4,849 research outputs found
Three-quark potentials in an effective Polyakov loop model
Three-quark potentials are studied in great details in the three-dimensional
pure gauge theory at finite temperature, for the cases of static
sources in the fundamental and adjoint representations. For this purpose, the
corresponding Polyakov loop model in its simplest version is adopted. The
potentials in question, as well as the conventional quark--anti-quark
potentials, are calculated numerically both in the confinement and
deconfinement phases. Results are compared to available analytical predictions
at strong coupling and in the limit of large number of colors . The
three-quark potential is tested against the expected and laws and
the string tension entering these laws is compared to the conventional
string tension. As a byproduct of this investigation, essential
features of the critical behaviour across the deconfinement transition are
elucidated.Comment: 28 pages, 18 figures, 4 tables; some text and a few references added;
version accepted for publication on Nucl. Phys.
The phase transitions in 2D Z(N) vector models for N>4
We investigate both analytically and numerically the renormalization group
equations in 2D Z(N) vector models. The position of the critical points of the
two phase transitions for N>4 is established and the critical index \nu\ is
computed. For N=7, 17 the critical points are located by Monte Carlo
simulations and some of the corresponding critical indices are determined. The
behavior of the helicity modulus is studied for N=5, 7, 17. Using these and
other available Monte Carlo data we discuss the scaling of the critical points
with N and some other open theoretical problems.Comment: 19 pages, 8 figures, 10 tables; version to appear on Phys. Rev.
Analytic model of Regge trajectories
A model for a Regge trajectory compatible with the threshold behavior
required by unitarity and asymptotics in agreement with analyticity constraints
is given in explicit form. The model is confronted in the time-like region with
widths and masses of the mesonic resonances and, in the space-like region, the
trajectory is compared with predictions derived from
charge-exchange reaction. Breaking of the exchange degeneracy is studied in the
model and its effect on both the masses and widths is determined.Comment: 17 pages, 3 figure
The fixed point action of the Schwinger model
We compute the fixed point action for the Schwinger model through an
expansion in the gauge field. The calculation allows a check of the locality of
the action. We test its perfection by computing the 1-loop mass gap at finite
spatial volume.Comment: 3 pages, LaTeX, 2 figures, uses styles [twoside,fleqn,espcrc2,
epsfig], talk presented at Lattice 9
Search for continuous gravitational waves from small-ellipticity sources at low frequencies
We present the results of an all-sky search for continuous gravitational wave signals with frequencies in the 20-500 Hz range from neutron stars with ellipticity of 1e-8. This frequency region is particularly hard to probe because of the quadratic dependence of signal strength on frequency. The search employs the Falcon analysis pipeline on LIGO O2 public data. Compared to previous Falcon analyses the coherence length has been quadrupled, with a corresponding increase in sensitivity. This enables us to search for small ellipticity neutron stars in this low frequency region up to 44 pc away. The frequency derivative range is up to 3e-13 Hz/s easily accommodating sources with ellipticities of 1e-7 and a corresponding factor of 10 increase in reach. New outliers are found, many of which we are unable to associate with any instrumental cause
Critical behavior of 3D Z(N) lattice gauge theories at zero temperature
Three-dimensional lattice gauge theories at zero temperature are
studied for various values of . Using a modified phenomenological
renormalization group, we explore the critical behavior of the generalized
model for . Numerical computations are used to simulate
vector models for for lattices with linear extension up
to . We locate the critical points of phase transitions and establish
their scaling with . The values of the critical indices indicate that the
models with belong to the universality class of the three-dimensional
model. However, the exponent derived from the heat capacity is
consistent with the Ising universality class. We discuss a possible resolution
of this puzzle. We also demonstrate the existence of a rotationally symmetric
region within the ordered phase for all at least in the finite
volume.Comment: 25 pages, 4 figures, 8 table
A frequency resolved atlas of the sky in continuous gravitational waves
We present the first atlas of the continuous gravitational wave sky, produced using LIGO O3a public data. For each 0.045 Hz frequency band and every point on the sky the atlas provides upper limits, signal-to-noise ratios (SNR) and frequencies where the search measures the maximum SNR. The results presented in the atlas are produced with the Falcon pipeline and cover nearly monochromatic gravitational wave signals in the 500-1000 Hz band, with up to +/-5e-11 Hz/s frequency derivative. Compared to the most sensitive results previously published (also produced with the Falcon pipeline) our upper limits are 50% more constraining. Neutron stars with ellipticity of 1e-8 can be detected up to 150 pc away, while allowing for a large fraction of the stars' energy to be lost through non-gravitational channels
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