Karlsruhe 2024 – wissenschaftliches Programm

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T: Fachverband Teilchenphysik

T 49: Flavour physics 2

T 49.9: Vortrag

Dienstag, 5. März 2024, 18:00–18:15, Geb. 30.41: HS 4

Using Gradient Flow to Renormalise Matrix Elements for Meson Mixing and Lifetimes — •Matthew Black¹, Robert Harlander², Fabian Lange^3,4,5,6, Antonio Rago⁷, Andrea Shindler², and Oliver Witzel¹ — ¹Theoretische Teilchenphysik, Center for Particle Physics Siegen, Universitaet Siegen, Germany — ²Institute for Theoretical Particle Physics and Cosmology, RWTH Aachen University, Germany — ³Physik-Institut, Universitaet Zuerich, Switzerland — ⁴Paul Scherrer Institut, Villigen PSI, Switzerland — ⁵Institut fuer Theoretische Teilchenphysik, Karlsruhe Institute of Technology, Germany — ⁶Institut fuer Astroteilchenphysik, Karlsruhe Institute of Technology, Germany — ⁷IMADA and Qauntum Theory Center, University of Southern Denmark, Odense, Denmark

Neutral meson mixing and meson lifetimes are theory-side parametrised in terms four-quark operators which can be determined by calculating weak decay matrix elements using lattice QCD. While calculations of meson mixing matrix elements are standard, determinations of lifetimes typically suffer from complications in renormalisation procedures because dimension-6 four-quark operators can mix with operators of lower mass dimension and, moreover, quark-line disconnected diagrams contribute.

We present work detailing the idea to use fermionic gradient flow to non-perturbatively renormalise matrix elements describing meson mixing or lifetimes, which later is to be combined with a perturbative calculation to match to the MS-bar scheme.

Keywords: Gradient Flow; B physics; Lifetimes; Matrix elements