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18.07.2022 / 13:00 / Zeuthen, Online
Lattice seminarContinuum Limit of Heavy Quarks Moments and their Perturbative Expansion
Leonardo Chimirri (Humboldt-Universität zu Berlin, DESY Zeuthen) (Lattice Group)
The QCD-coupling is a fundamental parameter of the standard model and as such it is an input in the computation of several QCD-related observables. The parametric error on the QCD-coupling can be a considerable source of uncertainty, for instance in H→gg, H→b¯b and in the stability of the electroweak vacuum, with implications for BSM studies. One way to extract the coupling is to compare lattice evaluated moments of heavy quark two-point functions with their O(α3s) perturbative computations [Maier, Maierhofer, Marquard, Smirnov NPB824 1-18,(2010)]. In this procedure, the truncation of the perturbative series as well as the continuum limit are sizeable systematic uncertainties that are hard to keep under control. In this seminar I give an overview of the first exploratory quenched lattice computation, which tries to address these issues in depth. We measure pseudo-scalar two-point functions in volumes of L=2 fm with twisted-mass Wilson fermions. We use full twist, the non-perturbative clover term and lattice spacings down to a=0.010 fm to try to tame the large discretization effects. The continuum limit is challenging not only due to the large mass of the quarks, but also because of cutoff effects associated with the integration of the two-point function at zero distance. We also show preliminary results for the Λ-parameter, where the mass of the heavy quarks has been varied from M∼Mcharm to M∼3Mcharm.
More Information: https://indico.desy.de/category/873/
