Cayetano Fernandez Ruiz

PhD thesis: Searches for exotic long-lived particles with the ATLAS Detector at the Large Hadron Collider of CERN

Experimental particle physics is currently traversing an exciting stage. In the past, we had several theories that required experimental confirmation and guided most of our experiments, as in the search for the Higgs boson. Nowadays, however, we know there must be physics beyond our current knowledge (What is dark matter? Why is there a matter-antimatter asymmetry? ...) but we do not have a predilect model guiding our steps. Therefore, experimentalists must look everywhere in the hope of finding the puzzle piece that fell under the table and will allow us to keep piecing physics together.

Hence, this project's objective is to look for exotic long-lived particles (LLP) in the ATLAS experiment of the LHC at CERN. Finding any such exotic LLP would be exciting, for they could manifest as a sign of new physics, such as dark matter or supersymmetric interactions. Who knows? Maybe LLP also stands for "Long Lost Piece"!

Who or what inspired you to pursue your research interests?

My grandfather loved puzzles. When I was a kid, he used to buy several 3D puzzles, and after solving them (or giving up) he would give them to me. Ever since, I have always loved puzzles as well.

Now, particle physicists are, in a way, puzzle solvers: The puzzle is our understanding of the Universe, and the pieces our physical laws and entities. However, although we know some pieces are missing, we cannot find them anywhere... Is this not an exciting puzzle to work on? It should be clear why, as a puzzle lover, I became interested in particle physics!