Emanuel Katz

Effective theories and black hole production in warped compactifications

We investigate aspects of the four-dimensional (4D) effective description of brane world scenarios based on warped compactification on anti-de Sitter space. The low-energy dynamics is described by visible matter gravitationally coupled to a “dark” conformal field theory. We give the linearized description of the 4D stress tensor corresponding to an arbitrary 5D matter distribution. In particular a 5D falling particle corresponds to a 4D expanding shell, giving a 4D interpretation of a trajectory that misses a black hole only by moving in the fifth dimension. Breakdown of the effective description occurs when either five-dimensional physics or strong gravity becomes important. In scenarios with a TeV brane, the latter can happen through the production of black holes near the TeV scale. This could provide an interesting experimental window on quantum black hole dynamics.

Five-branes, seven-branes and five-dimensional En field theories

We generalize the (p,q) 5-brane web construction of five-dimensional field theories by introducing (p,q) 7-branes, and apply this construction to theories with a one-dimensional Coulomb branch. The 7-branes render the exceptional global symmetry of these theories manifest. Additionally, 7-branes allow the construction of all En theories up to n = 8, previously not possible in 5-brane configurations. The exceptional global symmetry in the field theory is a subalgebra of an affine symmetry on the 7-branes, which is necessary for the existence of the system. We explicitly determine the quantum numbers of the BPS states of all En theories using two simple geometrical constraints.

Absence of a VVDZ discontinuity in AdSAdS

We clarify the role of gauge invariance for the theory of an AdS4-brane embedded in AdS5. The presence of a non-vanishing mass parameter even for the lightest KK mode of the graviton indicates that all of the spin-2 modes propagate five polarization states. Despite this fact, it was shown earlier that the classical theory has a smooth limit as the mass parameter is taken to zero. We argue that locality in the fifth dimension ensures that this property survives at the quantum level.

Supersymmetric partners of oblique corrections

Abstract We discuss the violation of the equality of the gauge coupling and gaugino coupling in the presence of soft supersymmetry breaking. Although this is a hard supersymmetry breaking effect, there are finite contributions to this difference that can be determined as a function of the soft supersymmetry breaking masses. The largest sources of this difference are the “super-oblique” corrections, which can be enhanced by a multiplicity factor and a logarithm of the soft supersymmetry breaking mass. This is to be contrasted to standard oblique corrections to the electroweak sector, which decouple for large supersymmetry breaking. We show that these parameters can be relatively large, particularly in models of supersymmetry breaking motivated by solving the supersymmetric flavor problem. We also perform a detailed study of the non-oblique corrections for the example of squark decay. We find that they can be significant, and should be accounted for in the theoretical prediction.

Mirror symmetry for Script N = 1 QED in three dimensions

We construct three-dimensional = 1 QED with Nf flavors using branes of type-IIB string theory. This theory has a mirror, which can be realized using the S-dual brane configuration. As in examples with more supersymmetry, the Higgs branch of the original theory gets mapped into the Coulomb branch of the mirror. We use parity invariance to argue that these branches cannot be lifted by quantum corrections.