502 research outputs found
Critical exponents for higher-representation sources in 3D SU(3) gauge theory from CFT
We establish an exact mapping between the multiplication table of the
irreducible representations of SU(3) and the fusion algebra of the
two-dimensional conformal field theory in the same universality class of 3D
SU(3) gauge theory at the deconfining point. In this way the Svetitsky-Yaffe
conjecture on the critical behaviour of Polyakov lines in the fundamental
representation naturally extends to whatever representation one considers.
As a consequence, the critical exponents of the correlators of these Polyakov
lines are determined. Monte Carlo simulations with sources in the symmetric
two-index representation, combined with finite-size scaling analysis, compare
very favourably with these predictions.Comment: 15 pages, 2 figure
Critical behavior of 3D SU(2) gauge theory at finite temperature: exact results from universality
We show that universality arguments, namely the Svetitsky-Yaffe conjecture,
allow one to obtain exact results on the critical behavior of 3D SU(2) gauge
theory at the finite temperature deconfinement transition,through a mapping
into the 2D Ising model. In particular, we consider the finite-size scaling
behavior of the plaquette operator, which can be mapped into the energy
operator of the 2D Ising model. We obtain exact predictions for the dependence
of the plaquette expectation value on the size and shape of the lattice and we
compare them to Monte Carlo results, finding complete agreement. We discuss the
application of this method to the computation of more general correlators of
the plaquette operator at criticality, and its relevance to the study of the
color flux tube structure.Comment: 10 pages, LaTeX file + 3 eps figure
Decomposing the Yang-Mills Field
Recently we have proposed a set of variables for describing the physical
parameters of SU(N) Yang--Mills field. Here we propose an off-shell
generalization of our Ansatz. For this we envoke the Darboux theorem to
decompose arbitrary one-form with respect to some basis of one-forms. After a
partial gauge fixing we identify these forms with the preimages of holomorphic
and antiholomorphic forms on the coset space , identified as
a particular coadjoint orbit. This yields an off-shell gauge fixed
decomposition of the Yang-Mills connection that contains our original variables
in a natural fashion.Comment: 5 pages, latex, no figure
Cyclotron-Synchrotron: harmonic fitting functions in the non-relativistic and trans-relativistic regimes
The present work investigates the calculation of absorption and emission
cyclotron line profiles in the non-relativistic and trans-relativistic regimes.
We provide fits for the ten first harmonics with synthetic functions down to
10^(-4) of the maximum flux with an accuracy of 20 per cent at worst. The lines
at a given particle energy are calculated from the integration of the Schott
formula over the photon and the particle solid angles relative to the magnetic
field direction. The method can easily be extended to a larger number of
harmonics. We also derive spectral fits of thermal emission line plasmas at
non-relativistic and trans-relativistic temperatures extending previous
parameterisations.Comment: 11 pages, 11 figures, accepted for publication in Astronomy &
Astrophysic
XMM-Newton monitoring of X-ray variability in the quasar PKS 0558-504
We present the temporal analysis of X-ray observations of the radio-loud
Narrow-Line Seyfert 1 galaxy (NLS1) PKS 0558-504 obtained during the XMM-Newton
Calibration and Performance Verification (Cal/PV) phase. The long term light
curve is characterized by persistent variability with a clear tendency for the
X-ray continuum to harden when the count rate increases. Another strong
correlation on long time scales has been found between the variability in the
hard band and the total flux. On shorter time scales the most relevant result
is the presence of smooth modulations, with characteristic time of ~ 2 hours
observed in each individual observation. The short term spectral variability
turns out to be rather complex but can be described by a well defined pattern
in the hardness ratio-count rate plane.Comment: 6 pages, 7 figures, accepted for publication in A&A special issue on
first results from XM
Glaciology of the Queen Maud Land Traverse, 1964-65 South Pole - Pole of Relative Inaccessibility
The University Archives has determined that this item is of continuing value to OSU's history.An oversnow traverse was made from the South Pole to the Pole of Relative Inaccessibility along a zigzag path of about 800 nautical miles during the period 4 December 1964 to 27 January 1965. The surface varied from very hard with many highly developed sastrugi to very soft and smooth. The average air temperature was -28.8°C, with an absolute maximum of -l8.2°C on 5 January and an absolute minimum of -44.7°C on 26 January. The absolute maximum wind speed recorded was 9.0 m/s on 29 December and 17 January; there was 3 percent calm in December and 1 percent calm in January. Solar halos were frequent. Firn temperatures were taken at 29 sites; the most striking anomaly occurred on the last leg of the traverse where there was an abrupt change in slope and as the height increased the temperature anomalously increased before decreasing as expected. The temperature profile at the Pole of Inaccessibility was similar to that obtained by the Soviets in 1964. Temperature gradients were negative at the South Pole but strikingly positive in the vicinity of the Pole of Inaccessibility. Density profiles to depths of 40 m were taken at 12 sites with a neutron-scattering device; most of the density curves showed a break at a density of 0.52 to 0.54 g/cm3. Snow accumulation studies in pits showed an accumulation generally between 5 and 10g/cm2. Snow accumulation measured at the anemometer mast and the instrument shelter at the Pole of Inaccessibility for the period 14 December 1958 to 30 January 1965 was 3-6 g/cm2/yr.National Science Foundation NSF Grant GA-13
String effects and the distribution of the glue in mesons at finite temperature
The distribution of the gluon action density in mesonic systems is
investigated at finite temperature. The simulations are performed in quenched
QCD for two temperatures below the deconfinment phase. Unlike the gluonic
profiles displayed at T=0, the action density iso-surfaces display a
prolate-spheroid like shape. The curved width profile of the flux-tube is found
to be consistent with the prediction of the free Bosonic string model at large
distances.Comment: 14 pages,10 figure
Buried AGNs in Advanced Mergers:Mid-infrared color selection as a dual AGN finder
A direct consequence of hierarchical galaxy formation is the existence of
dual supermassive black holes (SMBHs), which may be preferentially triggered as
active galactic nuclei (AGN) during galaxy mergers. Despite decades of
searching, however, dual AGNs are extremely rare, and most have been discovered
serendipitously. Using the all-sky WISE survey, we identified a population of
over 100 morphologically identified interacting galaxies or mergers that
display red mid-infrared colors often associated in extragalactic sources with
powerful AGNs. The vast majority of these advanced mergers are optically
classified as star-forming galaxies suggesting that they may represent an
obscured population of AGNs that cannot be found through optical studies. In
this work, we present Chandra/ACIS observations and near-infrared spectra with
the Large Binocular Telescope of six advanced mergers with projected pair
separations less than ~ 10 kpc. The combined X-ray, near-infrared, and
mid-infrared properties of these mergers provide confirmation that four out of
the six mergers host at least one AGN, with four of the mergers possibly
hosting dual AGNs with projected separations less than ~10 kpc, despite showing
no firm evidence for AGNs based on optical spectroscopic studies. Our results
demonstrate that 1) optical studies miss a significant fraction of single and
dual AGNs in advanced mergers, and 2) mid-infrared pre-selection is extremely
effective in identifying dual AGN candidates in late-stage mergers. Our
multi-wavelength observations suggest that the buried AGNs in these mergers are
highly absorbed, with intrinsic column densities in excess of N_H >10^24cm^-2,
consistent with hydrodynamic simulations.Comment: 23 pages, 11 figures, accepted for publication to Ap
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