The standard model (SM) plus a real gauge-singlet scalar field dubbed darkon (SM+D) is the simplest model possessing a weakly interacting massive particle (WIMP) dark-matter candidate. The upper limits for the WIMP-nucleon elastic cross-section as a function of WIMP mass from the recent XENON10 and CDMS-II experiments rule out darkon mass ranges from 10 to (50,70,75) GeV for Higgs-boson masses of (120,200,350) GeV, respectively. This may exclude the possibility of the darkon providing an explanation for the gamma-ray excess observed in the EGRET data. We show that by extending the SM+D to a two-Higgs-doublet model plus a darkon the experimental constraints on the WIMP-nucleon interactions can be circumvented due to suppression occurring at some values of the product tan(alpha)tan(beta), with alpha being the neutral-Higgs mixing angle and tan(beta) the ratio of vacuum expectation values of the Higgs doublets. We also comment on the implication of the darkon model for Higgs searches at the LHC.
In the extensive efforts to understand the nature of Dark Matter and searches at colliders, the LHCb experiment has a unique sensitivity to low mass Dark Matter candidates. These proceedings present recent results and prospects on Dark Matter searches with the LHCb experiment that achieve world-leading sensitivities.
This review discusses both experimental and theoretical aspects of searches for dark matter at the LHC. An overview of the various experimental search channels is given, followed by a summary of the different theoretical approaches for predicting dark matter signals. A special emphasis is placed on the interplay between LHC dark matter searches and other kinds of dark matter experiments, as well as among different types of LHC searches.
We present a summary of the current status of searches for dark matter at the LHC from the ATLAS and CMS experiments. For various assumptions in the simplified parameter space, the LHC exclusions is complementary to direct detection results. Mono-object analyses in search of dark matter and various analyses searching for dark matter mediators are presented.
The presence of a non-baryonic Dark Matter (DM) component in the Universe is inferred from the observation of its gravitational interaction. The ATLAS and CMS experiments located at the LHC have developed a broad search program for DM candidates, including resonance searches for the mediator and searches with large missing transverse momentum. Additionally, searches have been conducted in models where the Higgs Sector and the Dark Sector are connected leading for example to invisible Higgs boson decays. The results of recent searches on 13 TeV $pp$ data, their interplay and interpretation are …
Several new-physics (NP) models predict the existence of low-mass Higgs states and light dark matter candidates. Previous BABAR searches have given null results for these new states and have excluded large regions of the NP models parameter space. We report on new searches on light Higgs and light dark matter at BABAR using the 516 1/fb of data collected with the BABAR detector at the PEP-II asymmetric-energy e+e- collider at the SLAC National Accelerator Laboratory.
Direct detection experiments are gaining in mass reach. Here we show that the inclusion of dark Compton scattering, which has typically been neglected in absorption searches, has a substantial impact on the reach and discovery potential of direct detection experiments at high bosonic cold dark matter masses. We demonstrate this for relic dark photons and axion-like particles: we improve expected reach across materials, and further use results from SuperCDMS, EDELWEISS and GERDA to place enhanced limits on dark matter parameter space. We outline the implications for detector design and analysis…
Searches for dark matter at colliders typically involve signatures with energetic initial-state radiation without visible recoil particles. Searches for mono-jet or mono-photon signatures have yielded powerful constraints on dark matter interactions with Standard Model particles. We extend this to the mono-Z signature and reinterpret an ATLAS analysis of events with a Z boson and missing transverse momentum to derive constraints on dark matter interaction mass scale and nucleon cross sections in the context of effective field theories describing dark matter which interacts via heavy mediator p…
Dark matter is the name assigned to one of the most important contemporary challenges that fundamental physics research is facing. In recent years, the hypothesis that dark matter might be "light" is gaining interest. Following this idea, dark matter particles belong to a new, unexplored dark sector, that is communicating with the Standard Model through one (or more) dark mediator particles. The mass scale of such dark sector particles, i.e. the mediators and the stable dark matter particles, could be comparable to the proton mass or below. Light dark matter would be very difficult to detect w…
The searches for new particles that could be constituents of the dark matter in the universe are an essential part of the physics program of the experiments at the Large Hadron Collider. An overview of recent dark matter candidate searches is presented with a focus on new results obtained by the ATLAS and CMS experiments from the analysis of the proton-proton collision data at 13 TeV center-of-mass energy collected in the first part of Run 2.
Direct searches of dark matter are performed at accelerator facilities. The existence of a new vector boson has been postulated in different scenarios where in the most basic scheme the coupling to the SM can be achieved via a kinetic mixing term due to the U boson. The KLOE experiment at DA$ϕ$NE searched for the U boson both in Dalitz decays of the $ϕ$ meson and in continuum events. For all of these searches an upper limit for the U boson coupling $ε^{2}$ has been established in the mass range $50 \, \text{MeV} < m_U < 1000\,\text{MeV}$. A summary of the different models and searches along wi…
We review the limitations to the use of the effective field theory approach to study dark matter at the LHC. Due to the high energy reach, the low energy description breaks down, and may lead to incorrect results. The use of simplified models is suggested.
Plots summarizing the constraints on Dark Matter models can help visualize synergies between different searches for the same kind of experiment, as well as between different experiments. In this whitepaper, we present an update to the European Strategy Briefing Book plots, from the perspective of collider searches within the Dark Matter at the Energy Frontier (EF10) Snowmass Topical Group, starting from inputs from future collider facilities. We take as a starting point the plots currently made for LHC searches using benchmark models recommended by the Dark Matter Working Group, also used for …
We present projections for future collider searches for dark matter produced in association with bottom or top quarks. Such production channels give rise to final states with missing transverse energy and one or more b-jets. Limits are given assuming an effective scalar operator coupling dark matter to quarks, where the dedicated analysis discussed here improves significantly over a generic monojet analysis. We give updated results for an anticipated high-luminosity LHC run at 14 TeV and for a 33 TeV hadron collider.
Searches for dark photons provide serendipitous discovery potential for other types of vector particles. We develop a framework for recasting dark photon searches to obtain constraints on more general theories, which includes a data-driven method for determining hadronic decay rates. We demonstrate our approach by deriving constraints on a vector that couples to the $B\!-\!L$ current, a leptophobic $B$ boson that couples directly to baryon number and to leptons via $B$-$γ$ kinetic mixing, and on a vector that mediates a protophobic force. Our approach can easily be generalized to any massive g…
In these proceedings we review the interplay between LHC searches for dark matter and direct detection experiments. For this purpose we consider two prime examples: the effective field theory (EFT) approach and the minimal supersymmetric standard model (MSSM). In the EFT scenario we show that for operators which do not enter directly direct detection at tree-level, but only via loop effects, LHC searches give complementary constraints. In the MSSM stop and Higgs exchange contribute to the direct detection amplitude. Therefore, LHC searches for supersymmetric particles and heavy Higgses place c…
Current searches for dark matter at the LHC focus on mono-X signatures: the production of dark matter in association with a Standard Model (SM) particle. The simplest benchmark introduces a massive spin-1 mediator, the $Z^\prime$ boson, between the dark matter $χ$ and the SM. Limits derived from mono-X channels are most effective when the mediator can decay into two on-shell dark matter particles: $M_{Z'}\gtrsim 2M_χ$. We broaden the experimental reach into the complementary region, where the $Z^\prime$ mediator is much lighter than the dark matter. In this scenario the $Z^\prime$ mediates an …
A glimpse into the most recent searches for Dark Matter at the LHC performed by the ATLAS and CMS collaborations is presented. The results covered in this document are all based on Run-2 proton-proton collision data recorded at $\sqrt{s}=13\text{ TeV}$ and corresponding to an integrated luminosity of just under 140 $\text{fb}^{-1}$
In this review we discuss and compare the usage of simplified models and Effective Field Theory (EFT) approaches in dark matter searches. We provide a state of the art description on the subject of EFTs and simplified models, especially in the context of collider searches for dark matter, but also with implications for direct and indirect detection searches, with the aim of constituting a common language for future comparisons between different strategies. The material is presented in a form that is as self-contained as possible, so that it may serve as an introductory review for the newcomer …
We point out that two models that reconcile the neutron lifetime anomaly via dark decays of the neutron, also predict dark matter-neutron ($\barχ-n$) annihilation that may be observable in neutron-antineutron oscillation and proton decay searches at Super-Kamiokande, Hyper-Kamiokande and DUNE. We study signatures of $\barχn\to γπ^0$ (or multi-$π^0$) and $\barχn\to ϕγπ^0$ (or $ϕ+$multi-$π^0$), where $ϕ$ is an almost massless boson in one of the two models.
Recent results from the Tevatron are reported on Higgs boson searches in models beyond the standard model (SM). The models include fermiophobic Higgs bosons, the extension of the SM to a fourth generation of fermions, supersymmetric scenarios and heavy Higgs boson cascade decays.
Colliders, among the most successful tools of particle physics, have revealed much about matter. This review describes how colliders contribute to the search for particle dark matter, focusing on the highest-energy collider currently in operation, the Large Hadron Collider (LHC) at CERN. In the absence of hints about the character of interactions between dark matter and standard matter, this review emphasizes what could be observed in the near future, presents the main experimental challenges, and discusses how collider searches fit into the broader field of dark matter searches. Finally, it h…
If only tree-level processes are included in the analysis, LHC monojet searches give weak constraints on the dark matter-proton scattering cross section arising from the exchange of a new heavy scalar or pseudoscalar mediator with Yukawa-like couplings to quarks. In this letter we calculate the constraints on these interactions from the CMS 5.0/fb and ATLAS 4.7/fb searches for jets with missing energy including the effects of heavy-quark loops. We find that the inclusion of such contributions leads to a dramatic increase in the predicted cross section and therefore a significant improvement of…
In the past few years, the interest to collider searches for direct dark matter (DM) production has been growing exponentially. A variety of "Mono-X" signatures have been considered, where X stands for a probe particle recoiling against DM particles, which allows for the event to be triggerable. So far, the analysis of these signatures has been largely carried out in the framework of effective field theory (EFT), which allows for a comparison of the collider searches with searches in direct detection experiments. Unfortunately, as it has been recently pointed out by a number of authors, the EF…
We explore the possibility of having a fermionic dark matter candidate within $U(1)'$ models for CE$ν$NS experiments in light of the latest COHERENT data and the current and future dark matter direct detection experiments. A vector-like fermionic dark matter has been introduced which is charged under $U(1)'$ symmetry, naturally stable after spontaneous symmetry breaking. We perform a complementary investigation using CE$ν$NS experiments and dark matter direct detection searches to explore dark matter as well as $Z^{\prime}$ boson parameter space. Depending on numerous other constraints arising…
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 supersymmetric 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…
Large panels of etched plastic, situated aboard the Skylab Space Station and inside the Ohya quarry near Tokyo, have been used to set limits on fluxes of cosmogenic particles. These plastic particle track detectors also provide the best sensitivity for some heavy dark matter that interacts strongly with nuclei. We revisit prior dark matter bounds from Skylab, and incorporate geometry-dependent thresholds, a halo velocity distribution, and a complete accounting of observed through-going particle fluxes. These considerations reduce the Skylab bound's mass range by a few orders of magnitude. Howe…
The ATLAS collaboration has recently reported a 2.6 sigma excess in the search for a heavy resonance decaying into a pair of weak gauge bosons. Only fully hadronic final states are being looked for in the analysis. If the observed excess really originates from the gauge bosons' decays, other decay modes of the gauge bosons would inevitably leave a trace on other exotic searches. In this paper, we propose the use of the Z boson decay into a pair of neutrinos to test the excess. This decay leads to a very large missing energy and can be probed with conventional dark matter searches at the LHC. W…
We study the implications of LHC searches on SUSY particle spectra using flat scans of the 19-parameter pMSSM phase space. We apply constraints from flavour physics, g_mu-2, dark matter and earlier LEP and Tevatron searches. The sensitivity of the LHC SUSY searches with jets, leptons and missing energy is assessed by reproducing with fast simulation the recent CMS analyses after validation on benchmark points. We present results in terms of the fraction of pMSSM points compatible with all the constraints which are excluded by the LHC searches with 1 fb^{-1} and 15 fb^{-1} as a function of the …
Very Heavy and Composite Dark Matter: Theory and Experimental Searches
Arthur B. McDonald Canadian Astroparticle Physics Research Institute（阿瑟·B·麦克唐纳加拿大高能粒子物理研究所）；Queen’s University（女王大学）；Perimeter Institute for Theoretical Physics（基础物理前沿研究所）
We present results from several searches for various exotic physics phenomena like large extra dimensions, leptoquarks, and dark matter, in proton-proton collisions at $\sqrt{s}$ = 7 and 8 TeV delivered by the LHC and collected with the CMS detector. Many different final states are analyzed using data collected in 2011 and 2012 corresponding to an integrated luminosity up to 5.0 fb$^{-1}$ and 19.7 fb$^{-1}$. No sign of physics beyond the standard model has been observed so far and the results are used to set new limits on various new physics model parameters.
We analyze the potential dark matter implications of LHC events with missing transverse momentum and a resonance, such as a Z', decaying to a pair of jets or leptons. This final state contains significant discovery potential, but has not yet been examined in detail by the LHC experiments. We introduce models of Z' production in association with dark matter particles, propose reconstruction and selection strategies, and estimate the sensitivity of the current LHC dataset.
Dark matter remains one of the most puzzling mysteries in Fundamental Physics of our times. Experiments at high-energy physics colliders are expected to shed light to its nature and determine its properties. This review talk focuses on recent searches for dark-matter signatures at the Large Hadron Collider, either within specific theoretical scenarios, such as supersymmetry, or in a model-independent scheme looking for mono-X events arising in WIMP-pair production.
We analyse a combination of ATLAS and CMS searches for dijet resonances at run I and run II, presenting the results in a way that can be easily applied to a generic Z' model. As an illustrative example, we consider a simple model of a Z' coupling to quarks and dark matter. We first study a benchmark case with fixed couplings and then focus on the assumption that the Z' is responsible for setting the dark matter relic abundance. Dijet constraints place significant bounds on this scenario, allowing us to narrow down the allowed range of dark matter masses for given Z' mass and width.
Collider signatures with top quarks provide sensitive probes of dark matter (DM) production at the Large Hadron Collider (LHC). In this article, we review the results of DM searches in final states with top quarks conducted by the ATLAS and CMS Collaborations at the LHC, including the most recent results on the full LHC Run 2 dataset. We highlight the complementarity of DM searches in final states with top quarks with searches in other final states in the framework of various simplified models of DM. A re-interpretation of a DM search with top quarks in the context of an effective-field theory…
We propose a new approach to the LHC dark matter search analysis within the effective field theory (EFT) framework by utilising the K-matrix unitarisation formalism. This approach provides a reasonable estimate of the dark matter production cross section at high energies, and hence allows reliable bounds to be placed on the cut-off scale of relevant operators without running into the problem of perturbative unitarity violation. We exemplify this procedure for the effective operator D5 in monojet dark matter searches in the collinear approximation. We compare our bounds to those obtained using …
In this paper we study the possible searches at colliders using Vector Boson Fusion topology in the context of Simplified Models signatures. We examine the possible physics reach of these searches with regard to monojet-type searches, and determine how these two signatures are complementary.
In the past few years there has been a great deal of theoretical and experimental activity related to the search for low-mass scalars, pseudoscalars, and vectors in various scenarios of physics beyond the standard model. I review the current status of this topic, focusing on results obtained since FPCP 2014.
Two equations for the calculation of the critical energy required for homogeneous nucleation in a superheated liquid, and the related critical radius of the nucleated vapour bubble, are obtained, the former by the direct application of the first law of thermodynamics, the latter by considering that the bubble formation implies the overcoming of a barrier of the free enthalpy potential. Comparisons with the currently used relationships demonstrate that the sensitivity of the bubble chambers employed in dark matter searches can be sometimes notably overestimated.
We discuss the limitations to the use of the effective field theory approach to study dark matter at the LHC. We introduce and study a few quantities, some of them independent of the ultraviolet completion of the dark matter theory, which quantify the error made when using effective operators to describe processes with very high momentum transfer. Our criteria indicate up to what cutoff energy scale, and with what precision, the effective description is valid, depending on the dark matter mass and couplings.
Despite the fact that dark matter constitutes one of the cornerstones of the standard cosmological paradigm, its existence has so far only been inferred from astronomical observations and its microscopic nature remains elusive. Theoretical arguments suggest that dark matter might be connected to the symmetry-breaking mechanism of the electroweak interactions or of other symmetries extending the Standard Model of particle physics. The resulting Higgs bosons, including the $125 \, {\rm GeV}$ spin-0 particle discovered recently at the Large Hadron Collider therefore represent a unique tool to sea…
The MicroBooNE neutrino experiment at Fermilab is constructing a liquid-argon time-projection chamber for the Booster Neutrino Beam to study neutrino oscillations and interactions with nucleons and nuclei, starting in 2014. We describe the experiment and focus on its unique abilities to measure cross sections at low values of $Q^2$. In particular, the neutral-current elastic scattering cross section is especially interesting, as it is sensitive to the contribution of the strange sea quark spin to the angular-momentum of the nucleon, $Δs$. Implications for dark-matter searches are discussed.
Light cold dark matter consisting of weakly interacting slim (or sub-eV) particles (WISPs) has been in the focus of a large number of studies made over the past two decades. The QCD axion and axion-like particles with masses in the $0.1\,μ$eV--$100\,$meV are strong candidates for the dark matter particle, together with hidden photons with masses below $\lesssim 100\,$meV. This motivates several new initiatives in the field, including the WISP Dark Matter eXperiment (WISPDMX) and novel conceptual approaches for broad-band WISP searches using radiometry measurements in large volume chambers. Fir…
Dark matter is one of the biggest open questions in physics today. It is known that it interacts gravitationally with luminous matter, so accelerometer-based searches are inherently interesting. In this article we present recent (and future) searches for dark matter candidates such as feebly interacting matter trapped inside the Earth, scalar-matter domain walls and axion quark nuggets, with accelerometer networks and give an outlook of how new atomic-interferometry-based accelerometer networks could support dark matter searches.
Dark matter may consist of light, very weakly interacting bosons, produced non-thermally in the early Universe. Prominent examples of such very weakly interacting slim particles (WISPs) are axions and hidden photons. Direct detection experiments for such particles are based on the conversion of these particles into photons. This can be done in resonant cavities, featuring a resonant enhancement, or by using suitably shaped reflecting surfaces that allow for broadband searches. In this note we want to elucidate the relation between the two setups and study the transition from resonant to broadb…
We present a novel study of the non-abelian vector dark matter candidate $W^\prime$ with a MeV$-$GeV low mass range, accompanied by a dark photon $A^\prime$ and a dark $Z^\prime$ of similar masses in the context of a simplified gauged two-Higgs-doublet model. The model is scrutinized by taking into account various experimental constraints including dark photon searches, electroweak precision data, relic density of dark matter together with its direct and indirect searches, mono-jet and Higgs collider physics from LHC. The viable parameter space of the model consistent with all experimental and…
