A single-parameter family of covariant gauge fixing conditions in bosonic
string field theory is proposed. It is a natural string field counterpart of
the covariant gauge in the conventional gauge theory, which includes the Landau
gauge as well as the Feynman (Siegel) gauge as special cases. The action in the
Landau gauge is largely simplified in such a way that numerous component fields
have no derivatives in their kinetic terms and appear in at most quadratic in
the vertex.Comment: 24 page
As an extension of the so-called BMN conjecture, we investigate the plane-wave limit for possible holographic connection between bulk string theories in non-conformal backgrounds of Dp-branes and the corresponding supersymmetric gauge theories for p < 5.Our work is based on the tunneling picture for dominant null trajectories of strings in the limit of large angular momentum. The tunneling null trajectories start from the near-horizon boundary and return to the boundary, and the resulting backgrounds are time-dependent for general Dp-branes except for p = 3. We develop a general method for extracting diagonalized two-point functions for boundary theories as Euclidean (bulk) S-matrix in the time-dependent backgrounds. For the case of D0-brane, two-point functions of supergravity modes are shown to agree with the results derived previously by the perturbative analysis of supergravity. We then discuss the implications of the holography for general cases of Dp-branes including the stringy excitations. All the cases (p = 3, p < 5) exhibit interesting infra-red behaviors, which are different from free-field theories, suggesting the existence of quite nontrivial fixed-points in dual gauge theories.
The canonical theory of N = 1 supergravity is applied to Bianchi class A spatially homogeneous cosmologies. The full set of quantum constraints are then solved with the possible ordering ambiguity taken into account by introducing a free parameter. The wave functions are explicitly given for all the Bianchi class A models in a unified way. Some comments are made on the Bianchi type IX cases.
We investigate the holographic correspondence between (p + 1)-dimensional (0 ≤ p ≤ 4) SYM theories with 16 supercharges and superstring theories on the near-horizon limit of Dp-brane backgrounds. Following an approach based on the tunneling picture, we study Euclidean superstring semi-classically along null geodesics which connect two points on the boundary of the spacetime. We extend the analysis of hep-th/0308024 and study the fermionic sector of the superstring. For p = 3, we do not have world-sheet supersymmetry, and the energies of bosonic and fermionic fluctuations do not match. By interpreting the superstring amplitudes as correlators of gauge theory operators with large R-charge J, we obtain gauge theory two-point functions including those of fermionic operators. Our approach yields results consistent with the previous supergravity analysis for the D0branes, including the subleading part in J. Our prediction from holography is that the two-point functions for the supergravity modes are power-law behaved, even for the nonconformal (p = 3) SYM theories.
It is well-known that the standard no-ghost theorem can be extended straightforwardly to the general c = 26 CFT on IR d−1,1 × K, where 2 ≤ d ≤ 26 and K is a compact unitary CFT of appropriate central charge. We prove the no-ghost theorem for d = 1, i.e., when only the timelike direction is flat. This is done using the technique of Frenkel, Garland and Zuckerman.
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