55,400 research outputs found
Forfeiture of Attorney\u27s Fees Under RICO and CCE
We present the matching relations of the variable flavor number scheme at next-to-leading order, which are of importance to define heavy quark partonic distributions for the use at high energy colliders such as Tevatron and the LHC. The consideration of the two-mass effects due to both charm and bottom quarks, having rather similar masses, are important. These effects have not been considered in previous investigations. Numerical results are presented for a wide range of scales. We also present the corresponding contributions to the structure function
The two-mass contribution to the three-loop pure singlet operator matrix element
We present the two-mass QCD contributions to the pure singlet operator matrix
element at three loop order in x-space. These terms are relevant for
calculating the structure function at as well as
for the matching relations in the variable flavor number scheme and the heavy
quark distribution functions at the same order. The result for the operator
matrix element is given in terms of generalized iterated integrals that include
square root letters in the alphabet, depending also on the mass ratio through
the main argument. Numerical results are presented.Comment: 28 papges Latex, 3 figure
The Three Loop Two-Mass Contribution to the Gluon Vacuum Polarization
We calculate the two-mass contribution to the 3-loop vacuum polarization of
the gluon in Quantum Chromodynamics at virtuality for general masses
and also present the analogous result for the photon in Quantum
Electrodynamics.Comment: 5 pages Late
Diffusion of Neon in White Dwarf Stars
Sedimentation of the neutron rich isotope Ne may be an important
source of gravitational energy during the cooling of white dwarf stars. This
depends on the diffusion constant for Ne in strongly coupled plasma
mixtures. We calculate self-diffusion constants from molecular dynamics
simulations of carbon, oxygen, and neon mixtures. We find that in a
mixture does not differ greatly from earlier one component plasma results. For
strong coupling (coulomb parameter few), has a modest
dependence on the charge of the ion species, .
However depends more strongly on for weak coupling (smaller
). We conclude that the self-diffusion constant for
Ne in carbon, oxygen, and neon plasma mixtures is accurately known so
that uncertainties in should be unimportant for simulations of
white dwarf cooling.Comment: 6 pages, 5 figures, minor changes, Phys. Rev. E in pres
A Note on Asymptotic Freedom at High Temperatures
This short note considers, within the external field approach outlined in
hep-ph/0202026, the role of the lowest lying gluon Landau mode in QCD in the
high temperature limit. Its influence on a temperature- and field-dependent
running coupling constant is examined. The thermal imaginary part of the mode
is temperature-independent in our approach and exactly cancels the well-known
zero temperature imaginary part, thus rendering the Savvidy vacuum stable.
Combining the real part of the mode with the contributions from the higher
lying Landau modes and the vacuum contribution, a field-independent coupling
alpha_s(T) is obtained. It can be interpreted as the ordinary zero temperature
running coupling constant with average thermal momenta \approx 2pi T for
gluons and \approx pi T for quarks.Comment: 4 pages; minor changes, version to appear in Phys. Rev.
The Two-mass Contribution to the Three-Loop Gluonic Operator Matrix Element
We calculate the two-mass QCD contributions to the massive operator matrix
element at in analytic form in Mellin
- and -space, maintaining the complete dependence on the heavy quark mass
ratio. These terms are important ingredients for the matching relations of the
variable flavor number scheme in the presence of two heavy quark flavors, such
as charm and bottom. In Mellin -space the result is given in the form of
nested harmonic, generalized harmonic, cyclotomic and binomial sums, with
arguments depending on the mass ratio. The Mellin inversion of these quantities
to -space gives rise to generalized iterated integrals with square root
valued letters in the alphabet, depending on the mass ratio as well. Numerical
results are presented.Comment: 99 pages LATEX, 2 Figure
Origin of Lagrangian Intermittency in Drift-Wave Turbulence
The Lagrangian velocity statistics of dissipative drift-wave turbulence are
investigated. For large values of the adiabaticity (or small collisionality),
the probability density function of the Lagrangian acceleration shows
exponential tails, as opposed to the stretched exponential or algebraic tails,
generally observed for the highly intermittent acceleration of Navier-Stokes
turbulence. This exponential distribution is shown to be a robust feature
independent of the Reynolds number. For small adiabaticity, algebraic tails are
observed, suggesting the strong influence of point-vortex-like dynamics on the
acceleration. A causal connection is found between the shape of the probability
density function and the autocorrelation of the norm of the acceleration
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