Electroweak supersymmetry around the electroweak scale

WIMP dark matter and supersymmetry searches with neutrino telescopes

Gauge coupling unification and the success of TeV-scale weakly interacting dark matter are usually taken as evidence of low energy supersymmetry (SUSY). However, if we assume that the tuning of the higgs can be explained in some unnatural way, from environmental considerations for example, SUSY is no longer a necessary component of any Beyond the Standard Model theory. In this paper we study the minimal model with a dark matter candidate and gauge coupling unification. This consists of the SM plus fermions with the quantum numbers of SUSY higgsinos, and a singlet. It predicts thermal dark matter with a mass that can range from 100 GeV to around 2 TeV and generically gives rise to an electric dipole moment that is just beyond current experimental limits, with a large portion of its allowed parameter space accessible to next generation EDM and direct detection experiments. We study precision unification in this model by embedding it in a 5-D orbifold GUT where certain large threshold corrections are calculable, achieving gauge coupling and b-tau unification, and predicting a rate of proton decay just beyond current limits.

We introduce a Minimal Simplified Dark Matter (MSDM) framework to quantitatively characterise dark matter (DM) searches at the LHC. We study two MSDM models where the DM is a Dirac fermion which interacts with a vector and axial-vector mediator. The models are characterised by four parameters: m DM , M med , g DM and g q, the DM and mediator masses, and the mediator couplings to DM and quarks respectively. The MSDM models accurately capture the full event kinematics, and the dependence on all masses and couplings can be systematically studied. The interpretation of mono-jet searches in this framework can be used to establish an equal-footing comparison with direct detection experiments. For theories with a vector mediator, LHC mono-jet searches possess better sensitivity than direct detection searches for light DM masses (≲5 GeV). For axial-vector mediators, LHC and direct detection searches generally probe orthogonal directions in the parameter space. We explore the projected limits of these searches from the ultimate reach of the LHC and multi-ton xenon direct detection experiments, and find that the complementarity of the searches remains. Finally, we provide a comparison of limits in the MSDM and effective field theory (EFT) frameworks to highlight the deficiencies of the EFT framework, particularly when exploring the complementarity of mono-jet and direct detection searches.

The search for dark matter at accelerators has gained a lot of attention in recent years. Among the theoretical scenarios that can be studied, an attractive one is postulating a new $U_D(1)$ gauge symmetry mediated by a massive boson often named dark photon $A'$. The $A'$ could be the bridge between the Standard Model (SM) and a hypothetical Dark Sector (DM), having a small coupling $\epsilon$ with SM particles. PADME (Positron Annihilation to Dark Matter Experiment) is the first fixed target experiment searching for the $A'$ produced in association with a photon in $e^+e^-$ annihilations. It exploits the missing mass technique and does not make any assumption on the decay mode of the $A'$. PADME is located at the Laboratori Nazionali di Frascati (LNF) of INFN and it is designed to be sensitive to the production of a dark photon with mass $M_{A'} \le 23.7 \ \rm{MeV}$. Its setup is also ideal to investigate other scenarios of low mass dark matter: axion-like particles (ALPs), dark Higgs, and the $X_{17}$ boson claimed to explain anomalies observed recently in a nuclear physics experiment.

Models of natural supersymmetry seek to solve the little hierarchy problem by positing a spectrum of light higgsinos \lesssim 200 GeV and light top squarks \lesssim 500 GeV along with very heavy squarks and TeV-scale gluinos. Such models have low electroweak finetuning and are safe from LHC searches. However, in the context of the MSSM, they predict too low a value of m(h) and the relic density of thermally produced higgsino-like WIMPs falls well below dark matter (DM) measurements. Allowing for high scale soft SUSY breaking Higgs mass m_{H_u}> m_0 leads to natural cancellations during RG running, and to radiatively induced low finetuning at the electroweak scale. This model of radiative natural SUSY (RNS), with large mixing in the top squark sector, allows for finetuning at the 5-10% level with TeV-scale top squarks and a 125 GeV light Higgs scalar h. If the strong CP problem is solved via the PQ mechanism, then we expect an axion-higgsino admixture of dark matter, where either or both the DM particles might be directly detected.

It was shown recently that mirror fermions, naturally present in a number of directions for new physics, seem to require an inert scalar doublet in order to pass the electroweak precision tests. This provides a further motivation for considering the inert doublet as a dark matter candidate. Moreover, the presence of extra families enhances the standard model Higgs-nucleon coupling, which has crucial impact on the Higgs and dark matter searches. We study the limits on the inert dark matter mass in view of recent Xenon100 data. We find that the mass of the inert dark matter must lie in a very narrow window $75\ifmmode\pm\else\textpm\fi{}1\text{ }\text{ }\mathrm{GeV}$ while the Higgs boson must weigh more than 400 GeV. For the sake of completeness we discuss the cases with fewer extra families, where the possibility of a light Higgs boson opens up, enlarging the dark matter mass window to $\frac{1}{2}{m}_{h}\mathrm{\text{\ensuremath{-}}}76\text{ }\text{ }\mathrm{GeV}$. We find that Xenon100 constrains the DM-Higgs interaction, which in turn implies a lower bound on the monochromatic gamma ray flux from DM annihilation in the galactic halo. For the mirror case, the predicted annihilation cross section lies a factor of 4--5 below the current limit set by Fermi LAT, thus providing a promising indirect detection signal.

A search for dark matter in events with a displaced nonresonant muon pair and missing transverse momentum is presented. The analysis is performed using an integrated luminosity of 138 fb−1 of proton-proton (pp) collision data at a center-of-mass energy of 13 TeV produced by the LHC in 2016–2018. No significant excess over the predicted backgrounds is observed. Upper limits are set on the product of the inelastic dark matter production cross section σ(pp→A′→χ1χ2) and the decay branching fraction B(χ2→χ1μ+μ−), where A′ is a dark photon and χ1 and χ2 are states in the dark sector with near mass degeneracy. This is the first dedicated collider search for inelastic dark matter. © 2024 CERN, for the CMS Collaboration 2024 CERN

In this work, we study multicomponent dark sectors comprised of a fermionic and a scalar dark matter candidate. In the scalar sector, we mostly focus on the Inert Doublet Model while in the fermionic sector we study three different models. For all of them, we investigate the impact that dark matter conversion and regular WIMP dark matter annihilating processes have on the relic abundance. We mostly recover the region between the electroweak scale and ∼ 550 GeV for the scalar dark matter mass, which is usually excluded in the Inert Doublet Model. We also consider current constraints from both direct detection and indirect detection experiments and include future prospects to probe the models. Additionally, we investigate constraints from collider searches on the fermionic dark matter candidates.

We investigate dwarf irregular(dIrr) galaxies as a new category of targets for indirect Dark Matter(DM) searches with gamma-rays. In the framework of point-like analysis, dwarf spheroidal(dSph) galaxies are usually considered as one of the best category of targets for indirect DM searches. Nonetheless, as a result of their uncertain kinematics, the DM content and astrophysical J-factors of dSphs are usually affected by significant errors. In this paper, we study a sample of 36 dIrrs as prospective targets of interest. In the framework of the universal rotation curve, the kinematics of dIrr galaxies provides a good estimation of their DM halo density distribution and, consequently, of their astrophysical J-factors. We calculate the J-factors for these 36 dIrr galaxies. We find a range of values comparable with the J-factors of dSph galaxies. However, differently from dSphs an extra astrophysical gamma-ray background component is expected in dIrrs, that is due to their star-formation activity. In this paper, we show via a theoretical approach that for galaxies in our sample the extra astrophysical background component is negligible. Therefore, we conclude that dIrr galaxies can be potentially considered as additional point-like targets for DM searches with gamma-rays. As a first application of this study, we show the sensitivity limits of the Fermi-LAT telescope to these objects and we calculate constraints on the DM particle mass and annihilation cross-section. We conclude that the results of the individual study of several dIrr galaxies are not yet competitive with respect to the analysis of one of the most promising dSph galaxies, ie SEGUE1. However, taking into account SEGUE1's symmetry-related uncertainties in the J-factor calculation might alter this conclusion. Additionally, we calculate constraints for the combined analysis of the 7 most promising dIrr galaxies of our sample.

Recent developments in string theory have led to ``realistic string compactifications which lead to moduli stabilization while generating a hierarchy between the Electroweak and Planck scales at the same time. However, this seems to suggest a rethink of our standard notions of cosmological evolution after the end of inflation and before the beginning of BBN. This epoch is crucial for addressing the issues of neutrino masses, baryon asymmetry, Dark Matter (DM) abundance and the moduli (gravitino) problem. We argue that within classes of realistic string compactifications as defined above, there generically exists a light modulus with a mass comparable to that of the gravitino which is typically much smaller than the Hubble parameter during inflation. Therefore, it is destabilized and generates a large late-time entropy when it decays. Thus, all known elegant mechanisms of generating the baryon asymmetry of the Universe in the literature have to take this fact into account. In this work, we find that it is still possible to naturally generate the observed baryon asymmetry of the Universe as well as light left-handed neutrino masses from a period of Affleck-Dine (AD) leptogenesis shortly after the end of inflation, in classes of realistic string constructions with a minimal extension of the MSSM below the unification scale (consisting only of right-handed neutrinos) and satisfying certain microscopic criteria described in the text. The AD mechanism has already been used to generate the baryon asymmetry in the literature; however in this work we have embedded the above mechanism within a framework well motivated from string theory and have tried to describe the epoch from the end of inflation to the beginning of BBN in a complete and self-consistent manner. The consequences of our analysis are as follows. The lightest left-handed neutrino is required to be virtually massless. The moduli (gravitino) problem can be naturally solved in this framework both within gravity and gauge mediation. The observed upper bound on the relic abundance constrains the moduli-matter and moduli-gravitino couplings since the DM is produced non-thermally within this framework. Finally, although not a definite prediction, the framework naturally allows a light right-handed neutrino and sneutrinos around the electroweak scale which could have important implications for the nature of DM as well as the LHC.

Axion-like particles (ALPs) arise from well-motivated extensions to the Standard Model and could account for dark matter. ALP dark matter would manifest as a field oscillating at an (as of yet) unknown frequency. The frequency depends linearly on the ALP mass and plausibly ranges from 10−22 to 10 eV/c2. This motivates broadband search approaches. We report on a direct search for ALP dark matter with an interferometer composed of two atomic K-Rb-3He comagnetometers, one situated in Mainz, Germany, and the other in Kraków, Poland. We leverage the anticipated spatio-temporal coherence properties of the ALP field and probe all ALP-gradient-spin interactions covering a mass range of nine orders of magnitude. No significant evidence of an ALP signal is found. We thus place new upper limits on the ALP-neutron, ALP-proton and ALP-electron couplings reaching below gaNN < 10−9 GeV−1, gaPP < 10−7 GeV−1 and gaee < 10−6 GeV−1, respectively. These limits improve upon previous laboratory constraints for neutron and proton couplings by up to three orders of magnitude.

The U(1) extended supersymmetric standard model (UMSSM) can accommodate a Higgs boson at 125 GeV without relying on large corrections from the top/stop sector. After imposing LHC results on the Higgs sector, on B-physics and on new particle searches as well as dark matter constraints, we show that this model offers two viable dark matter candidates, the right-handed (RH) sneutrino or the neutralino. Limits on super-symmetric partners from LHC simplified model searches are imposed using SModelS and allow for light squarks and gluinos. Moreover the upper limit on the relic abundance often favours scenarios with long-lived particles. Searches for a Z ′ at the LHC remain the most unambiguous probes of this model. Interestingly, the D-term contributions to the sfermion masses allow to explain the anomalous magnetic moment of the muon in specific corners of the parameter space with light smuons or left-handed (LH) sneutrinos. We finally emphasize the interplay between direct searches for dark matter and LHC simplified model searches.

The mechanism behind electroweak symmetry breaking (EWSB) and the nature of dark matter (DM) are currently very important issues in particle physics. Usually, in most models, these two issues are not or poorly connected. However, since a natural dark matter candidate is a weakly interacting massive particle or WIMP, with mass around the electroweak scale, it is clearly of interest to investigate the possibility that DM and EWSB are closely related. In the context of a very simple extension of the Standard Model, the Inert Doublet Model, we show that dark matter could play a crucial role in the breaking of the electroweak symmetry. In this model, dark matter is the lightest component of an inert scalar doublet which can induce dynamically electroweak symmetry breaking at one loop level. Moreover, in a large fraction of the parameter space of this model, the mass of the dark matter particle is essentially determined by the electroweak scale, so that the fact that the WIMP DM mass is around the electroweak scale is not a coincidence.

The search for dark matter has been ongoing for decades within both astrophysics and particle physics. Both fields have employed different approaches and conceived a variety of methods for constraining the properties of dark matter, but have done so in relative isolation of one another. From an astronomer's perspective, it can be challenging to interpret the results of dark matter particle physics experiments and how these results apply to astrophysical scales. Over the past few years, the ESCAPE Dark Matter Test Science Project has been developing tools to aid the particle physics community in constraining dark matter properties; however, ESCAPE itself also aims to foster collaborations between research disciplines. This is especially important in the search for dark matter, as while particle physics is concerned with detecting the particles themselves, all of the evidence for its existence lies solely within astrophysics and cosmology. Here, we present a short review of the progress made by the Dark Matter Test Science Project and their applications to existing experiments, with a view towards how this project can foster complementary with astrophysical observations.

Dark matter production in the early Universe: Beyond the thermal WIMP paradigm