17485311
Cross section of a resonant-mass detector for scalar gravitational waves
Gravitationally coupled scalar fields, originally introduced by Jordan, Brans and Dicke to account for a non-constant gravitational coupling, are a prediction of many non-Einsteinian theories of gravity not excluding perturbative formulations of string theory. In this paper, we compute the cross sections for scattering and absorption of scalar and tensor gravitational waves by a resonant-mass detector in the framework of the Jordan-Brans-Dicke theory. The results are then specialized to the case of a detector of spherical shape and shown to reproduce those obtained in general relativity in a certain limit. Eventually we discuss the potential detectability of scalar waves emitted in a spherically symmetric gravitational collapse. @S0556-2821~98!04908-X#
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.
94785817
Freezing E3-brane instantons with fluxes
E3-instantons that generate non-perturbative superpotentials in IIB N{script} = 1 compactifications have a much more frequent occurrence than currently believed. Worldvolume fluxes will typically lift the E3-brane geometric moduli and their fermionic superpartners, leaving only the two required universal fermionic zero-modes. We consistently incorporate SL(2, ℤ) monodromies and world-volume fluxes in the effective theory of the E3-brane fermions and study the resulting zero modes spectrum, highlighting the relation between F-theory and perturbative IIB results. This leads us to a IIB derivation of the index for generation of superpotential terms, which reproduces and generalizes available results. Furthermore, we show how E3 worldvolume fluxes can be explicitly constructed in a one-modulus compactification, such that the instanton has exactly two fermonic zero-modes. This construction is readily applicable to numerous scenarios. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
15057808
(Non)perturbative tests of the AdS / CFT correspondence
I summarize perturbative and non-perturbative field theory tests of the holographic correspondence between type IIB superstring on AdS5 × S5 and N = 4 SYM theory. The holographic duality between D-instantons and YM instantons is briefly described. Non renormalization of two- and three-point functions of CPO's and their extremal and next-to-extremal correlators are then reviewed. Finally, partial non-renormalization of four-point functions of lowest CPO's is analyzed in view of the interpretation of short distance logarithmic behaviours in terms of anomalous dimensions of unprotected operators.
118440611
On stable higher spin states in heterotic string theories
We study properties of 1/2 BPS Higher Spin states in heterotic compactifications with extended supersymmetry. We also analyze non BPS Higher Spin states and give explicit expressions for physical vertex operators of the first two massive levels. We then study on-shell tri-linear couplings of these Higher Spin states and confirm that BPS states with arbitrary spin cannot decay into lower spin states in perturbation theory. Finally, we consider scattering of vector bosons off higher spin BPS states and extract form factors and polarization effects in various limits.
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.
118703017
Diurnal effects on radiation sensitivity
54173371
One loop amplitudes in ABJM
A bstractFor three dimensional $ \mathcal{N} = 6 $ superconformal field theories we compute oneloop scattering amplitudes for any number of external particles. We focus on a particular subsector of $ \mathcal{N} = 2 $ invariant superamplitudes for which the ordinary perturbative evaluation becomes very easy. The result we obtain is in general non-vanishing. For six external particles our findings are sufficient for determining the complete expression of the $ \mathcal{N} = 6 $ superamplitude at this order. We discuss the symmetries of the result and its anomalous variation under superconformal generators.
119236388
Infrared stability of ABJ-like theories
We consider marginal deformations of the superconformal ABJM/ABJ models which preserve $ \mathcal{N} = 2 $ supersymmetry. We determine perturbatively the spectrum of fixed points and study their infrared stability. We find a closed line of fixed points which is IR stable. The fixed point corresponding to the ABJM/ABJ models is stable under marginal deformations which respect the original SU(2)A × SU(2)B invariance, while deformations which break this group destabilize the theory which then flows to a less symmetric fixed point. We discuss the addition of flavor degrees of freedom. We prove that in general a flavor marginal superpotential does not destabilize the system in the IR. An exception is represented by a marginal coupling which mixes matter charged under different gauge sectors. Finally, we consider the case of relevant deformations which should drive the system to a strongly coupled IR fixed point recently investigated in arXiv:0909.2036 [hep-th].
11105828
Nonanticommutative U(1) SYM theories: renormalization, fixed points and infrared stability
Renormalizable nonanticommutative SYM theories with chiral matter in the adjoint representation of the gauge group have been recently constructed in [arXiv: 0901.3094]. In the present paper we focus on the U(1) case with matter interacting through a cubic superpotential. For a single flavor, in a superspace setup and manifest background covariant approach we perform the complete one-loop renormalization and compute the beta-functions for all couplings appearing in the action. We then generalize the calculation to the case of SU(3) flavor matter with a cubic superpotential viewed as a nontrivial NAC generalization of the ordinary abelian N = 4 SYM and its marginal deformations. We find that, as in the ordinary commutative case, the NAC N = 4 theory is one-loop finite. We provide general arguments in support of all-loop finiteness. Instead, deforming the superpotential by marginal operators gives rise to beta-functions which are in general non-vanishing. We study the spectrum of fixed points and the RG flows. We find that nonanticommutativity always makes the fixed points unstable.
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.