4,849 research outputs found

    Three-quark potentials in an SU(3)SU(3) effective Polyakov loop model

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    Three-quark potentials are studied in great details in the three-dimensional SU(3)SU(3) 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 NN. The three-quark potential is tested against the expected Δ\Delta and YY laws and the 3q3q string tension entering these laws is compared to the conventional qqˉq\bar{q} 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

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    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

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    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 ρ\rho trajectory is compared with predictions derived from πN\pi-N 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

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    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

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    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

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    Three-dimensional Z(N)Z(N) lattice gauge theories at zero temperature are studied for various values of NN. Using a modified phenomenological renormalization group, we explore the critical behavior of the generalized Z(N)Z(N) model for N=2,3,4,5,6,8N=2,3,4,5,6,8. Numerical computations are used to simulate vector models for N=2,3,4,5,6,8,13,20N=2,3,4,5,6,8,13,20 for lattices with linear extension up to L=96L=96. We locate the critical points of phase transitions and establish their scaling with NN. The values of the critical indices indicate that the models with N>4N>4 belong to the universality class of the three-dimensional XYXY model. However, the exponent α\alpha 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 N5N\geq 5 at least in the finite volume.Comment: 25 pages, 4 figures, 8 table

    A frequency resolved atlas of the sky in continuous gravitational waves

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    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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