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Rein H.,Institute for Advanced Study
Monthly Notices of the Royal Astronomical Society: Letters | Year: 2012

The Kepler planet candidates are an interesting test bed for planet formation scenarios. We present results from N-body simulations of multiplanetary systems that resemble those observed by Kepler. We add both smooth (Type I/II) and stochastic migration forces. The observed period ratio distribution is inconsistent with either of those two scenarios on its own. However, applying both stochastic and smoothmigration forces to the planets simultaneously results in a period ratio distribution that is similar to the observed one. This is a natural scenario if planets form in a turbulent protoplanetary disc where these forces are always present. We show how the observed period ratio and eccentricity distribution can constrain the relative strength of these forces, a parameter which has been notoriously hard to predict for decades. We make the source code of our simulations and the initial conditions freely available to enable the community to expand this study and include effect other than planetary migration. © 2012 The Authors. Monthly Notices of the Royal Astronomical Society © 2012 RAS. Source


Henn J.M.,Institute for Advanced Study
Physical Review Letters | Year: 2013

Scattering amplitudes at loop level can be expressed in terms of Feynman integrals. The latter satisfy partial differential equations in the kinematical variables. We argue that a good choice of basis for (multi)loop integrals can lead to significant simplifications of the differential equations, and propose criteria for finding an optimal basis. This builds on experience obtained in supersymmetric field theories that can be applied successfully to generic quantum field theory integrals. It involves studying leading singularities and explicit integral representations. When the differential equations are cast into canonical form, their solution becomes elementary. The class of functions involved is easily identified, and the solution can be written down to any desired order in Ïμ within dimensional regularization. Results obtained in this way are particularly simple and compact. In this Letter, we outline the general ideas of the method and apply them to a two-loop example. © 2013 American Physical Society. Source


Slatyer T.R.,Institute for Advanced Study
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2013

Dark matter annihilation or deexcitation, decay of metastable species, or other new physics may inject energetic electrons and photons into the photon-baryon fluid during and after recombination. As such particles cool, they partition their energy into a large number of efficiently ionizing electrons and photons, which in turn modify the ionization history. Recent work has provided a simple method for constraining arbitrary energy-deposition histories using the cosmic microwave background (CMB); in this note, we present results describing the energy-deposition histories for photons and electrons as a function of initial energy and injection redshift. With these results, the CMB bounds on any process injecting some arbitrary spectrum of electrons, positrons and/or photons with arbitrary redshift dependence can be immediately computed. © 2013 American Physical Society. Source


Gaiotto D.,Institute for Advanced Study
Journal of High Energy Physics | Year: 2012

We study the generalization of S-duality and Argyres-Seiberg duality for a large class of N = 2 superconformal gauge theories. We identify a family of strongly interacting SCFTs and use them as building blocks for generalized superconformal quiver gauge theories. This setup provides a detailed description of the "very strongly coupled" regions in the moduli space of more familiar gauge theories. As a byproduct, we provide a purely four dimensional construction of N = 2 theories defined by wrapping M5 branes over a Riemann surface. © SISSA 2012. Source


Jafferis D.L.,Institute for Advanced Study
Journal of High Energy Physics | Year: 2012

The three sphere partition function, Z, of three dimensional theories with four supercharges and an R-symmetry is computed using localization, resulting in a matrix integral over the Cartan of the gauge group. There is a family of couplings to the curved background, parameterized by a choice of R-charge, such that supersymmetry is preserved; Z is a function of those parameters. The magnitude of the result is shown to be extremized for the superconformal R-charge of the infrared conformal field theory, in the absence of mixing of the R-symmetry with accidental symmetries. This exactly determines the IR superconformal R-charge. © SISSA 2012. Source

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