239 research outputs found
Some Computations in Background Independent Open-String Field Theory
Recently, background independent open-string field theory has been formally
defined in the space of all two-dimensional world-sheet theories. In this
paper, to make the construction more concrete, I compute the action for an
off-shell tachyon field of a certain simple type. From the computation it
emerges that, although the string field action does not coincide with the
world-sheet (matter) partition function in general, these functions do coincide
on shell. This can be demonstrated in general, as long as matter and ghosts are
decoupled.Comment: 14 p
Role of Short Distance Behavior in Off-Shell Open-String Field Theory
A recent proposal for a background independent open string field theory is
studied in detail for a class of backgrounds that correspond to general
quadratic boundary interactions on the world-sheet. A short-distance cut-off is
introduced to formulate the theory with a finite number of local and
potentially unrenormalizable boundary couplings. It is shown that
renormalization of the boundary couplings makes both the world-sheet partition
function and the string field action finite and cut-off independent, although
the resulting string field action has an unpalatable dependence on the leading
unrenormalizable coupling.Comment: 16 page
A Note on Open Strings in the Presence of Constant B-Field
We consider the open string sigma-model in the presence of a constant
Neveu-Schwarz B-field on the world-sheet that is topologically equivalent to a
disk with n holes. First, we compute the sigma-model partition function.
Second, we make a consistency check of ideas about the appearance of
noncommutative geometry within open strings.Comment: 4 pages, references corrected and remarks adde
Pair Creation of Open Strings in an Electric Field
We calculate exactly the rate of pair production of open bosonic and
supersymmetric strings in a constant electric field. The rate agrees with
Schwinger's classic result in the weak-field limit, but diverges when the
electric field approaches some critical value of the order of the string
tension. (Phyzzx file)Comment: 13 pages, CPTH-A182.089
On the Problems with Background Independence in String Theory
The problems with background independence are discussed in the example of
open string theory. Based on the recent proposal by Witten I calculate the
String Field Theory action in conformal perturbation theory to second order and
demonstrate that the proper treatment of contact terms leads to nontrivial
equations of motion. I conjecture the form of the field theory action to all
orders.Comment: 15p., Preprint IASSNS-HEP-93/6
The origin of noncommutativity?
Consistent boundary Poisson structures for open string theory coupled to
background -field are considered using the new approach proposed in
hep-th/0111005. It is found that there are infinitely many consistent Poisson
structures, each leads to a consistent canonical quantization of open string in
the presence of background -field. Consequently, whether the -branes to
which the open string end points are attached is noncommutative or not depends
on the choice of a particular Poisson structure.Comment: Revtex4, published versio
Constrained Quantization of Open String in Background B Field and Noncommutative D-brane
In a previous paper we provided a consistent quantization of open strings
ending on D-branes with a background field. In this letter, we show that
the same result can also be obtained using the more traditional method of
Dirac's constrained quantization. We also extend the discussion to the
fermionic sector.Comment: 12 pages, LaTex, no figure; v2: 3 references and a footnote added in
sec. 2 (version to appear in Nucl. Phys. B
Probing bound states of D-branes
A zero-brane is used to probe non-threshold BPS bound states of (p,
p+2,p+4)-branes. At long distances the stringy calculation agrees with the
supergravity calculations. The supergravity description is given, using the
interpretation of the D=8 dyonic membrane as the bound state of a two-brane
inside a four-brane. We investigate the short distance structure of these bound
states, compute the phase shift of the scattered zero-brane and find the bound
states characteristic size. It is found that there should be a supersymmetric
solution of type IIa supergravity, describing a bound state of a zero-brane and
two orthogonal two-brane, all inside a four-brane , with an additional unbound
zero-brane. We comment on the relationship between p-branes and (p-2)-branes.Comment: Minor changes, misprints corrected, two refrences added, 19 pages,
Late
A Scaling Limit With Many Noncommutativity Parameters
We derive the worldsheet propagator for an open string with different
magnetic fields at the two ends, and use it to compute two distinct
noncommutativity parameters, one at each end of the string. The usual scaling
limit that leads to noncommutative Yang-Mills can be generalized to a scaling
limit in which both noncommutativity parameters enter. This corresponds to
expanding a theory with U(N) Chan-Paton factors around a background U(1)^N
gauge field with different magnetic fields in each U(1).Comment: 14 pages, harvma
p-branes from (p-2)-branes in the Bosonic String Theory
We show that Dirichlet p-brane can be expressed as a configuration of
infinitely many Dirichlet (p-2)-branes in the bosonic string theory. Using this
fact, we interpret the massless fields on the p-brane worldvolume as
deformations of the configuration of the (p-2)-branes. Especially we find that
the worldvolume gauge field parametrizes part of the group of diffeomorphisms
on the worldvolume.Comment: 16 pages, latex. The treatment of boundary interactions is correcte
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