292,544 research outputs found
On Goldstone bosons decoupling from high-lying hadrons
In this paper, we discuss a decoupling of the Goldstone bosons from highly
excited hadrons in relation to the restoration of chiral symmetry in such
hadrons. We use a generalised Nambu-Jona-Lasinio model with the interaction
between quarks in the form of an instantaneous Lorentz-vector confining
potential. This model is known to provide spontaneous breaking of chiral
symmetry in the vacuum via the standard selfenergy loops for valence quarks.
For highly excited hadrons, where the typical momentum of valence quarks is
large, the loop contributions represent only a small correction to the
chiral-invariant classical contributions and asymptotically vanish.
Consequently the chiral symmetry violating Lorentz-scalar dynamical mass of
quarks vanishes. Then the conservation of the axial vector current in the
chiral limit requires, via the Goldberger-Treiman relation, that the valence
quarks decouple from the Goldstone boson. As a consequence, the whole hadron
decouples from the Goldstone boson as well, which implies that its axial
constant also vanishes.Comment: RevTeX4, 21 pages, 5 Postscript figures, uses epsfig.sty, new chapter
with numerical estimates added, to appear in Phys.Rev.
Статичні змішувачі в циркуляційних системах промивальної рідини бурових установок
The work of three static mixer designs in flushing fluid circulation systems of drilling rigs was studied taking into account the basic parameters of drilling mud. Modelling was carried out, and parametric slurry fields were obtained in the pipe work area, that is in a static mixer installation site and in the area of pipeline behind it. The following models were obtained: velocity fields, vorticity fields, turbulence intensity fields, scale turbulence fields
along the travel path. Graphs of the parameters changes regarding the tube axis were plotted. The comparative analysis of patterns and curves was carried out. The rational design of static mixer for obtaining of optimum mud mixing technology features is grounded.Досліджено роботу трьох конструкцій статичного змішувача в циркуляційній системі промивальної рідини бурових установок, ураховуючи основні параметри бурового розчину. Виконано моделювання та отримано параметричні поля гідросуміші у робочій зоні труби, а саме в місці установки статичного змішувача і в зоні трубопроводу за ним. Отримано моделі: поля швидкостей, поля завихреності, поля
інтенсивності турбулентності, поля масштабу турбулентностей по довжині шляху перемішування. Побудовано графіки зміни досліджуваних параметрів відносно осі труби. Виконано порівняльний аналіз моделей та кривих. Обґрунтовано раціональну конструкцію статичного змішувача для отримання оптимальних технологічних характеристик перемішування бурового розчину
Slow cross-symmetry phase relaxation in complex collisions
We discuss the effect of slow phase relaxation and the spin off-diagonal
-matrix correlations on the cross section energy oscillations and the time
evolution of the highly excited intermediate systems formed in complex
collisions. Such deformed intermediate complexes with strongly overlapping
resonances can be formed in heavy ion collisions, bimolecular chemical
reactions and atomic cluster collisions. The effects of quasiperiodic energy
dependence of the cross sections, coherent rotation of the hyperdeformed
intermediate complex, Schr\"odinger cat states and
quantum-classical transition are studied for Mg+Si heavy ion
scattering.Comment: 10 pages including 2 color ps figures. To be published in Physics of
Atomic Nuclei (Yadernaya fizika
On two- and three-body descriptions of hybrid mesons
Hybrid mesons are exotic mesons in which the color field is not in its ground
state. Their understanding deserves interest from a theoretical point of view,
because it is intimately related to nonperturbative aspects of QCD. In this
work, we analyze and compare two different descriptions of hybrid mesons,
namely a two-body system with an excited string, or a three-body
system. In particular, we show that the constituent gluon approach
is equivalent to an effective excited string in the heavy hybrid sector.
Instead of a numerical resolution, we use the auxiliary field technique. It
allows to find simplified analytical mass spectra and wave functions, and still
leads to reliable qualitative predictions. We also investigate the light hybrid
sector, and found a mass for the lightest hybrid meson which is in satisfactory
agreement with lattice QCD and other effective models.Comment: 2 figure
On bosonic limits of two recent supersymmetric extensions of the Harry Dym hierarchy
Two generalized Harry Dym equations, recently found by Brunelli, Das and
Popowicz in the bosonic limit of new supersymmetric extensions of the Harry Dym
hierarchy [J. Math. Phys. 44:4756--4767 (2003)], are transformed into
previously known integrable systems: one--into a pair of decoupled KdV
equations, the other one--into a pair of coupled mKdV equations from a
bi-Hamiltonian hierarchy of Kupershmidt.Comment: 7 page
Generation time and utilization of energy by aquatic bacteria. [Translation from: Trudy Instituta Biologii Vnutrennykh Vodnany 11(14), 198-202, 1966.]
Recent research has shown that the biomass of bacteria in lakes and other water-bodies can attain significant values. The huge production of bacteria is brought about by their great rate of reproduction. In a series of cases their biomass exceeds the biomass of phytoplankton. Therefore in a study of the biological productivity of water bodies it is necessary to calculate the biomass and production not only of the phyto- and zooplankton, but also of bacteria.The authors uses different methods and formulae to to compare the time of one generation of the bacteria
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