48 research outputs found
Absorption by Threebranes and the AdS/CFT Correspondence
In the first part of this talk I discuss two somewhat different supergravity
approaches to calculating correlation functions in strongly coupled Yang-Mills
theory. The older approach relates two-point functions to cross-sections for
absorption of certain incident quanta by threebranes. In this approach the
normalization of operators corresponding to the incident particles is fixed
unambiguously by the D3-brane DBI action. By calculating absorption
cross-sections of all partial waves of the dilaton we find corresponding
two-point functions at strong `t Hooft coupling and show that they are
identical to the weak coupling results. The newer approach to correlation
functions relates them to boundary conditions in AdS space. Using this method
we show that for a certain range of negative mass-squared there are two
possible operator dimensions corresponding to a given scalar field in AdS, and
indicate how to calculate correlation functions for either of these choices. In
the second part of the talk I discuss an example of AdS/CFT duality which
arises in the context of type 0 string theory. The CFT on N coincident electric
and magnetic D3-branes is argued to be stable for sufficiently weak `t Hooft
coupling. It is suggested that its transition to instability at a critical
coupling is related to singularity of planar diagrams.Comment: 14 pages, LaTeX; Talk at Strings '99, Potsdam, German
Absorption of dilaton s-wave in type 0B string theory
We find the absorption probability of dilaton field in type 0B string theory.
Since the background solutions are of the form on both
regions, we use the semiclassical formalism adopted in type IIB theory to find
the absorption cross section. The background tachyon field solution was used as
a reference to relate the solutions of the two regions. We also consider the
possible corrections to absorption probability and the form of the
correction is expected as in the calculation of the confinement solution.Comment: minor corrections, reference added, version to appear PR
Beta-functions in Yang-Mills Theory from Non-critical String
The renormalization group equations of the Yang-Mills theory are examined in
the non-critical string theory according to the framework of the holography.
Under a simple ansatz for the tachyon, we could find several interesting
solutions which are classified by the value of the tachyon potential at the
vacuum. We show two typical, asymptotic-free solutions which are different in
their infrared behaviors. For both types of solutions, we could obtain
quark-confinement potential from the Wilson-loop. The stability of the tachyon
and the ZigZag symmetry are also discussed for these solutions.Comment: 16 pages, 5 figure
Baryons and Domain Walls in an N = 1 Superconformal Gauge Theory
Coincident D3-branes placed at a conical singularity are related to string
theory on , for a suitable five-dimensional Einstein manifold
. For the example of the conifold, which leads to
, the infrared limit of the theory on
D3-branes was constructed recently. This is supersymmetric
gauge theory coupled to four bifundamental chiral
superfields and supplemented by a quartic superpotential which becomes marginal
in the infrared. In this paper we consider D3-branes wrapped over the 3-cycles
of and identify them with baryon-like chiral operators built out of
products of chiral superfields. The supergravity calculation of the
dimensions of such operators agrees with field theory. We also study the
D5-brane wrapped over a 2-cycle of , which acts as a domain wall in
. We argue that upon crossing it the gauge group changes to . This suggests a construction of supergravity duals of
supersymmetric gauge theories.Comment: 14 pages, latex; v2: discussion at the end of section 3 modified, the
version to appear in Physical Review
Yang-Mills theory from non-critical string
The correspondence of the non-critical string theory and the Yang-Mills
theory is examined according to the recent Polyakov's proposal, and two
possible solutions of the bulk equations are addressed near the fixed points of
the pure Yang-Mills theory: (i) One solution asymptotically approaches to the
AdS space at the ultraviolet limit where the conformally invariant field theory
is realized. (ii) The second one approaches to the flat space in both the
infrared and the ultraviolet limits. The area law of the Wilson-loop and the
asymptotic freedom with logarithmic behaviour are seen in the respective limit.Comment: 17 pages, no figure, Late
On Four-point Functions in the CFT/AdS Correspondence
We discuss the properties of four-point functions in the context of the
correspondence between a classical supergravity theory in the bulk of the Anti
de Sitter space and quantum conformal field theory at the boundary. The
contribution to a four-point function from the exchange of a scalar field of
arbitrary mass in AdS space is explicitly identified with that of the
corresponding operator in the conformal partial wave expansion of a four-point
function on the CFT side. Integral representations are found for the massless
vector and graviton exchanges. We also discuss some aspects of the four-point
functions of Tr F^2 and Tr F F^* (`dilaton' and `axion') operators in the N =4
supersymmetric Yang-Mills.Comment: 23 pages, using harvmac and epsf, three figures; v2,v3: minor
corrections; v4: argument at the end of section 5 corrected and is now
consistent with hep-th/9808006 by Freedman et a
Superconformal Gauge Theories and Non-Critical Superstrings
We consider effective actions for six-dimensional non-critical superstrings.
We show that the addition of units of R-R flux and of space-time
filling D5-branes produces solutions with curvature
comparable to the string scale. These solutions have the right structure to be
dual to supersymmetric SU(N) gauge theories with flavors. We
further suggest bounds on the mass-squared of tachyonic fields in this
background that should restrict the theory to the conformal window.Comment: 16 pages, 1 figure v4: Minor change
ADS/CFT String Duality and Conformal Gauge Field Theories
Compactification of Type IIB superstring on an
background leads to SU(N) gauge field theories with prescribed matter
representations. In the 't Hooft limit of large N such theories are conformally
finite. For finite N and broken supersymmetry ( = 0) I derive the
constraints to be two-loop conformal and examine the consequences for a wide
choice of and its embedding .Comment: 10 pages LaTe
Probing AdS/CFT correspondence via world-sheet methods and 2d gravity like scaling arguments
We show how some features of the AdS/CFT correspondence for AdS_3 can easily
be understood via standard world-sheet methods and 2d gravity like scaling
arguments. To do this, we propose a stringy way for perturbing two-dimensional
CFT's around their critical points. Our strategy is to start from a stringy
(world-sheet) representation of 2d CFT in space-time. Next we perturb a
world-sheet action by some marginal operators such that the space-time symmetry
becomes finite dimensional. As a result, we get a massive FT in space-time with
a scale provided by two-dimensional coupling constant. It turns out that there
exists a perturbation that leads to string theory on AdS_3. In this case the
scale is equivalently provided by the radial anti-de-Sitter coordinate.Comment: 15 pages; corrected some typo
Correlation functions in the Coulomb branch of N=4 SYM from AdS/CFT correspondence
In the present paper we study SU(N)->S(U(N/2)xU(N/2)) symmetry breaking in
N=4 SYM via AdS/CFT correspondence. We consider two stacks of N/2 parallel D3
branes separated by a distance 2\vec d. In this case there is mixing between
the different l-wave dilatonic KK modes. We calculate certain the two point
correlation functions in the dual gauge theory. Due to mode mixing, the
diagonal correlation functions have 1/N conformal-like correction as well as
deformation terms. The off-diagonal correlators are also non-vanishing and
their leading order is 1/N. We discuss briefly the spectrum of the glueball
exitations.Comment: 25 pages, more comments on two throat geometry, decoupling limit and
correction terms, a few typos corrected, two references added; to appear in
Phys.Rev.