2,872 research outputs found
Constraining Higher Derivative Supergravity with Scattering Amplitudes
We study supersymmetry constraints on higher derivative deformations of type
IIB supergravity by consideration of superamplitudes. Combining constraints of
on-shell supervertices and basic results from string perturbation theory, we
give a simple argument for the non-renormalization theorem of Green and Sethi,
and some of its generalizations.Comment: 9 pages, 2 figures; references ad
Supermoduli and PCOs at Genus Two
We illustrate the relation between supermoduli integration and picture
changing operators (PCOs) particularly concerning the role of vertical
integration, in the context of superstring vacuum amplitudes, by an explicit
comparison of different parameterizations of the supermoduli space of genus two
super Riemann surfaces.Comment: 26 pages, 3 figure
On Higher Derivative Couplings in Theories with Sixteen Supersymmetries
We give simple arguments for new non-renormalization theorems on higher
derivative couplings of gauge theories to supergravity, with sixteen
supersymmetries, by considerations of brane-bulk superamplitudes. This leads to
some exact results on the effective coupling of D3-branes in type IIB string
theory. We also derive exact results on higher dimensional operators in the
torus compactification of the six dimensional (0, 2) superconformal theory.Comment: 31 pages, 10 figures, section 2 reconstructured, new result in
section 3.2, additional clarifications adde
(2,2) Superconformal Bootstrap in Two Dimensions
We find a simple relation between two-dimensional BPS N=2 superconformal
blocks and bosonic Virasoro conformal blocks, which allows us to analyze the
crossing equations for BPS 4-point functions in unitary (2,2) superconformal
theories numerically with semidefinite programming. We constrain gaps in the
non-BPS spectrum through the operator product expansion of BPS operators, in
ways that depend on the moduli of exactly marginal deformations through chiral
ring coefficients. In some cases, our bounds on the spectral gaps are observed
to be saturated by free theories, by N=2 Liouville theory, and by certain
Landau-Ginzburg models.Comment: 56 pages, 14 figure
Supersymmetry Constraints and String Theory on K3
We study supervertices in six dimensional (2,0) supergravity theories, and
derive supersymmetry non-renormalization conditions on the 4- and 6-derivative
four-point couplings of tensor multiplets. As an application, we obtain exact
non-perturbative results of such effective couplings in type IIB string theory
compactified on K3 surface, extending previous work on type II/heterotic
duality. The weak coupling limit thereof, in particular, gives certain
integrated four-point functions of half-BPS operators in the nonlinear sigma
model on K3 surface, that depend nontrivially on the moduli, and capture
worldsheet instanton contributions.Comment: 47 pages, 4 figure
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