847 research outputs found
Couplings of heavy hadrons with soft pions from QCD sum rules
We estimate the couplings in the Heavy Hadron Chiral Theory (HHCT) lagrangian
from the QCD sum rules in an external axial field. We take into account the
perturbative correction to the meson correlator in the infinite mass limit.
With the perturbative correction and three successive power corrections, the
meson correlator in an axial field becomes one of the best known correlators.
In spite of this, the corresponding sum rule is not very stable. It yields the
result g_1 F^2/(380MeV)^3 = 0.1 - 0.2, where F^2 = f_M^2 m/4 = (380MeV)^3 is
the central value of the heavy meson decay constant with the perturbative
correction. This result is surprisingly low as compared with the constituent
quark model estimate g_1 = 0.75. The sum rules for g_{2,3} following from
nondiagonal Sigma-Sigma and diagonal Lambda-Sigma baryon correlators in an
external axial field suggest g_{2,3} = 0.4 - 0.7, while diagonal Sigma-Sigma
and nondiagonal Lambda-Sigma baryon sum rules have too large uncertainties.Comment: 15 pages, LaTeX2e, 6 ps figures include
Geochemical aspect of impact cratering: Studies in Vernadsky Institute
Studies of the geochemical effects of impact cratering at the Vernadsky Institute in collaboration with the Institute of Dynamics of Geospheres, Moscow State University, Leningrad State University, and some other institutions were fulfilled by several approaches. At the initial stage, three approaches were used: (1) experimental studies of high-temperature vaporization of geological materials (basalts, granites, and so on) in vacuum that was considered as a model of behavior of impact melt and vapor; (2) search of impact-induced geochemical effects in the rock from terrestrial impact craters; and (3) studies of samples of lunar regolith. The next stage of the studies included experiments on quasi-equilibrium vaporization of geological material in Knudsen cells. The results of this investigation are discussed
Two -loop radiative corrections to the Higgs decay width for large Higgs boson masses
This note is devoted to the calculation of the two-loop
radiative corrections to the Higgs decay width for large
values of the Higgs boson mass within the Minimal Standard Model.
The use of the Equivalence Theorem makes it possible to reduce the problem to
the consideration of the physical Higgs boson field and the Goldstone bosons
. We present analytical results for the various two- and
three-particle absorptive parts of two-loop contributions, using dispersive
techniques, analytic results for all but one of the dispersive contributions.
The typical size of the correction is percent for a Higgs boson
mass of order .Comment: 21 pages, 7 uuencoded figure
Sudy of the Propagation of Decimeter Radiowaves in the Atmosphere of Venus with the Aid of AIS ''venera 4''
Radio wave propagation in Venus atmosphere based on approximating inhomogeneity of refractivit
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