119886680
Planar duality in the discrete series
Abstract The models of the discrete series of Belavin, Polyakov and Zamolodchikov may be generalized by allowing for suitable open-string sectors. The resulting open-string disk amplitudes have planar duality and proper factorization in the presence of a global internal Chan-Paton symmetry.
3091781
Open Strings and Dualities
In the fruitful interplay between gauge fields and strings and in many conjectured M-theory dualities, open strings play a prominent role. We review the construction of open-string descendants (un-orientifolds) of closed-string theories admitting a generalized orientation reversal involution. We then specialize the construction to some classes of non-supersymmetric models in D=10 that have been recently considered in the context of duality without supersymmetry. We also discuss the propagation of open and unoriented strings on the NS pentabrane (N5-brane). This background is a prototype of the configurations of branes and orientifold planes that represent a powerful alternative to the geometric engineering of Supersymmetric Yang-Mills Theories. The resulting description of D-branes in non-trivial backgrounds looks very different from the one naively expected. In particular the very distinction between different Dp-branes becomes ambiguous in the presence of strong curvature effects.
120082660
Toroidal compactification and symmetry breaking in open-string theories
Abstract In toroidal compactification of open-string theories, the background fields of the “parent” closed string (metric and antisymmetric tensor, with suitable restrictions) are accompanied by open-string Wilson lines. In the SO(32) superstring, these control the breaking of the Chan-Paton symmetry in a way that presents interesting analogies with the corresponding phenomenon in the heterotic string. An extension of the closed-string results to include contributions from the disk and the projective plane shows that these fields are genuine “moduli”, since their amplitudes vanish when the momenta are all scaled to zero.
119081797
The open story of the magnetic fluxes
We discuss the effects of oblique internal magnetic fields on the spectrum of type I superstrings compactified on tori. In particular we derive general formulae for the magnetic shifts and multiplicities of open strings connecting D9-branes with arbitrary magnetic fluxes. We discuss the flux induced potential and offer an interpretation of the stabilization of R-R moduli associated to deformations of the complex structure of T6 in terms of non-derivative mixings with NS-NS moduli. Finally we briefly comment on how to extract other low energy couplings and generalize our results to toroidal orbifolds and other configurations governed by rational conformal field theories on the worldsheet.
119040998
Instanton Effects in Supersymmetric Yang-Mills Theories on ALE Gravitational Backgrounds
In this letter we report on the computation of instanton-dominated correlation functions in supersymmetric YM theories on ALE spaces. Following the approach of Kronheimer and Nakajima, we explicitly construct the self-dual connection on ALE spaces necessary to perform such computations. We restrict our attention to the simplest case of an $SU(2)$ connection with lowest Chern class on the Eguchi-Hanson gravitational background.
121785638
Twist symmetry and open string Wilson lines
Abstract The Mobius amplitude plays an important role in open-string theories, since it determines which sectors of a given model consist of unoriented open strings. It also fixes the Chan-Paton representations of all their states, according to the behavior under the interchange of the ends of open strings (“twist”). In this paper we discuss the role played by conventional Wilson lines in Chan-Paton symmetry breaking, and we show that the presence of an extended symmetry algebra allows, in general, a number of choices for the behavior of massive states under twist. This freedom may be ascribed to additional discrete Wilson lines, and yields consistent modifications of the group assignments, that are illustrated in a number of examples.
123488833
Scattering amplitudes in three-dimensional superconformal field theory
Recent progress in computation of loop amplitudes in three-dimensional superconformal models is reviewed.
56038769
BPS Wilson loops and Bremsstrahlung function in ABJ(M): a two loop analysis
A bstractWe study a family of circular BPS Wilson loops in $ \mathcal{N} $ = 6 super Chern-Simons-matter theories, generalizing the usual 1/2-BPS circle. The scalar and fermionic couplings depend on two deformation parameters and these operators can be considered as the ABJ(M) counterpart of the DGRT latitudes defined in $ \mathcal{N} $ = 4 SYM. We perform a complete two-loop analysis of their vacuum expectation value, discuss the appearance of framing-like phases and propose a general relation with cohomologically equivalent bosonic operators. We make an all-loop proposal for computing the Bremsstrahlung function associated to the 1/2-BPS cusp in terms of these generalized Wilson loops. When applied to our two-loop result it reproduces the known expression. Finally, we comment on the generalization of this proposal to the bosonic 1/6-BPS case.
119117490
Nonplanarity through unitarity in the ABJM theory
We use unitarity techniques to compute the two-loop non-planar corrections to the Sudakov form factor and the four-point amplitude in ABJM theory. We start by reconstructing non-planar integrals from two-particle cuts in three dimensions. This causes ambiguities, due to the one-loop four-point amplitude being subleading in dimensional regularization. We provide a prescription to circumvent them and show that it leads to the correct results, as checked against the recent Feynman diagram computation. For the amplitude we point out an alternative basis of integrals, including a non-planar double-box with a numerator inspired by color-kinematics duality. We reproduce the result using a combination thereof with the coefficients fixed by generalized unitarity. For BLG theory we propose that this gives the form of the amplitude satisfying color-kinematics duality. Finally, we compute the complete two-loop amplitude of three-dimensional N = 8 SYM, and the corresponding four-point amplitude in N = 16 supergravity as a double copy.
80725226
Differences in the radiosensitivity of male germ cells determined in various strains of mice
119249635
ABJM amplitudes and WL at finite N
A bstractWe evaluate ABJM observables at two loops, for any value of the rank N of the gauge group. We compute the color subleading contributions to the four-point scattering amplitude in ABJM at two loops. Contrary to the four dimensional case, IR divergent N-subleading contributions are proportional to leading poles in the regularization parameter. We then exploit the non-planar calculation for the amplitude to derive an expression for the two-loop Sudakov form factor at any N. In the planar limit the result coincides with the one recently obtained in literature by using Feynman diagrams and unitarity. Finally, we analyze the subleading contributions to the light-like four-cusps Wilson loop and interpret the result in terms of the non-abelian exponentiation theorem. All these perturbative results satisfy the uniform transcendentality principle, hinting at its validity in ABJM beyond the planar limit.