REVIEW
The compressed bino--wino dark matter in the GmSUGRA and the LHC soft-lepton searches
High Energy Physics - Phenomenology · Submitted 22 Sep 2026 · 52 references
Pith's verdict: Honest existence proof of a GmSUGRA compressed bino–wino spectrum, but the 19 GeV 'attractor' claim outruns the evidence.
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Referee report
The paper
The paper claims
Generalized minimal supergravity naturally produces an almost pure bino dark matter particle at 260–266 GeV with a wino-like partner pair 18.5–19.1 GeV heavier, matching both the Planck relic abundance and the LHC soft-lepton searches.
The reading
What carries the argument
The load-bearing object is the GmSUGRA gaugino-mass relation at the unification scale, $M_3=\frac{5}{2}M_1-\frac{3}{2}M_2$, which lets $M_1$ and $M_2$ evolve to nearly degenerate bino and wino masses at the weak scale while the gluino stays multi-TeV. On the dark-matter side the machinery is standard bino–wino coannihilation, with the equilibrium weight $r_i(x)\propto g_i(1+\Delta_i)^{3/2}e^{-x\Delta_i}$ keeping the wino states populated at freeze-out when $\Delta_{\widetilde W}\simeq0.070$–$0.073$. On the collider side the same $\Delta m_{21}$ sets the dilepton endpoint, $m_{\ell\ell}^{\max}\simeq\Delta m_{21}$, below the $Z$ and $W$ on-shell thresholds, so the off-shell gauge-boson decays populate the soft-lepton signal regions. The argument's punch is that the relic-density condition and the soft-lepton kinematics select the same spectral quantity, $\Delta m_{21}$, which is generated by the high-scale relation rather than imposed at the weak scale.
Extended reading notes
Core claim
The central claim is that generalized minimal supergravity, through the GUT-scale gaugino relation $M_3=\frac{5}{2}M_1-\frac{3}{2}M_2$, produces a compressed bino–wino electroweakino sector without fixing $\Delta m_{21}$ as an electroweak-scale input. In the Planck-compatible branch the lightest neutralino is 99.8–99.95\% bino with mass 259.7–266.2 GeV, the $\widetilde\chi_2^0/\widetilde\chi_1^\pm$ pair is 99.7–99.93\% wino with mass 278.6–285.9 GeV, and the splitting is concentrated at $\Delta m_{21}=18.5$–$19.1$ GeV. The paper argues that this gap is selected by the relic condition: at $x=m_{\widetilde\chi_1^0}/T\sim20$–$25$ the wino Boltzmann factor remains near 0.17–0.25, so bino–wino coannihilation brings the relic abundance into the interval $0.114\le\Omega_\chi h^2\le0.126$. The same gap places the $Z^{(*)}$/$W^{(*)}$ decays below the on-shell gauge-boson thresholds, giving a dilepton endpoint near 19 GeV and placing the spectra in the ATLAS/CMS soft-lepton region. The paper also isolates an underabundant branch with $\Delta m_{21}=22$–$25$ GeV in which a stau 6–8\% above the LSP assists freeze-out and opens stau-mediated cascades, and it presents both branches as spectra for a dedicated detector-level recast rather than as a claim of survival against the full Run-2 likelihood.
Load-bearing premise
The argument rests on the premise that standard thermal freeze-out, with bino–wino coannihilation and no additional annihilation channels, is the sole mechanism setting the relic density, and that the $\sim19$ GeV gap is a common outcome of the GmSUGRA scan rather than a rare corner selected by the four printed benchmarks.
Editorial extensions
If this is right
- A future exclusion of wino–bino production around 280 GeV with an 18–19 GeV splitting would directly test the cosmological branch, because the same gap that sets the relic density also sets the soft-lepton kinematics.
- Soft-lepton searches become relic-density probes: in this framework, a spectrum in the soft-lepton mass region should also satisfy the Planck abundance, unless the stau-assisted branch is active.
- The underabundant branch predicts a stau 6–8\% above the LSP with on-shell $\widetilde\chi_2^0\to\widetilde\tau_1\tau$ and $\widetilde\chi_1^\pm\to\widetilde\tau_1\nu$ decays, so any complete test must include soft-tau and slepton final states rather than the pure $Z^{(*)}W^{(*)}$ topology.
- The surviving Planck-compatible spectra predict spin-independent neutralino–proton cross sections of $3\times10^{-14}$ to $3\times10^{-13}$ pb, close to current direct-detection sensitivity, with a sign-of-$\mu$ dependent interference in the Higgs-mediated amplitude.
- Because the paper's branches are correlated spectra, not simplified models, a claim of exclusion or discovery in this region requires a point-by-point recast using spectrum-specific branching fractions.
Reading between the lines
- Editorial inference: the same gaugino relation that fixes the bino–wino gap fixes the gluino mass, so a future gluino mass measurement would over-constrain this framework independently of the neutralino sector.
- Editorial inference: the stau-assisted branch implies that slepton searches near 270–290 GeV, not only electroweakino searches, are the fastest experimental route to excluding or confirming the underabundant solutions.
- Editorial inference: a much denser scan that publishes the density of Planck-compatible points would show whether the $\sim19$ GeV band is a prediction-generating peak across the whole GmSUGRA parameter space.
- Editorial inference: if Run-3 soft-lepton analyses confirm a genuine excess near a 19 GeV dilepton endpoint, these GmSUGRA spectra provide a concrete particle-physics template, with correlated masses, mixings, and branching fractions, for interpreting the excess beyond simplified models.
Original abstract
The search for electroweak supersymmetric particles remains an important part of the LHC program since neutralinos and charginos with masses around a few hundred GeV are still compatible with the present constraints in compressed spectra. Run-2 searches for the ``golden channel'', $pp\to\widetilde\chi_2^0\widetilde\chi_1^\pm\to\widetilde\chi_1^0 Z^{(*)}\widetilde\chi_1^0 W^{\pm(*)}$, have reported mild excesses in parts of the soft two- and three-lepton data, with the corresponding simplified-model interpretations emphasizing $m_{\widetilde\chi_2^0}\simeq m_{\widetilde\chi_1^\pm}\gtrsim200$~GeV and a neutralino mass difference near $20$~GeV. We study this configuration in the Minimal Supersymmetric Standard Model (MSSM) with the Generalized minimal Supergravity (GmSUGRA) boundary conditions, imposing the Higgs, flavor, collider, relic-density and direct-detection constraints relevant to the spectrum. For both signs of $\mu$, the solutions compatible with the Planck experiment contain an almost pure bino $\widetilde\chi_1^0$ with mass about $260$--$266$~GeV and a nearly degenerate wino-like $\widetilde\chi_2^0/\widetilde\chi_1^\pm$ pair near $280$~GeV. The resulting splitting, $\Delta m_{21}\simeq18.5$--$19.1$~GeV, lies in the mass-difference region probed by the ATLAS and CMS soft-lepton searches and places the $Z^{(*)}/W^{(*)}$ decays below the on-shell gauge-boson thresholds. The same compressed hierarchy keeps the wino states thermally populated during freeze-out, so bino-wino coannihilation yields a neutralino relic abundance consistent with the Planck experiment while the surviving solutions remain compatible with the direct-detection experimental bounds. Thus, the GmSUGRA boundary conditions provide a high-scale realization of the compressed bino-wino spectrum relevant to the LHC soft-lepton channel.
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.
The abstract, sentence by sentence
The search for electroweak supersymmetric particles remains an important part of the LHC program since neutralinos and charginos with masses around a few hundred GeV are still compatible with the present constraints in compressed spectra. Run-2 searches for the ``golden channel'', $pp\to\widetilde\chi_2^0\widetilde\chi_1^\pm\to\widetilde\chi_1^0 Z^{(*)}\widetilde\chi_1^0 W^{\pm(*)}$, have reported mild excesses in parts of the soft two- and three-lepton data, with the corresponding simplified-model interpretations emphasizing $m_{\widetilde\chi_2^0}\simeq m_{\widetilde\chi_1^\pm}\gtrsim200$~GeV and a neutralino mass difference near $20$~GeV. We study this configuration in the Minimal Supersymmetric Standard Model (MSSM) with the Generalized minimal Supergravity (GmSUGRA) boundary conditions, imposing the Higgs, flavor, collider, relic-density and direct-detection constraints relevant to the spectrum. For both signs of $\mu$, the solutions compatible with the Planck experiment contain an almost pure bino $\widetilde\chi_1^0$ with mass about $260$--$266$~GeV and a nearly degenerate wino-like $\widetilde\chi_2^0/\widetilde\chi_1^\pm$ pair near $280$~GeV. The resulting splitting, $\Delta m_{21}\simeq18.5$--$19.1$~GeV, lies in the mass-difference region probed by the ATLAS and CMS soft-lepton searches and places the $Z^{(*)}/W^{(*)}$ decays below the on-shell gauge-boson thresholds. The same compressed hierarchy keeps the wino states thermally populated during freeze-out, so bino-wino coannihilation yields a neutralino relic abundance consistent with the Planck experiment while the surviving solutions remain compatible with the direct-detection experimental bounds. Thus, the GmSUGRA boundary conditions provide a high-scale realization of the compressed bino-wino spectrum relevant to the LHC soft-lepton channel.
background contribution method result interpretation main claim
| # | sentence | role | the authors' own work | states the main conclusion | strength |
|---|---|---|---|---|---|
| s0 | The search for electroweak supersymmetric particles remains an important part of the LHC program since neutralinos and charginos with masses around a few hundred GeV are still compatible with the present constraints in compressed spectra. | background 1.00 | 0.04 | 0.03 | asserted 0.88 |
| s1 | Run-2 searches for the ``golden channel'', $pp\to\widetilde\chi_2^0\widetilde\chi_1^\pm\to\widetilde\chi_1^0 Z^{(*)}\widetilde\chi_1^0 W^{\pm(*)}$, have reported mild excesses in parts of the soft two- and three-lepton data, with the corresponding simplified-model interpretations emphasizing $m_{\widetilde\chi_2^0}\simeq m_{\widetilde\chi_1^\pm}\gtrsim200$~GeV and a neutralino mass difference near $20$~GeV. | background 1.00 | 0.05 | 0.03 | asserted 0.95 |
| s2 | We study this configuration in the Minimal Supersymmetric Standard Model (MSSM) with the Generalized minimal Supergravity (GmSUGRA) boundary conditions, imposing the Higgs, flavor, collider, relic-density and direct-detection constraints relevant to the spectrum. | method 0.63 | 0.88 | 0.03 | asserted 0.86 |
| s3 | For both signs of $\mu$, the solutions compatible with the Planck experiment contain an almost pure bino $\widetilde\chi_1^0$ with mass about $260$--$266$~GeV and a nearly degenerate wino-like $\widetilde\chi_2^0/\widetilde\chi_1^\pm$ pair near $280$~GeV. | result 1.00 | 0.90 | 0.20 | asserted 1.00 |
| s4 | The resulting splitting, $\Delta m_{21}\simeq18.5$--$19.1$~GeV, lies in the mass-difference region probed by the ATLAS and CMS soft-lepton searches and places the $Z^{(*)}/W^{(*)}$ decays below the on-shell gauge-boson thresholds. | result 0.91 | 0.83 | 0.11 | asserted 1.00 |
| s5 | The same compressed hierarchy keeps the wino states thermally populated during freeze-out, so bino-wino coannihilation yields a neutralino relic abundance consistent with the Planck experiment while the surviving solutions remain compatible with the direct-detection experimental bounds. | interpretation 0.52 | 0.80 | 0.17 | asserted 0.96 |
| s6 | Thus, the GmSUGRA boundary conditions provide a high-scale realization of the compressed bino-wino spectrum relevant to the LHC soft-lepton channel. | interpretation 0.94 | 0.70 | 0.91 | asserted 1.00 |
What was examined, and what was not
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Figures
Showing 1 of the paper's 2 figures. See all figures in the PDF ↗ Figures reproduced from arXiv:2609.26533 by the authors.
References
Discussion
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