Discovery of Matter Anti-matter Asymmetry in the Charm Sector

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Symmetries play an essential role in our understanding of the universe. Nature exhibits a stunning level of symmetry across all scales, from the bilateral symmetry of many animal's bodies to the mathematical symmetry of the fundamental physical laws. But only the imperfections of symmetries reveal the full picture. In astrophysics for example, the anisotropy of the cosmic microwave background radiation has given insight into the structure of the universe roughly 300,000 years after the big bang.At the Large Hadron Collider (LHC) we study the type of physics which governed the processes just a fraction of a second after the big bang. The LHC, located 100m underground just outside Geneva, collides protons at energies that have never previously been reached in a laboratory on earth. The smallest of the four large experiments at the LHC is known as LHCb, and is specifically designed to discover asymmetries in the behaviour of matter and antimatter.In our current understanding, matter consists of twelve fundamental particles: the six quarks (u, d, s, c, b, t ordered by increasing mass), and an electron with its heavier partners muon and tau and their three associated neutrinos. These interact by the exchange of so-called bosons, which are fundamental force carrying particles. The standard model of particle physics (SM) explains these matter interactions and has so far held up to all experimental tests. However, it fails to give explanations to basic questions like the reason why the t-quark is over 50,000 times heavier than the u-quark. Another is the puzzle that perfect symmetry would lead to equal amounts of matter and antimatter and the annihilation of the universe shortly after the big-bang. Questions like these tell us that the SM does not cover all aspects of fundamental interactions and therefore has to be extended.Nature has given us three special laboratories to study matter and antimatter interaction: neutral mesons (called K, B and D-meson), particles consisting of one quark (matter) and one antiquark (antimatter). Studies of the decays of these mesons have proven to be an excellent laboratory for discovering differences between the matter and anti-matter world. The studies of two of these systems (K and B mesons) have led to Nobel-prize winning breakthroughs. Together with a post-doctoral researcher, I will search for tiny differences of decays of D-mesons and anti-D-mesons. Half a year ago, scientists from the LHCb experiment have published a measurement showing a first indication for such a matter anti-matter asymmetry.Our group will focus on complementary measurements that are necessary to understand the origin of this asymmetry. Within the SM the relations between our measurements are predicted to high precision. Deviations from these predictions will unveil the presence of thus far unknown particles which are involved in this process.Particle physics research continues to lead to technological benefits to society, from the World Wide Web to medical imaging, but its true purpose will always be the search for fundamental understanding of our universe. My goal is to further this understanding, using the matter-antimatter asymmetry to reveal nature's beauty. And true beauty lies in imperfections.