Andreas Lund

Hello!

I am a PhD student in theoretical particle physics, working under the supervision of Professor Sandhya Choubey at the department of Particle Physics, Astrophysics and Medical Imaging at KTH.

My research focuses on the phenomenology of neutrino oscillations.

Neutrinos are fundamental particles whose basic properties are not yet fully understood. We do not know their masses, only that they are more than a million times lighter than the electron. In fact, we do not even know why they have mass, since the Higgs mechanism, which explains the masses of all other massive fundamental particles, cannot generate mass for neutrinos in the standard model of particle physics. The only evidence we have for neutrino mass is neutrino oscillations, a phenomenon discovered in 1998 in which neutrinos change their so-called flavor as they travel from source to detector.

The difficulty of studying neutrinos is that they interact extremely weakly. Despite the fact that around one hundred trillion neutrinos pass through your body every second, you will not notice them, and almost all those neutrinos pass straight through the entire Earth and disappear into space. Modern experiments with detectors weighing tens of thousands of metric tons manage to detect a few tens of neutrinos per day.

Some of the biggest open questions in neutrino physics are:

• The value of leptonic CP violation. If it is large, this could help explain why there is more matter than antimatter in the Universe today.

• The neutrino mass ordering, that is which of the three known neutrino flavors is the heaviest.

• The value and octant of the mixing angle θ₂₃. This parameter appears to be very close to maximal, which is thought to be due to an underlying symmetry of nature.

My research concerns these type of questions. I write code to simulate neutrino oscillation and statistically analyze neutrino oscillation data in a combination of different experiments. I also study different proposed theories beyond the standard model, which could give a signature in these neutrino experiments.