2,007 research outputs found
Chiral symmetry breaking in the truncated Coulomb Gauge II. Non-confining power law potentials
In this paper we study the breaking of chiral symmetry with non-confining
power-like potentials. The region of allowed exponents is identified and, after
the previous study of confining (positive exponent) potentials, we now
specialize in shorter range non-confining potentials, with a negative exponent.
These non-confining potentials are close to the Coulomb potential, and they are
also relevant as corrections to the linear confinement, and as models for the
quark potential at the deconfinement transition. The mass-gap equation is
constructed and solved, and the quarks mass, the chiral angle and the quark
energy are calculated analytically with a exponent expansion in the
neighbourhood of the Coulomb potential. It is demonstrated that chiral symmetry
breaking occurs, but only the chiral invariant false vacuum and a second
non-trivial vacuum exist. Moreover chiral symmetry breaking is led by the UV
part of the potential, with no IR enhancement of the quark mass. Thus the
breaking of chiral symmetry driven by non-confining potentials differs from the
one lead by confining potentials.Comment: 8 pages, 3 figure
Short distance physics with heavy quark potentials
We present lattice studies of heavy quark potentials in the quenched
approximation of QCD at finite temperatures. Both, the color singlet and color
averaged potentials are calculated. While the potentials are well known at
large distances, we give a detailed analysis of their short distance behavior
(from 0.015 fm to 1 fm) near the critical temperature. At these distances we
expect that the T-dependent potentials go over into the zero temperature
potential. Indeed, we find evidences that the temperature influence gets
suppressed and the potentials starts to become a unique function of the
underlying distance scale. We use this feature to normalize the heavy quark
potentials at short distances and extract the free energy of the quark system
in a gluonic heat bath.Comment: Lattice2001(hightemp), 3 pages, 2 figure
Heavy quark free energies, potentials and the renormalized Polyakov loop
We discuss the renormalized free energy of a heavy quark anti-quark pair in
the color singlet channel for quenched and full QCD at finite temperature. The
temperature and mass dependence, as well as its short distance behavior is
analyzed. Using the free energies we calculate the heavy quark potential and
entropy in quenched QCD. The asymptotic large distance behavior of the free
energy is used to define the non-perturbatively renormalized Polyakov loop
which is well behaved in the continuum limit. String breaking is studied in the
color singlet channel in 2-flavor QCD.Comment: 3 pages, Lattice2003(nonzero
Renormalized quark-anti-quark free energy
We present results on the renormalized quark-anti-quark free energy in SU(3)
gauge theory at finite temperatures. We discuss results for the singlet, octet
and colour averaged free energies and comment on thermal relations which allow
to extract separately the potential energy and entropy from the free energy.Comment: 5 pages, 2 figures, To appear in the proceedings of Workshop on
Strong and Electroweak Matter (SEWM 2002), Heidelberg, Germany, 2-5 Oct 200
An new order parameter with renormalized Polyakov loops
It is well established that physical quantities like the heavy quark
potentials get temperature independent at sufficiently short distances. As a
first application of this feature we suggest a new order parameter for the
confinement/deconfinement phase transition. Our investigations are based on
recent lattice studies.Comment: 2 pages, 2 figures, contribution to 'Statistical QCD', Bielefeld,
August 26-30, 200
Conjugate gradient solvers on Intel Xeon Phi and NVIDIA GPUs
Lattice Quantum Chromodynamics simulations typically spend most of the
runtime in inversions of the Fermion Matrix. This part is therefore frequently
optimized for various HPC architectures. Here we compare the performance of the
Intel Xeon Phi to current Kepler-based NVIDIA Tesla GPUs running a conjugate
gradient solver. By exposing more parallelism to the accelerator through
inverting multiple vectors at the same time, we obtain a performance greater
than 300 GFlop/s on both architectures. This more than doubles the performance
of the inversions. We also give a short overview of the Knights Corner
architecture, discuss some details of the implementation and the effort
required to obtain the achieved performance.Comment: 7 pages, proceedings, presented at 'GPU Computing in High Energy
Physics', September 10-12, 2014, Pisa, Ital
The QCD string tension curve, the ferromagnetic magnetization, and the quark-antiquark confining potential at finite Temperature
We study the string tension as a function of temperature, fitting the SU(3)
lattice QCD finite temperature free energy potentials computed by the Bielefeld
group. We compare the string tension points with order parameter curves of
ferromagnets, superconductors or string models, all related to confinement. We
also compare the SU(3) string tension with the one of SU(2) Lattice QCD. With
the curve providing the best fit to the finite temperature string tensions, the
spontaneous magnetization curve, we then show how to include finite
temperature, in the state of the art confining and chiral invariant quark
models.Comment: 9 pages, 12 figure
Heavy Quark Potentials and Quarkonia Binding
I review recent progress in studying in-medium modification of inter-quark
forces at finite temperature in lattice QCD. Some applications to the problem
of quarkonium binding in potential models is also discussed.Comment: Invited plenary talk presented at Hard Probes 2004, International
Conference on Hard and Electromagnetic Probes of High Energy Nuclear
Collisions, Nov. 4-10, 2004, Ericeira, Portuga
Static quark anti-quark free energy and the running coupling at finite temperature
We analyze the free energy of a static quark anti-quark pair in quenched QCD
at short and large distances. From this we deduce running couplings, g^2(r,T),
and determine the length scale that separates at high temperature the short
distance perturbative regime from the large distance non-perturbative regime in
the QCD plasma phase. Ambiguities in the definition of a coupling beyond the
perturbative regime are discussed in their relation to phenomenological
considerations on heavy quark bound states in the quark gluon plasma. Our
analysis suggests that it is more appropriate to characterize the
non-perturbative properties of the QCD plasma phase close to T_c in terms
remnants of the confinement part of the QCD force rather than a strong
Coulombic force.Comment: 8 pages, 9 EPS-files, revtex
- …