Karlsruhe 2024 – wissenschaftliches Programm
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T: Fachverband Teilchenphysik
T 91: Standard model 3 (strong/QCD)
T 91.5: Vortrag
Donnerstag, 7. März 2024, 17:00–17:15, Geb. 30.23: 2/0
Two-loop matching of the chromo-magnetic dipole operator with the gradient flow — •Janosch Borgulat1, Robert Harlander1, Matthew D. Rizik2, and Andrea Shindler1,3,4 — 1TTK, RWTH Aachen University, 52056 Aachen, Germany — 2Department of Physics and Astronomy, Michigan State University, East Lansing, MI 48824, USA — 3NSD, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA — 4Department of Physics, University of California, Berkeley, CA 94720, USA
The baryon asymmetry of the universe requires sources of CP-violation beyond those predicted by the standard model. On the other hand, experimental constraints on the neutron electric dipole moment leave a large window for CP-violating contributions beyond the standard model. Such contributions can be described by CP-violating effective interactions at hadronic energies in QCD. Because of confinement, these contributions cannot be computed perturbatively. However, they are accessible to lattice simulations. These, on the other hand, suffer from power divergences in the inverse lattice spacing.
A useful tool to circumvent these inconveniences is the gradient flow which acts on the fields similar to the heat equation, smoothing them along an auxiliary fifth dimension, the flow time. This removes all ultraviolet divergences and leads to well-behaved flowed operators on the lattice. The mixing matrix translating between regular and flowed operators is accessible to perturbative calculations. In our work, we compute the renormalized mixing matrix for the chromomagnetic dipole operator through next-to-next-to-leading order.
Keywords: Gradient Flow; CP-Violation; Perturbative QCD; Lattice QCD