3,192 research outputs found
Study on the mechanism of open-flavor strong decays
The open-flavor strong decays are studied based on the interaction of
potential quark model. The decay process is related to the s-channel
contribution of the same scalar confinment and one-gluon-exchange(OGE)
interaction in the quark model. After we adopt the prescription of massive
gluons in time-like region from the lattice calculation, the approximation of
four-fermion interaction is applied. The numerical calculation is performed to
the meson decays in , , light flavor sector. The analysis of the
ratios of and show
that the scalar interaction should be dominant in the open-flavor decays
Nonequilibrium Dynamics and Aging in the Three--Dimensional Ising Spin Glass Model
The low temperature dynamics of the three dimensional Ising spin glass in
zero field with a discrete bond distribution is investigated via MC
simulations. The thermoremanent magnetization is found to decay algebraically
and the temperature dependent exponents agree very well with the experimentally
determined values. The nonequilibrium autocorrelation function shows
a crossover at the waiting (or {\em aging}) time from algebraic {\em
quasi-equilibrium} decay for times to another, faster algebraic
decay for with an exponent similar to one for the remanent
magnetization.Comment: Revtex, 11 pages + 4 figures (included as Latex-files
Phase Ordering Dynamics of the O(n) Model - Exact Predictions and Numerical Results
We consider the pair correlation functions of both the order parameter field
and its square for phase ordering in the model with nonconserved order
parameter, in spatial dimension and spin dimension .
We calculate, in the scaling limit, the exact short-distance singularities of
these correlation functions and compare these predictions to numerical
simulations. Our results suggest that the scaling hypothesis does not hold for
the model. Figures (23) are available on request - email
[email protected]: 23 pages, Plain LaTeX, M/C.TH.93/2
2s Hyperfine Structure in Hydrogen Atom and Helium-3 Ion
The usefulness of study of hyperfine splitting in the hydrogen atom is
limited on a level of 10 ppm by our knowledge of the proton structure. One way
to go beyond 10 ppm is to study a specific difference of the hyperfine
structure intervals 8 Delta nu_2 - Delta nu_1. Nuclear effects for are not
important this difference and it is of use to study higher-order QED
corrections.Comment: 10 pages, presented at Hydrogen Atom II meeting (2000
Muon spin rotation and relaxation in magnetic materials
A review of the muon spin rotation and relaxation (SR) studies on
magnetic materials published from July 1993 is presented. It covers the
investigation of magnetic phase diagrams, of spin dynamics and the analysis of
the magnetic properties of superconductors. We have chosen to focus on selected
experimental works in these different topics. In addition, a list of published
works is provided.Comment: Review article, 59 pages, LaTeX with IoP macro
Coordinate-space approach to the bound-electron self-energy: Self-Energy screening calculation
The self-energy screening correction is evaluated in a model in which the
effect of the screening electron is represented as a first-order perturbation
of the self energy by an effective potential. The effective potential is the
Coulomb potential of the spherically averaged charge density of the screening
electron. We evaluate the energy shift due to a , ,
, or electron screening a , ,
, or electron, for nuclear charge Z in the range . A detailed comparison with other calculations is made.Comment: 54 pages, 10 figures, 4 table
Properties of the Strange Axial Mesons in the Relativized Quark Model
We studied properties of the strange axial mesons in the relativized quark
model. We calculated the decay constant in the quark model and showed how
it can be used to extract the mixing angle
() from the weak decay . The ratio is the most sensitive
measurement and also the most reliable since the largest of the theoretical
uncertainties factor out. However the current bounds extracted from the
TPC/Two-Gamma collaboration measurements are rather weak: we typically obtain
at 68\% C.L. We also calculated the
strong OZI-allowed decays in the pseudoscalar emission model and the flux-tube
breaking model and extracted a mixing angle of . Our analysis also indicates that the heavy quark limit does not give a
good description of the strange mesons.Comment: Revised version to be published in Phys. Rev. D. Minor changes. Latex
file uses revtex version 3 and epsfig, 4 postcript figures are attached. The
full postcript version with embedded figures is available at
ftp://ftp.physics.carleton.ca/pub/theory/godfrey/ocipc9512.ps.
Perturbative Corrections to the Ohta-Jasnow-Kawasaki Theory of Phase-Ordering Dynamics
A perturbation expansion is considered about the Ohta-Jasnow-Kawasaki theory
of phase-ordering dynamics; the non-linear terms neglected in the OJK
calculation are reinstated and treated as a perturbation to the linearised
equation. The first order correction term to the pair correlation function is
calculated in the large-d limit and found to be of order 1/(d^2).Comment: Revtex, 27 pages including 2 figures, submitted to Phys. Rev. E,
references adde
Nonperturbative mechanisms of strong decays in QCD
Three decay mechanisms are derived systematically from the QCD Lagrangian
using the field correlator method. Resulting operators contain no arbitrary
parameters and depend only on characteristics of field correlators known from
lattice and analytic calculations. When compared to existing phenomenological
models, parameters are in good agreement with the corresponding fitted values.Comment: 12 pages, latex2
Measurement of the 6s - 7p transition probabilities in atomic cesium and a revised value for the weak charge Q_W
We have measured the 6s - 7p_{1/2,3/2} transition probabilities in atomic
cesium using a direct absorption technique. We use our result plus other
previously measured transition rates to derive an accurate value of the vector
transition polarizability \beta and, consequently, re-evaluate the weak charge
Q_W. Our derived value Q_W=-72.65(49) agrees with the prediction of the
standard model to within one standard deviation.Comment: 4 pages, 2 figure
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