Who: Niklas Grønlund Nielsen (CP3-Origins)
When: Saturday, August 31, 2013
Dark matter is an explanation for one of the most important problems in modern physics. It is a well established scientific paradigm that excess gravity is caused by a new and unobserved particle.
Some of the most important experiments trying to detect dark matter is direct detection experiments, a method where one tries to measure recoils from collisions between dark matter particles and atomic nuclei. These collisions are very rare and hard to measure. In the first part of this bachelor thesis we will look at the theory behind direct detection, and we will test some of the astrophysical assumptions that must be made prior to any experiment.
In the second part we will construct a model, where dark matter is a scalar field that interacts with a detector nucleus via two channels: through an exchange of the Higgs boson and through a small dipole interaction that allows a photon exchange. The dipole allows dark matter to feel the electric charge of the proton very weakly. As shown in e.g. Del Nobile et al: Light Magnetic Dark Matter in Direct Detection Searches 2012 differentiating how dark matter interacts with protons and neutrons, can alleviate tension between prominent direct detection experiments. We will see that the correct differentiation can be achieved via the dipole and Higgs interactions, and find how the coupling parameters of our model must be tuned.
In the end we will extend the possibilities of our model by considering which possible interactions can be included in a generic theory of scalar dark matter acting as a singlet under the symmetries of the Standard Model.