-Julich), D. R. Phillips (Ohio U.), H. K. Dreiner (Bonn U.), U. Langenfeld (Bonn U.). "Supernovae and Light Neutralinos: SN1987A Bounds on Supersymmetry Revisited." arXiv:hep-ph/0304289 (2003). https://pith.science/paper/5I32KDDO
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The paper

The paper claims

The supernova 1987A neutrino signal barely constrains squark masses, but does exclude a band of selectron masses for light neutralinos.

The reading

The paper asks how strongly the observed neutrino burst from supernova 1987A constrains supersymmetric particles, in the scenario where the lightest neutralino is light (below about 200 MeV) and almost a pure bino, so that collider searches give no lower mass bound at all. The logic is that such neutralinos, if produced copiously in the core, would carry energy out and shorten the neutrino signal; requiring that they not do so turns into a lower limit on the neutralino mass as a function of the selectron and squark masses that control production. The authors redo this calculation for two production channels, electron-positron annihilation and nucleon-nucleon neutralinostrahlung, using realistic radial and temporal profiles of core temperature and electron degeneracy for the first channel and an on-shell nucleon-nucleon amplitude for the second. The headline outcome is asymmetric: the annihilation channel still excludes selectron masses in a broad band, while the nucleon channel leaves almost nothing, in contrast to earlier work that had excluded squark masses over a wide range. If correct, this removes most of a long-standing supernova constraint on squarks and shifts the interesting target to the selectron.

What carries the argument

The load-bearing device is a soft-radiation relation: for a fermion pair that couples axially to nucleons, the bremsstrahlung emissivity from $NN to NN + pair$ is fixed, at leading order in the emitted energy, by the on-shell nucleon-nucleon scattering matrix, because the two emission diagrams are the only ones that diverge as $1/omega$ and the intermediate nucleon is nearly on shell. This makes the strong-interaction input model-independent and lets the authors take it from published phase-shift analyses. The neutralino's coupling to nucleons is reduced to a single number, the ratio $alpha_chi$ of the neutralino to neutrino spin-summed matrix elements, which factorizes into a coupling ratio and the hadronic tensor, so the hadronic response cancels and all nuclear-model dependence sits in one factor built from the quark spin content $Delta u, Delta d, Delta s$. Production is then compared against the Raffelt criterion, an emissivity ceiling of $10^{19}$ erg/g/s, and against an integrated-energy ceiling of $10^{52}$ erg; a separate optical-depth test on neutralino scattering off electrons and neutrons decides whether the neutralinos actually free-stream out or merely diffuse.

Extended reading notes

Core claim

The paper's central claim is that the supernova bound on squark masses, as computed since the late 1980s, was too strong, and that once three corrections are made the surviving excluded region shrinks to a narrow window around $M_{q} = 300$ GeV that closes entirely once $M_chi$ exceeds roughly 20 MeV. The three corrections are: the neutralino is taken to be a bino rather than a photino, which weakens its effective coupling to nucleons; the strong-interaction part of the neutralinostrahlung rate is taken from on-shell nucleon-nucleon scattering data rather than the single-pion-exchange approximation, which lowers the axial response by about a factor of four; and the neutralino mass dependence of the emissivity is kept in full rather than dropped. For the electron-positron channel the paper finds a real constraint: for $M_chi$ around 100 MeV, selectron masses between roughly 300 and 900 GeV are inconsistent with the observed neutrino signal, and for a massless neutralino selectron masses below about 1275 GeV are excluded. The authors also check that a local emissivity criterion and a global integrated-energy criterion agree for the annihilation channel, which is what licenses them to use the local criterion for the nucleon channel.

Load-bearing premise

The claim that only a narrow squark window is excluded rests on the free-streaming test in which each neutralino is assigned a single representative energy and the electron and neutron densities are taken constant across the core; that test fixes the lower edge of the window, so a different choice of energy or density could open or close it.

Editorial extensions

If this is right

  • For a light bino, the supernova constraint worth pursuing is on the selectron mass, not the squark mass: selectron masses in the few-hundred-GeV to roughly 900 GeV range are excluded for neutralino masses near 100 MeV.
  • If the selectron mass exceeds about 1200 GeV, no lower bound on the lightest neutralino mass survives from SN1987A, so a very light neutralino remains allowed by supernova cooling arguments.
  • The squark-mass exclusion is confined to a narrow window near 300 GeV and disappears above $M_chi$ of about 20 MeV, so future work on supernova cooling of supersymmetric particles should not quote a broad squark bound.
  • Because the same soft-radiation machinery applies to any light pair axially coupled to nucleons, the derived emissivity formula can be reused for other exotic bremsstrahlung channels in supernovae.
  • The comparison of a local emissivity criterion with a global integrated-energy criterion, found to agree to within a factor of about two, supports the use of the cheaper local test in future supernova cooling studies.

Reading between the lines

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

  • The narrowness of the excluded squark window is a statement about the gap between the production bound and the trapping bound, not about the quality of either; a modest shift in the assumed neutralino energy or in the core density profile could close the window altogether, which would make the paper's headline result stronger than it currently reads.
  • Because the two channels have such different selectron and squark reach, the natural next step is a joint two-parameter scan rather than the one-dimensional slices presented here, since a heavy selectron and a light squark could conspire to keep the total exotic emissivity just under the ceiling.
  • The paper's own remark that many-body corrections such as the Landau-Pomeranchuk-Migdal effect should further suppress axial radiation suggests that even the residual squark window may be an artifact of neglecting those corrections.
  • The scenario requires R-parity violation to avoid over-closing the universe with a quasi-stable neutralino, so the supernova limits are only meaningful jointly with laboratory bounds on the violating couplings; that joint space is not mapped here.
Original abstract

For non-universal gaugino masses, collider experiments do not provide any lower bound on the mass of the lightest neutralino. We review the supersymmetric parameter space which leads to light neutralinos, $M_\lsp \lsim {\cal O}(1\gev)$, and find that such neutralinos are almost pure bino. In light of this, we examine the neutralino lower mass bound obtained from supernova 1987A (SN1987A). We consider the production of binos in both electron-positron annihilation and nucleon-nucleon binostrahlung. For electron-positron annihilation, we take into account the radial and temporal dependence of the temperature and degeneracy of the supernova core. We also separately consider the Raffelt criterion and show that the two lead to consistent results. For the case of bino production in $NN$ collisions, we use the Raffelt criterion and incorporate recent advances in the understanding of the strong-interaction part of the calculation in order to estimate the impact of bino radiation on the SN1987A neutrino signal. Considering these two bino production channels allows us to determine separate and combined limits on the neutralino mass as a function of the selectron and squark masses. For $M_\lsp \sim 100 \mev$ values of the selectron mass between 300 and 900 GeV are inconsistent with the supernova neutrino signal. On the other hand, in contrast to previous works, we find that SN1987A provides almost no bound on the squark masses: only a small window of values around 300 GeV can be excluded, and even then this window closes once $M_\lsp \gsim 20 \mev$.

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, 7,880 input tokens, $0.0003 reported.

What the abstract itself states, as probabilities: claims first 0.05 · states limitation 0.44 · human participants 0.01 · controlled comparison 0.07 · randomized assignment 0.01 · states quantitative result 0.98 · compares with prior results 0.94 · mentions code or data availability 0.01.

The abstract, sentence by sentence

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

For non-universal gaugino masses, collider experiments do not provide any lower bound on the mass of the lightest neutralino. We review the supersymmetric parameter space which leads to light neutralinos, $M_\lsp \lsim {\cal O}(1\gev)$, and find that such neutralinos are almost pure bino. In light of this, we examine the neutralino lower mass bound obtained from supernova 1987A (SN1987A). We consider the production of binos in both electron-positron annihilation and nucleon-nucleon binostrahlung. For electron-positron annihilation, we take into account the radial and temporal dependence of the temperature and degeneracy of the supernova core. We also separately consider the Raffelt criterion and show that the two lead to consistent results. For the case of bino production in $NN$ collisions, we use the Raffelt criterion and incorporate recent advances in the understanding of the strong-interaction part of the calculation in order to estimate the impact of bino radiation on the SN1987A neutrino signal. Considering these two bino production channels allows us to determine separate and combined limits on the neutralino mass as a function of the selectron and squark masses. For $M_\lsp \sim 100 \mev$ values of the selectron mass between 300 and 900 GeV are inconsistent with the supernova neutrino signal. On the other hand, in contrast to previous works, we find that SN1987A provides almost no bound on the squark masses: only a small window of values around 300 GeV can be excluded, and even then this window closes once $M_\lsp \gsim 20 \mev$.

background contribution method result interpretation main claim

What the classifier reports for each sentence. The number is the probability it gave the label.
#sentencerolethe authors' own workstates the main conclusionstrength
s0 For non-universal gaugino masses, collider experiments do not provide any lower bound on the mass of the lightest neutralino. background 0.66 0.10 0.07 asserted 1.00
s1 We review the supersymmetric parameter space which leads to light neutralinos, $M_\lsp \lsim {\cal O}(1\gev)$, and find that such neutralinos are almost pure bino. result 0.67 0.91 0.08 asserted 1.00
s2 In light of this, we examine the neutralino lower mass bound obtained from supernova 1987A (SN1987A). contribution 0.79 0.58 0.04 unclear 0.56
s3 We consider the production of binos in both electron-positron annihilation and nucleon-nucleon binostrahlung. method 0.77 0.78 0.02 asserted 0.90
s4 For electron-positron annihilation, we take into account the radial and temporal dependence of the temperature and degeneracy of the supernova core. method 0.99 0.85 0.02 asserted 0.98
s5 We also separately consider the Raffelt criterion and show that the two lead to consistent results. result 0.52 0.85 0.04 asserted 0.97
s6 For the case of bino production in $NN$ collisions, we use the Raffelt criterion and incorporate recent advances in the understanding of the strong-interaction part of the calculation in order to estimate the impact of bino radiation on the SN1987A neutrino signal. method 0.97 0.84 0.05 asserted 0.84
s7 Considering these two bino production channels allows us to determine separate and combined limits on the neutralino mass as a function of the selectron and squark masses. contribution 0.55 0.89 0.14 asserted 0.97
s8 For $M_\lsp \sim 100 \mev$ values of the selectron mass between 300 and 900 GeV are inconsistent with the supernova neutrino signal. result 1.00 0.89 0.21 asserted 1.00
s9 On the other hand, in contrast to previous works, we find that SN1987A provides almost no bound on the squark masses: only a small window of values around 300 GeV can be excluded, and even then this window closes once $M_\lsp \gsim 20 \mev$. result 1.00 0.95 0.53 asserted 1.00

What kind of paper the classifier reports this is: theoretical result 0.92 · evidence from analysis of existing data 0.39.

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. The neutralino mass as a function of M2 for various values of M1 and with tan β = 10, µ = 300 GeV. The downward spikes correspond to true zeros of the neutralino mass. The bold horizontal line indicates the value Mχ˜ = 200 MeV, below which we consider in this paper. To the right of the bold vertical line at about M2 = 120 GeV the chargino mass satisfies the lower mass bound from LEP2. which are shown in
Figure 2. Neutralino power Pχ˜(Mχ˜, t) for t = 0.5 seconds as a function of the neutralino mass, Mχ˜, with the selectron mass Me˜ = 200 GeV. The solid curve shows our numerical computation while the dashed curve represents the fit Eq. (18). The two curves are almost indistinguishable. (Throughout we assume radial symmetry [25].) The time t = 0 of Ref. [25] corresponds to the time when the incoming shock wave stops and bounces outwards again. The boundary conditions at this time are not well known [33]. However, the exact shape of the initial conditions has little effect on the subsequent…
Figure 3. The dependence of the neutralino lower mass bound on the selectron mass. Here we chose Emax χ˜ = 1052 erg and t0 = 1 s. The green-dashed line indicates the lower bound on the selectron mass from LEP2. Beyond Me˜ = 1 TeV the exclusion curve drops rapidly. The numerical fit in Eq. (18) is shown as the dashed curve in
Figure 4. The minimum allowed value of Mχ˜, Mmin χ˜ , as a function of the time over which we integrate, t0. The curves correspond to three different values of the selectron mass: Me˜ = 300, 500, 1000 GeV. Here Emax χ˜ = 1052 erg and the neutralino is pure bino. Our choice of t0 = 1 second is indicated by the grey vertical line. the supernova. This is indeed the case. If we integrate the power out further, thereby increasing t0, and again apply the criterion (7), we obtain the bounds shown in
Figure 5. The neutralino mass bound as a function of Emax χ˜ for three different values of the selectron mass: Me˜ = 300, 500, 1000 GeV. Here t0 = 1 s and the neutralino is again pure bino. Our choice of Eq. (7) is represented by the black vertical line. 0 200 400 600 800 1000 Me (GeV) 0 50 100 150 200 250 300 M χ min (MeV) EXCLUDED
Figure 6. The neutralino lower mass bound as a function of the selectron mass Me˜, when the Raffelt criterion is applied to the emissivity for electron-positron annihilation to neutralinos. The vertical line indicates the lower bound on the selectron mass from LEP2 [35]. be computed. Previous work suggests Tc = 30 MeV is a reasonable choice [13, 14, 36]. Computing the emissivity due to e +e − → χ˜χ˜ at this temperature, and at a density of 3 × 1014 g/cm3 , produces the constraint on neutralino and selectron masses shown in
Figure 7. Two diagrams contributing to neutralinostrahlung from the nucleon-nucleon system. Time flows from left to right. The nucleons are denoted by double lines. The (yellow) oval indicates the nucleon-nucleon interaction. The black circle indicates the effective neutralino￾nucleon coupling which we compute in Sec. 4. Two diagrams which are the same, except that the neutralinos are radiated from the bottom lines, are not shown. line indicates the neutralino and selectron masses for which the emissivity of the process (11) is exactly 1019 ergs/g/s. Neutralino masses below the solid (red)…
Figure 8. The two diagrams contributing to neutralinostrahlung from a nucleon. The (green) oval denotes the nucleon bound state. The horizontal lines are the partons with q = u, d, s. The virtual squark ˜q can be either left- or right-handed. In this section, we focus on the other piece of input to these diagrams: the neutralino-nucleon coupling. We will show that in the limit of long-wavelength (i.e. soft) neutralinos this coupling is expressible in terms of the spin content of the nucleon, ∆q. We evaluate the ˜χn coupling using two different sets of results for ∆u, ∆d, and ∆s: the…
Figure 9. Neutralino emissivity in units of 1019 ergs/g/s as a function of the neutralino mass Mχ˜. The red solid line shows the full result for αχ˜ = 10 α crit χ˜ , whereas the black dashed line shows the fit according to Eq. (77). The horizontal blue solid line shows the emissivity 1019 ergs/g/s that is used when the Raffelt criterion is applied. 5.2 Emissivity We now return to the computation of the emissivity Eq. (63). Doing the angular integrals as described leaves us with a four-dimensional integral which we decompose as E˙ = αχ˜ G2 F c 2 A 8(2π) 11 (2MTc) 9/2M4 χ˜ Z ∞ Mˆ χ˜ dδ…
Figure 10. The region of the αχ˜-Mχ˜(MeV) plane that is excluded by our soft-radiation calcu￾lation, when applying the Raffelt criterion (at Tc = 30 MeV) is indicated by the grey shading. The blue solid line is the curve that defines the values of αχ˜ and Mχ˜ which produce a neutralino emissivity of exactly 1019 ergs/g/s. The horizontal (red) dashed line indicates the uppermost value of Mχ˜ at which the soft-radiation approximation should be trusted. E˙ = 4αχ˜ (1 + 2Mˆ χ˜ + 0.55Mˆ 2 χ˜ ) e −2Mˆχ˜ × 1023 [ergs/g/s], (77) where Mˆ χ˜ ≡ Mχ˜/Tc as defined in Eq. (69). The fit is good for Mχ˜ <∼…
Figure 11. Me˜ − Mq˜ parameter space, with the regions excluded by the arguments of this paper for the case Mχ˜ = 0 shaded. The regions already explored by LEP searches are shown in grey. The white regions indicate areas of parameter space in which we are unable to set bounds. When this is because of diffusive propagation of the neutralino we have indicated the mechanism that leads to diffusion. Values of (Me˜, Mq˜) in the upper-right-hand corner are permitted because there the neutralino production rate is too low to affect the SN1987A neutrino signal significantly. The bounds shown in

Figures reproduced from arXiv:hep-ph/0304289 by the authors.

References
How later papers used it

51 later papers cite it

Evidence: some. 33 of the citing papers share no author with it, and 6 of those carry a confident label from Pith's citation classifier.

Pith read 9 of the 78 citing sentences, choosing only those whose citation markers point at this paper alone, and wrote the paraphrases from them. The summary, the counts, the evidence level, the links and the quotes come from code; the summary counts the papers listed below. A later paper is listed under a label when Pith's citation classifier gives one of its sentences that label at probability 0.8 or more (0.95 for support), Pith's reading finds that the citing paper itself did it, and a second check confirms the paraphrase against the sentence. This section lists uses only. It does not list criticism or disagreement, so their absence here says nothing about how the paper has been received. Papers that share an author with this one are listed apart, under "By the same authors". A quote is the citing authors' own sentence, shown when their paper's licence is CC BY, CC BY-SA or CC0. JSON

Uses its method or tool 3 of 5 papers with this label
How the literature uses it

49 arXiv papers cite this in 76 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 · 57 sentences without a confident label

Uses its method or tool 5 papers
  • The Raffelt criterion is applied at a characteristic radius and requires the local emissivity of the sterile neutrinos at $r_0$ to not exceed more than 10$%$ of the total neutrino emissivity [ref] , i.e., [equation] For the integrated luminosity criterion, the energy-loss rate per unit mass can be converted to a total luminosity loss by taking the mass of the SN core and the duration of the SN event into account.

    Probing the Sterile Neutrino Dipole Portal with SN1987A and Low-Energy Supernovae · Supernovae Bounds · 0.95

  • On the flip side, the lower boundary in couplings for energy loss to be efficient can be estimated by calculating the energy production rate of $χ$ particles by electron-positron annihilation within the SN core, [equation] following [ref] .[For interactions studied here, the contribution from plasmon decay is either comparable or sub-leading, and neglected for simplicity.] The corresponding momentum distributions of electron and positron, $f_e^-$ and $f_e^+$, as functions of the temperature and (opposite) chemical potentials for each $r$, are also given by the same SN model [ref] .

    Light dark states with electromagnetic form factors · Supernova cooling · 0.97

  • Here we follow the simple energy argument introduced in [ref] that determines the particle mass for which this effect becomes important.

    Dipole portal to heavy neutral leptons · Escape · 0.96

Uses its data or values 2 papers
  • Supernova [ref] or white dwarf cooling [ref] , give a lower mass bound: $m_χ̃^0_1 250$MeV, for selectron masses around 320 GeV.

    R-Parity Violation and Light Neutralinos at SHiP and the LHC · A Light Neutralino · 0.91

  • The corresponding input data are adopted from [ref] , where they obtained the data from the simulation of SN model SFHo-18.8 [ref] [equation] Now, as it has been explained in [ref] (and subsequently in [ref] ), In the non-relativistic soft-radiation limit, the polar-vector contribution to the $𝒩 𝒩→𝒩 𝒩+ X$ matrix element vanishes at lowest order for purely central (Landau-type) nucleon–nucleon interactions, independent of the detailed form of the Landau parameters.

    From WIMP to FIMP during reheating: collider vs non-collider probes for p-wave annihilation · Supernova bounds · 0.96

Cites it as support 4 papers
Cites it as background 7 papers
  • This is a summary of previous work [ref] .

    Comments on a Massless Neutralino · Introduction · 0.97

  • Here we ask the question `How light can the lightest neutralino be?', and discuss bounds from collider physics and precision observables, to summarize previous works [ref] .

    How light can the lightest neutralino be? · Introduction · 0.95

  • The cooling of stars and supernova 1987A are known to place strong bounds on light new physics, and as such there has been great effort to quantify these constraints (for some examples of these studies, see e.g. Refs. [ref] ).

    Light Dark Sectors through the Fermion Portal · Limits from Supernova 1987A and stellar cooling · 0.87

Discussion

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