501 research outputs found
Color screening in flavor QCD at large distances
We study correlation functions of spatially separated static quark-antiquark
pairs in flavor QCD in order to investigate the nature of color screening
at high temperatures. We perform lattice calculations in a wide temperature
range, , using the highly improved
staggered quark (HISQ) action and several lattice spacings to control
discretization effects. We alleviate the UV noise problem through the use of
four dimensional hypercubic (HYP) smearing, which enables the reconstruction of
correlators and determination of screening properties even at low temperatures
and at large distances.Comment: 8 pages, 9 figure
Strong coupling constant from moments of quarkonium correlators revisited
We revisit the previous determination of the strong coupling constant from
moments of quarkonium correlators in (2+1)-flavor QCD. We use previously
calculated moments obtained with Highly Improved Staggered Quark (HISQ) action
for five different quark masses and several lattice spacings. We perform a
careful continuum extrapolation of the moments, and from the comparison of
these to the perturbative result we determine the QCD Lambda parameter,
MeV. This corresponds
to .Comment: 18 pages, 6 figure
Exploring the anisotropic HISQ (aHISQ) action
The fate of heavy quarkonia states in quark-gluon plasma is encoded in the
temperature dependence of their spectral functions. Reconstruction of spectral
functions from Euclidean lattice correlators is an ill-posed problem. Despite a
variety of techniques developed recently, many questions remain unresolved. It
is known that the situation may be improved using anisotropic ensembles that
provide finer resolution in the temporal direction. To date, the effort focused
on Wilson fermions. We report on our first study with anisotropic improved
staggered quarks. To compute the spectrum of the anisotropic Highly Improved
Staggered Quarks (aHISQ) we generated a library of anisotropic pure gauge
ensembles. We discuss the gauge anisotropy tuning that is performed with the
Wilson and Symanzik gradient flow, as well as tuning of the strange quark mass
and quark anisotropy with aHISQ, using spectrum measurements on quenched
ensembles. Finally, we discuss the impact of anisotropy on pion taste
splittings for aHISQ.Comment: 8 pages, 4 figures, The 40th International Symposium on Lattice Field
Theory (Lattice 2023), July 31st - August 4th, 2023, Fermi National
Accelerator Laborator
In-medium static inter-quark potential on high resolution quenched lattices
We re-investigate the interactions between static color sources in a finite
temperature gluonic medium using both high resolution isotropic and anisotropic
quenched lattice QCD ensembles. The underlying ill-posed inverse problem,
related to the extraction of spectral functions, is attacked with a range of
different methods, including Bayesian inference, Pad\'e interpolation and model
fits. Among the latter we include a tail amended Gaussian ansatz and a
HTL-inspired fit ansatz. We reconfirm the presence of a dominant low-lying
spectral feature that supports the existence of a potential picture for the
in-medium evolution of the static charges at late real times. Using the raw
unmodified lattice data, all applicable methods show clear signs of screening
of the real-part of the potential. After applying a subtraction procedure
featured in a previous study we find however that screening disappears from the
extracted potential. Paths towards the resolution of this puzzle are discussed.Comment: 54 pages, 40 figure
Supersphere non-linear sigma model on the lattice
Two-dimensional O(N) non-linear sigma models are exactly solvable theories and have many applications, from statistical mechanics to their use as QCD toy models. We consider a supersymmetric extension, the non-linear sigma model on the supersphere~SN+2m−1|2m≡OSP(N+2m|2m)OSP(N+2m−1|2m) . We briefly describe its renormalization properties and lattice discretization, and present a strategy for numerical simulations together with some preliminary numerical results
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