Lattice Field Theory, Quantum Fields under Extreme Conditions

Group Members 

 Permanent Staff:

Prof Gert Aarts

Prof Chris Allton

Prof Simon Hands

Prof Biagio Lucini 

 Postdoctoral Research Officers:

Dr Pietro Giudice 

Dr. Ari Hietanen

Postgraduate Research Students:

Alessandro Amato

Edward Bennett

Wynne Evans

Frank James

The research of the group focuses on QCD spectroscopy and thermodynamics, the properties of QCD-like theories with varying numbers of colors and matter field representations, and in 2+1 dimensional field theories with applications in condensed matter systems. 

 Recent research highlights:

   * a study of the critical line and equation of state across the quark/hadron phase transition for QCD with small but non-zero baryon chemical potential, relevant for the heavy-ion collision programme at RHIC and LHC (CA,SH).

  * studies of superfluid gap formation at large chemical potential via BCS diquark condensation in a phenomenologically-motivated NJL model similar to those used is studies of color superconductivity in neutron star interiors (SH).

  * studies of quark matter and deconfinement in SU(2) QCD at high baryon density   (SH).

  * light hadron spectroscopy in QCD using both non-perturbatively improved dynamical fermions, ensuring a more controlled extrapolation to the continuum limit, and domain wall fermions, ensuring a better passage to the chiral limit  (CA).

  * development of two-particle irreducible diagrammatic techniques to model quantum thermofield dynamics away from equilibrium via numerical integration of equations of motion, with applications in both cosmology and heavy-ion phenomenology (GA). 

 * stochastic quantization and complex Langevin dynamics: the sign problem for theories with a complex action due to a nonzero chemical potential (GA).

*  charmonium in the deconfined phase: spectral functions on highly anisotropic lattices (GA, CA).

*  bottomonium in the quark-gluon plasma using non-relativistic QCD (NRQCD) (GA, CA).

*  Study from first principles of gauge theories relevant for the scenario of dynamical electroweak symmetry breaking (BL)

 * evidence that corrections to the N_c=infinity limit of SU(N_c) gauge theory, analytically accessible via gauge/gravity duality and related string-inspired techniques, and numerically small for the physical case N_c=3 (BL).

  * first precise evaluations of k-string tensions in lattice gauge theories with N_c>3, enabling a test of various analytic non-perturbative scenarios   (BL). 

 * study of gap formation and quantum criticality in an effective field theory of graphene (SH).

 * first reliable lattice calculation of a QCD transport coefficient, the electrical conductivity of the quark-gluon plasma in quanched lattice QCD, via analysis of the current-current spectral density using the Maximum Entropy method (GA,CA,SH).