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Proposing Institution

Fachgebiet Theoretische Physik ,TUM
Project Manager

Dr. Viljami Leino
James-Franck-Straße 1
85748 Garching
We calculate the static energy using lattice QCD with either 2+1+1 or 2+1 flavors at zero and nonzero temperature on lattices down to extraordinarily fine lattices with lattice spacings of a ≈0.025 fm. We employ a novel renormalization scheme: we subtract twice the mass of a static-strangemeson to obtain, up to a known constant, the static energy with a well-defined continuum limit andsignificantly smaller uncertainties than previously possible. The static energy is also perturbatively calculable with an effective field theory (EFT) called potential nonrelativistic QCD (pNRQCD). We use pNRQCD and include an EFT description of the leading cutoff effects to enhance the control ofdiscretization errors. The innovative combination of this EFT description and the refined numerical results from lattice QCD allows us to determine the strong coupling αs at outstanding precision and to contribute to the resolution of the current αs discrepancy. At finite temperature, the static energy develops an imaginary part. EFT shows that the imaginary part is the origin of quarkonium dissociation in a weakly-coupled quark-gluon plasma (QGP). Theoretical knowledge of quarkonium dissociation in a strongly-coupled QGP is key for the correct interpretation of quarkonium suppression in heavy-ion collisions. We compute the complex static energy from the spectral function, which needs to be reconstructed from the static correlation function. Before we can calculate the correlation function at finite temperature, we must generate the corresponding lattices using the rational hybrid Monte Carlo (RHMC) algorithm for 2+1+1 flavors of highly improved staggered quarks (HISQ). We generate five lattices with large temporal extent (Nτ = 16 or 20) and temperatures between 200and 500 MeV. The large temporal extent is necessary for successful reconstruction of the spectralfunction, which allows us to extend the applicability of the EFT to the strongly-coupled QGP.

Impressum, Conny Wendler