361 research outputs found
Universality in a Class of Q-Ball Solutions: An Analytic Approach
The properties of Q-balls in the general case of a sixth order potential have
been studied using analytic methods. In particular, for a given potential, the
initial field value that leads to the soliton solution has been derived and the
corresponding energy and charge have been explicitly evaluated. The proposed
scheme is found to work reasonably well for all allowed values of the model
parameters.Comment: 9 Pages, 6 Figure
On decay of large amplitude bubble of disoriented chiral condensate
The time evolution of initially formed large amplitude bubble of disoriented
chiral condensate (DCC) is studied. It is found that the evolution of this
object may have a relatively long pre-decay stage. Simple explanation of such
delay of the DCC bubble decay is given. This delay is related to the existence
of the approximate solutions of multi-soliton type of the corresponding radial
sine-Gordon equation in (3+1) dimensions at large bubble radius.Comment: 6 pages, LaTeX, 5 PostScript figure
The bubbles of matter from multiskyrmions
The multiskyrmions with large baryon number B given by rational map (RM)
ansaetze can be described reasonably well within the domain wall approximation,
or as spherical bubbles with energy and baryon number density concentrated at
their boundary. A special class of profile functions is considered
approximating the true profile and domain wall behaviour at the same time. An
upper bound is obtained for the masses of RM multiskyrmions which is close to
the calculated masses, especially at large B. The gap between rigorous upper
and lower bounds for large B multiskyrmions is less than 4%. The basic
properties of such bubbles of matter are investigated, some of them being of
universal character, i.e. they do not depend on baryon number of configuration
and on the number of flavors. As a result, the lagrangian of the Skyrme type
models provides field theoretical realization of the bag model of special kind.Comment: 7 pages, no figure
Kink-antikink interactions in the double sine-Gordon equation and the problem of resonance frequencies
We studied the kink-antikink collision process for the "double sine-Gordon"
(DSG) equation in 1+1 dimensions at different values of the potential parameter
. For small values of we discuss the problem of resonance frequencies.
We give qualitative explanation of the frequency shift in comparison with the
frequency of the discrete level in the potential well of isolated kink. We show
that in this region of the parameter the effective long-range interaction
between kink and antikink takes place.Comment: 9 pages, LaTeX, 4 figures (eps
Multiskyrmions and baryonic bags
Analytical treatment of skyrmions given by rational map (RM) ansaetze
proposed recently for the Skyrme model is extended to the model including the
6-th order term in chiral fields derivatives in the lagrangian (the SK6 variant
of the model) and used for calculation of different properties of
multiskyrmions. For special class of profile functions approximating the true
profile and the domain wall behaviour at the same time, the masses and other
static properties of multiskyrmions are expressed in terms of the Euler-type
integrals. An upper bound is obtained for the masses of RM multiskyrmions which
is close to the calculated masses, especially at large B. The gap between
rigorous upper bound and lower bound, obtained for the SK6 model as well, for
large B multiskyrmions is less than 9%, in comparison with about 4% for the SK4
(Skyrme) variant. The basic properties of such bubbles of matter are
investigated, some of them, e.g. the thickness of the bubbles envelope, being
of universal character, i.e. they do not depend on baryon number of
configuration, or reveal a simple and natural dependence. The dependence of
these properties on the number of flavours is absent or very weak in both
models. Qualitatively, the properties of the baryonic bags are the same for the
SK6 and SK4 variants of the model, although differ in some details.Comment: 16 pages, no figure
Ferromagnetism in the Mott insulator Ba2NaOsO6
Results are presented of single crystal structural, thermodynamic, and
reflectivity measurements of the double-perovskite Ba2NaOsO6. These
characterize the material as a 5d^1 ferromagnetic Mott insulator with an
ordered moment of ~0.2 Bohr magnetons per formula unit and TC = 6.8(3) K. The
magnetic entropy associated with this phase transition is close to Rln2,
indicating that the quartet groundstate anticipated from consideration of the
crystal structure is split, consistent with a scenario in which the
ferromagnetism is associated with orbital ordering.Comment: 5 pages, 5 figures, added reference
Low molecular weight thymic factor inhibits histamine release from basophils
Low molecular weight thymic factor stimulates the suppressor function of T-lymphocytes, increases cAMP content (but not cGMP) in lymphocytes and inhibits histamine release from sensitized basophils. The mechanisms of LTF action are discussed
Towards an Abelian Formulation of Lattice QCD Confinement
We probe for operators occurring in the APQCD(``abelian-projected QCD'')
action by evaluating abelian-projected -plaquette spectral densities in pure
gauge fixed to maximal abelian gauge. Couplings are
extracted from the spectral densities for each representation ,
plaquette. While APQCD is dominated by a resonance, we also find
evidence for weakly coupled plaquettes. Moreover, since even if , plaquettes must be
significant since APQCD is confining.Comment: 1+11 pages, fixed minor postscript erro
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