Conveners
Open Session A): #1
- Greg Landsberg (Brown University (US))
- Michael Kramer (Rheinisch Westfaelische Tech. Hoch. (DE))
Open Session A): #2
- Michael Kramer (Rheinisch Westfaelische Tech. Hoch. (DE))
- Greg Landsberg (Brown University (US))
We study universal properties of dark matter models with a pseudoscalar mediator at the Large Hadron Collider. A simplified model with a second Higgs doublet and effective couplings to the dark sector is investigated.
Constraints from Higgs signal strength measurements, flavor and electroweak precision observables are considered. The remaining parameter space overlaps with a region in which...
We present a recent search for dark matter (DM) production in association with a leptonically decaying Z boson. The search is performed with 36.1 fb−1 of 13 TeV proton-proton collision data collected by the ATLAS experiment at the LHC. No significant excess above the SM back- ground is observed. For simplified models with vector or axial-vector mediators, including extensions to lepton...
A search for dark matter pair production in association with a Z' boson in
pp colisions, at 13 TeV, using 36.1fb-1 data, recoreded with the ATLAS
detector is presented. Events are characterised by large missing transverse
momentum and a hadronically decaying vector boson reconstructed as either a
pair of small-radius jets, or as a single large-radius jet with substructure.
Results are...
Mono-X processes provide promising channels for DM searches at the LHC. Two types of topologies for these processes are initial state X-radiation and decays in the final state. For ISR, I will consider a Z'-mediator toy model and argue that mono-jet is the most promising ISR channel. This motivates studying final state decays for mono-Z, mono-h, and di-h processes. To this end, I will use the...
A search for dark matter in association with a Higgs boson decaying to two photons based on 36.1 fb$^{-1}$ data collected with the ATLAS detector at the LHC at the energy of 13 TeV will be presented. No significant excess over the expected background is observed. Upper limits at 95% confidence levels are set for the Standard Model Higgs boson decaying into two photons in association with...
I discuss a novel signature of DM production at the LHC resulting from an additional Higgs boson in the dark sector, whose presence is motivated by the need to generate the masses of the dark sector particles and the possibility to relax constraints from the DM relic abundance by opening up a new annihilation channel. If the dark Higgs boson decays into SM states via a small mixing with the SM...
After a brief review of the searches for Dark Matter produced in association
with the Standard Model electroweak gauge or Higgs bosons from the ATLAS
experi- ment, exclusion limits with reduced model dependence will be
presented for each of them. Their impact on the allowed parameter space of
the 2HDM+a model will be compared with the direct interpretation in the
context of this model.
The two-Higgs-doublet model with an additional pseudoscalar represents a simplified and ultraviolet-complete model for Dark Matter. It provides a wide spectrum of collider signatures, including a $Z$ or a Higgs boson and missing transverse momentum, with detectable cross-sections at the LHC. In the context of this model, the sensitivity of an existing search of the ATLAS experiment for the...
My talk will base on Higgs portal DM models with fermion, vector and scalar DMs.
I will show that the LHC is unable to probe any parameter space of these models. On the other hand, in terms of four benchmark points, those model will be not only probable but also distinguishable at 500 GeV electron-positron collider and 100 TeV proton-proton collider.
Many extensions of the Standard Model predict resonances with significant couplings to quarks and gluons, including resonances which also couple to dark matter particles. Such hadronic resonances
has been probed well into the TeV range at LHC. Therefore, focusing on the searches for low mass resonances is crucial for the completeness of the diet resonance searches. In order to suppress the...
Searches for dark matter are conducted in events with highly boosted, hadronically decaying heavy resonances. The searches isolate final states containing large missing transverse energy or containing a beyond-Standard Model resonance. These studies are performed using proton-proton collisions at a center-of-mass energy of 13 TeV, in data recorded by the CMS detector in 2016 at the LHC,...
I will propose a new search for dark matter at the LHC, characteristic of scenarios beyond the Standard Model with a pseudoscalar portal between the dark and visible sectors. This search explores large regions of parameter space that are not probed by missing energy signatures, searches for new scalars and flavour bounds. I will also show how this search could be used to test the dark matter...
WE present a dijet resonance search, where a resonance may be an indicator of a dark matter mediator. However, the very high luminosity at the LHC has lead to high trigger thresholds that throttle the search at mediator masses below 1 TeV using conventional data taking techniques. A technique, known as the Trigger-Object Level Analysis, has been developed to lift this limitation. The technique...
I will discuss how event rates at the LHC can be compared to
reaction rates in the early Universe in a model-independent way. This
approach makes it possible to demonstrate that hidden sectors that never
reach thermal equilibrium in the early Universe are also inaccessible
for the LHC. The conclusion is that any particle that can be produced at
the LHC must either have been in thermal...
In this talk, we discuss the long-range effect of the Higgs boson on the density of thermal dark matter. While Sommerfeld enhancement via exchange of electroweak gauge bosons or gluons has been studied previously, the Higgs boson is typically thought to mediate contact interactions only. We demonstrate, however, that the Sommerfeld enhancement due to a 125 GeV Higgs can deplete TeV-scale dark...
I present a search for Higgs bosons produced via vector boson fusion and decaying into invisible particles. The search is performed with 36.1/fb of data recorded by the ATLAS detector. The mass and the cross section of the Higgs boson are assumed to be the SM values. The result is an upper limit on the Higgs boson branching ratio at 95% CL. For hypothetical scalars with masses in the range...
