Scientific Series

Displaying 3505 - 3516 of 5085

The Effective Field Theory of Large Scale Structures

Enrico Pajer Utrecht University
March 19, 2013

PIRSA:13030110
Astrophysics
A CDT Hamiltonian from Horava-Lifshitz gravity

Yuki Sato Nagoya University
March 14, 2013

PIRSA:13030091
General Relativity & Quantum Cosmology
The dynamics of asymptotically anti-de Sitter spacetimes

Claude Warnick
March 14, 2013

PIRSA:13030077
General Relativity & Quantum Cosmology
The Higgs confronts 3 universes at the LHC

Markus Luty University of California, Davis
March 13, 2013

PIRSA:13030095
High Energy Physics
Neorealism and the Internal Language of Topoi

Sander Wolters Radboud Universiteit Nijmegen
March 12, 2013

PIRSA:13030107
Quantum Physics
Large N Chern-Simons-matter theories and three dimensional bosonization

Ofer Aharony Weizmann Institute of Science
March 12, 2013

PIRSA:13030106
High Energy Physics
Renormalization of Entanglement Entropy

Markus Luty University of California, Davis
March 12, 2013

PIRSA:13030108
High Energy Physics
Effective field theory approach to quasi-single field inflation

Masahide Yamaguchi Tokyo Institute of Technology
March 12, 2013

PIRSA:13030096
Astrophysics
Efficient Distributed Quantum Computing

Oliver Gray University of Bristol
March 11, 2013

PIRSA:13030104
Quantum Physics
One-photon and two-photon switching in graphene and optical nanomaterials

Mahi Singh Western University
March 08, 2013

PIRSA:13030094
Condensed Matter
Is the electron round?

Edward Hinds Imperial College London
March 08, 2013

PIRSA:13030100
High Energy Physics
A Self-consistent Model of the Black Hole Evaporation

Yuki Yokokura RIKEN
March 07, 2013

PIRSA:13030093
General Relativity & Quantum Cosmology

The Effective Field Theory of Large Scale Structures

Enrico Pajer Utrecht University
March 19, 2013

PIRSA:13030110
Astrophysics
An analytical understanding of large-scale matter inhomogeneities is an important cornerstone of our cosmological model and helps us interpreting current and future data. The standard approach, namely Eulerian perturbation theory, is unsatisfactory for at least three reasons: there is no clear expansion parameter since the density contrast is not small everywhere; it does not consistently account for deviations at large scales from a perfect pressureless fluid induced by short-scale non-linearities; for generic initial conditions, loop corrections are UV divergent, making predictions cutoff dependent and hence unphysical. I will present the systematic construction of an Effective Field Theory of Large Scale Structures and show that it successfully addresses all of the above issues. The idea is to smooth the density and velocity fields on a scale larger than the non-linear scale. The resulting smoothed fields are then small everywhere and provide a well-defined small parameter for perturbation theory. Smoothing amounts to integrating out the short scales, whose non-linear dynamics is hard to describe analytically. Their effects on the large scales are then determined by the symmetries of the problems. They introduce additional terms in the fluid equations such as an effective pressure, dissipation and stochastic noise. These terms have exactly the right scale dependence to cancel all divergences at one loop, and this should hold at all loops.
I will present a clean example of the renormalization of the theory in an Einstein de Sitter universe with self-similar initial conditions and discuss the relative importance of loop and effective corrections.
A CDT Hamiltonian from Horava-Lifshitz gravity

Yuki Sato Nagoya University
March 14, 2013

PIRSA:13030091
General Relativity & Quantum Cosmology
Causal Dynamical Triangulations” (CDT) is a lattice theory where aspects of quantum gravity can be studied. Two-dimensional CDT can be solved analytically and the continuum (quantum) Hamiltonian obtained.
In this talk I will show that this continuum Hamiltonian is the one obtained by quantizing two-dimensional projectable Horava-Lifshitz gravity.
The dynamics of asymptotically anti-de Sitter spacetimes

Claude Warnick
March 14, 2013

PIRSA:13030077
General Relativity & Quantum Cosmology
The majority of work on asymptotically anti-de Sitter spacetimes, much of it motivated by the AdS/CFT correspondence, assumes configurations which are either at or close to equilibrium. Recently it has been discovered that genuinely dynamical spacetimes with AdS asymptotics can exhibit some surprising behaviour. In particular, numerical studies suggest AdS is dynamically unstable. I will discuss recent analytical (in)stability results for asymptotically AdS spacetimes, in particular how stability can be affected by boundary conditions at the timelike conformal infinity.
The Higgs confronts 3 universes at the LHC

Markus Luty University of California, Davis
March 13, 2013

PIRSA:13030095
High Energy Physics
The recent discovery of the Higgs boson is a fundamental advance in particle physics. This talk gives a theorist's perspective of the significance of this discovery. The Higgs boson was proposed in the 1960s, but it is best understood in the context of the quest to understand the weak interactions, which began with Fermi's theory of weak interactions almost 80 years ago. This has led to three very different paradigms for the structure of fundamental interactions at the TeV scale: supersymmetry, compositeness/extra dimensions, and anthropic selection. The Large Hadron Collider is the experimentum crucis for deciding between these different possible universes, and the discovery of the Higgs is a crucial clue. This talk will describe these paradigms, the implications of the Higgs discovery for them, and the outlook for further discoveries that would decide between them.
Neorealism and the Internal Language of Topoi

Sander Wolters Radboud Universiteit Nijmegen
March 12, 2013

PIRSA:13030107
Quantum Physics
Crudely formulated, the idea of neorealism, in the way that Chris Isham and Andreas Doering use it, means that each theory of physics, in its mathematical formulation should share certain structural properties of classical physics. These properties are chosen to allow some degree of realism in the interpretation (for example, physical variables always have values). Apart from restricting the form of physical theories, neorealism does increase freedom in the shape of physical theories in another way. Theories of physics may be interpreted in other topoi than the category of sets and functions. In my talk I will concentrate on two topos models for quantum theory. The contravariant model of Butterfield, Isham and Doering on the one hand, and the covariant model of Heunen, Landsman and Spitters on the other. I will argue that when we think of the topoi as generalized categories of sets (i.e. when we use the internal perspective of the topoi at hand), these two models are closely related, and both resemble classical physics. I will assume no background knowledge in topos theory.
Large N Chern-Simons-matter theories and three dimensional bosonization

Ofer Aharony Weizmann Institute of Science
March 12, 2013

PIRSA:13030106
High Energy Physics
I will discuss the conformal theories of N complex scalars or fermions in 2+1 dimensions, coupled to a U(N) Chern-Simons (CS) theory at level k. In the large N limit these theories have a high-spin symmetry, and, as I will review, they are dual to Vasiliev's high-spin gravity theories on four dimensional anti-de Sitter space. Maldacena and Zhiboedov showed that the high-spin symmetry determines the 2-point and 3-point functions of these theories at large N, up to two parameters. The duality to Vasiliev's gravity suggests that there is some mapping between the CS+scalar and CS+fermion theories (when one adds a quartic coupling to the scalar theories, to flow to their "critical fixed point"). We compute explicitly the large N limit of some 2-point and 3-point functions in these theories. We show that the results match with the general results of Maldacena and Zhiboedov, and they are consistent with an equivalence between the critical theory of N scalars coupled to a U(N) CS theory at level k, and the theory of k fermions coupled to a U(k) CS theory at level (N-1/2). We conjecture that this large N equivalence may be an exact duality between the scalar and fermion theories also at finite N, thus providing a bosonization of the fermionic theory. Similar results hold for real scalars (fermions) when U(N) is replaced by O(N).
Renormalization of Entanglement Entropy

Markus Luty University of California, Davis
March 12, 2013

PIRSA:13030108
High Energy Physics
The Standard Model Higgs boson may be mixed with another scalar that does not couple singly to gauge bosons or fermions. The electroweak quantum numbers of such an additional scalar can be determined by measuring the quartic Higgs-Higgs-vector-vector couplings, which contribute—along with the coveted triple Higgs coupling—to double Higgs production in e+e− collisions. We show that simultaneous sensitivity to the quartic Higgs-Higgs-vector-vector coupling and the triple Higgs coupling can be obtained using measurements of the double Higgs production cross section at two different e+e− center-of-mass energies. Kinematic distributions of the two Higgs bosons in the final state could provide additional discriminating power.
Effective field theory approach to quasi-single field inflation

Masahide Yamaguchi Tokyo Institute of Technology
March 12, 2013

PIRSA:13030096
Astrophysics
We apply the effective field theory approach to quasi-single field inflation, which contains an additional scalar field with Hubble scale mass other than inflaton. Based on the time-dependent spatial diffeomorphism, which is not broken by the time-dependent background evolution, the most generic action of quasi-single field inflation is constructed up to third order fluctuations. Using the obtained action, the effects of the additional massive scalar field on the primordial curvature perturbations are discussed. In particular, we calculate the power spectrum and discuss the momentum-dependence of three point functions in the squeezed limit for general settings of quasi-single field inflation. Our framework can be also applied to inflation models with heavy particles. We make a qualitative discussion on the effects of heavy particles during inflation and that of sharp turning trajectory in our framework.
Efficient Distributed Quantum Computing

Oliver Gray University of Bristol
March 11, 2013

PIRSA:13030104
Quantum Physics
I will explain how to simulate arbitrary quantum circuits on a distributed quantum computer (DQC), in which the pairs of qubits that are allowed to interact are restricted to the edges of some (connected) graph G. Even for graphs with only a modest number of long-range qubit interactions, such as the hypercube, this simulation is, in fact, efficient. Furthermore, for all graphs, the emulation scheme is very close to being optimal. Secondly I will present an efficient quantum algorithm for parallel unrestricted memory look-up. As an application, I will show that the space-time trade off for Element Distinctness and Collision Finding can be improved. Both results arise from applying the ideas of reversible sorting networks to quantum computing.http://arxiv.org/abs/1207.2307
One-photon and two-photon switching in graphene and optical nanomaterials

Mahi Singh Western University
March 08, 2013

PIRSA:13030094
Condensed Matter
In this talk we will discuss both the one-photon and two-photon switching mechanisms in hybrid nanomaterials made from two or more semiconductor, metallic and optical nanostructures. The most prominent examples of these nanostructures are graphene, semiconductor quantum dots, metallic nanoparticles, and photonic and polaritonic crystals. Advances in nanoscience have allowed for the construction of these new classes of hybrid nanomaterials. Optical excitations in semiconductor nanostructures are electron-hole pairs (excitons) whereas excitations in metallic nanostructures are surface plasmons which are collective oscillations of electrons. Therefore, the combination of these systems can provide attractive opportunities to modify, design and control optical properties and to observe new phenomena which are based on exciton-plasmon interactions. It is expected that this research will provide a theoretical road map for the development of optical sensing and optical switching.
Is the electron round?

Edward Hinds Imperial College London
March 08, 2013

PIRSA:13030100
High Energy Physics
We have made a new measurement of the electron’s electric dipole moment (EDM) using a beam of YbF molecules. By measuring atto-eV energy shifts in a molecule, this experiment probes new physics at the tera-eV energy scale. According to the standard model, this EDM is d_e=10^(-38) e.cm – some eleven orders of magnitude below the current experimental limit. However, most extensions to the standard model predict much larger values, potentially accessible to measurement . Hence, the search for the electron EDM is a search for physics beyond the standard model. I will describe our experimental method, our current results and their implications for particle physics. I will also outline the prospects for further major improvement in sensitivity.
A Self-consistent Model of the Black Hole Evaporation

Yuki Yokokura RIKEN
March 07, 2013

PIRSA:13030093
General Relativity & Quantum Cosmology
We construct a self-consistent model which describes a black hole from formation to evaporation including the back reaction from the Hawking radiation. In the case where a null shell collapses, at the beginning the evaporation occurs, but it stops eventually, and a horizon and singularity appear. On the other hand, in the generic collapse process of a continuously distributed null matter, the black hole evaporates completely without forming a macroscopically large horizon nor singularity. We also find a stationary solution in the heat bath, which can be regarded as a normal thermodynamic object. (hep-th: 1302.4733)

Title	Speaker(s)	Date	Talk Type	Info link
The Effective Field Theory of Large Scale Structures	Enrico Pajer	2013-03-19	Scientific Series	View details
A CDT Hamiltonian from Horava-Lifshitz gravity	Yuki Sato	2013-03-14	Scientific Series	View details
The dynamics of asymptotically anti-de Sitter spacetimes	Claude Warnick	2013-03-14	Scientific Series	View details
The Higgs confronts 3 universes at the LHC	Markus Luty	2013-03-13	Scientific Series	View details
Neorealism and the Internal Language of Topoi	Sander Wolters	2013-03-12	Scientific Series	View details
Large N Chern-Simons-matter theories and three dimensional bosonization	Ofer Aharony	2013-03-12	Scientific Series	View details
Renormalization of Entanglement Entropy	Markus Luty	2013-03-12	Scientific Series	View details
Effective field theory approach to quasi-single field inflation	Masahide Yamaguchi	2013-03-12	Scientific Series	View details
Efficient Distributed Quantum Computing	Oliver Gray	2013-03-11	Scientific Series	View details
One-photon and two-photon switching in graphene and optical nanomaterials	Mahi Singh	2013-03-08	Scientific Series	View details
Is the electron round?	Edward Hinds	2013-03-08	Scientific Series	View details
A Self-consistent Model of the Black Hole Evaporation	Yuki Yokokura	2013-03-07	Scientific Series	View details

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The Effective Field Theory of Large Scale Structures

A CDT Hamiltonian from Horava-Lifshitz gravity

The dynamics of asymptotically anti-de Sitter spacetimes

The Higgs confronts 3 universes at the LHC

Neorealism and the Internal Language of Topoi

Large N Chern-Simons-matter theories and three dimensional bosonization

Renormalization of Entanglement Entropy

Effective field theory approach to quasi-single field inflation

Efficient Distributed Quantum Computing

One-photon and two-photon switching in graphene and optical nanomaterials

Is the electron round?

A Self-consistent Model of the Black Hole Evaporation

The Effective Field Theory of Large Scale Structures

A CDT Hamiltonian from Horava-Lifshitz gravity

The dynamics of asymptotically anti-de Sitter spacetimes

The Higgs confronts 3 universes at the LHC

Neorealism and the Internal Language of Topoi

Large N Chern-Simons-matter theories and three dimensional bosonization

Renormalization of Entanglement Entropy

Effective field theory approach to quasi-single field inflation

Efficient Distributed Quantum Computing

One-photon and two-photon switching in graphene and optical nanomaterials

Is the electron round?

A Self-consistent Model of the Black Hole Evaporation