Strong and Electro-Weak Matter 2026

Topological Susceptibility at High Temperatures from Unquenched Lattice QCD

18 Aug 2026, 11:45

15m

F4050 (4th floor) (University of Helsinki Main Building)

talk (15min) QCD in extreme conditions and dense nuclear matter QCD in Extreme Conditions Contributions 2

Speaker

Simon Stendebach (TU Darmstadt)

Description

The QCD topological susceptibility $ \chi $ gives the mass of the hypothetical QCD axion. Understanding its behavior at high temperatures $ T $ is important for the axion’s cosmological history and possible role as the dark matter. In this work, we measure $ \chi $ directly from unquenched 2+1+1 flavor Lattice QCD in a temperature range of 435 MeV to 1020 MeV. To resolve the problem of insufficient sampling of topology and to traverse the barrier between topological sectors, we use reweighting in terms of a combination of the topological charge and the peak action density. Additionally, we reweight in terms of the caloron radius.