2,271 research outputs found
Quark-Antiquark Forces From SU(2) and SU(3) Gauge Theories on Large Lattices
We present results on the spin-independent quark-antiquark potential in SU(3)
gauge theory from a simulation on a 48^3*64 lattice at Beta = 6.8,
corresponding to a volume of (1.7 fm)^3. Moreover, a comprehensive analysis of
spin- and velocity-dependent potentials is carried out for SU(2) gauge theory,
with emphasis on the short range structure, on lattices with resolutions
ranging from .02 fm to .04 fm.Comment: 10 pages, uucompressed latex with 5 ps figures, epsf style require
Three-Dimensional SU(3) gauge theory and the Spatial String Tension of the (3+1)-Dimensional Finite Temperature SU(3) Gauge Theory
We establish a close relation between the spatial string tension of the
(3+1)-dimensional gauge theory at finite temperature () and
the string tension of the 3-dimensional gauge theory () which
is similar to what has been found previously for . We obtain
and , respectively. For temperatures larger than twice the critical
temperature results are consistent with a temperature dependent coupling
running according to the two-loop -function with .Comment: 11 pages (4 figures
Robust functional principal components: A projection-pursuit approach
In many situations, data are recorded over a period of time and may be
regarded as realizations of a stochastic process. In this paper, robust
estimators for the principal components are considered by adapting the
projection pursuit approach to the functional data setting. Our approach
combines robust projection-pursuit with different smoothing methods.
Consistency of the estimators are shown under mild assumptions. The performance
of the classical and robust procedures are compared in a simulation study under
different contamination schemes.Comment: Published in at http://dx.doi.org/10.1214/11-AOS923 the Annals of
Statistics (http://www.imstat.org/aos/) by the Institute of Mathematical
Statistics (http://www.imstat.org
Lattice simulations with improved Wilson fermions at a fixed strange quark mass
The explicit breaking of chiral symmetry of the Wilson fermion action results
in additive quark mass renormalization. Moreover, flavour singlet and
non-singlet scalar currents acquire different renormalization constants with
respect to continuum regularization schemes. This complicates keeping the
renormalized strange quark mass fixed when varying the light quark mass in
simulations with sea quark flavours. Here we present and validate our
strategy within the CLS (Coordinated Lattice Simulations) effort to achieve
this in simulations with non-perturbatively order- improved Wilson fermions.
We also determine various combinations of renormalization constants and
improvement coefficients.Comment: 18 pages, 11 Figures, V2: References added/updated, all fits rerun
with improved statistics for ensemble N204, also using the final values for
the improvement coefficients A and b_P-b_A (very minor impact), The figures
have been replotted accordingly. (The differences with respect to V1 are
invisible to the human eye). Minor change
The Spatial String Tension in the Deconfined Phase of the (3+1)-Dimensional SU(2) Gauge Theory
We present results of a detailed investigation of the temperature dependence
of the spatial string tension in SU(2) gauge theory. We show, for the first
time, that the spatial string tension is scaling on the lattice and thus is
non-vanishing in the continuum limit. It is temperature independent below Tc
and rises rapidly above. For temperatures larger than 2Tc we find a scaling
behaviour consistent with sigma_s(T) = 0.136(11) g^4(T) T^2, where g(T) is the
2-loop running coupling constant with a scale parameter determined as Lambda_T
= 0.076(13) Tc.Comment: 8 pages (Latex, shell archive, 3 PostScript figures), HLRZ-93-43,
BI-TP 93/30, FSU-SCRI-93-76, WUB 93-2
String breaking in Lattice QCD
The separation of a heavy quark and antiquark pair leads to the formation of
a tube of flux, or string, which should break in the presence of light
quark-antiquark pairs. This expected zero temperature phenomenon has proven
elusive in simulations of lattice QCD. We present simulation results that show
that the string does break in the confining phase at nonzero temperature.Comment: LATTICE98(hightemp), 3 pages, 4 figures, LaTe
A fresh look on the flux tube in Abelian-projected SU(2) gluodynamics
We reconsider the properties of the flux tube within
Abelian-projected SU(2) lattice gauge theory in terms of electric field and
monopole current. In the maximal Abelian gauge we assess the influence of the
Gribov copies on the apparent flux-tube profile. For the optimal gauge fixing
we study the independence of the profile on the lattice spacing for
2.3, 2.4, and 2.5115 on a lattice. We decompose the Abelian Wilson loop
into monopole and photon parts and compare the electric and monopole profile
emerging from different sources with the field strength and monopole current
within the dual Ginzburg-Landau theory.Comment: 3 pages, 6 figures, Lattice2002(topology
The Perceptions of Teachers, Parents and Students on the Effects of Mobile Phone Use on Student Learning in Tanzania
The use of mobile phones enables learners to interact with vast resource materials to facilitate learning. Yet in Tanzania, mobile phones are strictly prohibited in many schools. This study examined parentsâ, teachersâ and studentsâ perceptions of the effects of studentsâ access to mobile phones on students learning performance. It was conducted in four selected secondary schools in Dodoma municipality. Both qualitative and quantitative research methods were employed as data were collected from 280 respondents through questionnaire, interview schedule and documentary review. Cross-tabulation and Chi-square tests were among data analysis techniques employed in the understanding of different perceptions of respondents. The findings show that, parents and teachers agree that students with mobile phones perform poorly and misbehave more often than students without mobile phones. Also, in order to have value-based control system for appropriate use of mobile phones, providing proper education on mobile phone use and re-introducing censorship board to control the quality of contents on websites are recommended. Keywords: mobile phone use in school, effects of mobile phone use on academic performance, school mobile phone use policy in Tanzania
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