Near the second order phase transition point, QCD with two flavours of massless quarks can be approximated by an O(4) model, where a symmetry breaking external field H can be added to play the role of quark mass.
The Lee-Yang theorem states that the equation of state in this model has a branch cut along the imaginary H axis for |Im[H]|>Hc, where Hc indicates a second order critical point.
This point, known as Lee-Yang edge singularity, is of importance to the thermodynamics of the system.
We report here on ongoing work to determine the location of Hc via complex Langevin simulations.

F. Attanasio, M. Bauer, L. Kades, J. M. Pawlowski, “Searching for Yang-Lee zeros in O(N)
models”, PoS LATTICE2021, 223 (2022).


Related to Project A02