Higgsino Dark Matter Research Articles

Consistent excesses in the search for χ~20χ~1±:\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\varvec{\ ilde{\\chi }_{2}^0\ ilde{\\chi }_{1}^\\pm :}$$\\end{document} wino/bino vs. Higgsino dark matter

The quest for supersymmetric (SUSY) particles is among the main search channels currently pursued at the LHC. Particularly, electroweak (EW) particles with masses as low as a few hundred GeV are still viable. Recent searches for the “golden channel”, pp→χ~20χ~1±→χ~10Z(∗)χ~10W±(∗)\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$pp \\rightarrow \ ilde{\\chi }_{2}^0 \ ilde{\\chi }_{1}^\\pm \\rightarrow \ ilde{\\chi }_{1}^0 Z^{(*)} \\, \ ilde{\\chi }_{1}^0 W^{\\pm (*)}$$\\end{document} show consistent excesses between ATLAS and CMS in the 2 lepton, 3-lepton and mono-jet searches, assuming and Δm:=mχ~20-mχ~10≈20GeV\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\Delta m:= m_{\ ilde{\\chi }_{2}^0} - m_{\ ilde{\\chi }_{1}^0} \\approx 20 \\,\\, \ extrm{GeV}$$\\end{document}. This mass configuration arises naturally in SUSY scenarios with wino/bino Dark Matter (DM) or higgsino DM. In these scenarios the lightest supersymmetric particle (LSP), assumed to be the lightest neutralino, χ~10\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\ ilde{\\chi }_{1}^0$$\\end{document}, as a DM candidate is in good agreement with the observed limits on the DM content of the universe, as well as with negative results from Direct Detection (DD) experiments. We analyze these two scenarios with respect to the observed excesses, taking into account all relevant experimental constraints. We show that in particular wino/bino DM with different signs of the SU(2) and U(1) soft SUSY-breaking parameters can describe well the experimental excesses, while being in agreement with all other constraints.

Investigating higgsino dark matter in the semi-constrained NMSSM* *Supported by the National Natural Science Foundation of China (12275066, 11605123)

In this study, we explored the characteristics of higgsino-dominated dark matter (DM) within the semi-constrained Next-to-Minimal Supersymmetric Standard Model (scNMSSM), covering a mass range from hundreds of GeV to several TeV. We carefully analyzed the parameter space under existing theoretical and experimental constraints to confirm the viability of higgsino-dominated lightest supersymmetric particles (LSPs) with masses between 100 GeV and 4 TeV. Our study examined various DM annihilation mechanisms, emphasizing the significant role of coannihilation with the next-to-lightest supersymmetric particle (NLSP), which includes other higgsino-dominated particles such as and . We categorize the annihilation processes into three main classes: coannihilation, Higgs funnel annihilation, and coannihilation. Each class combines interactions with . Our results indicate that achieving the correct relic density in heavier higgsino LSPs requires a combination of coannihilation and Higgs funnel mechanisms. We also assessed the potential of future experiments, such as XENONnT, LUX-ZEPLIN (LZ), PandaX-xT, and the Cherenkov Telescope Array (CTA), to probe these DM scenarios through direct and indirect detections. In particular, future spin-independent DM detections may cover all samples with the correct DM relic density for GeV. Furthermore, future colliders such as the International Linear Collider (ILC) and Compact Linear Collider (CLIC) are expected to exceed the detection capabilities of current hadron colliders, especially for higher mass NLSPs. Notably, CLIC, which will operate at 3000 GeV, is anticipated to enable thorough investigation of all samples with insufficient DM relic density for GeV.

CTA and SWGO can discover Higgsino dark matter annihilation

Thermal Higgsino dark matter (DM), with a mass near 1.1 TeV, is one of the most well-motivated and untested DM candidates. Leveraging recent hydrodynamic cosmological simulations that give DM density profiles in Milky Way analog galaxies we show that the linelike gamma-ray signal predicted from Higgsino annihilation in the Galactic Center could be detected at high significance with the upcoming Cherenkov Telescope Array (CTA) and Southern Wide-field Gamma-ray Observatory (SWGO) for all but the most pessimistic DM profiles. We perform the most sensitive search to-date for the linelike signal using 15 years of data from the Fermi Large Area Telescope, coming within an order one factor of the necessary sensitivity to detect the Higgsino for some Milky Way analog DM density profiles. We show that H.E.S.S. has subleading sensitivity relative to Fermi for the Higgsino at present. In contrast, we analyze H.E.S.S. inner Galaxy data for the thermal wino model with a mass near 2.8 TeV; we find no evidence for a DM signal and exclude the wino by over a factor of two in cross section for all DM profiles considered. In the process, we identify and attempt to correct what appears to be an inconsistency in previous H.E.S.S. inner Galaxy analyses for DM annihilation related to the analysis effective area, which may weaken the DM cross-section sensitivity claimed in those works by around an order of magnitude. Published by the American Physical Society 2024

Search for supersymmetry in final states with disappearing tracks in proton-proton collisions at s=13 TeV

A search is presented for charged, long-lived supersymmetric particles in final states with one or more disappearing tracks. The search is based on data from proton-proton collisions at a center-of-mass energy of 13 TeV collected with the CMS detector at the CERN LHC between 2016 and 2018, corresponding to an integrated luminosity of 137 fb−1. The search is performed over final states characterized by varying numbers of jets, b-tagged jets, electrons, and muons. The length of signal-candidate tracks in the plane perpendicular to the beam axis is used to characterize the lifetimes of wino- and Higgsino-like charginos produced in the context of the minimal supersymmetric standard model. The dE/dx energy loss of signal-candidate tracks is used to increase the sensitivity to charginos with a large mass and thus a small Lorentz boost. The observed results are found to be statistically consistent with the background-only hypothesis. Limits on the pair-production cross section of gluinos and squarks are presented in the framework of simplified models of supersymmetric particle production and decay, and for electroweakino production based on models of wino and Higgsino dark matter. The limits presented are the most stringent to date for scenarios with light third-generation squarks and a wino- or Higgsino-like dark matter candidate capable of explaining the observed dark matter relic density. © 2024 CERN, for the CMS Collaboration 2024 CERN

Third family quasi-Yukawa unification: Higgsino dark matter, NLSP gluino, and all that

Third family quasi-Yukawa unification: Higgsino dark matter, NLSP gluino, and all that

Higgsino Dark Matter Confronts 14Years of Fermi γ-Ray Data.

Thermal Higgsino dark matter (DM), with mass around 1TeV, is a well-motivated, minimal DM scenario that arises in supersymmetric extensions of the standard model. Higgsinos may naturally be the lightest superpartners in split-supersymmetry models that decouple the scalar superpartners while keeping Higgsinos and gauginos close to the TeV scale. Higgsino DM may annihilate today to give continuum γ-ray emission at energies less than a TeV in addition to a linelike signature at energies equal to the mass. Previous searches for Higgsino DM, for example with the H.E.S.S. γ-ray telescope, have not reached the necessary sensitivity to probe the Higgsino annihilation cross section. In this work we make use of 14years of data from the Fermi Large Area Telescope at energies above ∼10 GeV to search for the continuum emission near the Galactic Center from Higgsino annihilation. We interpret our results using DM profiles from MilkyWay analog galaxies in the FIRE-2 hydrodynamic cosmological simulations. We set the strongest constraints to date on Higgsino-like DM. Our results show a mild, ∼2σ preference for Higgsino DM with a mass near the thermal Higgsino mass and, depending on the DM density profile, the expected cross section.

Toward the ultimate reach of current imaging atmospheric Cherenkov telescopes and their sensitivity to TeV dark matter

Indirect detection opens a unique window for probing thermal dark matter (DM): the same annihilation process that determined the relic abundance in the early Universe drives the present day astrophysical signal. While TeV-scale particles weakly coupled to the Standard Model face undoubted challenges from decades of null searches, the scenario remains compelling, and simple realizations such as Higgsino DM remain largely unexplored. The fate of such scenarios could be determined by gamma-ray observations of the centre of the Milky Way with Imaging Atmospheric Cherenkov Telescopes (IACTs). We consider the ultimate sensitivity of current IACTs to a broad range of TeV-scale DM candidates - including specific ones such as the Wino, Higgsino, and Quintuplet. To do so, we use realistic mock H.E.S.S.-like observations of the inner Milky Way halo, and provide a careful assessment of the impact of recent Milky Way mass modeling, instrumental and astrophysical background uncertainties in the Galactic Center region, and the theoretical uncertainty on the predicted signal. We find that the dominant systematic for IACT searches in the inner Galaxy is the unknown distribution of DM in that region, however, beyond this the searches are currently statistically dominated indicating a continued benefit from more observations. For two-body final states at $1~{\rm TeV}$, we find a H.E.S.S.-like observatory is sensitive to $\langle \sigma v \rangle \sim 3 \times 10^{-26}-4 \times 10^{-25}~{\rm cm}^3{\rm s}^{-1}$, except for neutrino final states, although we find results competitive with ANTARES. In addition, the thermal masses for the Wino and Quintuplet can be probed; the Higgsino continues to be out of reach by at least a factor of a few. Our conclusions are also directly relevant to the next generation Cherenkov Telescope Array, which remains well positioned to be the discovery instrument for thermal DM.

Muon and electron (g-2) anomalies with non-holomorphic interactions in MSSM

The recent Fermilab muon g-2 result and the same for electron due to fine-structure constant measurement through {}^{133}textrm{Cs} matter-wave interferometry are probed in relation to MSSM with non-holomorphic (NH) trilinear soft SUSY breaking terms, referred to as NHSSM. Supersymmetric contributions to charged lepton (g-2)_l can be enhanced via the new trilinear terms involving a wrong Higgs coupling with left and right-handed scalars. Bino-slepton loop is used to enhance the SUSY contribution to g-2 where wino mass stays at 1.5 TeV and the left and right slepton mass parameters for the first two generations are considered to be the same. Unlike many MSSM-based analyses completed before, the model does not require a light electroweakino, or light sleptons, or unequal left and right slepton masses, or a very large higgsino mass parameter. In absence of popular UV complete models, we treat the NH terms at par with MSSM soft terms, in a model independent framework of Minimal Effective Supersymmetry. The first part of the analysis involves the study of (g-2)_mu constraint along with the limits from Higgs mass, B-physics, collider data, direct detection of dark matter (DM), while focusing on a higgsino DM which is underabundant in nature. We then impose the constraint from electron g-2 where a large Yukawa threshold correction (an outcome of NHSSM) and opposite signs of trilinear NH coefficients associated with mu and e fields are used to satisfy the dual limits of Delta {a_mu } and Delta {a_e} (where the latter comes with negative sign). Varying Yukawa threshold corrections further provide the necessary flavor-dependent enhancement of Delta {a_e}/m_e^2 compared to that of Delta {a_mu }/m_mu ^2. A larger Yukawa threshold correction through A^prime _e for y_e also takes away the direct proportionality of a_e with respect to tan beta . With a finite intercept, a_e becomes only an increasing function of tan beta . We identified the available parameter space in the two cases while also satisfying the ATLAS data from slepton pair production searches in the plane of slepton mass parameter and the mass of the lightest neutralino.

A combined approach to the analysis of space and ground experimental data within a simplified E_6SSM

Within the Exceptional Supersymmetric Standard Model (E_6SSM), we investigate signatures at the Large Hadron Collider (LHC) for a long-lived charged inert higgsino, which is degenerate with the inert neutralino at tree level and a small mass splitting is generated at the loop level, resulting in a lifetime mathcal{O}(0.02) nanoseconds. We focus on the most sensitive search for long-lived charged inert higgsino decays to the lightest neutral inert higgsino dark matter and very soft charged leptons, which are eventually stopped in the detector resulting in a disappearing-track signal. Furthermore, we study the displaced vertex signature of the inert chargino in the case where it is produced via the Z^{prime } portal. We illustrate how difficult it is to construct displaced vertices in this class of models, though some evidence could be gained at the High Luminosity LHC. Finally, we compare the spin independent and spin dependent cross sections of the lightest inert higgsino DM to those of current direct detection experiments, proving that it is possible to gain sensitivity to the active DM component of this scenario in the near future. The combination of these signatures with the one emerging from Z' production and decay via Drell–Yan, which can be characterised as belonging to the E_6SSM via both the cross section and Forward–Backward Asymmetry, could point uniquely to this non-minimal realisation of Supersymmetry.

Discovery potential for split supersymmetry with thermal dark matter

Supersymmetric extensions of the Standard Model with scalar superpartners above 10 TeV are well motivated since the Higgs boson mass can be explained by quantum corrections while maintaining gauge coupling unification. If supersymmetry breaking is transmitted to gauginos via anomaly mediation, the gaugino masses are loop suppressed compared to scalar masses, and the lightest supersymmetric particle is the Higgsino or wino, which can be the dark matter. In this setup, we identify the regions of parameter space that reproduce the observed Higgs boson mass and the thermal abundance of dark matter. We analyze the effects of complex phases in the gaugino mass parameters on the electron electric dipole moment (EDM) and the dark matter scattering cross section. We find that, for scalar masses up to 10 PeV and any size of the complex phases, the model with Higgsino dark matter is within reach of planned experiments -- Advanced ACME via electron EDM and LUX-ZEPLIN via dark matter direct detection -- with complementary discovery potentials, and the model with wino dark matter is within reach of future electron EDM experiments.

(g−2)μ and SUSY

The persistent [Formula: see text] discrepancy between the experimental result from Brookhaven National Laboratory (BNL) for the anomalous magnetic moment of the muon, [Formula: see text], and its Standard Model (SM) prediction, was confirmed recently by the “MUON G-2” result from Fermilab. The combination of the two measurements yields a deviation of [Formula: see text] from the SM value. Here, we review an analysis of the parameter space of the electroweak (EW) sector of the Minimal Supersymmetric Standard Model (MSSM), which can provide a suitable explanation of the anomaly while being in full agreement with other latest experimental data like the direct searches for EW particles at the LHC and dark matter (DM) relic density and direct detection constraints. Taking the lightest supersymmetric particle (LSP) (the lightest neutralino in our case) to be the DM candidate, we discuss the case of a mixed bino/wino LSP, which can account for the full DM relic density of the universe and that of wino and higgsino DM, where we take the relic density only as an upper bound. We observe that an upper limit of [Formula: see text] can be obtained for the LSP and next-to (N)LSP masses establishing clear search targets for the future HL-LHC EW searches, but in particular for future high-energy [Formula: see text] colliders such as the ILC or CLIC.

Higgsino dark matter in pure gravity mediated supersymmetry

We consider the prospects for the direct detection of dark matter in pure gravity meditation (PGM) models of supersymmetry breaking. Minimal PGM models require only two parameters, the gravitino mass, $m_{3/2}$, which sets the UV mass for all scalar masses, and $\tan\beta$. Gaugino masses are generated through anomaly mediation. Typically the lightest supersymmetric state (the dark matter candidate) is a wino. Here, we consider a one-parameter extension of the minimal model by allowing the Higgs soft masses to deviate from universality. For simplicity, we take these to be equal and use the $\mu$-term as a surrogate. We also consider non-universal stop masses. When $|\mu| \sim 1$ TeV, the Higgsino is a viable dark matter candidate when the gravitino mass is of order $\sim 1$ PeV and $\tan\beta \simeq 2$. We calculate the spin-dependent and spin-independent cross sections for dark matter scattering on protons. For spin-independent scattering, existing experimental limits place constraints on the PGM parameter space. Much of the currently allowed parameter space lies above the irreducible neutrino background. Thus, future direct detection experiments will be able to probe much of the remaining PGM parameter space.

Deep learning jet images as a probe of light Higgsino dark matter at the LHC

A Higgsino in supersymmetric standard models can play the role of a dark matter particle. In conjunction with the naturalness criterion, the Higgsino mass parameter is expected to be around the electroweak scale. In this work, we explore the potential of probing the nearly degenerate light Higgsinos with machine learning at the LHC. By analyzing jet images and other jet substructure information, we use the convolutional neural network to enhance the signal significance. We find that our deep learning jet image method can improve the previous result based on the conventional cut flow by about a factor of 2 at the High-Luminosity LHC.

Rebalance and Smear for multi-jet background estimation

For particle collider searches for physics beyond the Standard Model in final states with jets and missing transverse momentum, events from QCD multi-jet processes are an important and challenging background contribution. The CMS and ATLAS experiments have previously developed data-driven methods designed to succeed where Monte Carlo methods suffer large theoretical and experimental uncertainties. One such method is Rebalance and Smear (R&S), which predicts QCD backgrounds by applying a series of folding and unfolding techniques to data control regions. A top-to-bottom description of the R&S method is presented, along with a discussion of its applicability and limitations. A software application is provided that performs the R&S method using public, non-proprietary tools, interfacing with data sets produced by Delphes3. In general, the method is suitable for predicting multi-jet backgrounds in searches for stable non-detectable particles, such as dark matter candidates. A case study is carried out in simulated events of proton-proton collisions at √s = 14 TeV in the context of a potential search for Higgsino dark matter produced in the decay products of supersymmetric quark partners. Sources of potential bias are explored and prescriptions for evaluating systematic uncertainties are suggested.

(g-2)_mu and SUSY dark matter: direct detection and collider search complementarity

The electroweak (EW) sector of the Minimal Supersymmetric Standard Model (MSSM) can account for a variety of experimental data. The EW particles with masses of a few hundred GeV evade the LHC searches owing to their small production cross sections. Such a light EW sector can in particular explain the reinforced 4.2,sigma discrepancy between the experimental result for the anomalous magnetic moment of the muon, (g-2)_mu , and its Standard Model (SM) prediction. The lightest supersymmetric particle (LSP), assumed to be the lightest neutralino, {tilde{chi }_{1}}^0, as a Dark Matter (DM) candidate is furthermore in agreement with the observed limits on the DM content of the universe. Here the Next-to LSP (NLSP) serves as a coannihilation partner and is naturally close in mass to the LSP. Such scenarios are also to a large extent in agreement with negative results from Direct Detection (DD) experiments. The DM relic density can fully be explained by a nearly pure bino or a mixed bino/wino LSP. Relatively light wino and higgsino DM, on the other hand, remains easily below the DM relic density upper bound. Using the improved limits on (g-2)_mu , we explore the mass ranges of the LSP and the NLSP in their correlation with the DM relic density for bino, bino/wino, wino and higgsino DM. In particular, we analyze the sensitivity of future DM DD experiments to these DM scenarios. We find that higgsino, wino and one type of bino scenario can be covered by future DD experiments. Mixed bino/wino and another type of bino DM can reach DD cross sections below the neutrino floor. In these cases we analyze the complementarity with the (HL-)LHC and future e^+e^- linear colliders. We find that while the prospects for the HL-LHC are interesting, but not conclusive, an e^+e^- collider with sqrt{s} lesssim 1 ,, mathrm {TeV} can cover effectively all points of the MSSM that may be missed by DD experiments.

Race to find split Higgsino dark matter

Split higgsinos are a compelling class of models to explain dark matter and may be on the verge of detection by multiple current experimental avenues. The idea is based on a large split in scales between the electroweak scale and decoupled scalars, with relatively light higgsinos between the two. Such models enjoy the merit of depending on very few parameters while still explaining gauge coupling unification, dark matter, and most of the hierarchy between the Planck and electroweak scales, and they remain undetected by past experiments. We analyze split higgsinos in view of current and next generation experiments. We discuss the direct and indirect detection prospects and further demonstrate promising discovery potentials in the upcoming electron electric dipole moment experiments. The parameter space of this model is analyzed in terms of experiments expected to run in the coming years and where we should be looking for the next potential discoveries.

Improved {(g-2)_mu } measurements and wino/higgsino dark matter

The electroweak (EW) sector of the Minimal Supersymmetric Standard Model (MSSM) can account for a variety of experimental data. In particular it can explain the persistent 3-4,sigma discrepancy between the experimental result for the anomalous magnetic moment of the muon, (g-2)_mu , and its Standard Model (SM) prediction. The lightest supersymmetric particle (LSP), which we take as the lightest neutralino, {tilde{chi }}_{1}^0, can furthermore account for the observed Dark Matter (DM) content of the universe via coannihilation with the next-to-LSP (NLSP), while being in agreement with negative results from Direct Detection (DD) experiments. Concerning the unsuccessful searches for EW particles at the LHC, owing to relatively small production cross-sections a comparably light EW sector of the MSSM is in full agreement with the experimental data. The DM relic density can fully be explained by a mixed bino/wino LSP. Here we take the relic density as an upper bound, which opens up the possibility of wino and higgsino DM. We first analyze which mass ranges of neutralinos, charginos and scalar leptons are in agreement with all experimental data, including relevant LHC searches. We find roughly an upper limit of sim 600 ,, mathrm {GeV} for the LSP and NLSP masses. In a second step we assume that the new result of the Run 1 of the “MUON G-2” collaboration at Fermilab yields a precision comparable to the existing experimental result with the same central value. We analyze the potential impact of the combination of the Run 1 data with the existing (g-2)_mu data on the allowed MSSM parameter space. We find that in this case the upper limits on the LSP and NLSP masses are substantially reduced by roughly 100 ,, mathrm {GeV}. We interpret these upper bounds in view of future HL-LHC EW searches as well as future high-energy e^+e^- colliders, such as the ILC or CLIC.

Resolving the (g \u2212 2)\u03bc discrepancy with mathcal{F} \u2013SU(5) intersecting D-branes

A discrepancy between the measured anomalous magnetic moment of the muon (g − 2)μ and computed Standard Model value now stands at a combined 4.2σ following experiments at Brookhaven National Lab (BNL) and the Fermi National Accelerator Laboratory (FNAL). A solution to the disagreement is uncovered in flipped SU(5) with additional TeV-Scale vector-like 10 + overline{mathbf{10}} multiplets and charged singlet derived from local F-Theory, collectively referred to as mathcal{F} –SU(5). Here we engage general No-Scale supersymmetry (SUSY) breaking in mathcal{F} –SU(5) D-brane model building to alleviate the (g −2)μ tension between the Standard Model and observations. A robust ∆aμ(SUSY) is realized via mixing of M5 and M1X at the secondary SU(5) × U(1)X unification scale in mathcal{F} –SU(5) emanating from SU(5) breaking and U(1)X flux effects. Calculations unveil ∆aμ(SUSY) = 19.0–22.3 × 10−10 for gluino masses of M( overset{sim }{g} )= 2.25–2.56 TeV and higgsino dark matter, aptly residing within the BNL+FNAL 1σ mean. This (g − 2)μ favorable region of the model space also generates the correct light Higgs boson mass and branching ratios of companion rare decay processes, and is further consistent with all LHC Run 2 constraints. Finally, we also examine the heavy SUSY Higgs boson in light of recent LHC searches for an extended Higgs sector.

Monophoton signals at e+e− colliders in a simplified E6SSM

The mono-photon signature emerging in an ${\mathrm{E}}_{6}$ supersymmetric standard model (${\mathrm{E}}_{6}\mathrm{SSM}$) from inert Higgsino dark matter (DM) is analyzed at future ${e}^{+}{e}^{\ensuremath{-}}$ colliders. As the inert neutral and charged Higgsinos are nearly degenerate, the inert chargino is a rather long lived particle and the charged particle associated with its decay to the inert Higgsino is quite soft. We show that the pair production of inert charginos at a 500 GeV electron-positron collider with an initial or final state photon is the most promising channel for probing the inert Higgsino as one DM candidate within the ${\mathrm{E}}_{6}\mathrm{SSM}$. We also emphasize that this signal has no chance of being observed at the Large Hadron Collider (LHC) with higher energy and/or luminosity. Finally, we remark that, combined with a DM signal produced in direct detection (DD) experiments involving an active Higgsino state as the second DM candidate, this dual evidence could point to a two-component DM version of the ${\mathrm{E}}_{6}\mathrm{SSM}$.

Hunting wino and higgsino dark matter at the muon collider with disappearing tracks

We study the capabilities of a muon collider experiment to detect disappearing tracks originating when a heavy and electrically charged long-lived particle decays via X+→ Y+Z0, where X+ and Z0 are two almost mass degenerate new states and Y+ is a charged Standard Model particle. The backgrounds induced by the in-flight decays of the muon beams (BIB) can create detector hit combinations that mimic long-lived particle signatures, making the search a daunting task. We design a simple strategy to tame the BIB, based on a detector-hit-level selection exploiting timing information and hit-to-hit correlations, followed by simple requirements on the quality of reconstructed tracks. Our strategy allows us to reduce the number of tracks from BIB to an average of 0.08 per event, hence being able to design a cut-and-count analysis that shows that it is possible to cover weak doublets and triplets with masses close to sqrt{s}/2 in the 0.1–10 ns range. In particular, this implies that a 10 TeV muon collider is able to probe thermal MSSM higgsinos and thermal MSSM winos, thus rivaling the FCC-hh in that respect, and further enlarging the physics program of the muon collider into the territory of WIMP dark matter and long-lived signatures. We also provide parton-to-reconstructed level efficiency maps, allowing an estimation of the coverage of disappearing tracks at muon colliders for arbitrary models.