Searches for physics beyond the standard model with the CMS detector – long-lived particles and dark photons

Supervisor: Alberto Escalante del Valle

Projekt: CMS Analyse

Within this master thesis project, you will work in developing a new search for long-lived particles at the CMS experiment using collisions from the Large Hadron Collider (LHC).

At the LHC, most of the searches target potential new particles that exist only a fraction of a second before they decay into lighter particles. As an example, the Higgs boson has a predicted lifetime of ~ 10-22 s. However, several models of new physics predict new particles with even longer lifetimes, and the experimental constraints for these models are still weak.

In particular, you will study different dark photon scenarios. A dark photon is a predicted BSM new particle of a "dark sector" that would also contain the particle representing the dark matter in the universe. The dark photon interacts with the Standard Model via mixing with photon and the Z
boson through the hyper-charge portal. When the mixing parameter is sufficiently small, the decay products of the dark photon are displaced leading to striking signatures in the CMS detector.

In this project you will study with data and simulation the capabilities of the CMS detector to discover a long-lived dark photon as a function of its mass, lifetime or production mechanism.

At least a basic knowledge of linux, python, C/C++ and git is required. You should be ready to work within a group that also includes theoretical physicists.