10,463 research outputs found
Gauge Fields and D-branes
We prove that self-dual gauge fields in type I superstring theory are
equivalent to configurations of Dirichlet 5-branes, by showing that the
world-sheet theory of a Dirichlet 1-brane moving in a background of 5-branes
includes an ``ADHM sigma model.'' This provides an explicit construction of the
equivalent self-dual gauge field. We also discuss type II.Comment: harvmac, 9p
Theta Dependence In The Large N Limit Of Four-Dimensional Gauge Theories
The theta dependent of pure gauge theories in four dimensions can be studied
using a duality of large N gauge theories with string theory on a certain
spacetime. Via this duality, one can argue that for every theta, there are
infinitely many vacua that are stable in the large N limit. The true vacuum,
found by minimizing the energy in this family, is a smooth function of theta
except at theta equal to pi, where it jumps. This jump is associated with
spontaneous breaking of CP symmetry. Domain walls separating adjacent vacua are
described in terms of wrapped sixbranes.Comment: 8 p
Thermodynamic Instability of Black Holes of Third Order Lovelock Gravity
In this paper, we compute the mass and the temperature of the uncharged black
holes of third order Lovelock gravity and compute the entropy through the use
of first law of thermodynamics. We perform a stability analysis by studying the
curves of temperature versus the mass parameter, and find that there exists an
intermediate thermodynamically unstable phase for black holes with hyperbolic
horizon. The existence of this unstable phase for the uncharged topological
black holes of third order Lovelock gravity does not occur in the lower order
Lovelock gravity. We also perform a stability analysis for a spherical,
7-dimensional black hole of Lovelock gravity and find that while these kinds of
black holes for small values of Lovelock coefficients have an intermediate
unstable phase, they are stable for large values of Lovelock coefficients. We
also find that there exists an intermediate unstable phase for these black
holes in higher dimensions. This stability analysis shows that the
thermodynamic stability of black holes with curved horizons is not a robust
feature of all the generalized theories of gravity.Comment: 16 pages, 8 figure
MHV Vertices And Tree Amplitudes In Gauge Theory
As an alternative to the usual Feynman graphs, tree amplitudes in Yang-Mills
theory can be constructed from tree graphs in which the vertices are tree level
MHV scattering amplitudes, continued off shell in a particular fashion. The
formalism leads to new and relatively simple formulas for many amplitudes, and
can be heuristically derived from twistor space.Comment: 27 p
Perspectives on Pfaffians of Heterotic World-sheet Instantons
To fix the bundle moduli of a heterotic compactification one has to
understand the Pfaffian one-loop prefactor of the classical instanton
contribution. For compactifications on elliptically fibered Calabi-Yau spaces X
this can be made explicit for spectral bundles and world-sheet instantons
supported on rational base curves b: one can express the Pfaffian in a closed
algebraic form as a polynomial, or it may be understood as a theta-function
expression. We elucidate the connection between these two points of view via
the respective perception of the relevant spectral curve, related to its
extrinsic geometry in the ambient space (the elliptic surface in X over b) or
to its intrinsic geometry as abstract Riemann surface. We identify, within a
conceptual description, general vanishing loci of the Pfaffian, and derive
bounds on the vanishing order, relevant to solutions of W=dW=0.Comment: 40 pages; minor changes, discussion section 1.1 adde
A Non-Perturbative Superpotential With Symmetry
We compute the non-perturbative superpotential in -theory compactification
to four dimensions on a complex three-fold , where is a
rational elliptic surface. In contrast to examples considered previously, the
superpotential in this case has interesting modular properties; it is
essentially an theta function.Comment: Additional references and clarifications. Latex, 10 page
Free Fields Equations For Space-Time Algebras With Tensorial Momentum
Free field equations, with various spins, for space-time algebras with
second-rank tensor (instead of usual vector) momentum are constructed. Similar
algebras are appearing in superstring/M theories. The most attention is payed
to the gauge invariance properties, particularly the spin two equations with
gauge invariance are constructed for dimensions 2+2 and 2+4 and connection to
Einstein equation and diffeomorphism invariance is established
On Tensionless Strings in Dimensions
We argue for the existence of phase transitions in dimensions
associated with the appearance of tensionless strings. The massless spectrum of
this theory does not contain a graviton: it consists of one vector
multiplet and one linear multiplet, in agreement with the light-cone analysis
of the Green-Schwarz string in dimensions. In M-theory the string
decoupled from gravity arises when two 5-branes intersect over a
three-dimensional hyperplane. The two 5-branes may be connected by a 2-brane,
whose boundary becomes a tensionless string with supersymmetry in
dimensions. Non-critical strings on the intersection may also come from
dynamical 5-branes intersecting the two 5-branes over a string and wrapped over
a four-torus. The near-extremal entropy of the intersecting 5-branes is
explained by the non-critical strings originating from the wrapped 5-branes.Comment: latex, 16 pages; version to appear in Nucl. Phys.
Towards SO(2,10)-Invariant M-Theory: Multilagrangian Fields
The SO(2,10) covariant extension of M-theory superalgebra is considered, with
the aim to construct a correspondingly generalized M-theory, or 11d
supergravity. For the orbit, corresponding to the supergravity multiplet,
the simplest unitary representations of the bosonic part of this algebra, with
sixth-rank tensor excluded, are constructed on a language of field theory in
66d space-time. The main peculiarities are the presence of more than one
equation of motion and corresponding Lagrangians for a given field and that the
gauge and SUSY invariances of the theory mean that the sum of variations of
these Lagrangians (with different variations of the same field) is equal to
zero.Comment: Latex 16 pages, minor correction, To appear in Mod. Phys. Lett.
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