133 research outputs found
Topological Fluctuations in Dense Matter with Two Colors
We study the topological charge fluctuations of an SU(2) lattice gauge theory
containing both N_f=2 and 4 flavors of Wilson fermion, at low temperature with
non-zero chemical potential . The topological susceptibility, chi_T, is
used to characterize differing physical regimes as mu is varied between the
onset of matter at mu_o and and color deconfinement at mu_d. Suppression of
instantons by matter via Debye screening is also investigated, revealing
effects not captured by perturbative predictions. In particular, the breaking
of scale invariance leads to the mean instanton size rho becoming mu-dependent
in the regime between onset and deconfinement, with a scaling rho~1/mu^2 over
the range mu_o<mu<mu_d, resulting in an enhancement of chi_T immediately above
onset.Comment: 12 pages, 7 figure
Lattice-QCD based Schwinger-Dyson approach for Chiral Phase Transition
Dynamical chiral-symmetry breaking in QCD is studied with the Schwinger-Dyson
(SD) formalism based on lattice QCD data, i.e., LQCD-based SD formalism. We
extract the SD kernel function in an Ansatz-independent manner from
the lattice data of the quark propagator in the Landau gauge. As remarkable
features, we find infrared vanishing and intermediate enhancement of the SD
kernel function . We apply the LQCD-based SD equation to thermal QCD
with the quark chemical potential . We find chiral symmetry restoration
at for . The real part of the quark mass
function decreases as and . At finite density, there appears the
imaginary part of the quark mass function, which would lead to the width
broadening of hadrons.Comment: 4 pages, 4 figures, Presented at Workshop on QCD Down Under, Barossa
Valley and Adelaide, Australia, 10-19 Mar 200
Hadrons at high temperature: an update from the FASTSUM collaboration
We present the most recent results from the FASTSUM collaboration for hadron
properties at high temperature. This includes the temperature dependence of the
light and charmed meson and baryon spectrum, as well as properties of heavy
quarkonia. The results are obtained using anisotropic lattices with a fixed
scale approach. We also present the status of our next generation gauge
ensembles.Comment: 8 pages, 8 figures. Contribution to the XVth Quark Confinement and
the Hadron Spectrum, 1-6 August 2022, Stavanger, Norwa
DSE Hadron Phenomenology
A perspective on the contemporary use of Dyson-Schwinger equations, focusing
on some recent phenomenological applications: a description and unification of
light-meson observables using a one-parameter model of the effective
quark-quark interaction, and studies of leptonic and nonleptonic nucleon form
factors.Comment: 7 pages, sprocl.sty, epsfig.sty. Contribution to the Proceedings of
the Workshop on Light-Cone QCD and Nonperturbative Hadron Physics, Adelaide,
Australia, 13-22 Dec 199
Static-light mesons on a dynamical anisotropic lattice
We present results for the spectrum of static-light mesons from Nf=2 lattice
QCD. These results were obtained using all-to-all light quark propagators on an
anisotropic lattice, yielding an improved signal resolution when compared to
more conventional lattice techniques. In particular, we consider the inversion
of orbitally-excited multiplets with respect to the `standard ordering', which
has been predicted by some quark models.Comment: 3 pages with 3 figures. Talk by JF at "Quarks and Nuclear Physics",
Madrid 5th-10th June 200
Mesons at high temperature in Nf=2 QCD
We report first results for spectral functions of charmonium in 2-flavour
QCD. The spectral functions are determined from vector and pseudoscalar
correlators on a dynamical, anisotropic lattice. J/psi and eta_c are found to
survive well into the deconfined phase before melting away at T<~2T_c. Current
systematic uncertainties prevent us from drawing any definite conclusions at
this stage.Comment: 4 pages, 4 figures, to appear in proceedings of Computational Hadron
Physics, Nicosia, 14-17 Sep 200
Multi-hadron spectroscopy in a large physical volume
We demonstrate the efficacy of the stochastic LapH method to treat all-to-all
quark propagation on a CLS ensemble with large linear spatial
extent fm, allowing us to obtain the benchmark elastic isovector
p-wave pion-pion scattering amplitude to good precision already on a relatively
small number of gauge configurations. These results hold promise for
multi-hadron spectroscopy at close-to-physical pion mass with exponential
finite-volume effects under control.Comment: 8 pages, 4 figures. Presented at Lattice 2017, the 35th International
Symposium on Lattice Field Theory, Granada, Spain, 18-24 June 201
Modelling of an IR scintillation counter
A systematic study of the excitation and de-excitation mechanisms in ternary gas mixtures Ar+CO2+N2 is presented regarding the possibility of developing a proportional scintillation counter based on the detection of the infrared molecular emissions associated with the lowest vibrational states of molecules. The use of visible or near-infrared photons ([lambda]<1ĂÂ [mu]m) for applications like imaging and quality control of microstructure detectors has been reported. In view of these applications we analyse the processes leading to near-infrared emissions in pure argon and give an estimation of the number of photons emitted per electron, at several pressures, as a function of the charge gain.http://www.sciencedirect.com/science/article/B6TJM-3YXB101-2M/1/b5bfeb3739389bb6dbe4d84c8746dbf
Thermal Transitions in Dense Two-Colour QCD
The infamous sign problem makes it impossible to probe dense (baryon density ÎŒB > 0) QCD at temperatures near or below the deconfinement threshold. As a workaround, one can explore QCD-like theories such as twocolour QCD (QC2D) which donât suffer from this sign problem but are qualitively similar to real QCD. Previous studies on smaller lattice volumes have investigated deconfinement and colour superfluid to normal matter transitions. In this study we look at a larger lattice volume Ns = 24 in an attempt to disentangle finite volume and finite temperature effects. We also fit to a larger number of diquark sources to better allow for extrapolation to zero diquark source
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