490 research outputs found
Remarks on the Value of the Higgs Mass from the Present LEP Data
We perform a detailed comparison of the present LEP data with the one-loop
standard-model predictions. It is pointed out that for GeV the
``bulk'' of the data prefers a rather large value of the Higgs mass in the
range 500-1000 GeV, in agreement with the indications from the W mass. On the
other hand, to accommodate a light Higgs it is crucial to include the more
problematic data for the F-B asymmetry. We discuss further improvements
on the data taking required to obtain a firm conclusion.Comment: LaTeX Some comments were added to the note in relation to the new
data on the top-quark mass
Lepton distribution as a probe of new physics in production and decay of the t quark and its polarization
We investigate the possibilities of studying new physics in various processes
of t-quark production using kinematical distributions of the secondary lepton
coming from decay of t quarks. We show that the angular distributions of the
secondary lepton are insensitive to the anomalous tbW vertex and hence are pure
probes of new physics in a generic process of t-quark production. The energy
distribution of the lepton is distinctly affected by anomalous tbW couplings
and can be used to analyze them independent of the production process of t
quarks. The effects of t polarization on the distributions of the decay lepton
are demonstrated for top-pair production process at a gamma-gamma collider
mediated by a heavy Higgs boson.Comment: 15 pages, 7 figures, uses axodraw.sty (included), references added.
v3 to appear in Journal of High Energy Physics. Incorporates minor changes in
the discussion on radiative corrections which do not affect the results. Typo
in reference correcte
Dual Superconductor Mechanism of Confinement on the Lattice
We investigate the dual superconductor mechanism of confinement for pure
SU(2) lattice gauge theory in the maximally abelian gauge. We focus on the the
dual Meissner effect. We find that the transverse distribution of the
longitudinal chromoelectric field due to a static quark-antiquark pair
satisfies the dual London equation. Moreover we show that the size of the flux
tube scales according to asymptotic freedom.Comment: LaTeX, 9 pages, 6 figures available as a PostScript file from L.
Cosmai, BARI - TH 110/9
On the perfect lattice actions of abelian-projected SU(2) QCD
We study the perfect lattice actions of abelian-projected SU(2) gluodynamics.
Using the BKT and duality transformations on the lattice, an effective string
model is derived from the direction-dependent quadratic monopole action,
obtained numerically from SU(2) gluodynamics in maximally abelian gauge. The
string tension and the restoration of continuum rotational invariance are
investigated using strong coupling expansion of lattice string model
analytically. We also found that the block spin transformation can be performed
analytically for the quadratic monopole action.Comment: 3 pages, Latex, 1 figures; talk presented at LATTICE9
Systematic study of autocorrelation time in pure SU(3) lattice gauge theory
Results of our autocorrelation measurement performed on Fujitsu AP1000 are
reported. We analyze (i) typical autocorrelation time, (ii) optimal mixing
ratio between overrelaxation and pseudo-heatbath and (iii) critical behavior of
autocorrelation time around cross-over region with high statistic in wide range
of for pure SU(3) lattice gauge theory on , and
lattices. For the mixing ratio K, small value (3-7) looks optimal in the
confined region, and reduces the integrated autocorrelation time by a factor
2-4 compared to the pseudo-heatbath. On the other hand in the deconfined phase,
correlation times are short, and overrelaxation does not seem to matter For a
fixed value of K(=9 in this paper), the dynamical exponent of overrelaxation is
consistent with 2 Autocorrelation measurement of the topological charge on
lattice at = 6.0 is also briefly mentioned.Comment: 3 pages of A4 format including 7-figure
Autocorrelation in Updating Pure SU(3) Lattice Gauge Theory by the use of Overrelaxed Algorithms
We measure the sweep-to-sweep autocorrelations of blocked loops below and
above the deconfinement transition for SU(3) on a lattice using
20000-140000 Monte-Carlo updating sweeps. A divergence of the autocorrelation
time toward the critical is seen at high blocking levels. The peak is
near = 6.33 where we observe 440 210 for the autocorrelation time
of Wilson loop on blocked lattice. The mixing of 7 Brown-Woch
overrelaxation steps followed by one pseudo-heat-bath step appears optimal to
reduce the autocorrelation time below the critical . Above the critical
, however, no clear difference between these two algorithms can be seen
and the system decorrelates rather fast.Comment: 4 pages of A4 format including 6-figure
Finite Temperature Gauge Theory on Anisotropic Lattices
The finite temperature transition of QCD can be seen as a change in the
structure of the hadrons and as a symmetry breaking transition -- a change in
the structure of the vacuum. These phenomena are observed differently and carry
complementary information. We aim at a correlated analysis involving hadronic
correlators and the vacuum structure including field and density correlations,
both non-trivial questions.Comment: 3 pages, Talk presented at LATTICE96(finite temperature
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