Cold Quark matter
The phase diagram of quantum chromodynamics (QCD), the theory of the strong nuclear force, is poorly understood. At high enough temperatures or densities, the strong coupling constant $\alpha_s$, characterizing the interactions between fundamental quarks and gluons, becomes small. In this regime, perturbative calculations directly within QCD are possible.
Much of my research has been focussed on pushing perturbative QCD calculations beyond the next-to-next-to-leading order computations performed in the 1980s. Since 2018, my work has characterized the next-to-next-to-next-to-leading order equation of state of cold, zero-temperature quark matter, through a series of Physical Review Letter articles (in 2018, 2021, and 2023). The full N3LO computation is now within reach.
I have also improved the calculation of the finite-temperature equation of state of quark matter, adding the effect of quark masses in an article in Phys. Rev. D in 2022.