Experimental Study of Heavy Flavor and CP Violation with the LHCb Experiment at the CERN LHC Collider

One of the greatest scientific achievements of the past century has been the development of the Standard Model of elementary particles, the quarks and leptons, and their interactions. The precise tests of the fundamental elements of the Standard Model are among the most important goals of the continuing research in elementary particle physics. This project focuses on an experimental study of heavy flavor, which refers to the studies of the particles containing the charm (c) and the bottom (b) quarks, and CP violation, the differences in the properties of the particles and their antiparticles counterpart.

The studies, which will be conducted with the LHCb experiment at the Large Hadron Collider at CERN, include precise tests of the mechanism responsible for the differences in the properties of matter and antimatter as well as examination of the universal behavior of charged leptons, a cornerstone of the Standard Model. The findings of the flavor physics, in particular a potential discovery of new sources of CP violation beyond the Standard Model, will also likely have a profound impact on the understanding of the origin of the matter-antimatter asymmetry in the universe and the field of cosmology.

Experimental particle physics also serves as an extremely rich environment for training students at all levels, as well as postdoctoral researchers and engineers at the leading edge of a diverse range of technologies. The Maryland group has had strong record in this area, enabled by the development of the first upgrade of the LHCb detector, and aims to continue and strengthen this program with the next major improvement plan of the detector in the coming decade.

The proposed program includes the completion of the commissioning of the upstream tracker in the LHCb upgrade, whose construction has been a key focus of the group, as well as a major participation in the physics analysis of the data recorded by LHCb in Runs 1 & 2 and the anticipated data from the operation of the experiment in the next three years, Run 3. The physics studies program is focused on measurements related to two of the current anomalies in the decays of B mesons: (1) hints of departure from Lepton Flavor Universality in semileptonic B decays and (2) studies of CP violation in the family of B → Kπ decays, where the current measurements of the CP asymmetries deviate from the expected pattern based on isospin symmetry- the long standing so-called ”Kπ” puzzle.

These anomalies, if confirmed, could be due to the presence of new physics effects in flavor processes. The program also includes major participation in the development of the next major upgrade of the LHCb detector- Upgrade II, which is expected to lead to significant improvement in the precision of flavor processes. At the current level of precision, measurements of the key flavor observables, currently largely consistent with the Standard Model predictions, impose severe constraints on the energy scale and the structure of new physics models.

However, areas of deviations from the SM are emerging, such as signs of lepton non-universality in semileptonic B decays, which are highly sensitive to the presence of new scalars. The precision of future measurements in some key areas, based on the data from LHCb and its upgraded detector, are expected to reach the required sensitivity to clarify some of these anomalies or further strengthen the deviations from the SM predictions.

These results could, in conjunction with studies at the energy frontier, point the way to the structure of the physics beyond the SM.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.