1,056 research outputs found
Calculation of the renormalized charmed-quark mass in Lattice QCD
The correlator of heavy-quark currents is calculated in quenched Lattice QCD
on a -lattice for . The renormalized charmed
quark mass is extracted from the short-distance part of that correlator:
. We study the sensitivity of our data
to the strong coupling constant.Comment: 3 pages, LaTeX plus Postscript files of figures and the style-files.
Contribution to the Proceedings of LAT9
Sphaleron transitions in a realistic heat bath
We measure the diffusion rate of Chern-Simons number in the (1+1)-dimensional
Abelian Higgs model interacting with a realistic heat bath for temperatures
between 1/13 and 1/3 times the sphaleron energy. It is found that the measured
rate is close to that predicted by one-loop calculation at the lower end of the
temperature range considered but falls at least an orderof magnitude short of
one-loop estimate at the upper end of that range. We show numerically that the
sphaleron approximation breaks down as soon as the gauge-invariant two-point
function yields correlation length close to the sphaleron size.Comment: 13 pages, LATeX + 3 figures included as postscript files, to be
encapsulated using epsf. Also available as a compressed postscript file by
anonymous ftp from maggia.ethz.ch (login ftp, pw ftp; then: cd pub, binary,
get sphb.ps.Z). IPS Research Report No. 93-1
One-loop corrections to the instanton transition in the two-dimensional Abelian Higgs model
We present an evaluation of the fluctuation determinant which appears as a
prefactor in the instanton transition rate for the two-dimensional Abelian
Higgs model. The corrections are found to change the rate at most by a factor
of 2 for 0.4 < M_W/M_H < 2.0.Comment: DO-TH-94/17, 20 pages, 4 figures appended as uucompressed .eps files,
LaTeX, needs epsfig.st
Chern-Simons number diffusion in (1+1)-dimensional Higgs theory
We study the Chern-Simons number diffusion rate in the (1+1)-dimensional
latticeAbelian Higgs model at temperatures much higher than, as well as
comparable to, the sphaleron energy. It is found that in the high-temperature
limit the rate is likely to grow as power 2/3 of the temperature. In the
intermediate-temperature regime, our numerical simulations show that very weak
temperature dependence of the rate, found in previous work, persists at smaller
lattice spacings. We discuss possibilities of relating the observed behavior of
the rate to static finite-temperature properties of the model.Comment: 9 pages, LATeX + 4 figures included as postscript files, to be
encapsulated using epsf. Text + figures uuencoded. Also available as a
compressed postscript file by anonymous ftp from maggia.ethz.ch (login ftp,
pw ftp; then: cd pub, binary, get ahm.ps.Z). IPS Research Report No. 94-0
Sphaleron-Like Processes in a Realistic Heat Bath
We measure the diffusion rate of Chern-Simons number in the (1+1)-dimensional
Abelian Higgs model interacting with a realistic heat bath for temperatures
between 1/13 and 2/3 times the sphaleron energy. It is found that the measured
rate is close to that predicted by the sphaleron approximation at the lower end
of the temperature range considered but falls at least an order of magnitude
short of the sphaleron estimate at the upper end of that range. We show
numerically that the sphaleron approximation breaks down as soon as the
gauge-invariant two-point function yields correlation length close to the
sphaleron size.Comment: talk given at Lattice-93 conference (Dallas, October 1993), 3 pages,
uuencoded postscript file, IPS Research Report 93-1
Coupled-channels effects in elastic scattering and near-barrier fusion induced by weakly bound nuclei and exotic halo nuclei
The influence on fusion of coupling to the breakup process is investigated
for reactions where at least one of the colliding nuclei has a sufficiently low
binding energy for breakup to become an important process. Elastic scattering,
excitation functions for sub-and near-barrier fusion cross sections, and
breakup yields are analyzed for Li+Co. Continuum-Discretized
Coupled-Channels (CDCC) calculations describe well the data at and above the
barrier. Elastic scattering with Li (as compared to Li) indicates
the significant role of breakup for weakly bound projectiles. A study of
He induced fusion reactions with a three-body CDCC method for the
He halo nucleus is presented. The relative importance of breakup and
bound-state structure effects on total fusion is discussed.Comment: 29 pages, 9 figure
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