WINO+: Wino-Centered Supersymmetric Dark Matter

• WINO+ is a family of supersymmetric dark matter models centered on the SU(2)L wino, with context-dependent interpretations ranging from pure neutral winos to mixed scenarios.
• Key features include a small charged-neutral mass splitting (~150–170 MeV) and non-perturbative Sommerfeld enhancement, critically affecting annihilation rates and indirect detection signals.
• WINO+ constructions extend to wino-assisted relic histories, such as bino–wino co-annihilation and mixed axion–wino dark matter, underpinning diverse collider and astrophysical observables.

In the cited literature, “WINO+” is used for a family of wino-centered supersymmetric dark matter constructions rather than for a single uniquely fixed model. Depending on context, the term refers to a neutral wino lightest supersymmetric particle (LSP), the positively charged component of the wino multiplet, a bino LSP whose relic history is controlled by a nearby wino, or a wino sector augmented by an axion supermultiplet or by heavy-higgsino-induced long lifetimes. This suggests that the unifying content of WINO+ is not one benchmark spectrum but the recurrent role of the SU(2)$_L$ wino in relic density, indirect detection, direct detection, and collider phenomenology (Ibe et al., 2015, Ibe et al., 2013, Bae et al., 2015, Rolbiecki et al., 2015).

1. Meanings of the label in the literature

The usage of “WINO+” is explicitly context-dependent in the cited papers. In some works it denotes the wino itself, especially the charged state $\tilde W^+$; in others it denotes a “wino plus” construction in which the wino assists another dark matter sector.

Usage	Definition	Representative papers
Pure wino dark matter	Neutral wino LSP, often in anomaly mediation or pure gravity mediation	(Ibe et al., 2015, Hryczuk et al., 2014)
Charged wino	Positively charged component of the wino multiplet	(Ibe et al., 2022, Ibe et al., 2023)
Wino-assisted bino dark matter	Bino LSP with a slightly heavier wino NLSP	(Ibe et al., 2013)
Wino plus PQ sector	Mixed axion–wino dark matter	(Bae et al., 2015)
Long-lived bino–wino sector	Heavier bino or wino becomes long-lived for heavy higgsinos	(Rolbiecki et al., 2015)

A closely related collider usage appears in studies of a wino-like LSP at the LHC, where the standard trilepton analysis is re-optimized for a wino-dominated neutralino rather than the bino-like LSP assumed in conventional simplified models (Abdallah et al., 2017). The term therefore functions as a label for wino-centered phenomenology across several adjacent model classes.

2. Electroweak triplet structure and the canonical pure-wino picture

In supersymmetric extensions of the Standard Model, the winos form an $SU(2)_L$ triplet,

$\tilde W = (\tilde W^+, \tilde W^0, \tilde W^-)\,.$

In anomaly-mediated and pure-gravity-mediation-like settings with heavy Higgsinos, the lightest superparticle is often an almost pure neutral wino $\tilde W^0$, which is stable if $R$-parity is conserved and thus a dark matter candidate (Ibe et al., 2015).

A defining feature of the pure-wino spectrum is the small charged–neutral mass splitting. In the high-scale SUSY and co-annihilation literature this splitting is quoted as

$$\Delta m_{\tilde w} = m_{\tilde w^\pm}-m_{\tilde w^0} \simeq 150\text{–}170~\text{MeV},$$

while the AMS-02 wino study describes it more broadly as $O(100)\,\text{MeV}$ (Ibe et al., 2013, Ibe et al., 2015). This small splitting implies the dominant decay

$\tilde W^\pm \to \tilde W^0 + \pi^\pm,$

and produces the disappearing-track signature central to collider searches. The 2015 AMS-02 study quoted an ATLAS bound $M_{\tilde w}\gtrsim 270\,\text{GeV}$ from 8 TeV data with $\tilde W^+$0, together with prospects of $\tilde W^+$1 GeV at 14 TeV with $\tilde W^+$2 (Ibe et al., 2015). Later disappearing-track interpretations used an ATLAS exclusion around $\tilde W^+$3 at 13 TeV with $\tilde W^+$4 (Ibe et al., 2022).

The thermal relic point lies in the multi-TeV regime. One line of work quotes the thermal wino mass as

$\tilde W^+$5

once Sommerfeld enhancement is included in freeze-out (Ibe et al., 2015). A later direct-detection study summarizes the thermal window more broadly as $\tilde W^+$6 (Ellis et al., 2023). This multi-TeV mass scale is the benchmark against which most indirect-detection limits and next-generation direct-detection projections are formulated.

3. Annihilation dynamics, Sommerfeld enhancement, and indirect searches

For a pure neutral wino, the dominant present-day annihilation channel is

$\tilde W^+$7

Because the wino is an electroweak triplet, long-range $\tilde W^+$8 interactions generate a non-perturbative Sommerfeld enhancement at halo velocities $\tilde W^+$9. The AMS-02 analysis summarizes the resulting annihilation rate as

$SU(2)_L$0

for TeV-scale winos (Ibe et al., 2015). The 2014 indirect-detection case study likewise emphasized that near the resonance region the present-day annihilation rate can reach $SU(2)_L$1, with a pronounced Sommerfeld resonance around $SU(2)_L$2 (Hryczuk et al., 2014).

This large annihilation rate makes antiprotons and gamma rays the leading probes. In the AMS-02 antiproton analysis, the preferred wino masses were $SU(2)_L$3, $SU(2)_L$4, and $SU(2)_L$5 for the MIN, MED, and MAX propagation models, respectively, and the paper emphasized that the thermal $SU(2)_L$6 TeV wino gave a particularly good fit to the 2015 $SU(2)_L$7 spectrum. It also predicted that the ratio should decrease quickly at the energy several hundreds of GeV if this explanation is correct (Ibe et al., 2015).

At the same time, multichannel indirect-detection studies found strong exclusions under standard halo assumptions. One such analysis concluded that a pure wino constituting all of dark matter is excluded below $SU(2)_L$8 from antiprotons and between $SU(2)_L$9 and $\tilde W = (\tilde W^+, \tilde W^0, \tilde W^-)\,.$0 from the absence of a gamma-ray line feature toward the Galactic Center (Hryczuk et al., 2014). A more refined effective-field-theory treatment of the semi-inclusive $\tilde W = (\tilde W^+, \tilde W^0, \tilde W^-)\,.$1 channel later showed that LL′ corrections reduce the $\tilde W = (\tilde W^+, \tilde W^0, \tilde W^-)\,.$2 TeV wino rate by $\tilde W = (\tilde W^+, \tilde W^0, \tilde W^-)\,.$3 relative to LL, but still leave the thermal wino excluded by an order of magnitude in a HESS-like analysis (Baumgart et al., 2015).

The inferred status depends sensitively on the Galactic halo profile. A dedicated gamma-line study found that for $\tilde W = (\tilde W^+, \tilde W^0, \tilde W^-)\,.$4 and $\tilde W = (\tilde W^+, \tilde W^0, \tilde W^-)\,.$5, the predicted $\tilde W = (\tilde W^+, \tilde W^0, \tilde W^-)\,.$6 rate exceeds the HESS bound by more than an order of magnitude for an NFW halo, while viability can be restored by a cutoff-NFW core radius $\tilde W = (\tilde W^+, \tilde W^0, \tilde W^-)\,.$7 or a Burkert core radius $\tilde W = (\tilde W^+, \tilde W^0, \tilde W^-)\,.$8 (Baumgart et al., 2014). The resulting literature therefore presents a persistent tension: the thermal wino is simultaneously a sharply predictive relic candidate and a target of strong, profile-dependent indirect-detection exclusions.

4. Direct detection and loop-induced nucleon scattering

Pure-wino direct detection is loop-dominated when higgsinos and other superpartners are heavy. An early complete calculation in anomaly mediation found that the spin-independent wino–proton cross section lies in the range

$\tilde W = (\tilde W^+, \tilde W^0, \tilde W^-)\,.$9

is almost independent of the wino mass, and is highly sensitive to the Higgs boson mass because of an accidental cancellation among scalar and twist-2 contributions (Hisano et al., 2010).

The QCD completion of this program, carried out to next-to-leading order in $\tilde W^0$0, substantially sharpened the prediction. In the large-wino-mass limit it obtained

$\tilde W^0$1

with the first error from perturbative calculation and the second from input parameters, and found the NLO result to be larger than the leading-order one by about $\tilde W^0$2 (Hisano et al., 2015). That analysis emphasized that the resulting cross section lies well above the neutrino background.

More recent work revisited the electroweak loop sector in realistic AMSB and pure-gravity-mediation spectra. It found that one-loop electroweak corrections interfere constructively with the tree-level contribution for AMSB models with negative Higgsino mixing, $\tilde W^0$3, and in PGM-like models for both signs of $\tilde W^0$4, thereby lifting the cross section out of the neutrino fog and into a range potentially detectable in next-generation direct searches (Ellis et al., 2023). The same paper also showed that AMSB with $\tilde W^0$5 can instead exhibit destructive interference and even a near-cancellation. The direct-detection literature thus moved from a purely loop-suppressed “invisible wino” picture to one in which QCD matching, electroweak interference, and the sign of $\tilde W^0$6 all materially affect observability.

5. Wino-assisted relic histories and mixed dark sectors

Several papers use WINO+ to denote scenarios in which the wino is indispensable even though it is not the dominant relic. In the bino–wino co-annihilation scenario, the LSP is bino-like, the wino is the NLSP, and the relevant mass splitting satisfies

$\tilde W^0$7

Because bino–wino mixing is tiny,

$\tilde W^0$8

the LSP remains at least $\tilde W^0$9 bino-like, while wino annihilation channels dominate the effective freeze-out cross section (Ibe et al., 2013). When gravitino decay adds a nonthermal component, the final state is mixed cold+warm bino dark matter. In the allowed parameter space the warm fraction satisfies

$R$0

with free-streaming scale

$R$1

so that the most sensitive probe is not current galaxy-scale structure but future 21 cm observations at $R$2 (Ibe et al., 2013).

A different use of WINO+ appears in mixed axion–wino dark matter. There the wino-like LSP is underabundant thermally,

$R$3

so a $R$4 GeV wino gives $R$5, and the CSB benchmark yields $R$6 (Bae et al., 2015). Axino and saxion decays then non-thermally increase the wino abundance, while axion misalignment supplies the remaining relic density. The allowed Peccei–Quinn scale depends strongly on KSVZ versus DFSZ and on whether $R$7 is switched on, but no model in that analysis allowed $R$8 for the heavy saxion masses considered (Bae et al., 2015).

These constructions suggest a broader meaning of WINO+: a wino may function not only as the dark matter particle itself but also as the sector that fixes relic abundance, nonthermal history, or small-scale structure.

6. Long-lived electroweakinos, charged-wino precision, and collider searches

Heavy higgsinos can seclude the bino and wino sectors from each other. In that regime the bino–wino mixing angle scales as

$R$9

and the heavier of bino and wino can become long-lived because the relevant couplings scale as $$\Delta m_{\tilde w} = m_{\tilde w^\pm}-m_{\tilde w^0} \simeq 150\text{–}170~\text{MeV},$$0 or $$\Delta m_{\tilde w} = m_{\tilde w^\pm}-m_{\tilde w^0} \simeq 150\text{–}170~\text{MeV},$$1 (Rolbiecki et al., 2015). The long-lived phenomenology is especially pronounced when the bino–wino mass splitting is below the electroweak-boson thresholds, forcing decays into three-body channels. For a wino NLSP with $$\Delta m_{\tilde w} = m_{\tilde w^\pm}-m_{\tilde w^0} \simeq 150\text{–}170~\text{MeV},$$2, the paper gave the approximate neutral-wino lifetime

$$\Delta m_{\tilde w} = m_{\tilde w^\pm}-m_{\tilde w^0} \simeq 150\text{–}170~\text{MeV},$$3

while for a charged wino with $$\Delta m_{\tilde w} = m_{\tilde w^\pm}-m_{\tilde w^0} \simeq 150\text{–}170~\text{MeV},$$4,

$$\Delta m_{\tilde w} = m_{\tilde w^\pm}-m_{\tilde w^0} \simeq 150\text{–}170~\text{MeV},$$5

(Rolbiecki et al., 2015). These regimes motivate searches for displaced vertices, disappearing tracks, and heavy stable charged particles.

For the pure charged wino, precision lifetime calculations now exist. The NLO charged-wino decay analysis found that the decay rate is determined by the charged–neutral mass difference and scarcely depends on the wino mass itself in the heavy-wino limit, with the NLO correction increasing the lifetime by $$\Delta m_{\tilde w} = m_{\tilde w^\pm}-m_{\tilde w^0} \simeq 150\text{–}170~\text{MeV},$$6–$$\Delta m_{\tilde w} = m_{\tilde w^\pm}-m_{\tilde w^0} \simeq 150\text{–}170~\text{MeV},$$7 (Ibe et al., 2022). A later extension to chargino decays with larger mass splittings showed that the NLO corrections are universal for any SU(2)$$\Delta m_{\tilde w} = m_{\tilde w^\pm}-m_{\tilde w^0} \simeq 150\text{–}170~\text{MeV},$$8 multiplet with $$\Delta m_{\tilde w} = m_{\tilde w^\pm}-m_{\tilde w^0} \simeq 150\text{–}170~\text{MeV},$$9, and that the wino rate at fixed $O(100)\,\text{MeV}$0 is obtained from the pure-higgsino result by a factor of $O(100)\,\text{MeV}$1, while the tree-level scheme ambiguity of $O(100)\,\text{MeV}$2 is reduced to $O(100)\,\text{MeV}$3 for the width (Ibe et al., 2023).

Wino-like LSP collider searches are not limited to disappearing tracks. A dedicated trilepton study showed that standard LHC trilepton analyses, optimized for a bino-like LSP, are poorly tuned to the wino-like LSP case because the third lepton from $O(100)\,\text{MeV}$4 decay is soft. The paper therefore proposed an alternative channel,

$O(100)\,\text{MeV}$5

and an optimized selection that discards the transverse-mass cut on the third lepton while requiring $O(100)\,\text{MeV}$6 GeV and

$O(100)\,\text{MeV}$7

With this strategy, the combined significance from the two trilepton channels exceeded $O(100)\,\text{MeV}$8 for a wino-like DM mass around $O(100)\,\text{MeV}$9 with an integrated luminosity as low as $\tilde W^\pm \to \tilde W^0 + \pi^\pm,$0 at 14 TeV (Abdallah et al., 2017).

7. Status, tensions, and future directions

The cited literature consistently presents the thermal wino near $\tilde W^\pm \to \tilde W^0 + \pi^\pm,$1 TeV as one of the most sharply predictive supersymmetric dark matter candidates. It is selected by thermal freeze-out including Sommerfeld enhancement, can fit the AMS-02 antiproton spectrum under some propagation assumptions, and has a loop-generated direct-detection cross section in the $\tilde W^\pm \to \tilde W^0 + \pi^\pm,$2 range (Ibe et al., 2015, Hisano et al., 2015). At the same time, it is under sustained pressure from indirect searches, especially Galactic-center gamma-ray lines and semi-inclusive $\tilde W^\pm \to \tilde W^0 + \pi^\pm,$3 analyses, unless the Milky Way halo is sufficiently cored (Baumgart et al., 2014, Baumgart et al., 2015).

Several future tests recur across the papers. The AMS-02 antiproton interpretation predicts a rapid decrease in $\tilde W^\pm \to \tilde W^0 + \pi^\pm,$4 at several hundreds of GeV and emphasizes that improved B/C measurements will constrain propagation uncertainties (Ibe et al., 2015). Next-generation direct-detection searches are relevant because electroweak loop corrections can lift the wino signal out of the neutrino fog in AMSB with $\tilde W^\pm \to \tilde W^0 + \pi^\pm,$5 and in PGM-like models (Ellis et al., 2023). Collider reach continues to depend on disappearing-track systematics and precise lifetime predictions (Ibe et al., 2022). In indirect detection, improved determinations of dwarf-spheroidal $\tilde W^\pm \to \tilde W^0 + \pi^\pm,$6-factors, Galactic halo coring, and endpoint-sensitive $\tilde W^\pm \to \tilde W^0 + \pi^\pm,$7 calculations remain central (Baumgart et al., 2014, Baumgart et al., 2015).

A more specialized extension appears in electroweak WIMPonium. For SU(2) triplet dark matter, single-photon capture into bound states becomes possible for wino masses above $\tilde W^\pm \to \tilde W^0 + \pi^\pm,$8 TeV and relative velocity $\tilde W^\pm \to \tilde W^0 + \pi^\pm,$9, but the capture rate is suppressed relative to direct annihilation and therefore gives only a small correction to the overall annihilation rate (Asadi et al., 2016). The soft photons from capture and subsequent bound-state transitions were proposed as possible probes of the dark matter quantum numbers, though the paper described them as rare for wino-like dark matter (Asadi et al., 2016).

Taken together, these studies portray WINO+ as a technically mature but conceptually plural domain: pure thermal wino dark matter, wino-assisted relic scenarios, and long-lived electroweakino sectors all inherit the same electroweak-triplet dynamics, yet differ sharply in which observable—antiprotons, gamma rays, nucleon scattering, disappearing tracks, or small-scale structure—carries the decisive information.