198 research outputs found
CarpologĂa de algunas Cardueae (Asteraceae) de Asia oriental
The present paper deals with the morphological, anatomical structure of achenes in the East Asian species of Rhaponticum, Klasea Serratula and Synurus. The structure of pericarp epidermal cells, mesocarp, has been described, as well as the structure of testa epidermal cells. The specific characters of the genera, as well as the identification characters of the species, are described.El presente artĂculo se refiere a las caracterĂsticas morfolĂłgicas, la estructura anatĂłmica de los aquenios en las especies de Rhaponticum, Klasea Serratula y Synurus en Asia oriental. Se han descrito la estructura de cĂ©lulas epidĂ©rmicas del pericarpio, y el mesocarpio, asĂ como la de la testa de las cĂ©lulas epidĂ©rmicas. TambiĂ©n quedan descritos los caracteres especĂficos de los gĂ©neros, asĂ como los caracteres de identificaciĂłn de las especies
AdS/CFT duality at strong coupling
We study the strong coupling limit of AdS/CFT correspondence in the framework
of a recently proposed fermionic formulation of the Bethe Ansatz equations
governing the gauge theory anomalous dimensions. We provide examples of states
that do not follow the Gubser-Klebanov-Polyakov law at large 't Hooft coupling
, in contrast with recent results on the quantum string Bethe
equations valid in that regime. This result indicates that the fermionic
construction cannot be trusted at large , although it remains an
efficient tool to compute the weak coupling expansion of anomalous dimensions.Comment: Presented at Nonlinear Physics. Theory and Experiment. IV Gallipoli,
June 22 - July 1, 2006. To appear in the proceeding
Bethe Ansatz in Stringy Sigma Models
We compute the exact S-matrix and give the Bethe ansatz solution for three
sigma-models which arise as subsectors of string theory in AdS(5)xS(5):
Landau-Lifshitz model (non-relativistic sigma-model on S(2)),
Alday-Arutyunov-Frolov model (fermionic sigma-model with su(1|1) symmetry), and
Faddeev-Reshetikhin model (string sigma-model on S(3)xR).Comment: 37 pages, 11 figure
Correlators of Vertex Operators for Circular Strings with Winding Numbers in AdS5xS5
We compute semiclassically the two-point correlator of the marginal vertex
operators describing the rigid circular spinning string state with one large
spin and one windining number in AdS_5 and three large spins and three winding
numbers in S^5. The marginality condition and the conformal invariant
expression for the two-point correlator obtained by using an appropriate vertex
operator are shown to be associated with the diagonal and off-diagonal Virasoro
constraints respectively. We evaluate semiclassically the three-point
correlator of two heavy circular string vertex operators and one zero-momentum
dilaton vertex operator and discuss its relation with the derivative of the
dimension of the heavy circular string state with respect to the string
tension.Comment: 16 pages, LaTeX, no figure
Possible Pseudogap Phase in QCD
Thermal pion fluctuations, in principle, can completely disorder the phase of
the quark condensate and thus restore chiral symmetry. If this happens before
the quark condensate melts, strongly-interacting matter will be in the
pseudogap state just above the chiral phase transition. The quark condensate
does not vanish locally and quarks acquire constituent masses in the pseudogap
phase, despite chiral symmetry is restored.Comment: 8 pages, 1 figure; v2: references added; v3: argumerts modified; v4:
minor changes; v5: a misprint correcte
On string solutions of Bethe equations in N=4 supersymmetric Yang-Mills theory
The Bethe equations, arising in description of the spectrum of the dilatation
operator for the su(2) sector of the N=4 supersymmetric Yang-Mills theory, are
considered in the anti-ferromagnetic regime. These equations are deformation of
those for the Heisenberg XXX magnet. It is proven that in the thermodynamic
limit roots of the deformed equations group into strings. It is proven that the
corresponding Yang's action is convex, which implies uniqueness of solution for
centers of the strings. The state formed of strings of length (2n+1) is
considered and the density of their distribution is found. It is shown that the
energy of such a state decreases as n grows. It is observed that
non-analyticity of the left hand side of the Bethe equations leads to an
additional contribution to the density and energy of strings of even length.
Whence it is concluded that the structure of the anti-ferromagnetic vacuum is
determined by the behaviour of exponential corrections to string solutions in
the thermodynamic limit and possibly involves strings of length 2.Comment: LaTex, 9 pages, 1 figur
Correlators of Wilson loops and local operators from multi-matrix models and strings in AdS
We study correlation functions of Wilson loops and local operators in a
subsector of N=4 SYM which preserves two supercharges. Localization arguments
allow to map the problem to a calculation in bosonic two-dimensional Yang-Mills
theory. In turn, this can be reduced to computing correlators in certain
Gaussian multi-matrix models. We focus on the correlation function of a Wilson
loop and two local operators, and solve the corresponding three-matrix model
exactly in the planar limit. We compare the strong coupling behavior to string
theory in AdS_5xS^5, finding precise agreement. We pay particular attention to
the case in which the local operators have large R-charge J \sim sqrt{lambda}
at strong coupling.Comment: 50 pages, 9 figures. v2: minor changes, references adde
The classical origin of quantum affine algebra in squashed sigma models
We consider a quantum affine algebra realized in two-dimensional non-linear
sigma models with target space three-dimensional squashed sphere. Its affine
generators are explicitly constructed and the Poisson brackets are computed.
The defining relations of quantum affine algebra in the sense of the Drinfeld
first realization are satisfied at classical level. The relation to the
Drinfeld second realization is also discussed including higher conserved
charges. Finally we comment on a semiclassical limit of quantum affine algebra
at quantum level.Comment: 25 pages, 2 figure
Holographic three-point functions of semiclassical states
We calculate the holographic three-point functions in N = 4 super-Yang-Mills
theory in the case when two of the operators are semiclassical and one is dual
to a supergravity mode. We further discuss the transition to the regime when
all three operators are semiclassical.Comment: 17 pages, 3 figures; v2: refs. added, discussion in sec. 2.1
expanded; v3: misprint in (2.28) corrected, published versio
Dual neutral variables and knot solitons in triplet superconductors
In this paper we derive a dual presentation of free energy functional for
spin-triplet superconductors in terms of gauge-invariant variables. The
resulting equivalent model in ferromagnetic phase has a form of a version of
the Faddeev model. This allows one in particular to conclude that spin-triplet
superconductors allow formation of stable finite-length closed vortices (the
knotted solitons).Comment: Replaced with version published in PRL (added a discussion of the
effect of the coupling of the fields {\vec s} and {\vec C} on knot
stability). Latest updates of the paper and miscellaneous links related to
knotted solitons are also available at the homepage of the author
http://www.teorfys.uu.se/PEOPLE/egor/ . Animations of knotted solitons by
Hietarinta and Salo are available at
http://users.utu.fi/h/hietarin/knots/c45_p2.mp
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