3,069 research outputs found
Effective Tachyonic Potential in Closed String Field Theory
We calculate the effective tachyonic potential in closed string field theory
up to the quartic term in the tree approximation. This involves an elementary
four-tachyon vertex and a sum over the infinite number of Feynman graphs with
an intermediate massive state. We show that both the elementary term and the
sum can be evaluated as integrals of some measure over different regions in the
moduli space of four-punctured spheres. We show that both elementary and
effective coupling give negative contributions to the quartic term in the
tachyon potential. Numerical calculations show that the fourth order term is
big enough to destroy a local minimum which exists in the third order
approximation.Comment: 41 pages, LaTeX + psfig macro package, 15 uuencoded tar-compressed
postscript figures include
Thermodynamics of phase transition in higher dimensional Reissner-Nordstr\"{o}m-de Sitter black hole
It is well known that there are black hole and the cosmological horizons for
the Reissner-Nordstr\"{o}m-de Sitter spacetime. Although the thermodynamic
quantities on the horizons are not irrelevant, they satisfy the laws of black
hole thermodynamics respectively. In this paper by considering the relations
between the two horizons we give the effective thermodynamic quantities in
-dimensional Reissner-Nordstr\"{o}m-de Sitter spacetime. The
thermodynamic properties of these effective quantities are analyzed, moreover,
the critical temperature, critical pressure and critical volume are obtained.
We carry out an analytical check of Ehrenfest equations and prove that both
Ehrenfest equations are satisfied. So the spacetime undergoes a second order
phase transition at the critical point. This result is consistent with the
nature of liquid--gas phase transition at the critical point, hence deepening
the understanding of the analogy of charged dS spacetime and liquid--gas
systems.Comment: 18 pages, 7 figures, 1 tabl
On the Background Independence of String Field Theory: III. Explicit Field Redefinitions
Given two conformal field theories related to each other by a marginal
perturbation, and string field theories constructed around such backgrounds, we
show how to construct explicit redefinition of string fields which relate these
two string field theories. The analysis is carried out completely for quadratic
and cubic terms in the action. Although a general proof of existence of field
redefinitions which relate higher point vertices is not given, specific
examples are discussed. Equivalence of string field theories formulated around
two conformal field theories which are not close to each other, but are related
to each other by a series of marginal deformations, is also discussed. The
analysis can also be applied to study the equivalence of different formulation
of string field theories around the same background.Comment: 46 page
Phase transition of the higher dimensional charged Gauss-Bonnet black hole in de Sitter spacetime
We study the phase transition of charged Gauss-Bonnet-de Sitter (GB-dS) black
hole. For black holes in de Sitter spacetime, there is not only black hole
horizon, but also the cosmological horizon. The thermodynamic quantities on the
both horizons satisfy the first law of the black hole thermodynamics,
respectively; moreover, there are additional connections between them. Using
the effective temperature approach, we obtained the effective thermodynamic
quantities of charged GB-dS black hole. According to Ehrenfest classification,
we calculate some response functions and plot their figures, from which one can
see that the spacetime undergoes a second-order phase transition at the
critical point. It is shown that the critical values of effective temperature
and pressure decrease with the increase of the value of GB parameter .Comment: 9 pages, 16 figure
catena-Poly[[[diaquacadmium(II)]bis[μ-2-(pyridinium-1-yl)butanedioato]-κ2 O 1:O 4;κ2 O 4:O 1] tetrahydrate], a polymeric chain structure
In the title complex, {[Cd(C9H8NO4)2(H2O)2]·4H2O}n, the CdII atom (site symmetry 2) is coordinated by six O atoms from four crystallographically related 1-(1,2-dicarboxylÂate)pyridin-1-ium ligands (L) and from two water molecules in a distorted octahedral geometry. Paired L ligands connect CdII atoms into a chain motif parallel to [001], which is further interÂlinked by O—H⋯O hydrogen bonds into a three-dimensional supraÂmolecular net
Gauge and General Coordinate Invariance in Non-Polynomial Closed String Field Theory
An appropriate field configuration in non-polynomial closed string field
theory is shown to correspond to a general off-shell field configuration in low
energy effective field theory. A set of string field theoretic symmetries that
act on the fields in low energy effective field theory as general coordinate
transformation and antisymmetric tensor gauge transformation is identified. The
analysis is carried out to first order in the fields; thus the symmetry
transformations in string field theory reproduce the linear and the first
non-linear terms in the gauge transformations in the low energy effective field
theory.Comment: 29 page
Fractional phase transitions of RN-AdS black hole at Davies points
We perform a study of phase transitions of RN-AdS black hole at its Davies
points according to a generalized Ehrenfest classification of phase transition
established on the basis of fractional derivatives. Davies points label the
positions where heat capacity diverges. According to the usual Ehrenfest
classification, second-order phase transitions occur there. For RN-AdS black
hole, the Davies points can be classified into two types. The first type
corresponds to the extreme values of temperature and the second type
corresponds to the infection point(namely the critical point) of temperature.
Employing the generalized Ehrenfest classification, we find that the orders of
phase transition at the two types of Davies points are different. It is
-order for the first type and -order for the second type. Thus this
finer-grained classification can discriminate phase transitions that are
supposed to be in the same category, which may provide some new insights toward
a better understanding of black hole thermodynamics.Comment: 13 pages, 4 figures, to be published in Chinese Physics
5,6-Dimethyl-1,2,4-triazin-3-amine
In the crystal structure of the title compound, C5H8N4, adjacent molÂecules are connected through N—H⋯N hydrogen bonds, resulting in a zigzag chain along [100]. The amino groups and heterocyclic N atoms are involved in further N—H⋯N hydrogen bonds, forming R
2
2(8) motifs
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