The charming strangeness of the W boson
Published: 27 August 2021
Glasgow physicists have pinned down Vcs, a key parameter of the Standard Model, by combining their calculations on STFC's DIRAC supercomputer with results from particle physics experiments around the world for the rate of D meson decay to a K meson in a process akin to nuclear beta decay.
Glasgow physicists have pinned down Vcs, a key parameter of the Standard Model, by combining their calculations on STFC's DIRAC supercomputer with results from particle physics experiments around the world for the rate of D meson decay to a K meson in a process akin to nuclear beta decay. This rate depends on the coupling strength Vcs between the W boson of the weak interaction and the charm-strange quark pair, but also the strong interaction physics, encoded by ‘form factors’, that binds the quarks inside the mesons while this process happens. The numerical techniques of lattice QCD allow the form factors to be calculated, but in the past their uncertainty has limited the precision of Vcs. Using improved methods for quarks, developed in Glasgow, members of PPT have now obtained a value for Vcs of 0.9663(80), three times more accurate than previous work. This allows Vcs to be distinguished from 1 for the first time, giving tighter constraints on the possibilities for new physics beyond the Standard Model.
Full details can be found here
First published: 27 August 2021
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