Model independent analysis of interactions between dark matter and various quarks (original) (raw)
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Closing in on asymmetric dark matter I: model independent limits for interactions with quarks
Journal of High Energy Physics, 2012
It is argued that experimental constraints on theories of asymmetric dark matter (ADM) almost certainly require that the DM be part of a richer hidden sector of interacting states of comparable mass or lighter. A general requisite of models of ADM is that the vast majority of the symmetric component of the DM number density must be removed in order to explain the observed relationship Ω B ≈ 5Ω DM via the DM asymmetry. Demanding the efficient annihilation of the symmetric component leads to a tension with experimental limits if the annihilation is directly to Standard Model (SM) degrees of freedom. A comprehensive effective operator analysis of the model independent constraints on ADM from direct detection experiments and LHC monojet searches is presented. Notably, the limits obtained essentially exclude models of ADM with mass 1 GeV m DM 100 GeV annihilating to SM quarks via heavy mediator states. This motivates the study of portal interactions between the dark and SM sectors mediated by light states. Resonances and threshold effects involving the new light states are shown to be important for determining the exclusion limits.
Probing dark matter couplings to top and bottom quarks at the LHC
Physical Review D, 2013
Monojet searches are a powerful way to place model-independent constraints on effective operators coupling dark matter to the standard model. For operators generated by the exchange of a scalar mediator, however, couplings to light quarks are suppressed and the prospect of probing such interactions through the inclusive monojet channel at the LHC is limited. We propose dedicated searches, focusing on bottom and top quark final states, to constrain this class of operators. We show that a search in mono b-jets can significantly improve current limits. The mono-b signal arises partly from direct production of b-quarks in association with dark matter, but the dominant component is from top quark pair production in the kinematic regime where one top is boosted. A search for tops plus missing energy can strengthen the bounds even more; in this case signal and background have very different missing energy distributions. We find an overall improvement by several orders of magnitude in the bound on the direct detection cross section for scalar or pseudoscalar couplings.
2021
We consider the possibility that dark matter (DM) only interacts with the Standard Model leptons, but not quarks at tree-level, and analyze the future lepton collider prospects of such leptophilic DM in the mono-photon and mono-Z (both leptonic and hadronic) channels. Adopting a model-independent effective field theory framework, we consider all possible dimension-6 operators of scalar-pseudoscalar (S-P), vector-axialvector (V-A) and tensor-axialtensor (T-AT) types for a fermionic DM and derive the collider sensitivities on the effective cut-off scale Λ as a function of the DM mass. As a concrete example, we take the beam configurations of the International Linear Collider with √ s = 1 TeV and 1000 fb−1 integrated luminosity, including the effect of beam polarization, and show that it can probe leptophilic DM at 3σ level up to Λ values of 4.8 TeV, 6.5 TeV and 5.3 TeV for the S-P, V-A and T-AT type operators respectively. This is largely complementary to the direct and indirect searc...
Constraining dark sectors at colliders: Beyond the effective theory approach
Physical Review D, 2015
We outline and investigate a set of benchmark simplified models with the aim of providing a minimal simple framework for an interpretation of the existing and forthcoming searches of dark matter particles at the LHC. The simplified models we consider provide microscopic QFT descriptions of interactions between the Standard Model partons and the dark sector particles mediated by the four basic types of messenger fields: scalar, pseudo-scalar, vector or axial-vector. Our benchmark models are characterised by four to five parameters, including the mediator mass and width, the dark matter mass and an effective coupling(s). In the gluon fusion production channel we resolve the top-quark in the loop and compute full top-mass effects for scalar and pseudo-scalar messengers. We show the LHC limits and reach at 8 and 14 TeV for models with all four messenger types. We also outline the complementarity of direct detection, indirect detection and LHC bounds for dark matter searches. Finally, we investigate the effects which arise from extending the simplified model to include potential new physics contributions in production. Using the scalar mediator as an example we study the impact of heavy new physics loops which interfere with the top mediated loops. Our computations are performed within the MCFM framework and we provide fully flexible public Monte Carlo implementation. arXiv:1411.0535v2 [hep-ph] 5 Feb 2015 2 the recent Higgs discovery and assumes that the coupling strength of the new scalars to Standard Model fermions is proportional to their SM Yukawa couplings.
Limiting heavy-quark and gluonphilic real dark matter
Physical Review D
We investigate the phenomenological viability of real spin half, zero and one dark matter candidates, which interact predominantly with third generation heavy quarks and gluons via the twentyeight gauge invariant higher dimensional effective operators. The corresponding Wilson coefficients are constrained one at a time from the relic density Ω DM h 2 ≈ 0.1198. Their contributions to the thermal averaged annihilation cross-sections are shown to be consistent with the FermiLAT and H.E.S.S. experiments' projected upper bound on the annihilation cross-section in the bb mode. The tree-level gluon-philic and one-loop induced heavy-quark-philic DM-nucleon direct-detection cross-sections are analysed. The non-observation of any excess over expected background in the case of recoiled Xe-nucleus events for spin-independent DM-nucleus scattering in XENON-1T sets the upper limits on the eighteen Wilson coefficients. Our analysis validates the real DM candidates for the large range of accessible mass spectrum below 2 TeV for all but one interaction induced by the said operators.
Brazilian Journal of Physics, 2016
We propose a mirror model for ordinary and dark matter that assumes a new SU(3) gauge group of transformations, as a natural extension of the Standard Model (SM). A close study of big bang nucleosynthesis, baryon asymmetries, cosmic microwave background bounds, galaxy dynamics, together with the Standard Model assumptions, help us to set a limit on the mass and width of the new gauge boson. The cross section for the elastic scattering of a dark proton by an ordinary proton is estimated and compare to the WIMP-nucleon experimental upper bounds. It is observed that all experimental bounds for the various cross sections can be accommodated consistently within the gauge model. We also suggest a way for direct detection of the new gauge boson via one example of a SM forbidden process: e + + p → µ + + X, where X = Λ or Λc.
Mono-Wdark matter signals at the LHC: simplified model analysis
Journal of Cosmology and Astroparticle Physics, 2016
We study mono-W signals of dark matter (DM) production at the LHC, in the context of gauge invariant renormalizable models. We analyze two simplified models, one involving an s-channel Z mediator and the other a t-channel colored scalar mediator, and consider examples in which the DM-quark couplings are either isospin conserving or isospin violating after electroweak symmetry breaking. While previous work on mono-W signals have focused on isospin violating EFTs, obtaining very strong limits, we find that isospin violating effects are small once such physics is embedded into a gauge invariant simplified model. We thus find that the 8 TeV mono-W results are much less constraining than those arising from mono-jet searches. Considering both the leptonic (mono-lepton) and hadronic (mono fat jet) decays of the W , we determine the 14 TeV LHC reach of the mono-W searches with 3000 f b −1 of data. While a mono-W signal would provide an important complement to a mono-jet discovery channel, existing constraints on these models imply it will be a challenging signal to observe at the 14 TeV LHC.
Co-annihilating dark matter: Effective operator analysis and collider phenomenology
Physical Review D, 2014
We study dark matter (DM) models in which there are two dark sector particles, χ1 and χ2, of near mass. In such models, co-annihilation of χ1 and χ2 may be the dominant process controlling the DM relic density during freezeout in the early universe. In this scenario, there is no significant contribution to direct and indirect detection signals, unless there exists an extreme degeneracy in the masses of the lightest dark sector particles. Therefore, relic density constraints and collider searches provide the most relevant information about these models. We consider Dirac fermion dark matter which couples to standard model (SM) particles via an effective operator. For the collider phenomenology, where an effective field theory may not be valid, we adopt a simple Z' model to provide an appropriate UV completion. We explore the interesting LHC signals that arise from the dark matter production process pp → χ1 + χ2 + jet, followed by the decay χ2 → χ1 + SM .