369 research outputs found
Dynamics with Infinitely Many Time Derivatives and Rolling Tachyons
Both in string field theory and in p-adic string theory the equations of
motion involve infinite number of time derivatives. We argue that the initial
value problem is qualitatively different from that obtained in the limit of
many time derivatives in that the space of initial conditions becomes strongly
constrained. We calculate the energy-momentum tensor and study in detail time
dependent solutions representing tachyons rolling on the p-adic string theory
potentials. For even potentials we find surprising small oscillations at the
tachyon vacuum. These are not conventional physical states but rather
anharmonic oscillations with a nontrivial frequency--amplitude relation. When
the potentials are not even, small oscillatory solutions around the bottom must
grow in amplitude without a bound. Open string field theory resembles this
latter case, the tachyon rolls to the bottom and ever growing oscillations
ensue. We discuss the significance of these results for the issues of emerging
closed strings and tachyon matter.Comment: 46 pages, 14 figures, LaTeX. Replaced version: Minor typos corrected,
some figures edited for clarit
Seiberg-Witten Curve for the E-String Theory
We construct the Seiberg-Witten curve for the E-string theory in
six-dimensions. The curve is expressed in terms of affine E_8 characters up to
level 6 and is determined by using the mirror-type transformation so that it
reproduces the number of holomorphic curves in the Calabi-Yau manifold and the
amplitudes of N=4 U(n) Yang-Mills theory on 1/2 K3. We also show that our curve
flows to known five- and four-dimensional Seiberg-Witten curves in suitable
limits.Comment: 18 pages, 1 figure; appendix C adde
Quasilocality of joining/splitting strings from coherent states
Using the coherent state formalism we calculate matrix elements of the
one-loop non-planar dilatation operator of SYM between operators
dual to folded Frolov-Tseytlin strings and observe a curious scaling behavior.
We comment on the {\it qualitative} similarity of our matrix elements to the
interaction vertex of a string field theory. In addition, we present a solvable
toy model for string splitting and joining. The scaling behaviour of the matrix
elements suggests that the contribution to the genus one energy shift coming
from semi-classical string splitting and joining is small.Comment: 17 pages, 7 figures in 11 file
Anomalous dimensions at four loops in N=6 superconformal Chern-Simons theories
In arXiv:0908.2463 we computed the four-loop correction to a function
depending on the 't Hooft coupling(s) that appears in the magnon dispersion
relation of the spin chains derived from single trace operators in N=6
superconformal Chern-Simons theories. In this paper we give detailed
descriptions of this calculation and the computation of the four-loop wrapping
corrections for a length four operator in the 20 of SU(4), the R-symmetry group
for these theories. Here, we give all relevant Feynman diagrams and loop
integrals explicitly, and also demonstrate the cancellation of double poles in
the logarithm of the renormalization constant.Comment: LaTeX, feynmp, 70 pages; v2: signs of three diagrams due to
inconsistent Feynman rules corrected, modifying the final result, typos
corrected, formulations improve
Brane Decay and Death of Open Strings
We show how open strings cease to propagate when unstable D-branes decay. The
information on the propagation is encoded in BSFT two-point functions for
arbitrary profiles of open string excitations. We evaluate them in tachyon
condensation backgrounds corresponding to (i) static spatial tachyon kink (=
lower dimensional BPS D-brane) and (ii) homogeneous rolling tachyon. For (i)
the propagation is restricted to the directions along the tachyon kink, while
for (ii) all the open string excitations cease to propagate at late time and
are subject to a collapsed light cone characterized by Carrollian contraction
of Lorentz group.Comment: 19 pages, published version (typos corrected, a reference added
Instanton Expansions for Mass Deformed N=4 Super Yang-Mills Theories
We derive modular anomaly equations from the Seiberg-Witten-Donagi curves for
softly broken N=4 SU(n) gauge theories. From these equations we can derive
recursion relations for the pre-potential in powers of m^2, where m is the mass
of the adjoint hypermultiplet. Given the perturbative contribution of the
pre-potential and the presence of ``gaps'' we can easily generate the m^2
expansion in terms of polynomials of Eisenstein series, at least for relatively
low rank groups. This enables us to determine efficiently the instanton
expansion up to fairly high order for these gauge groups, e. g. eighth order
for SU(3). We find that after taking a derivative, the instanton expansion of
the pre-potential has integer coefficients. We also postulate the form of the
modular anomaly equations, the recursion relations and the form of the
instanton expansions for the SO(2n) and E_n gauge groups, even though the
corresponding Seiberg-Witten-Donagi curves are unknown at this time.Comment: harvmac(b) 28 page
Non-Douglas-Kazakov phase transition of two-dimensional generalized Yang-Mills theories
In two-dimensional Yang-Mills and generalized Yang-Mills theories for large
gauge groups, there is a dominant representation determining the thermodynamic
limit of the system. This representation is characterized by a density the
value of which should everywhere be between zero and one. This density itself
is determined through a saddle-point analysis. For some values of the parameter
space, this density exceeds one in some places. So one should modify it to
obtain an acceptable density. This leads to the well-known Douglas-Kazakov
phase transition. In generalized Yang-Mills theories, there are also regions in
the parameter space where somewhere this density becomes negative. Here too,
one should modify the density so that it remains nonnegative. This leads to
another phase transition, different from the Douglas-Kazakov one. Here the
general structure of this phase transition is studied, and it is shown that the
order of this transition is typically three. Using carefully-chosen parameters,
however, it is possible to construct models with phase-transition orders not
equal to three. A class of these non-typical models are also studied.Comment: 11 pages, accepted for publication in Eur. Phys. J.
Realization of Brane Descent Relations in Effective Theories
We examine Sen's descent relations among (non-)BPS D-branes by using low
energy effective field theories of DpDpbar system. We find that the fluctuation
around the kink solution reproduces the low energy matter content on a non-BPS
D(p-1)-brane. The effective action for these fluctuation modes turns out to be
a generalization of Minahan-Zwiebach model. In addition, it is shown that the
fluctuations around the vortex solution consist of massless fields on a BPS
D(p-2)-brane and they are subject to Dirac-Born-Infeld action. We find the
universality that the above results do not refer to particular forms of the
effective action.Comment: 24 pages, LaTeX, 1 eps figure; v2:minor correction
Plane wave limit of local conserved charges
We study the plane wave limit of the Backlund transformations for the
classical string in AdS space times a sphere and obtain an explicit expression
for the local conserved charges. We show that the Pohlmeyer charges become in
the plane wave limit the local integrals of motion of the free massive field.
This fixes the coefficients in the expansion of the anomalous dimension as the
sum of the Pohlmeyer charges.Comment: v2: added explanation
The Morphology of N=6 Chern-Simons Theory
We tabulate various properties of the language of N=6 Chern-Simons Theory, in
the sense of Polyakov. Specifically we enumerate and compute character formulas
for all syllables of up to four letters, i.e. all irreducible representations
of OSp(6|4) built from up to four fundamental fields of the ABJM theory. We
also present all tensor product decompositions for up to four singletons and
list the (cyclically invariant) four-letter words, which correspond to
single-trace operators of length four. As an application of these results we
use the two-loop dilatation operator to compute the leading correction to the
Hagedorn temperature of the weakly-coupled planar ABJM theory on R \times S^2.Comment: 41 pages, 1 figure; v2: minor correction
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