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Phenomenology

Collaborations with Particle Phenomenology

Compact Muon Solenoid Experiment

Collaborations with Particle Phenomenology

We have various collaborations with particle theorists within and outside DESY involving studies of simplified Dark Matter models [1], systematic investigations of the tt spin density matrix as used here, searches for Dark Higgs bosons as described here, and exploring and explaining local excesses in searches for exotic Higgs bosons & Dark Matter mediators, such as the one we found in our search for resonances in top quark pair production.

Towards the next generation of simplified Dark Matter models

Figure 1. Examples of diagrams with an exchange of a h1/h2 mediator that lead, respectively, to a mono-W/Z signal, a MET + 2j signature in vector boson fusion, MET + j events from a top quark loop, and a MET + tt ̄ signature.

We are working on the extension and refinement of simplified Dark Matter (DM) models [1]. This White Paper is not intended as a comprehensive review of the discussed subjects, but instead summarizes ideas and concepts arising from a brainstorming workshop that can be useful when defining the next generation of simplified DM models (SDMM). In this spirit, based on two concrete examples, we show how existing SDMM can be extended to provide a more accurate and comprehensive framework to interpret and characterise collider searches. In the first example we extend the canonical SDMM with a scalar mediator to include mixing with the Higgs boson. We show that this approach not only provides a better description of the underlying kinematic properties that a complete model would possess, but also offers the option of using this more realistic class of scalar mixing models to compare and combine consistently searches based on different experimental signatures. The second example outlines how a new physics signal observed in a visible channel can be connected to DM by extending a simplified model including effective couplings. In the next part of the White Paper we outline other interesting options for SDMM that could be studied in more detail in the future. Finally, we review important aspects of supersymmetric models for DM and use them to propose how to develop more complete SDMMs.

References:
[1] A. Albert (Aachen) et al., Towards the next generation of simplified Dark Matter models, Phys. Dark Univ. 16 (2017) 49, arXiv:1607.06680 [hep-ex].