1,828 research outputs found
On the possibility of applying the quasi-isothermal St\"ackel's model to our Galaxy
An earlier derived quasi-isothermal St\"ackel's model of mass distribution in
stellar systems and the corresponding formula for space density are applied to
our Galaxy. The model rotation curve is fitted to HI kinematical data. The
structural and scale parameters of the model are estimated and the
corresponding density contours for our Galaxy are presented.Comment: 7 pages, 3 figures. Accepted for publication in Baltic Astronomy (BA
The R.I. Pimenov unified gravitation and electromagnetism field theory as semi-Riemannian geometry
More then forty years ago R.I. Pimenov introduced a new geometry --
semi-Riemannian one -- as a set of geometrical objects consistent with a
fibering He suggested the heuristic principle according to
which the physically different quantities (meter, second, coulomb etc.) are
geometrically modelled as space coordinates that are not superposed by
automorphisms. As there is only one type of coordinates in Riemannian geometry
and only three types of coordinates in pseudo-Riemannian one, a multiple
fibered semi-Riemannian geometry is the most appropriate one for the treatment
of more then three different physical quantities as unified geometrical field
theory.
Semi-Euclidean geometry with 1-dimensional fiber and
4-dimensional Minkowski space-time as a base is naturally interpreted as
classical electrodynamics. Semi-Riemannian geometry with the
general relativity pseudo-Riemannian space-time and 1-dimensional
fiber responsible for the electromagnetism, provides the unified field
theory of gravitation and electromagnetism. Unlike Kaluza-Klein theories, where
the 5-th coordinate appears in nondegenerate Riemannian or pseudo-Riemannian
geometry, the theory based on semi-Riemannian geometry is free from defects of
the former. In particular, scalar field does not arise.
PACS: 04.50.Cd, 02.40.-k, 11.10.KkComment: 16 pages, 2 figures. Submited to Physics of Atomic Nucle
Possible quantum kinematics. II. Non-minimal case
The quantum analogs of the N-dimensional Cayley-Klein spaces with different
combinations of quantum and Cayley-Klein structures are described for
non-minimal multipliers, which include the first and the second powers of
contraction parameters in the transformation of deformation parameter. The
noncommutative analogs of (N-1)-dimensional constant curvature spaces are
introduced. Part of these spaces for N=5 are interpreted as the noncommutative
analogs of (1+3) space-time models. As a result the wide variety of the quantum
deformations of realistic kinematics are suggested.Comment: 13 pages, no figure
On contractions of classical basic superalgebras
We define a class of orthosymplectic and unitary
superalgebras which may be obtained from and
by contractions and analytic continuations in a similar way as the
special linear, orthogonal and the symplectic Cayley-Klein algebras are
obtained from the corresponding classical ones. Casimir operators of
Cayley-Klein superalgebras are obtained from the corresponding operators of the
basic superalgebras. Contractions of and are regarded as
an examples.Comment: 15 pages, Late
On the Fermionic Frequencies of Circular Strings
We revisit the semiclassical computation of the fluctuation spectrum around
different circular string solutions in AdS_5xS^5 and AdS_4xCP^3, starting from
the Green-Schwarz action. It has been known that the results for these
frequencies obtained from the algebraic curve and from the worldsheet
computations sometimes do not agree. In particular, different methods give
different results for the half-integer shifts in the mode numbers of the
frequencies. We find that these discrepancies can be removed if one carefully
takes into account the transition matrices in the spin bundle over the target
space.Comment: 13 pages, 1 figur
Phase space measure concentration for an ideal gas
We point out that a special case of an ideal gas exhibits concentration of
the volume of its phase space, which is a sphere, around its equator in the
thermodynamic limit. The rate of approach to the thermodynamic limit is
determined. Our argument relies on the spherical isoperimetric inequality of
L\'{e}vy and Gromov.Comment: 15 pages, No figures, Accepted by Modern Physics Letters
TBA, NLO Luscher correction, and double wrapping in twisted AdS/CFT
The ground-state energy of integrably-twisted theories is analyzed in finite
volume. We derive the leading and next-to-leading order (NLO) L\"uscher-type
corrections for large volumes of the vacuum energy for integrable theories with
twisted boundary conditions and twisted S-matrix. We then derive the twisted
thermodynamic Bethe ansatz (TBA) equations to describe exactly the ground
state, from which we obtain an untwisted Y-system. The two approaches are
compared by expanding the TBA equations to NLO, and exact agreement is found.
We give explicit results for the O(4) model and for the three-parameter family
of -deformed (non-supersymmetric) planar AdS/CFT model, where the
ground-state energy can be nontrivial and can acquire finite-size corrections.
The NLO corrections, which correspond to double-wrapping diagrams, are
explicitly evaluated for the latter model at six loops.Comment: 42 pages, 2 figures, v2: references added, v3: minor correction
\Lambda-buildings and base change functors
We prove an analog of the base change functor of \Lambda-trees in the setting
of generalized affine buildings. The proof is mainly based on local and global
combinatorics of the associated spherical buildings. As an application we
obtain that the class of generalized affine building is closed under ultracones
and asymptotic cones. Other applications involve a complex of groups
decompositions and fixed point theorems for certain classes of generalized
affine buildings.Comment: revised version, 29 pages, to appear in Geom. Dedicat
Hybrid-NLIE for the AdS/CFT spectral problem
Hybrid-NLIE equations, an alternative finite NLIE description for the
spectral problem of the super sigma model of AdS/CFT and its gamma-deformations
are derived by replacing the semi-infinite SU(2) and SU(4) parts of the AdS/CFT
TBA equations by a few appropriately chosen complex NLIE variables, which are
coupled among themselves and to the Y-functions associated to the remaining
central nodes of the TBA diagram. The integral equations are written explicitly
for the ground state of the gamma-deformed system. We linearize these NLIE
equations, analytically calculate the first correction to the asymptotic
solution and find agreement with analogous results coming from the original TBA
formalism. Our equations differ substantially from the recently published
finite FiNLIE formulation of the spectral problem.Comment: 63 pages, 1 figur
Massey products in symplectic manifolds
The paper is devoted to study of Massey products in symplectic manifolds.
Theory of generalized and classical Massey products and a general construction
of symplectic manifolds with nontrivial Massey products of arbitrary large
order are exposed. The construction uses the symplectic blow-up and is based on
the author results, which describe conditions under which the blow-up of a
symplectic manifold X along its submanifold Y inherits nontrivial Massey
products from X ot Y. This gives a general construction of nonformal symplectic
manifolds.Comment: LaTeX, 48 pages, 2 figure
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