Benjamin Jäger

The QCD phase diagram in the limit of heavy quarks using complex Langevin dynamics

A bstractComplex Langevin simulations allow numerical studies of theories that exhibit a sign problem, such as QCD, and are thereby potentially suitable to determine the QCD phase diagram from first principles. Here we study QCD in the limit of heavy quarks for a wide range of temperatures and chemical potentials. Our results include an analysis of the adaptive gauge cooling technique, which prevents large excursions into the non-compact directions of the SL(3, ℂ

Nucleons and parity doubling across the deconfinement transition

\mathrm{\mathbb{C}}

The leading hadronic vacuum polarisation on the lattice

) manifold. We find that such excursions may appear spontaneously and change the statistical distribution of physical observables, which leads to disagreement with known results. Results whose excursions are sufficiently small are used to map the boundary line between confined and deconfined quark phases.

Charge transport and vector meson dissociation across the thermal phase transition in lattice QCD with two light quark flavors

A bstractWe present a calculation of the hadronic vacuum polarization contribution to the muon anomalous magnetic moment, aμhvp, in lattice QCD employing dynamical up and down quarks. We focus on controlling the infrared regime of the vacuum polarization function. To this end we employ several complementary approaches, including Padé fits, time moments and the time-momentum representation. We correct our results for finite-volume effects by combining the Gounaris-Sakurai parameterization of the timelike pion form factor with the Lüscher formalism. On a subset of our ensembles we have derived an upper bound on the magnitude of quark-disconnected diagrams and found that they decrease the estimate for aμhvp by at most 2%. Our final result is aμhvp=654±32−23+21

Exploring the phase diagram of QCD with complex Langevin simulations

{a}_{\mu}^{\mathrm{hvp}} = \left(654 \pm {32}_{{}^{-23}}^{+21}\right)

Insights into the heavy dense QCD phase diagram using Complex Langevin simulations

·10−10, where the first error is statistical, and the second denotes the combined systematic uncertainty. Based on our findings we discuss the prospects for determining aμhvp with sub-percent precision.