3,108 research outputs found

### A brief review of "little string theories"

This is a brief review of the current state of knowledge on "little string
theories", which are non-gravitational theories having several string-like
properties. We focus on the six dimensional maximally supersymmetric "little
string theories" and describe their definition, some of their simple
properties, the motivations for studying them, the DLCQ and holographic
constructions of these theories and their behaviour at finite energy density.
(Contribution to the proceedings of Strings '99 in Potsdam, Germany.)Comment: 11 pages, contribution to Strings '99 proceeding

### The effective string spectrum in the orthogonal gauge

The low-energy effective action on long string-like objects in quantum field
theory, such as confining strings, includes the Nambu-Goto action and then
higher-derivative corrections. This action is diffeomorphism-invariant, and can
be analyzed in various gauges. Polchinski and Strominger suggested a specific
way to analyze this effective action in the orthogonal gauge, in which the
induced metric on the worldsheet is conformally equivalent to a flat metric.
Their suggestion leads to a specific term at the next order beyond the
Nambu-Goto action. We compute the leading correction to the Nambu-Goto spectrum
using the action that includes this term, and we show that it agrees with the
leading correction previously computed in the static gauge. This gives a
consistency check for the framework of Polchinski and Strominger, and helps to
understand its relation to the theory in the static gauge.Comment: 21 page

### Deconstructing (2,0) proposals

C. P. is supported by the U.S. Department of Energy under
Grant No. DE-FG02-96ER40959. M. S. S. is supported by
an EURYI award of the European Science Foundatio

### Stable Non-Supersymmetric Supergravity Solutions from Deformations of the Maldacena-Nunez Background

We study a deformation of the type IIB Maldacena-Nunez background which
arises as the near-horizon limit of NS5 branes wrapped on a two-cycle. This
background is dual to a "little string theory" compactified on a two-sphere, a
theory which at low energies includes four-dimensional N = 1 super Yang-Mills
theory. The deformation we study corresponds to a mass term for some of the
scalar fields in this theory, and it breaks supersymmetry completely. In the
language of seven-dimensional SO(4) gauged supergravity the deformation
involves (at leading order) giving a VEV, depending only on the radial
coordinate, to a particular scalar field. We explicitly construct the
corresponding solution at leading order in the deformation, both in
seven-dimensional and in ten-dimensional supergravity, and we verify that it
completely breaks supersymmetry. Since the original background had a mass gap
and we are performing a small deformation, the deformed background is
guaranteed to be stable even though it is not supersymmetric.Comment: 1+31 pages, one figure. v2: minor clarifications, refs adde

### Two loop partition function for large N pure Yang-Mills theory on a small three-sphere

We give a direct path-integral calculation of the partition function for pure
3+1 dimensional U(N) Yang-Mills theory at large N on a small three-sphere, up
to two-loop order in perturbation theory. From this, we calculate the one-loop
shift in the Hagedorn/deconfinement temperature for the theory at small volume,
finding that it increases (in units of the inverse sphere radius) as we go to
larger coupling (larger volume). Our results also allow us to read off the sum
of one-loop anomalous dimensions for all operators with a given engineering
dimension in planar Yang-Mills theory on R^4. As checks on our calculation, we
reproduce both the Hagedorn shift and some of the anomalous dimension sums by
independent methods using the results of hep-th/0412029 and hep-th/0408178. The
success of our calculation provides a significant check of methods used in
hep-th/0502149 to establish a first order deconfinement transition for pure
Yang-Mills theory on a small three-sphere.Comment: 40 pages, 4 figures, harvma

### Exactly Marginal Deformations of N=4 SYM and of its Supersymmetric Orbifold Descendants

In this paper we study exactly marginal deformations of field theories living
on D3-branes at low energies. These theories include N=4 supersymmetric
Yang-Mills theory and theories obtained from it via the orbifolding procedure.
We restrict ourselves only to orbifolds and deformations which leave some
supersymmetry unbroken. A number of new families of N=1 superconformal field
theories are found. We analyze the deformations perturbatively, and also by
using general arguments for the dimension of the space of exactly marginal
deformations. We find some cases where the space of perturbative exactly
marginal deformations is smaller than the prediction of the general analysis at
least up to three-loop order), and other cases where the perturbative result
(at low orders) has a non-generic form.Comment: 25 pages, 1 figure. v2: added preprint number, references adde

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