Search results for "Dark matter"
showing 10 items of 627 documents
Perturbative unitarity constraints on gauge portals
2017
Abstract Dark matter that was once in thermal equilibrium with the Standard Model is generally prohibited from obtaining all of its mass from the electroweak phase transition. This implies a new scale of physics and mediator particles to facilitate dark matter annihilation. In this work, we focus on dark matter that annihilates through a generic gauge boson portal. We show how partial wave unitarity places upper bounds on the dark gauge boson, dark Higgs and dark matter masses. Outside of well-defined fine-tuned regions, we find an upper bound of 9 TeV for the dark matter mass when the dark Higgs and dark gauge bosons both facilitate the dark matter annihilations. In this scenario, the uppe…
Lepton jets from radiating dark matter
2015
Journal of High Energy Physics 2015.7 (2015): 045 reproduced by permission of Scuola Internazionale Superiore di Studi Avanzati (SISSA)
New Methods of Axion Dark Matter Detection
2017
In this chapter, I consider new linear effects of axion (pseudoscalar) dark matter in atoms, molecules, nuclei and neutrons.
Search for Dark Matter in Events with a Hadronically DecayingWorZBoson and Missing Transverse Momentum inppCollisions ats=8 TeVwith the ATLAS Detect…
2014
A search is presented for dark matter pair production in association with a W or Z boson in pp collisions representing 20.3 fb(-1) of integrated luminosity at root s = 8 TeV using data recorded with the ATLAS detector at the Large Hadron Collider. Events with a hadronic jet with the jet mass consistent with a W or Z boson, and with large missing transverse momentum are analyzed. The data are consistent with the standard model expectations. Limits are set on the mass scale in effective field theories that describe the interaction of dark matter and standard model particles, and on the cross section of Higgs production and decay to invisible particles. In addition, cross section limits on the…
Exposing the dark sector with future Z factories
2017
We investigate the prospects of searching dark sector models via exotic Z-boson decay at future e⁺e⁻ colliders with Giga Z and Tera Z options. Four general categories of dark sector models, Higgs portal dark matter, vector-portal dark matter, inelastic dark matter, and axionlike particles, are considered. Focusing on channels motivated by the dark sector models, we carry out a model-independent study of the sensitivities of Z factories in probing exotic decays. The limits on branching ratios of the exotic Z decay are typically O(10⁻⁶–10⁻[superscript 8.5]) for the Giga Z and O(10⁻[superscript 7.5]–10⁻¹¹) for the Tera Z, and they are compared with the projection for the high luminosity LHC. W…
Search for Low-Mass Dijet Resonances Using Trigger-Level Jets with the ATLAS Detector in pp Collisions at s=13 TeV
2018
Searches for dijet resonances with sub-TeV masses using the ATLAS detector at the Large Hadron Collider can be statistically limited by the bandwidth available to inclusive single-jet triggers, who ...
Search for Invisible Decays of a Dark Photon Produced in e+e− Collisions at BaBar
2017
We search for single-photon events in 53 fb^{-1} of e^{+}e^{-} collision data collected with the BABAR detector at the PEP-II B-Factory. We look for events with a single high-energy photon and a large missing momentum and energy, consistent with production of a spin-1 particle A^{'} through the process e^{+}e^{-}→γA^{'}; A^{'}→invisible. Such particles, referred to as "dark photons," are motivated by theories applying a U(1) gauge symmetry to dark matter. We find no evidence for such processes and set 90% confidence level upper limits on the coupling strength of A^{'} to e^{+}e^{-} in the mass range m_{A^{'}}≤8 GeV. In particular, our limits exclude the values of the A^{'} coupling sugges…
Search for a Dark Photon ine+e−Collisions atBaBar
2014
Dark sectors charged under a new Abelian interaction have recently received much attention in the context of dark matter models. These models introduce a light new mediator, the so-called dark photon (A^{'}), connecting the dark sector to the standard model. We present a search for a dark photon in the reaction e^{+}e^{-}→γA^{'}, A^{'}→e^{+}e^{-}, μ^{+}μ^{-} using 514 fb^{-1} of data collected with the BABAR detector. We observe no statistically significant deviations from the standard model predictions, and we set 90% confidence level upper limits on the mixing strength between the photon and dark photon at the level of 10^{-4}-10^{-3} for dark photon masses in the range 0.02-10.2 GeV. W…
The coannihilation codex
2015
We present a general classification of simplified models that lead to dark matter (DM) coannihilation processes of the form DM + X $\rightarrow$ SM$_1$ + SM$_2$, where X is a coannihilation partner for the DM particle and SM$_1$, SM$_2$ are Standard Model fields. Our classification also encompasses regular DM pair annihilation scenarios if DM and X are identical. Each coannhilation scenario motivates the introduction of a mediating particle M that can either belong to the Standard Model or be a new field, whereby the resulting interactions between the dark sector and the Standard Model are realized as tree-level and dimension-four couplings. We construct a basis of coannihilation models, cl…
Prediction for the lightest Higgs boson mass in the CMSSM using indirect experimental constraints
2007
Measurements at low energies provide interesting indirect information about masses of particles that are (so far) too heavy to be produced directly. Motivated by recent progress in consistently and rigorously calculating electroweak precision observables and flavour related observables, we derive the preferred value for m_h in the Constrained Minimal Supersymmetric Standard Model (CMSSM), obtained from a fit taking into account electroweak precision data, flavour physics observables and the abundance of Cold Dark Matter. No restriction is imposed on m_h itself: the experimental bound from direct Higgs boson search at LEP is not included in the fit. A multi-parameter chi^2 is minimized with …