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Far from equilibrium energy flow in quantum critical systems
March 25, 2014

PIRSA:14030089
High Energy Physics
Naturalness and the Weak Gravity Conjecture

Clifford Cheung California Institute of Technology (Caltech) - Physics Office
March 25, 2014

PIRSA:14030119
High Energy Physics
Exact results in supersymmetric gauge theories in various dimensions

Sara Pasquetti University of Milan
March 19, 2014

PIRSA:14030084
High Energy Physics
Before the Bang

Raman Sundrum University of Maryland, College Park
March 18, 2014

PIRSA:14030113
High Energy Physics
Black Holes- the Harmonic Oscillators of the 21st Century

Andrew Strominger Harvard University
March 12, 2014

PIRSA:14030104
High Energy Physics
Line Defects and Tropicalization

Clay Cordova University of Chicago
March 11, 2014

PIRSA:14030106
High Energy Physics
How Much Information Can SUSY QM Conserve About SUSY QFT?

S. James Gates Jr. University of Maryland, College Park
March 04, 2014

PIRSA:14030101
High Energy Physics
Large Tensor-to-Scalar Ratio in Small-Field Inflation

Takeshi Kobayashi SISSA International School for Advanced Studies
February 25, 2014

PIRSA:14020152
High Energy Physics

Astrophysics
Quantum Liquids and Turbulent Black Holes

Allan Adams Massachusetts Institute of Technology (MIT) - Department of Physics
February 24, 2014

PIRSA:14020141
High Energy Physics
Sequestering the Standard Model Vacuum Energy

Nemanja Kaloper University of California, Davis
February 21, 2014

PIRSA:14020109
High Energy Physics
Causality, holography, and entanglement entropy
February 20, 2014

PIRSA:14020146
General Relativity & Quantum Cosmology

High Energy Physics

Condensed Matter

General Relativity & Quantum Cosmology
Cluster Polylogarithms for Scattering Amplitudes
February 18, 2014

PIRSA:14020147
High Energy Physics

Far from equilibrium energy flow in quantum critical systems
March 25, 2014

PIRSA:14030089
High Energy Physics
We investigate far from equilibrium energy transport in strongly coupled quantum critical systems. Combining results from gauge-gravity duality, relativistic hydrodynamics, and quantum field theory, we argue that long-time energy transport after a local thermal quench occurs via a universal steady-state for any spatial dimensionality. This is described by a boosted thermal state. We determine the transport properties of this emergent steady state, including the average energy flow and its long-time fluctuations.
Naturalness and the Weak Gravity Conjecture

Clifford Cheung California Institute of Technology (Caltech) - Physics Office
March 25, 2014

PIRSA:14030119
High Energy Physics
The weak gravity conjecture (WGC) asserts a powerful consistency condition on gauge theories coupled to quantum gravity: an Abelian, long-range force requires a state of charge q and mass m such that q > m/mPl. Failure of this condition implies the existence of stable black hole remnants and is in tension with no-hair theorems. In this paper, we argue that the WGC creates a non- perturbative obstruction to naturalness, which is the notion that dimensionless coefficients should take on O(1) values in the absence of enhanced symmetry. As an illustration, we show that for scalar quantum electrodynamics, a natural spectrum can actually be forbidden by the WGC, which bounds a radiatively unstable quantity, m, by a radiatively stable quantity, q. More generally, the WGC can be at odds with naturalness in any theory containing charged fundamental scalars. We extend the conditions of the WGC to more complicated theories with multiple gauge symmetries and particles. Finally, we discuss implications for the hierarchy problem and construct a simple model in which the natural value of the electroweak scale—at the cutoff—is forbidden by the WGC.
Exact results in supersymmetric gauge theories in various dimensions

Sara Pasquetti University of Milan
March 19, 2014

PIRSA:14030084
High Energy Physics
One of the central challenges in theoretical physics is to develop non-perturbative methods to describe quantitatively the dynamics of strongly coupled quantum fields. Much progress in this direction has been made for theories with a higher degree of symmetry, such as conformal symmetry or supersymmetry. In recent years the method of localisation has allowed to obtain a great deal of exact results for supersymmetric gauge theories in various dimensions which has led to the discovery of new surprising correspondences such as the celebrated Alday-Gaiotto-Tachikawa correspondence. I will review some recent results which indicate that partition functions of supersymmetric theories formulated on compact manifolds can be expressed in terms of a small set of fundamental building blocks.
Before the Bang

Raman Sundrum University of Maryland, College Park
March 18, 2014

PIRSA:14030113
High Energy Physics
The simplest black hole solution in asymptotic AdS spacetime, the eternal 3-dimensional BTZ black hole, is studied from the viewpoint of AdS/CFT duality. We identify a class of non-local correlators on the CFT side that allow us to generalize the notion of quantum gravity "S-matrix" to scattering inside the horizon. Since the interior of the horizon is a cosmological spacetime with a big bang/crunch-like singularity, our construction can be interpreted as identifying generally coordinate invariant observables of quantum gravity in a simple cosmology. We show in a certain precise sense, that these holographic observables lie "before the big bang" in a region of spacetime containing closed timelike curves. A central tool in our analysis is the realization of BTZ as a quotient of 3-dimensional AdS.
Black Holes- the Harmonic Oscillators of the 21st Century

Andrew Strominger Harvard University
March 12, 2014

PIRSA:14030104
High Energy Physics
In the twentieth century, many problems across all of physics were solved by perturbative methods which reduced them to harmonic oscillators. Black holes are poised to play a similar role for the problems of twenty-first century physics. They are at once the simplest and most complex objects in the physical universe. They are maximally complex in that the number of possible microstates, or entropy, of a black hole is believed to saturate a universal bound. They are maximally simple in that, according to Einstein's theory, they are featureless holes in space characterized only by their mass, charge and angular momentum. This dual relation between simplicity and complexity, as expressed in black holes, has recently been successfully applied to problems in a disparate variety of physical systems. I will give an introduction to the subject intended for a general audience.
Line Defects and Tropicalization

Clay Cordova University of Chicago
March 11, 2014

PIRSA:14030106
High Energy Physics
I will review BPS line defects in 4d N=2 field theories and describe a technique for calculating their spectra using quiver quantum mechanics.
How Much Information Can SUSY QM Conserve About SUSY QFT?

S. James Gates Jr. University of Maryland, College Park
March 04, 2014

PIRSA:14030101
High Energy Physics
In this presentation, evidence is given that supersymmetrical theories may be exceptional in their ability to conserve information about space-time representations under the impact of dimensional compactification. This is the essence of the concept of ``SUSY Holography.''
Large Tensor-to-Scalar Ratio in Small-Field Inflation

Takeshi Kobayashi SISSA International School for Advanced Studies
February 25, 2014

PIRSA:14020152
High Energy Physics

Astrophysics
The production of gravitational waves from cosmic inflation > is normally bounded by the inflaton field excursion. This relation, > which is often referred to as the Lyth bound, claims that > observationally large gravitational waves are produced only if the > inflaton has a super-Planckian field range. In this talk I will point > out that this general belief is not necessarily true when there are > additional light fields producing density perturbations. Perturbations > seeded by the inflaton can be suppressed under such situations, thus > allow large gravitational waves to be produced even from small-field (i.e. > sub-Planckian) inflation. I will also show that the field bound is > taken over by the light field when the inflaton-induced perturbations > are suppressed, thus present a generalized form of the Lyth bound that > applies to the total field space. The calculations are rather simple, > so I will explain my work on a blackboard.
Quantum Liquids and Turbulent Black Holes

Allan Adams Massachusetts Institute of Technology (MIT) - Department of Physics
February 24, 2014

PIRSA:14020141
High Energy Physics
The physics of black hole horizons is intimately connected to the physics of quantum liquids. In this talk I will review the connection and draw lessons about quantum turbulence from black hole dynamics and vice versa. For example, gravitational dynamics reveal that quantum turbulence can behave very differently from normal fluid turbulence in 2d, with long-wavelength excitations rapidly dissolving into small fluctuations and dissipating as in a 3d normal liquid. Meanwhile, familiar facts about turbulent flows in normal fluids imply that the horizons of certain accreting black holes evolve in time as if they have a non-trivial fractal dimension.
Sequestering the Standard Model Vacuum Energy

Nemanja Kaloper University of California, Davis
February 21, 2014

PIRSA:14020109
High Energy Physics
We propose a very simple reformulation of General Relativity, which completely sequesters from gravity {\it all} of the vacuum energy from a matter sector, including all loop corrections and renders all contributions from phase transitions automatically small. The idea is to make the dimensional parameters in the matter sector functionals of the 4-volume element of the universe. For them to be nonzero, the universe should be finite in spacetime. If this matter is the Standard Model of particle physics, our mechanism prevents any of its vacuum energy, classical or quantum, from sourcing the curvature of the universe. The mechanism is consistent with the large hierarchy between the Planck scale, electroweak scale and curvature scale, and early universe cosmology, including inflation. Consequences of our proposal are that the vacuum curvature of an old and large universe is not zero, but very small, that wDE≃−1 is a transient, and that the universe will collapse in the future.
Causality, holography, and entanglement entropy
February 20, 2014

PIRSA:14020146
General Relativity & Quantum Cosmology

High Energy Physics

Condensed Matter

General Relativity & Quantum Cosmology
After giving a brief overview of holographic entanglement entropy formulas, I will explore a curious feature they imply: when the bulk spacetime includes a black hole, the entanglement entropies often appear to depend on the spacetime geometry inside the horizon. I will ask whether this implies any loss of causality in the field theory. To answer this question, I will present a new general-relativity theorem concerning the causal structure of asymptotically AdS spacetimes, which implies an interesting relationship between bulk and boundary causal domains.
Cluster Polylogarithms for Scattering Amplitudes
February 18, 2014

PIRSA:14020147
High Energy Physics
Motivated by the cluster structure of two-loop scattering amplitudes in N = 4 Yang-Mills theory we define cluster polylogarithm functions. We find that all such functions of weight 4 are made up of a single simple building block associated to the A2 cluster algebra. Adding the requirement of locality on generalized Stasheff polytopes, we find that these A2 building blocks arrange themselves to form a unique function associated to the A3 cluster algebra. ThisA3 function manifests all of the cluster algebraic structure of the two-loop n-particle MHV amplitudes for all n, and we use it to provide an explicit representation for the most complicated part of the n = 7 amplitude as an example.

Title	Date	Collection	Type	Info
Far from equilibrium energy flow in quantum critical systems	2014‑03‑25	Quantum Fields and Strings	Scientific Series	View details
Naturalness and the Weak Gravity Conjecture	2014‑03‑25	Particle Physics	Scientific Series	View details
Exact results in supersymmetric gauge theories in various dimensions	2014‑03‑19	Colloquium	Scientific Series	View details
Before the Bang	2014‑03‑18	Particle Physics	Scientific Series	View details
Black Holes- the Harmonic Oscillators of the 21st Century	2014‑03‑12	Colloquium	Scientific Series	View details
Line Defects and Tropicalization	2014‑03‑11	Quantum Fields and Strings	Scientific Series	View details
How Much Information Can SUSY QM Conserve About SUSY QFT?	2014‑03‑04	Quantum Fields and Strings	Scientific Series	View details
Large Tensor-to-Scalar Ratio in Small-Field Inflation	2014‑02‑25	Particle Physics	Scientific Series	View details
Quantum Liquids and Turbulent Black Holes	2014‑02‑24	Quantum Fields and Strings	Scientific Series	View details
Sequestering the Standard Model Vacuum Energy	2014‑02‑21	Particle Physics	Scientific Series	View details
Causality, holography, and entanglement entropy	2014‑02‑20	Quantum Fields and Strings	Scientific Series	View details
Cluster Polylogarithms for Scattering Amplitudes	2014‑02‑18	Quantum Fields and Strings	Scientific Series	View details

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Format results

Far from equilibrium energy flow in quantum critical systems

Naturalness and the Weak Gravity Conjecture

Exact results in supersymmetric gauge theories in various dimensions

Before the Bang

Black Holes- the Harmonic Oscillators of the 21st Century

Line Defects and Tropicalization

How Much Information Can SUSY QM Conserve About SUSY QFT?

Large Tensor-to-Scalar Ratio in Small-Field Inflation

Quantum Liquids and Turbulent Black Holes

Sequestering the Standard Model Vacuum Energy

Causality, holography, and entanglement entropy

Cluster Polylogarithms for Scattering Amplitudes

Far from equilibrium energy flow in quantum critical systems

Naturalness and the Weak Gravity Conjecture

Exact results in supersymmetric gauge theories in various dimensions

Before the Bang

Black Holes- the Harmonic Oscillators of the 21st Century

Line Defects and Tropicalization

How Much Information Can SUSY QM Conserve About SUSY QFT?

Large Tensor-to-Scalar Ratio in Small-Field Inflation

Quantum Liquids and Turbulent Black Holes

Sequestering the Standard Model Vacuum Energy

Causality, holography, and entanglement entropy

Cluster Polylogarithms for Scattering Amplitudes