Scientific Series

Displaying 3373 - 3384 of 5090

Conformal symmetry and cosmology

Austin Joyce University of Chicago
October 22, 2013

PIRSA:13100070
Astrophysics
Heavy particle effective field theory: formalism, dark matter and the proton size puzzle

Richard Hill University of Kentucky
October 18, 2013

PIRSA:13100107
High Energy Physics
All AdS7 solutions of type II supergravity

Alessandro Tomasiello University of Milano-Bicocca
October 18, 2013

PIRSA:13100108
High Energy Physics
Vector Beta Function

Yu Nakayama University of California, Berkeley
October 17, 2013

PIRSA:13100082
High Energy Physics
Constructing theories from duality: my response to John Wheeler
October 17, 2013

PIRSA:13100072
General Relativity & Quantum Cosmology
Quasinormal modes of rapidly rotating black holes/ Stability of tidally perturbed neutron stars

Aaron Zimmerman The University of Texas at Austin
October 17, 2013

PIRSA:13100096
General Relativity & Quantum Cosmology
Simulating Hamiltonian evolution with quantum computers

Richard Cleve Institute for Quantum Computing (IQC)
October 16, 2013

PIRSA:13100097
Quantum Physics
Can ‘sub-quantum’ theories based on a background field escape Bell’s no-go theorem ?

Louis Vervoort Université de Montréal
October 15, 2013

PIRSA:13100085
Quantum Physics
Geometry of quantum phases and emergent Newtonian dynamics

Anatoli Polkovnikov Boston University
October 15, 2013

PIRSA:13100083
Condensed Matter
Bootstrapping the O(N) Vector Models

David Simmons-Duffin Institute for Advanced Study (IAS)
October 15, 2013

PIRSA:13100074
High Energy Physics
Including astroparticle observables in global fits to new physics scenarios

Patrick Scott McGill University
October 15, 2013

PIRSA:13100103
High Energy Physics
Hybrid quantization of the Gowdy model within loop quantum cosmology

Mercedes Martin-Benito Complutense University of Madrid
October 15, 2013

PIRSA:13100102
Astrophysics

Conformal symmetry and cosmology

Austin Joyce University of Chicago
October 22, 2013

PIRSA:13100070
Astrophysics
We will explore the role that conformal symmetries may play in cosmology. First, we will discuss the symmetries underlying the statistics of the primordial perturbations which seeded the temperature anisotropies of the Cosmic Microwave Background. I will show how symmetry considerations lead us to three broad classes of theories to explain these perturbations: single-field inflation, multi-field inflation, and the conformal mechanism. We will discuss the symmetries in each case and derive their model-independent consequences. Finally, we will examine the possibility of violating the null energy condition with a well-behaved quantum field theory.
Heavy particle effective field theory: formalism, dark matter and the proton size puzzle

Richard Hill University of Kentucky
October 18, 2013

PIRSA:13100107
High Energy Physics
Heavy particle expansions, familiar from heavy quark physics, have found important applications in the analysis of dark matter candidates and their interactions with the Standard Model. From a different direction, precision spectroscopy of muonic hydrogen has challenged QED and required more precise knowledge of proton structure. These problems have forced a closer examination of the construction of general heavy particle lagrangians at high orders in the 1/M expansion, and in the absence of known ultraviolet completions. Key aspects of this formalism, including the emergence of Lorentz invariance from "nonrelativistic" lagrangians, are reviewed, and several applications are presented. A status report on the proton radius puzzle is given.
All AdS7 solutions of type II supergravity

Alessandro Tomasiello University of Milano-Bicocca
October 18, 2013

PIRSA:13100108
High Energy Physics
In M-theory, the only AdS7 supersymmetric solutions are AdS7 × S4 and its orbifolds. In this talk, I will describe a classification of AdS7 supersymmetric solutions in type II supergravity. While in IIB none exist, in IIA with Romans mass (which does not lift to M-theory) there are many new ones. The classification starts from a pure spinor approach reminiscent of generalized complex geometry. Without the need for any Ansatz, the method determines uniquely the form of the metric and fluxes, up to solving a system of ODEs. Namely, the metric on M3 is that of an S2 fibered over an interval; this is consistent with the Sp(1) R-symmetry of the holographically dual (1,0) theory. One can obtain numerically many solutions, with D8 and/or D6 brane sources; topologically, the internal manifold M3 = S^3.
Vector Beta Function

Yu Nakayama University of California, Berkeley
October 17, 2013

PIRSA:13100082
High Energy Physics
We propose various properties of renormalization group beta functions for vector operators in relativistic quantum field theories. We argue that they must satisfy compensated gauge invariance, orthogonality with respect to scalar beta functions, Higgs-like relation among anomalous dimensions and a gradient property. We further conjecture that non-renormalization holds if and only if the vector operator is conserved. The local renormalization group analysis guarantees the first three within power counting renormalization. We verify all the conjectures in conformal perturbation theories and holography in the weakly coupled gravity regime.
Constructing theories from duality: my response to John Wheeler
October 17, 2013

PIRSA:13100072
General Relativity & Quantum Cosmology
The late physicist John Wheeler, was renowned for his Socratic method of conducting physics discussions. "Why is general relativity the way it is? What makes it special?" were reportedly questions one should expect in his presence. There are different answers to these questions, each requiring a set of assumptions - which Wheeler would likely question again - and each bringing with it new insights into physics as a whole. This talk will put forward new principles for deriving general relativity. Perhaps more than is the case with other construction principles, the principles introduced are not limited to the derivation of general relativity, requiring only an specification of the theory's phase space in order to be applicable. To be less enigmatic, one defines observable equivalence between physical theories in the Dirac constraint setting, and then the principle merely searches theory space for two equivalent (or dual) fully constrained theories. We find it quite remarkable that such a complex theory as general relativity emerges, when no initial presupposition even on the existence of space-time is made. If there is time (and I will argue there is!) I will discuss another issue that also distinguishes the present set of assumptions: the possibility that they are in a concrete sense ``self-selected", which I like to think would be more satisfactory to Wheeler's line of questioning (or at least give him more to chew on).
Quasinormal modes of rapidly rotating black holes/ Stability of tidally perturbed neutron stars

Aaron Zimmerman The University of Texas at Austin
October 17, 2013

PIRSA:13100096
General Relativity & Quantum Cosmology
I will review recent work in two very different topics. First, I will discuss the quasinormal mode spectrum of nearly extremal Kerr black holes, where a bifurcation of the frequency spectrum is observed. In addition, collective oscillations of many modes is possible, resulting in a power-law rather than exponentially decaying ringdown. Next, I will discuss a recent proposal for how tidally induced, multimode coupling of normal modes in neutron stars can destabilize the stars. Such an instability could hamper gravitational wave detection of neutron star binaries by matched filtering. By accounting for higher-order multimode couplings, it can be shown that there is no such instability for neutron star binaries, although a milder instability may exist for binaries with less compact objects.
Simulating Hamiltonian evolution with quantum computers

Richard Cleve Institute for Quantum Computing (IQC)
October 16, 2013

PIRSA:13100097
Quantum Physics
In 1982, Richard Feynman proposed the concept of a quantum computer as a means of simulating physical systems that evolve according to the Schrödinger equation. I will explain various quantum algorithms that have been proposed for this simulation problem, including my recent work (jointly with Dominic Berry and Rolando Somma) that significantly improves the running time as a function of the precision of the output data.
Can ‘sub-quantum’ theories based on a background field escape Bell’s no-go theorem ?

Louis Vervoort Université de Montréal
October 15, 2013

PIRSA:13100085
Quantum Physics
In systems described by Ising-like Hamiltonians, such as spin-lattices, the Bell Inequality can be strongly violated. Surprisingly, these systems are both local and non-superdeterministic. They are local, because 1) they include only local, near-neighbor interaction, 2) they satisfy, accordingly, the Clauser-Horne factorability condition, and 3) they can violate the Bell Inequality also in dynamic Bell experiments. Starting from this result we construct an elementary hidden-variable model, based on a generalized Ising Hamiltonian, describing the interaction of the Bell-particles with a stochastic ‘background’ medium. We suggest that such a model is a simple version of a variety of recently developed ‘sub-quantum’ theories, by authors as Nelson, Adler, De la Pena, Cetto, Groessing, Khrennikov, all based on a background field. We investigate how the model might be turned into a realistic theory. Finally, it appears that background-based models can be tested and discriminated from quantum mechanics by a straightforward extension of existing experiments.
Geometry of quantum phases and emergent Newtonian dynamics

Anatoli Polkovnikov Boston University
October 15, 2013

PIRSA:13100083
Condensed Matter
In the first part of this talk I will discuss how one can characterize geometry of quantum phases and phase transitions based on the Fubini-Study metric, which characterizes the distance between ground state wave-functions in the external parameter space. This metric is closely related to the Berry curvature. I will show that there are new geometric invariants based on the Euler characteristic. I will also show how one can directly measure this metric tensor in simple dynamical experiments. In the second part of the talk I will discuss emergent nature of macroscopic equations of motion (like Newton's equations) showing that they appear in the leading order of non-adiabatic expansion. I will show that the Berry curvature gives the Coriolis force and the Fubini-Study metric tensor is closely related to the inertia mass. Thus I will argue that any motion (not necessarily motion in space) is geometrical in nature.
Bootstrapping the O(N) Vector Models

David Simmons-Duffin Institute for Advanced Study (IAS)
October 15, 2013

PIRSA:13100074
High Energy Physics
We study the conformal bootstrap for 3D CFTs with O(N) global symmetry. We obtain rigorous upper bounds on the scaling dimensions of the first O(N) singlet and symmetric tensor operators appearing in the \phi_i x \phi_j OPE, where \phi_i is a fundamental of O(N). Comparing these bounds to previous determinations of critical exponents in the O(N) vector models, we find strong numerical evidence that the O(N) vector models saturate the bootstrap constraints at all values of N. We also compute general lower bounds on the central charge, giving numerical predictions for the values realized in the O(N) vector models. We compare our predictions to previous computations in the 1/N expansion, finding precise agreement at large values of N.
Including astroparticle observables in global fits to new physics scenarios

Patrick Scott McGill University
October 15, 2013

PIRSA:13100103
High Energy Physics
Searches for physics beyond the standard model come in many forms, from terrestrial probes to astroparticle experiments and cosmological observations. Efforts to combine multiple search channels in 'global fits' to new physics scenarios typically consider only a subset of the available channels. Astroparticle searches in particular are usually only included in a very approximate way, if at all. In this talk I will review recent progress in including detailed gamma-ray, neutrino and CMB searches for dark matter in global fits. I will also preview some of the future developments and challenges in this field, where the applicability of global fits will move well beyond the small range of constrained supersymmetric models they have so far mostly been applied to.
Hybrid quantization of the Gowdy model within loop quantum cosmology

Mercedes Martin-Benito Complutense University of Madrid
October 15, 2013

PIRSA:13100102
Astrophysics
Loop quantum cosmology (LQC) proposes a quantization for homogeneous cosmologies which success in solving the classical singularity problem. Realistic scenarios call for the consideration of inhomogeneities. Focusing on the simplest inhomogenous cosmological model, the Gowdy model with three-torus spatial topology and linearly polarized gravitational waves, I'll describe an approach to treat inhomogeneities in the framework of loop quantum cosmology. This is a hybrid approach that combines LQC methods with Fock quantization. Furthermore, I'll discuss justified approximations that allow us to find approximate solutions to the (very complicated) Hamiltonian constraint of the model.

Title	Speaker(s)	Date	Talk Type	Info link
Conformal symmetry and cosmology	Austin Joyce	2013-10-22	Scientific Series	View details
Heavy particle effective field theory: formalism, dark matter and the proton size puzzle	Richard Hill	2013-10-18	Scientific Series	View details
All AdS7 solutions of type II supergravity	Alessandro Tomasiello	2013-10-18	Scientific Series	View details
Vector Beta Function	Yu Nakayama	2013-10-17	Scientific Series	View details
Constructing theories from duality: my response to John Wheeler		2013-10-17	Scientific Series	View details
Quasinormal modes of rapidly rotating black holes/ Stability of tidally perturbed neutron stars	Aaron Zimmerman	2013-10-17	Scientific Series	View details
Simulating Hamiltonian evolution with quantum computers	Richard Cleve	2013-10-16	Scientific Series	View details
Can ‘sub-quantum’ theories based on a background field escape Bell’s no-go theorem ?	Louis Vervoort	2013-10-15	Scientific Series	View details
Geometry of quantum phases and emergent Newtonian dynamics	Anatoli Polkovnikov	2013-10-15	Scientific Series	View details
Bootstrapping the O(N) Vector Models	David Simmons-Duffin	2013-10-15	Scientific Series	View details
Including astroparticle observables in global fits to new physics scenarios	Patrick Scott	2013-10-15	Scientific Series	View details
Hybrid quantization of the Gowdy model within loop quantum cosmology	Mercedes Martin-Benito	2013-10-15	Scientific Series	View details

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Format results

Conformal symmetry and cosmology

Heavy particle effective field theory: formalism, dark matter and the proton size puzzle

All AdS7 solutions of type II supergravity

Vector Beta Function

Constructing theories from duality: my response to John Wheeler

Quasinormal modes of rapidly rotating black holes/ Stability of tidally perturbed neutron stars

Simulating Hamiltonian evolution with quantum computers

Can ‘sub-quantum’ theories based on a background field escape Bell’s no-go theorem ?

Geometry of quantum phases and emergent Newtonian dynamics

Bootstrapping the O(N) Vector Models

Including astroparticle observables in global fits to new physics scenarios

Hybrid quantization of the Gowdy model within loop quantum cosmology

Conformal symmetry and cosmology

Heavy particle effective field theory: formalism, dark matter and the proton size puzzle

All AdS7 solutions of type II supergravity

Vector Beta Function

Constructing theories from duality: my response to John Wheeler

Quasinormal modes of rapidly rotating black holes/ Stability of tidally perturbed neutron stars

Simulating Hamiltonian evolution with quantum computers

Can ‘sub-quantum’ theories based on a background field escape Bell’s no-go theorem ?

Geometry of quantum phases and emergent Newtonian dynamics

Bootstrapping the O(N) Vector Models

Including astroparticle observables in global fits to new physics scenarios

Hybrid quantization of the Gowdy model within loop quantum cosmology