1,225 research outputs found
Hadron resonance gas and nonperturbative QCD vacuum at finite temperature
We study the nonperturbative QCD vacuum with two light quarks at finite
temperature in the framework of hadron resonance gas. Temperature dependence of
the quark and gluon condensates in the confined phase are obtained. We
demonstrate that the quark condensate and one half (chromo-electric component)
of gluon condensate evaporate at the same temperature, which corresponds to the
temperature of quark-hadron phase transition. Critical temperature is T_c~190
MeV when temperature shift of hadron masses is taken into account.Comment: 8 pages, 4 figures; to appear in JETP Lett.; v2: references adde
Static potential in baryon in the method of field correlators
The static three-quark potential in arbitrary configuration of quarks is
calculated analytically. It is shown to be in a full agreement with the precise
numerical simulations in lattice QCD. The results of the work have important
application in nuclear physics, as they allow to perform accurate analytic
calculations of spectra of the baryons.Comment: 12 pages, 4 eps figures, latex2e, to appear in Yad.Fi
Mixing of scalar glueballs and flavour-singlet scalar mesons
We discuss in detail the extraction of hadronic mixing strengths from lattice
studies. We apply this to the mixing of a scalar glueball and a scalar meson in
the quenched approximation. We also measure correlations appropriate for
flavour-singlet scalar mesons using dynamical quark configurations from UKQCD.
This enables us to compare the results from the quenched study of the mixing
with the direct determination of the mixed spectrum. Improved methods of
evaluating the disconnected quark diagrams are also presented.Comment: 23 pages, 5 postscript figure
Experimental Study of Concrete Class Influence on Cracks Openings
The aim of this experimental work is to study reinforced concrete continuous beams cracking by considering different classes of concretes. As it is well known, the design of reinforced concrete structures considers three limit states (limit state of collapse, limit state of strain and limit state of cracking). The cracks in reinforced concrete structures are admitted in the phase II (cracked sections). Thus, the phenomenon of cracks can be treated as a normal state only when the cracks opening is limited to avoid a permanent risk of collapse and ensure durability for the civil engineering constructions. Tests on real scale reinforced concrete continuous beams were carried out under concentrated loads increasing from zero up to collapse. The influence of the concrete classes on crack opening has been investigated
On the non-Abelian Stokes theorem for SU(2) gauge fields
We derive a version of non-Abelian Stokes theorem for SU(2) gauge fields in
which neither additional integration nor surface ordering are required. The
path ordering is eliminated by introducing the instantaneous color orientation
of the flux. We also derive the non-Abelian Stokes theorem on the lattice and
discuss various terms contributing to the trace of the Wilson loop.Comment: Latex2e, 0+14 pages, 3 figure
Quarkonium Suppression
I discuss quarkonium suppression in equilibriated strongly interacting
matter. After a brief review of basic features of quarkonium production I
discuss the application of recent lattice data on the heavy quark potential to
the problem of quarkonium dissociation as well as the problem of direct lattice
determination of quarkonium properties in finite temperature lattice QCD.Comment: Invited plenary talk presented on 4th International Conference on
Physics and Astrophysics of Quark Gluon Plasma (ICPAQGP-2001), November
26-30, 2001, Jaipur; 12 pp, LaTeX, uses pramana.st
Ab Initio Calculation of Relativistic Corrections to the Static Interquark potential I: SU(2) Gauge Theory
We test the capability of state-of-the-art lattice techniques for a precise
determination of relativistic corrections to the static interquark potential,
by use of SU(2) gauge theory. Emphasis is put on the short range structure of
the spin dependent potentials, with lattice resolution a ranging from a approx
0.04 fm (at beta=2.74) down to a approx 0.02 fm (at beta=2.96) on volumes of
32^4 and 48^4 lattice sites. We find a new short range Coulomb-like
contribution to the spin-orbit potential V_1'.Comment: 37 pages REVTeX with 20 encapsuled ps figure
Can a Logarithmically Running Coupling Mimic a String Tension?
It is shown that a Coulomb potential using a running coupling slightly
modified from the perturbative form can produce an interquark potential that
appears nearly linear over a large distance range. Recent high-statistics SU(2)
lattice gauge theory data fit well to this potential without the need for a
linear string-tension term. This calls into question the accuracy of string
tension measurements which are based on the assumption of a constant
coefficient for the Coulomb term. It also opens up the possibility of obtaining
an effectively confining potential from gluon exchange alone.Comment: 13 pages, LaTeX, two figures not included, available from author.
revision - Line lengths fixed so it will tex properl
Decay Constants of Heavy-Light Mesons
The decay constants of the heavy-light pseudoscalar mesons are studied in a
high statistics run using the Wilson action at and , and
the clover action at . The systematics of discretisation
errors are discussed. Our best estimates of the decay constants are: =
218(9) MeV, = 1.11(1) and we obtain preliminary values for .Comment: at the Dallas Lattice Conference, October 1993. 3 pages in a single
postscript file, uuencoded form. Rome Preprint 93/98
Quark mass dependence of hadron masses from lattice QCD
We discuss lattice methods to obtain the derivatives of a lattice meson mass
with respect to the bare sea and valence quark masses. Applications are made to
quenched and dynamical fermion configurations. We find evidence for significant
differences between quenched and dynamical fermion configurations. We discuss
how to relate dependence on the bare lattice parameters to more
phenomenologically useful quantities.Comment: 18 pages, 5 figures, typos fixed and reference adde
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