Measuring Matter/Anti-Matter Asymmetry and searching for New Physics through Rare Decays

Measuring Matter/Anti-Matter Asymmetry and searching for New Physics through Rare Decays

We expect to offer an STFC-funded studentship in this area starting in Sept/Oct 2020

The main focus of the LHCb experiment, located at the Large Hadron Collider at CERN, is the study of CP asymmetry, believed to be one of the causes of the matter-antimatter asymmetry of the present universe. The origin of CP violation in the Standard Model is through the so-called CKM matrix that describes the level of quantum mechanical mixing amongst quarks. Because the CKM matrix contains a complex term, this causes a small time-dependent asymmetry between the decay of particles and their anti-matter counterparts. This effect will be particularly strong in the decay of B and anti-B mesons (particles that have a B or “bottom” quark).

The Glasgow group has worked on a range of analyses at LHCb, including:

Measuring the unitarity angle gamma, which is particularly poorly known:  one of the main aims of the LHCb experiment is to measure this angle gamma in a variety of decay channels, and search for New Physics by comparing channels that are sensitive to new CP violating mechanisms with those that mainly measure the Standard Model gamma.  A leading candidate for such a measurement comes from the comparison of time dependent asymmetries in the decays of channels Bd->D-pi+ and Bs->Ds-K+; this research culminates in a measurement of the Standard Model value of gamma with unprecedented accuracy, which can be compared with a measurement of gamma sensitive to New Physics.  This programme of research also includes unbiased measurements of the lifetime of the B mesons, resulting in the world’s best measurement of the Bd and Bs lifetimes.

Looking for new physics effects in rare decays; for example the angular distribution of the particles produced in the decay of the B meson to a K* meson plus two muons.

PhD students in this area work within the Glasgow LHCb group of seven research staff and four PhD students.  Activities include the analysis of data, and running and operating the experiment.  Students are expected to travel to CERN in Geneva regularly, and to spend a period of around one year based at CERN.