141 research outputs found
Confinement and short distance physics
We consider non-perturbative effects at short distances in theories with
confinement. The analysis is straightforward within the Abelian models in which
the confinement arises on classical level. In all cases considered (compact
U(1) in 3D and 4D, dual Abelian Higgs model) there are non-perturbative
contributions associated with short distances which are due to topological
defects. In QCD case, both classical and quantum effects determine the role of
the topological defects and the theoretical analysis has not been completed so
far. Generically, the topological defects would result in 1/Q^2 corrections
going beyond the standard Operator Product Expansion. We review existing data
on the power corrections and find that the data favor existence of the novel
corrections, at least at the mass scale of (1-2) GeV. We indicate crucial
experiments which could further clarify the situation on the phenomenological
side.Comment: 11 pp., Latex2e, 4 figures, epsfig.sty. Accepted for publication in
Physics Letters
Alfven Wave Generation by means of High Orbital Injection of Barium Cloud in Magnetosphere
An analysis of the Alfven wave generation associated with the barium vapor
release at altitudes ~ 5.2 Earth's radii (ER) in the magnetosphere is
presented. Such injections were executed in G-8 and G-10 experiments of the
Combined Radiation and Radiation Effects Satellite (CRRES) mission. It is shown
that the generation of Alfven waves is possible during the total time of plasma
expansion. The maximum intensity of these waves corresponds to the time of
complete retardation of the diamagnetic cavity created by the expansion of
plasma cloud. The Alfven wave exhibits a form of an impulse with an effective
frequency ~ 0.03-0.05 Hz. Due to the background conditions and wave frequency,
the wave mainly oscillates along the geomagnetic field between the mirror
reflection points situated at ~ 0.7 ER. The wave amplitude is sufficient to the
generation of plasma instabilities and longitudinal electric field, and to an
increase in the longitudinal energy of electrons to ~ 1 keV. These processes
are the most probable for altitudes ~ 1 ER. The auroral kilometric radiation
(AKR) at frequencies ~ 100 kHz is associated with these accelerated electrons.
The acceleration of electrons and AKR can be observed almost continuously
during the first minute and then from time to time with pauses about 35-40 s
till 6-8 min after the release. The betatron acceleration of electrons at the
recovery of the geomagnetic field is also discussed. This mechanism could be
responsible for the acceleration of electrons resulting in the aurorae and
ultra short radio wave storm at frequencies 50-300 MHz observed at the 8-10th
min after the release.Comment: Presented at COSPAR 200
Chiral symmetry breaking in confining theories and asymptotic limits of operator product expansion
The pattern of spontaneous chiral symmetry breaking (CSB) in confining
background fields is analyzed. It is explicitly demonstrated how to get the
inverse square root large proper time asymptotic of the operator product
expansion which is needed for CSB.Comment: LaTeX, 20 pages; minor revision
Monopole clusters at short and large distances
We present measurements of various geometrical characteristics of monopole
clusters in SU(2) lattice gauge theory. The maximal Abelian projection is
employed and both infinite, or percolating cluster and finite clusters are
considered. In particular, we observe scaling for average length of segments of
the percolating cluster between self-crossings, correlators of vacuum monopole
currents, angular correlation between links along trajectories. Short clusters
are random walks and their spectrum in length corresponds to free particles. At
the hadronic scale, on the other hand, the monopole trajectories are no longer
random walks. Moreover, we argue that the data on the density of finite
clusters suggest that there are long-range correlations between finite clusters
which can be understood as association of the clusters with two-dimensional
surfaces, whose area scales.Comment: 9 pages, 11 figure
Study of the process of thermal dissociation of tantal pentachloride in vacuum
The dependence of the degree of dissociation of TaCl₅α(T, P) vapors on the temperature in the range of 1470...1820 K in a vacuum of 1.33·10⁻² Pa was by using of equilibrium chemical thermodynamics obtained. The experimental data on the dependence of αex(Т, Р) on temperature and vapor mass flow TaCl₅ were analyzed and compared with calculations.У рамках рівноважної хімічної термодинаміки отримана залежність ступеня дисоціації парів TaCl₅α(T, P) від температури в інтервалі 1470…1820 К і вакуумі 1,33·10⁻² Па. Проаналізовано та порівняно з розрахунковими експериментальні дані залежності αексп(Т, Р) від температури і масового потоку парів TaCl₅.В рамках равновесной химической термодинамики получена зависимость степени диссоциации паров TaCl₅α(T, P) от температуры в интервале 1470…1820 К и вакууме 1,33·10⁻² Па. Проанализированы и сравниваются расчетные данные с экспериментальными данными зависимости αэксп(Т, Р) от температуры и массового потока паров TaCl₅
Anatomy of the lattice magnetic monopoles
We study the Abelian and non-Abelian action densitynear the monopole in the
maximal Abelian gauge of SU(2) lattice gauge theory. We find that the
non-Abelian action density near the monopoles belonging to the percolating
cluster decreases when we approach the monopole center. Our estimate of the
monopole radius is R_mon ~ 0.04 fm.Comment: 9 pp., Latex2e, 2 figure (epsfig), published versio
Towards understanding structure of the monopole clusters
We consider geometrical characteristics of monopole clusters of the lattice
SU(2) gluodynamics. We argue that the polymer approach to the field theory is
an adequate means to describe the monopole clusters. Both finite-size and the
infinite, or percolating clusters are considered. We find out that the
percolation theory allows to reproduce the observed distribution of the
finite-size clusters in their length and radius. Geometrical characteristics of
the percolating cluster reflect, in turn, the basic properties of the ground
state of a system with a gap.Comment: 20 pages, RevTeX
Dirac Strings and Monopoles in the Continuum Limit of SU(2) Lattice Gauge Theory
Magnetic monopoles are known to emerge as leading non-perturbative
fluctuations in the lattice version of non-Abelian gauge theories in some
gauges. In terms of the Dirac quantization condition, these monopoles have
magnetic charge |Q_M|=2. Also, magnetic monopoles with |Q_M|=1 can be
introduced on the lattice via the 't Hooft loop operator. We consider the
|Q_M|=1,2 monopoles in the continuum limit of the lattice gauge theories. To
substitute for the Dirac strings which cost no action on the lattice, we allow
for singular gauge potentials which are absent in the standard continuum
version. Once the Dirac strings are allowed, it turns possible to find a
solution with zero action for a monopole--antimonopole pair. This implies
equivalence of the standard and modified continuum versions in perturbation
theory. To imitate the nonperturbative vacuum, we introduce then a nonsingular
background. The modified continuum version of the gluodynamics allows in this
case for monopoles with finite non-vanishing action. Using similar techniques,
we construct the 't Hooft loop operator in the continuum and predict its
behavior at small and large distances both at zero and high temperatures.Comment: 24 pp., Latex2e, no figures. Minor correction
Search for light pseudoscalar sgoldstino in K- decays
A search for the light pseudoscalar sgoldstino production in the three body
K- decay K-->pipi0P has been performed with the ISTRA+ detector exposed to the
25 GeV negative secondary beam of the U70 proton synchrotron. No signal is
seen. An upper limit for the branching ratio Br(K->pipi0P), at 90% confidence
level, is found to be around 9*10**-6 in the effective mass m(P) range from 0
till 200 MeV, excluding the region near m(pi0) where it degrades to 3.5*10**-5.Comment: 10 pages, LATEX, 8 EPS figures, revised version, to be published in
Phys.Lett.
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