Aoife Kelly

Quark-gluon plasma phenomenology from anisotropic lattice QCD

The FASTSUM collaboration has been carrying out simulations of N-f = 2 + 1 QCD at nonzero temperature in the fixed-scale approach using anisotropic lattices. Here we present the status of these studies, including recent results for electrical conductivity and charge diffusion, and heavy quarkonium (charm and beauty) physics.

2+1 flavour thermal studies on an anisotropic lattice

The FASTSUM collaboration has initiated a detailed study of thermal QCD using 2+1 flavours of improved Wilson quarks on anisotropic lattices. Spatial volumes of (3fm)^3 and (4fm)^3 are used at fixed cut-off with temperatures ranging from 40 to 350 MeV (corresponding to temporal lattice extents of 128 to 16 lattice units). Results presented here include the deconfinement temperature and a study of the restoration of chiral symmetry, together with a brief summary of our collaborations other results from these ensembles.

Spectral functions of charmonium from 2 flavour anisotropic lattice data

The spectral functions of QCD can give us insight into properties of hadrons, and they are useful in probing the QCD vacuum. I will discuss the correlators and spectral functions of charmonium in high temperature two flavour QCD. The spectral functions have been obtained using the Maximum Entropy Method from anisotropic lattice data using the conserved vector current. This work has been done as part of the FASTSUM collaboration. We find that the spectral functions for zero momentum are stable. At non-zero momentum the spectral functions are less stable but still produce resonance and transport peaks. This work is part of our programme to calculate the heavy quark diffusion constant.

Thermal D mesons from anisotropic lattice QCD

We present results for correlators and spectral functions of open charm mesons using 2+1 flavours of clover fermions on anisotropic lattices. The D mesons are found to dissociate close to the deconfinement crossover temperature T c . Our preliminary results suggest a shift in the thermal D meson mass below T c . Mesons containing strange quarks exhibit smaller thermal modifications than those containing light quarks.

Quark-gluon plasma phenomenology from the lattice

The FASTSUM Collaboration has calculated several quantities relevant for QCD studies at non-zero temperature using the lattice technique. We report here our results for the (i) interquark potential in charmonium; (ii) bottomonium spectral functions; and (iii) electrical conductivity. All results were obtained with 2+1 flavours of dynamical fermions on an anisotropic lattice which allows greater resolution in the temporal direction.

Bottomonium from lattice QCD as a probe of the Quark-Gluon Plasma

We study the temperature dependence of bottomonium for temperatures in the range 0.4Te < T < 2.1Tc, using non-relativistic dynamics for the bottom quark and full relativistic lattice QCD simulations for Nf = 2 light flavors. We consider the behaviour of the correlators in Euclidean space, we analyze the associated spectral functions and we study the dependence on the momentum. Our results are amenable to a successful comparison with effective field theories. They help build a coherent picture of the behaviour of bottomonium in the plasma, consistent which the current LHC results.

Bottomonium in the plasma : Lattice results

We present results on the heavy quarkonium spectrum and spectral functions obtained by performing large-scale simulations of QCD for temperatures ranging from about 100 to 500 MeV, in the same range as those explored by LHC experiments. We discuss our method and perspectives for further improvements towards the goal of full control over the many systematic uncertainties of these studies.

Quark-Gluon Plasma: from lattice simulations to experimental results

Theoretical studies of quarkonia can elucidate some of the important properties of the quark-gluon plasma, the state of matter realised when the temperature exceeds O(150) MeV, currently probed by heavy-ion collisions experiments at BNL and the LHC. We report on our results of lattice studies of bottomonia for temperatures in the range 100 MeV T 450 MeV, introducing and discussing the methodologies we have applied. Of particular interest is the analysis of the spectral functions, where Bayesian methods borrowed and adapted from nuclear and condensed matter physics have proven very successful.