My research is in the area of theoretical particle physics. Broadly speaking, I am interested in learning about what particles exist in nature at the most fundamental level, and I am most interested in theories with new particles beyond our existing Standard Model of particle physics. My work is largely motivated by observations from cosmology and astrophysics, namely the nature and properties of dark matter and the matter-antimatter asymmetry (i.e., why are we made of matter instead of antimatter?). I am also interested in the physics of neutrinos, the origin of their masses, and the connections between neutrinos and other unsolved questions in particle physics.
A major focus of my research in recent years is to propose new methods to search for the existence of new particles motivated by dark matter and "hidden sectors" of new particles, especially using particle colliders such as the Large Hadron Collider (LHC), and to ensure that the best-motivated theories are tested with current and upcoming experiments. This has led to many fruitful collaborations with experimentalists and theorists alike that I hope to build upon in the coming years.
The Standard Model of Particle Physics
Our current theory of particle physics, the Standard Model, was first proposed approximately 50 years ago and predicted the existence of many as-yet undiscovered particles. Over the intervening years, each of its predictions has come true, and the final piece was put into place in 2012 with the discovery of the Higgs boson at the LHC. Consisting of a handful of elementary "matter" particles, and three forces that act between these elementary particles, the Standard Model is spectacularly successful at explaining how the building blocks of matter assemble into nuclei, atoms, molecules, and everything on up.
For more information on the Standard Model, click here.
The Standard Model explains nearly all physical phenomena we see on Earth. When we look to the heavens, though, it is a different story. For example, we can use the gravitational pull between astrophysical objects to measure how much mass each object has, and compare this mass to the amount of matter that gives off light in the form of stars, gas, etc. We find that there is significantly more matter in galaxies (and pretty much everywhere else we look) than can be explained by the stars and other luminous objects. This missing mass is creatively called dark matter. It is exciting and troubling that we are ignorant about the dominant form of matter in our Universe.
A significant component of my research aims to identify what kind of elementary particles comprise this dark matter and what forces exist between us and dark matter. This includes understanding how dark matter was created in the early Universe, and whether we can create dark matter at particle colliders (or see it in other experiments).
For more information on dark matter, click here.
The Matter-Antimatter Asymmetry
For every type of particle in the Standard Model, there exists a corresponding antiparticle. Antiparticles have exactly the same properties as the original particle, but with opposite signs for all charges (for instance, an antiproton has the same mass as a proton, but with a charge of -e instead of +e). Since the discovery of antimatter in 1932, scientists have faced an important question: why is everything in our world made up of matter (protons, electrons) and not antimatter (antiprotons, positrons). The Standard Model puts particles and antiparticles on largely the same footing, and so our existence in the form of matter and not antimatter tells us that there is a missing piece from the Standard Model.
Explaining the matter-antimatter asymmetry requires very special kinds of particles and interactions. My research connects these hypothesized particles & forces to current and upcoming experiments to understand what kinds of signals we should be looking for and what connections exist with dark matter and Standard Model particles (particularly neutrinos). I also think of new ways to generate a matter-antimatter asymmetry and how we can experimentally test these theories.
For more information on the matter-antimatter asymmetry, click here.
Hunting New Particles at Colliders
According to Einstein's famous mass-energy relation, new types of heavy particles can be produced with a sufficient concentration of energy. One way to do this is to take protons and electrons, accelerate them to extremely high speeds/energies, and then smash them together. Heavy particles in the Standard Model, as well as previously unknown particles (potentially related to dark matter or the matter-antimatter asymmetry), are produced in the collisions and can be studied. The biggest collider ever built, the 27-km-long Large Hadron Collider (LHC) at CERN on the Swiss-French border, is currently colliding protons at record-breaking energies and giving us new insight into the basic building blocks of matter. However, trying to find a new particle amidst the debris of these collisions is like trying to find a needle in a haystack: we need to know what we are looking for before we find it!
Motivated by the missing pieces of the Standard Model, I work to identify ways in which current experimental search strategies could be failing to find new particles that are lurking, undetected, in existing collider data. I also put my ideas into practice, having joined a now-discontinued particle collider experiment called BaBar to look for evidence for dark matter and hidden forces in their data.
For more information on particle collider and accelerator experiments, click here.