This grant supports a team at Imperial College London that aims to discover evidence for one or more new fundamental particles that may explain an important open question in physics: why the universe is filled with matter yet lacks antimatter. This question will be addressed by carefully measuring the shape of an electron – whether it’s round or aspherical – because an electron will be aspherical if it interacts with particles that treat matter and antimatter differently. These particles could explain the observed matter/antimatter asymmetry. Michael Tarbutt, a Professor of Physics at Imperial College London, will lead a five-year project to improve the relevant measurement precision by a factor of forty. The increased precision will either reveal evidence for one or more new fundamental particles, or set a new upper limit that constrains the properties of as-yet-undiscovered particles. The laws of physics treat matter and antimatter identically, and it’s thought that there were equal amounts of matter and antimatter immediately after the big bang, so the absence of antimatter in the universe is a deep mystery that challenges fundamental physics. The discovery of a new particle could explain this mystery, along with others such as the nature of dark matter. There are two leading detection approaches that achieve comparable precision. One approach measures a high density of neutral molecules for a brief time (milliseconds) as molecules move rapidly through a measurement apparatus; here, limited measurement time constrains achievable precision. The second approach measures static molecular ions for a relatively long time (seconds) and measurement precision is limited by the fact that ions cannot be tightly packed because they’re electrically charged, and they perturb one another. Professor Tarbutt proposes a new best-of-both-worlds approach: use molecules that are static so they can be measured for a long time, and neutral so they can be compacted to high density (measure many molecules). He aims to achieve this by performing an experiment using neutral molecules contained within an optical-trap. An optical-trap (or optical-lattice) is a type of container for atoms and molecules formed by overlapping several laser beams in a region of space.