72 research outputs found
The U(1)s in the Finite N Limit of Orbifold Field Theories
We study theories generated by orbifolding the {\cal N}=4 super conformal
U(N) Yang Mills theory with finite N, focusing on the r\^ole of the remnant
U(1) gauge symmetries of the orbifold process. It is well known that the one
loop beta functions of the non abelian SU(N) gauge couplings vanish in these
theories. It is also known that in the large N limit the beta functions vanish
to all order in perturbation theory. We show that the beta functions of the non
abelian SU(N) gauge couplings vanish to two and three loop order even for
finite N. This is the result of taking the abelian U(1) of U(N)=SU(N)xU(1) into
account. However, the abelian U(1) gauge couplings have a non vanishing beta
function. Hence, those theories are not conformal for finite N. We analyze the
renormalization group flow of the orbifold theories, discuss the suppression of
the cosmological constant and tackle the hierarchy problem in the non
supersymmetric models.Comment: 2+35 pages, 2 figures, LaTe
Confinement in 4D Yang-Mills Theories from Non-Critical Type 0 String Theory
We study five dimensional non critical type 0 string theory and its
correspondence to non supersymmetric Yang Mills theory in four dimensions. We
solve the equations of motion of the low energy effective action and identify a
class of solutions that translates into a confining behavior in the IR region
of the dual gauge theories. In particular we identify a setup which is dual to
pure SU(N) Yang-Mills theory. Possible flows of the solutions to the UV region
are discussed. The validity of the solutions and potential sub-leading string
corrections are also discussed.Comment: 25 pages, Latex. 1 figure. v2: refs. added, minor corrections, note
added in section
On the classical equivalence of superstring field theories
We construct mappings that send solutions of the cubic and non-polynomial
open superstring field theories to each other. We prove that the action is
invariant under the maps and that gauge orbits are mapped into gauge orbits. It
follows that the perturbative spectrum around solutions is the same in both
theories. The mappings also preserve the string field reality condition.
We generalize to the cases of a non-BPS D-brane and of multi-D-brane systems.
We analyze the recently found analytical solutions of the cubic action, both in
the BPS sector and the non-BPS sector and show that they span a one parameter
family of solutions with empty cohomology and identical action, which suggests
that they are gauge equivalent. We write the gauge transformations relating
these solutions explicitly. This seems to suggest that open superstring field
theory is able to describe a vacuum solution even around a BPS D-brane.Comment: v2: Action proof revised, discussion improved, typos corrected,
conclusions unchanged. 25 page
Schnabl's L_0 Operator in the Continuous Basis
Following Schnabl's analytic solution to string field theory, we calculate
the operators for a scalar field in the
continuous basis. We find an explicit and simple expression for them
that further simplifies for their sum, which is block diagonal in this basis.
We generalize this result for the bosonized ghost sector, verify their
commutation relation and relate our expressions to wedge state representations.Comment: 1+16 pages. JHEP style. Typos correcte
On the validity of the solution of string field theory
We analyze the realm of validity of the recently found tachyon solution of
cubic string field theory. We find that the equation of motion holds in a non
trivial way when this solution is contracted with itself. This calculation is
needed to conclude the proof of Sen's first conjecture. We also find that the
equation of motion holds when the tachyon or gauge solutions are contracted
among themselves.Comment: JHEP style, 9+1 pages. Typos correcte
Normalization anomalies in level truncation calculations
We test oscillator level truncation regularization in string field theory by
calculating descent relations among vertices, or equivalently, the overlap of
wedge states. We repeat the calculation using bosonic, as well as fermionic
ghosts, where in the bosonic case we do the calculation both in the discrete
and in the continuous basis. We also calculate analogous expressions in field
level truncation. Each calculation gives a different result. We point out to
the source of these differences and in the bosonic ghost case we pinpoint the
origin of the difference between the discrete and continuous basis
calculations. The conclusion is that level truncation regularization cannot be
trusted in calculations involving normalization of singular states, such as
wedge states, rank-one squeezed state projectors and string vertices.Comment: 1+20 pages, 6 figures. v2: Ref. added, typos correcte
Virasoro operators in the continuous basis of string field theory
In this work we derive two important tools for working in the \kappa basis of
string field theory. First we give an analytical expression for the finite part
of the spectral density \rho_{fin}. This expression is relevant when both
matter and ghost sectors are considered. Then we calculate the form of the
matter part of the Virasoro generators L_n in the \kappa basis, which construct
string field theory's derivation Q_{BRST}. We find that the Virasoro generators
are given by one dimensional delta functions with complex arguments.Comment: 16 page
Marginal deformations in string field theory
We describe a method for obtaining analytic solutions corresponding to exact
marginal deformations in open bosonic string field theory. For the photon
marginal deformation we have an explicit analytic solution to all orders. Our
construction is based on a pure gauge solution where the gauge field is not in
the Hilbert space. We show that the solution itself is nevertheless perfectly
regular. We study its gauge transformations and calculate some coefficients
explicitly. Finally, we discuss how our method can be implemented for other
marginal deformations.Comment: 23 pages. v2: Some paragraphs improved, typos corrected, ref adde
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