6,098 research outputs found
Closed Superstring in Noncommutative Compact Spacetime
In this paper we study the effects of noncommutativity on a closed
superstring propagating in the spacetime that is compactified on tori. The
effects of compactification and noncommutativity appear in the momentum,
quantization, supercurrent, super-conformal generators and in the boundary
state of the closed superstring emitted from a D-brane with the
NSNS background -field.Comment: 11 pages, Latex, no figur
3D gauged supergravity from SU(2) reduction of 6D supergravity
We obtain Yang-Mills gauged supergravity in three dimensions
from group manifold reduction of (1,0) six dimensional supergravity
coupled to an anti-symmetric tensor multiplet and gauge vector multiplets in
the adjoint of . The reduced theory is consistently truncated to 3D
supergravity coupled to bosonic and fermionic propagating degrees of freedom. This is in contrast to the
reduction in which there are also massive vector fields. The scalar manifold is
, and there is a gauge group. We then
construct Chern-Simons three dimensional gauged supergravity with scalar
manifold and
explicitly show that this theory is on-shell equivalent to the Yang-Mills
gauged supergravity theory obtained from the reduction,
after integrating out the scalars and gauge fields corresponding to the
translational symmetries .Comment: 24 pages, no figures, references added and typos correcte
On Subleading Contributions to the AdS/CFT Trace Anomaly
In the context of the AdS/CFT correspondence, we perform a direct computation
in AdS_5 supergravity of the trace anomaly of a d=4, N=2 SCFT. We find
agreement with the field theory result up to next to leading order in the 1/N
expansion. In particular, the order N gravitational contribution to the anomaly
is obtained from a Riemann tensor squared term in the 7-brane effective action
deduced from heterotic - type I duality. We also discuss, in the AdS/CFT
context, the order N corrections to the trace anomaly in d=4, N=4 SCFTs
involving SO or Sp gauge groups.Comment: 25 pages, LaTeX, v2: references adde
On the perturbative corrections around D-string instantons
We study -threshold corrections in an eight dimensional S-dual
pair of string theories, as a prototype of dual string vacua with sixteen
supercharges. We show that the orbifold CFT description of D-string instantons
gives rise to a perturbative expansion similar to the one appearing on the
fundamental string side. By an explicit calculation, using the Nambu-Goto
action in the static gauge, we show that the first subleading term agrees
precisely on the two sides. We then give a general argument to show that the
agreement extends to all orders.Comment: 12 page
Towards a string bit formulation of N=4 super Yang-Mills
We show that planar cal N=4 Yang-Mills theory at zero 't Hooft coupling can
be efficiently described in terms of 8 bosonic and 8 fermionic oscillators. We
show that these oscillators can serve as world-sheet variables, the string
bits, of a discretized string. There is a one to one correspondence between the
on shell gauge invariant words of the free Y-M theory and the states in the
oscillators' Hilbert space, obeying a local gauge and cyclicity constraints.
The planar two-point functions and the three-point functions of all gauge
invariant words are obtained by the simple delta-function overlap of the
corresponding discrete string world sheet. At first order in the 't Hooft
coupling, i.e. at one-loop in the Y-M theory, the logarithmic corrections of
the planar two-point and the three-point functions can be incorporated by
nearest neighbour interactions among the discretized string bits. In the SU(2)
sub-sector we show that the one-loop corrections to the structure constants can
be uniquely determined by the symmetries of the bit picture. For the SU(2)
sub-sector we construct a gauged, linear, discrete world-sheet model for the
oscillators, with only nearest neighbour couplings, which reproduces the
anomalous dimension Hamiltonian up to two loops. This model also obeys BMN
scaling to all loops.Comment: 64 pages, 6 figures, typos fixed, references adde
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