701 research outputs found
Heat and mass transfer in gases due to pressure and temperature gradients in a laser radiation field
Heat and mass transfer in a one-component gas through a capillary in the field of resonant laser radiation in the presence of pressure and temperature gradients are considered. On the basis of the Boltzmann type kinetic equations in the linear approximation the expression for entropy production is obtained. Kinetic coefficients satisfy the Onsager reciprocity relations at all Knudsen numbers and for any nature of the interaction of gas atoms with the surface of the capillary. The pressure and temperature gradients established in the insulated system in a laser field are defined in a nearly free molecular regime. © 2012 American Institute of Physics
Mass Spectrum in SQCD and Problems with the Seiberg Duality. Another Scenario
N=1 SQCD with SU(N_c) colors and N_F flavors of light quarks is considered
within the dynamical scenario which assumes that quarks can be in two different
phases only. These are: a) either the HQ (heavy quark) phase where they are
confined, b) or they are higgsed, at the appropriate values of parameters of
the Lagrangian.
The mass spectra of this (direct) theory and its Seiberg's dual are obtained
and compared, for quarks of equal or unequal masses. It is shown that in all
cases when there is the additional small parameter at hand (it is
0<(3N_c-N_F)/N_F << 1 for the direct theory, or its analog 0<(2N_F-3N_c)/N_F <<
1 for the dual one), the mass spectra of the direct and dual theories are
parametrically different. A number of other regimes are also considered.Comment: 30 pages, purely technical improvements for readers convenienc
Light Cone Sum Rules for the pi0-gamma*-gamma Form Factor Revisited
We provide a theoretical update of the calculations of the pi0-gamma*-gamma
form factor in the LCSR framework, including up to six polynomials in the
conformal expansion of the pion distribution amplitude and taking into account
twist-six corrections related to the photon emission at large distances. The
results are compared with the calculations of the B-> pi l nu decay and pion
electromagnetic form factors in the same framework. Our conclusion is that the
recent BaBar measurements of the pi0-gamma*-gamma form factor at large momentum
transfers are consistent with QCD, although they do suggest that the pion DA
may have more structure than usually assumed.Comment: 20 pages, 14 figures, 5 table
Light Cone Sum Rules for gamma* N -> Delta Transition Form Factors
A theoretical framework is suggested for the calculation of gamma* N -> Delta
transition form factors using the light-cone sum rule approach. Leading-order
sum rules are derived and compared with the existing experimental data. We find
that the transition form factors in a several GeV region are dominated by the
``soft'' contributions that can be thought of as overlap integrals of the
valence components of the hadron wave functions. The ``minus'' components of
the quark fields contribute significantly to the result, which can be
reinterpreted as large contributions of the quark orbital angular momentumComment: 38 pages, 10 figures; some typos fixed and references added, to
appear in Phys. Rev.
Light-induced cross transport phenomena in a single-component gas
The cross transport processes that occur in a single-component gas in a capillary and are caused by resonance laser radiation and pressure and temperature gradients are studied. An expression for entropy production is derived using a system of kinetic Boltzmann equations in a linear approximation. The kinetic coefficients that determine the transport processes are shown to satisfy the Onsager reciprocal relations at any Knudsen numbers and any character of the elastic interaction of gas particles with the capillary surface. The light-induced baro- and thermoeffects that take place in a closed heat-insulated system in the field of resonance laser radiation are considered. Analytical expressions are obtained for the Onsager coefficients in an almost free-molecular regime. The light-induced pressure and temperature gradients that appear in a closed heat-insulated capillary under typical experimental conditions are numerically estimated. © 2013 Pleiades Publishing, Ltd
Light-cone Distribution Amplitudes of Xi and their Applications
We present the light-cone distribution amplitudes of the Xi baryons up to
twist six on the basis of QCD conformal partial wave expansion to the leading
order conformal spin accuracy. The nonperturbative parameters relevant to the
DAs are determined in the framework of the QCD sum rule. The light-cone QCD sum
rule approach is used to investigate both the electromagnetic form factors of
Xi and the exclusive semileptonic decay of Xi_c as applications. Our
estimations on the magnetic moments are and
. The decay width of the process Xi_c->Xi
e^+\nu_e is evaluated to be , which is in
accordance with the experimental measurements and other theoretical approaches.Comment: 23 pages, 8 figures, version to appear in Phys. Rev.
Leading-twist pion and kaon distribution amplitudes in the gauge-invariant nonlocal chiral quark model from the instanton vacuum
We investigate the leading-twist light-cone distribution amplitudes for the
pion and kaon based on the gauge-invariant nonlocal chiral quark model from the
instanton vacuum in the presence of external axial-vector currents. We find
that the nonlocal contribution from the gauge invariance has much effects on
the pion distribution amplitudes, while it changes mildly the kaon ones. We
also study the Gegenbauer moments of the distribution amplitudes and compare
them with the empirical analysis of the CLEO data.Comment: 14 pages, 10 figure
The Meson Light-Cone Distribution Amplitudes of Leading Twist Revisited
We give a complete re-analysis of the leading twist quark-antiquark
light-cone distribution amplitudes of longitudinal and transverse
mesons. We derive Wandzura-Wilczek type relations between different
distributions and update the coefficients in their conformal expansion using
QCD sum rules including next-to-leading order radiative corrections. We find
that the distribution amplitudes of quarks inside longitudinally and
transversely polarized mesons have a similar shape, which is in
contradiction to previous analyses.Comment: 21 pages, latex2e, requires a4wide.sty and epsf.sty, 6 PS figures
include
A three-loop check of the 'a - maximization' in SQCD with adjoint(s)
The 'a - maximization' was introduced by K. Inrtiligator and B. Wecht for
finding anomalous dimensions of chiral superfields at the IR fixed points of
the RG flow. Using known explicit calculations of anomalous dimensions in the
perturbation theory of SQCD (with one or two additional adjoint fields), it is
checked here at the three-loop level.Comment: 5 pages; the title changed, the text improved and expande
Periodic and Quasi-Periodic Compensation Strategies of Extreme Outages caused by Polarization Mode Dispersion and Amplifier Noise
Effect of birefringent disorder on the Bit Error Rate (BER) in an optical
fiber telecommunication system subject to amplifier noise may lead to extreme
outages, related to anomalously large values of BER. We analyze the Probability
Distribution Function (PDF) of BER for various strategies of Polarization Mode
Dispersion (PMD) compensation. A compensation method is proposed that is
capable of more efficient extreme outages suppression, which leads to
substantial improvement of the fiber system performance.Comment: 3 pages, 1 figure, Submitted to IEEE Photonics Letter
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