The standard model (SM) has been so successful in describing experimental data that searches for new physics effects require predictions with errors at the few percent level. Two particularly important areas are: new physics in B meson decays, and the muon anomalous magnetic moment (called g-2). The dominant theory uncertainty in both comes from hadronic corrections (HC) to SM processes which are very difficult to calculate precisely. Lattice QCD has uses high performance computing to calculate these numerically and has been very successful for many hadronic physics calculations.
This proposal has two parallel themes. The first involves using lattice QCD to calculate HC in B-meson decays. This project will carry out the first calculation of B-meson mixing beyond the standard model with physical quark masses. This eliminates a dominant error and will constrain new physics models. The project will provide the first calculation of form factors for B to D semileptonic decays at physical quark masses. This is used to normalise a rare leptonic decay at LHCb and allows for calculation of an element of the CKM matrix, an important standard model parameter. This calculation will be able to reduce this portion of the error in the experimental rate below other sources, allowing for tighter constraints on new physics. The researcher is already experienced in using these methods and will carry out these calculations independently.
The second theme concerns a 3-sigma discrepancy between experiment and theory in g-2. Future experiments at Fermilab and J-PARC will reduce experimental errors to the point where theory errors from HC are dominant. The scientist in charge has performed pioneering work on the g-2 calculation and the researcher will work on improving this and one of the first calculations of the next to leading order component. This has not yet been calculated on the lattice and will involve learning and developing several different techniques.
Call for proposal
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