1,349 research outputs found

### The Free Energy of N=4 Super-Yang-Mills and the AdS/CFT Correspondence

We compute the high-temperature limit of the free energy for four-dimensional
N=4 supersymmetric SU(N_c) Yang-Mills theory. At weak coupling we do so for a
general ultrastatic background spacetime, and in the presence of slowly-varying
background gauge fields. Using Maldacena's conjectured duality, we calculate
the strong-coupling large-N_c expression for the special case that the
three-space has constant curvature. We compare the two results paying
particular attention to curvature corrections to the leading order expressions.Comment: 26 pages.Minor corrections to eqs.(19),(21). Results and conclusions
unchanged. References adde

### Fractional Branes and the Entropy of 4D Black Holes

We reconsider the four dimensional extremal black hole constructed in type
IIB string theory as the bound state of D1-branes, D5-branes, momentum, and
Kaluza-Klein monopoles. Specifically, we examine the case of an arbitrary
number of monopoles. Consequently, the weak coupling calculation of the
microscopic entropy requires a study of the D1-D5 system on an ALE space. We
find that the complete expression for the Bekenstein-Hawking entropy is
obtained by taking into account the massless open strings stretched between the
fractional D-branes which arise in the orbifold limit of the ALE space. The
black hole sector therefore arises as a mixed Higgs-Coulomb branch of an
effective 1+1 dimensional gauge theory.Comment: 12 pages. 1 figure. v2: References adde

### Non-abelian instantons on a fuzzy four-sphere

We study the compatibility between the $BPST SU(2)$ instanton and the fuzzy
four-sphere algebra. By using the projective module point of view as an
intermediate step, we are able to identify a non-commutative solution of the
matrix model equations of motion which minimally extends the SU(2) instanton
solution on the classical sphere $S^4$. We also propose to extend the
non-trivial second Chern class with the five-dimensional noncommutative
Chern-Simons term

### Operator Mixing and the BMN Correspondence

In this note we update the discussion of the BMN correspondence and string interactions in hep-th/0205089 to incorporate the effects of operator mixing. We diagonalize the matrix of two point functions of single and double trace operators, and compute the eigen-operators and their anomalous dimensions to order g_2^2 \lambda'. Surprisingly, operators in different R symmetry multiplets remain degenerate at this order. We also calculate the corresponding energy shifts in string theory, and find a discrepancy with field theory results, indicating possible new effects in light-cone string field theory

### PP-wave String Interactions from String Bit Model

We construct the string states $|O_{p}^J>_J$, $|O_{q}^{J_1}>_{{J_1}{J_2}}$
and $|O_{0}^{J_{1}J_{2}}>_{{J_1}{J_2}}$ in the Hilbert space of the quantum
mechanical orbifold model so as to calculate the three point functions and the
matrix elements of the light-cone Hamiltonian from the interacting string bit
model. With these string states we show that the three point functions and the
matrix elements of the Hamiltonian derived from the interacting string bit
model up to $g^{2}_2$ order precisely match with those computed from the
perturbative SYM theory in BMN limit.Comment: 20 pages, no figure, LaTeX, some changes made and references adde

### Strong Evidence In Favor OF The Existence Of S-Matrix For Strings In Plane Waves

Field theories on the plane wave background are considered. We discuss that
for such field theories one can only form 1+1 dimensional freely propagating
wave packets. We analyze tree level four point functions of scalar field theory
as well as scalars coupled to gauge fields in detail and show that these four
point functions are well-behaved so that they can be interpreted as S-matrix
elements for 2 particle $\to$ 2 particle scattering amplitudes. Therefore, at
least classically, field theories on the plane wave background have S-matrix
formulation.Comment: Latex file, 26 pages, 4 eps figures. v3: In the end of paper there is
a "Note Added" as an update of the result

### On Time-dependent Collapsing Branes and Fuzzy Odd-dimensional Spheres

We study the time-dependent dynamics of a collection of N
collapsing/expanding D0-branes in type IIA String Theory. We show that the
fuzzy-S^3 and S^5 provide time-dependent solutions to the Matrix Model of
D0-branes and its DBI generalisation. Some intriguing cancellations in the
calculation of the non-abelian DBI Matrix actions result in the fuzzy-S^3 and
S^5 having the same dynamics at large-N. For the Matrix model, we find analytic
solutions describing the time-dependent radius, in terms of Jacobi elliptic
functions. Investigation of the physical properties of these configurations
shows that there are no bounces for the trajectory of the collapse at large-N.
We also write down a set of useful identities for fuzzy-S^3, fuzzy-S^5 and
general fuzzy odd-spheres.Comment: 35 pages, latex; v2: discussion in Appendix B on the large-N limit of
the associator is modified, main results of paper unchange

### Non-Abelian BIonic Brane Intersections

We study "fuzzy funnel" solutions to the non-Abelian equations of motion of
the D-string. Our funnel describes n^6/360 coincident D-strings ending on n^3/6
D7-branes, in terms of a fuzzy six-sphere which expands along the string. We
also provide a dual description of this configuration in terms of the world
volume theory of the D7-branes. Our work makes use of an interesting non-linear
higher dimensional generalization of the instanton equations.Comment: 17 pages uses harvmac; v2: small typos corrected, refs adde

### Predictions for PP-wave string amplitudes from perturbative SYM

The role of general two-impurity multi-trace operators in the BMN
correspondence is explored. Surprisingly, the anomalous dimensions of all
two-impurity multi-trace BMN operators to order g_2^2\lambda' are completely
determined in terms of single-trace anomalous dimensions. This is due to
suppression of connected field theory diagrams in the BMN limit and this fact
has important implications for some string theory processes on the PP-wave
background. We also make gauge theory predictions for the matrix elements of
the light-cone string field theory Hamiltonian in the two string-two string and
one string-three string sectors.Comment: 46 pages, 12 figures. V3:typos correcte

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