Scientific Series

Displaying 3169 - 3180 of 5007

Line Defects and Tropicalization

Clay Cordova University of Chicago
March 11, 2014

PIRSA:14030106
High Energy Physics
SDSS-III BOSS and Beyond: fundamental physics with galaxy redshift surveys

Beth Reid Lawrence Berkeley National Laboratory
March 11, 2014

PIRSA:14030096
Astrophysics
A one-dimensional action for simplicial gravity in three dimensions

Wolfgang Wieland University of Erlangen-Nuremberg
March 06, 2014

PIRSA:14030088
General Relativity & Quantum Cosmology
Sequestering Lorentz violation in the Lifshitz sector

Maxim Pospelov University of Minnesota
March 06, 2014

PIRSA:14030092
General Relativity & Quantum Cosmology
The Unreasonable Effectiveness Of Quantum Physics in Modern Mathematics

Robbert Dijkgraaf Institute for Advanced Study (IAS)
March 05, 2014

PIRSA:14030083
Mathematical 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
Cosmology Results from the Pan-STARRs Supernova Survey

Danial Scolnic Johns Hopkins University
March 04, 2014

PIRSA:14030095
Astrophysics
Nonlocal cosmology

Richard Woodard University of Florida
February 27, 2014

PIRSA:14020137
General Relativity & Quantum Cosmology
À la recherche du temps perdu - Templeton Frontiers Colloquia

Flavio Mercati University of Naples Federico II
February 26, 2014

PIRSA:14020100
General Relativity & Quantum Cosmology
Numerical detection of symmetry protected and symmetry enriched topological phases

Frank Pollmann Max Planck Institute for Physics, Munich (Werner-Heisenberg-Institut)
February 25, 2014

PIRSA:14020140
Condensed Matter
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
Probing the Small Scale Structure of Dark Matter with Indirect Detection

Sheldon Campbell Ohio State University
February 25, 2014

PIRSA:14020097
Astrophysics

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.
SDSS-III BOSS and Beyond: fundamental physics with galaxy redshift surveys

Beth Reid Lawrence Berkeley National Laboratory
March 11, 2014

PIRSA:14030096
Astrophysics
The SDSS-III Baryon Oscillation Spectroscopic Survey, now nearly complete, is measuring the three-dimensional cosmic structure with 1.35 million new redshifts. Galaxy clustering measurements provide constraints on the cosmic expansion history through the baryon acoustic oscillation feature and the Alcock-Paczynski effect. In addition, the imprint of galaxy peculiar velocities on the observed galaxy clustering, "redshift-space distortions", provides a measurement of the growth rate of matter perturbations. Taken together, these measurements provide excellent constraints on dark energy and test the relation between expansion history and growth of perturbations expected in General Relativity. I will summarize results from BOSS's recent DR11 results and highlight what we may learn about fundamental physics (especially neutrinos) from the upcoming Dark Energy Spectroscopic Instrument (DESI).
A one-dimensional action for simplicial gravity in three dimensions

Wolfgang Wieland University of Erlangen-Nuremberg
March 06, 2014

PIRSA:14030088
General Relativity & Quantum Cosmology
Loop quantum gravity has a spinorial representation. Spinors simplify the symplectic structure of the theory, but can they also teach us something about the dynamics? We study this question in three dimensions, and derive the Ponzano–-Regge model from a spinorial action. Our construction starts from the first-order Palatini formalism, and gives the discretised action in the spinorial representation. A one-dimensional refinement limit brings us back to a continuum theory. The three-dimensional action turns into a line integral over the edges of the discretisation. We compute the gauge-fixed path integral for a generic simplicial discretisation. The resulting amplitudes reproduce the Ponzano–-Regge model.
Sequestering Lorentz violation in the Lifshitz sector

Maxim Pospelov University of Minnesota
March 06, 2014

PIRSA:14030092
General Relativity & Quantum Cosmology
Horava's proposal to use Lifshitz propagators for gravitons above certain energy scales may provide a viable theory of quantum gravity without further need of UV completion. In my talk, I will address the question of whether the complete lack of Lorentz invariance above a certain energy scale is a big problem for any realistic construction. I will argue that it is not, provided that the onset of Lifshitz scaling for gravitons occurs at momentum scale much lower than the Planck mass. I will also discuss consequences of combining Lifshitz gravity and supersymmetric matter sector.
The Unreasonable Effectiveness Of Quantum Physics in Modern Mathematics

Robbert Dijkgraaf Institute for Advanced Study (IAS)
March 05, 2014

PIRSA:14030083
Mathematical Physics
Mathematics has proven to be "unreasonably effective" in understanding nature. The fundamental laws of physics can be captured in beautiful formulae. In this lecture I want to argue for the reverse effect: Nature is an important source of inspiration for mathematics, even of the purest kind. In recent years ideas from quantum field theory, elementary particles physics and string theory have completely transformed mathematics, leading to solutions of deep problems, suggesting new invariants in geometry and topology, and, perhaps most importantly, putting modern mathematical ideas in a `natural’ context.
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.''
Cosmology Results from the Pan-STARRs Supernova Survey

Danial Scolnic Johns Hopkins University
March 04, 2014

PIRSA:14030095
Astrophysics
The Pan-STARRs supernova survey has discovered one of the largest samples of Type Ia supernovae. Measurements of the distances to these supernovae allow us to probe some of the most fundamental questions about the properties of the universe like what is dark energy. When combining measurements from various astrophysical probes, we find hints of interesting tension with the Lambda-CDM model. I discuss the various combinations of astrophysical probes and the source of this tension. It is possible that this tension is due to systematic uncertainties in the various measurements, and I show how we analyze these uncertainties in the Pan-STARRs sample.
Nonlocal cosmology

Richard Woodard University of Florida
February 27, 2014

PIRSA:14020137
General Relativity & Quantum Cosmology
I review a class of nonlocally modified gravity models which were proposed to explain the current phase of cosmic acceleration without dark energy. Among the topics considered are deriving causal and conserved field equations, adjusting the model to make it support a given expansion history, why these models do not require an elaborate screening mechanism to evade solar system tests, degrees of freedom and kinetic stability, and the negative verdict of structure formation. Although these simple models are not consistent with data on the growth of cosmic structures many of their features are likely to carry over to more complicated models which are in better agreement with the data.
À la recherche du temps perdu - Templeton Frontiers Colloquia

Flavio Mercati University of Naples Federico II
February 26, 2014

PIRSA:14020100
General Relativity & Quantum Cosmology
Augustine of Hippo declared he knew what time is until someone asked him. After 16 centuries we still largely ignore the true essence of time, but we made definite progress in studying its properties. The most striking, and somewhat intuitively (and tragically) obvious one is the irreversibility of its flow. And yet, our fundamental theories are time-reversal invariant, they do not distinguish between past and future. This is usually accounted for by assuming an immensely special initial condition of the Universe, dressed with statistical arguments. In this talk, I will show how an irreversible behaviour, and with it a growth of complexity and information, can emerge from time-reversal invariant laws, without assuming any special initial condition and without thermodynamical arguments. This phenomenon is present in General Relativity, our most advanced theory of the Universe. This irreversibility will also allow me to propose a solution of another puzzle associated with time, namely the incompatibility between the quantum and the general-relativistic notions of time.
Numerical detection of symmetry protected and symmetry enriched topological phases

Frank Pollmann Max Planck Institute for Physics, Munich (Werner-Heisenberg-Institut)
February 25, 2014

PIRSA:14020140
Condensed Matter
A topological phase is a phase of matter which cannot be characterized by a local order parameter. We first introduce non-local order parameters that can detect symmetry protected topological (SPT) phases in 1D systems and then show how to generalize the idea to detect symmetry enriched topological (SET) phases in 2D. SET phases are new structures that occur in topologically ordered systems in the presence of symmetries. We introduce simple methods to detect the SET order directly from a complete set of topologically degenerate ground state wave functions. We first show how to directly determine the characteristic symmetry fractionalization of the quasiparticles from the reduced density matrix of the minimally entangled states. Second, we show how a simple generalization of a non-local order parameter can be measured to detect SETs. The usefulness of the proposed approached is demonstrated by examining two concrete model states which exhibit SET: (i) a spin-1 model on the honeycomb lattice and (ii) the resonating valence bond state on a kagome lattice. We conclude that the spin-1 model and the RVB state are in the same SET phases.
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.
Probing the Small Scale Structure of Dark Matter with Indirect Detection

Sheldon Campbell Ohio State University
February 25, 2014

PIRSA:14020097
Astrophysics
Direct observation of the small scale structure of matter in the Universe provides potentially important information about a wealth of physics, from complex galaxy evolution processes to fundamental particle properties of dark matter. Detecting this fine structure in dark matter, though, is notoriously difficult. Dark matter indirect detection--through observation of radiation products of particle annihilation--may be the most direct method for observing small scale structure. However, in an observed signal, the amount of dark matter clustering is degenerate with the annihilation cross section. This talk outlines ways this degeneracy may be broken with indirect detection alone. Scenarios are discussed where either abundant substructure leads to discovery of annihilation radiation (revealing properties of the substructure), or a discovery strongly constrains the presence of significant dark matter halo substructure.

Title	Speaker(s)	Date	Talk Type	Info link
Line Defects and Tropicalization	Clay Cordova	2014-03-11	Scientific Series	View details
SDSS-III BOSS and Beyond: fundamental physics with galaxy redshift surveys	Beth Reid	2014-03-11	Scientific Series	View details
A one-dimensional action for simplicial gravity in three dimensions	Wolfgang Wieland	2014-03-06	Scientific Series	View details
Sequestering Lorentz violation in the Lifshitz sector	Maxim Pospelov	2014-03-06	Scientific Series	View details
The Unreasonable Effectiveness Of Quantum Physics in Modern Mathematics	Robbert Dijkgraaf	2014-03-05	Scientific Series	View details
How Much Information Can SUSY QM Conserve About SUSY QFT?	S. James Gates Jr.	2014-03-04	Scientific Series	View details
Cosmology Results from the Pan-STARRs Supernova Survey	Danial Scolnic	2014-03-04	Scientific Series	View details
Nonlocal cosmology	Richard Woodard	2014-02-27	Scientific Series	View details
À la recherche du temps perdu - Templeton Frontiers Colloquia	Flavio Mercati	2014-02-26	Scientific Series	View details
Numerical detection of symmetry protected and symmetry enriched topological phases	Frank Pollmann	2014-02-25	Scientific Series	View details
Large Tensor-to-Scalar Ratio in Small-Field Inflation	Takeshi Kobayashi	2014-02-25	Scientific Series	View details
Probing the Small Scale Structure of Dark Matter with Indirect Detection	Sheldon Campbell	2014-02-25	Scientific Series	View details

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Format results

Line Defects and Tropicalization

SDSS-III BOSS and Beyond: fundamental physics with galaxy redshift surveys

A one-dimensional action for simplicial gravity in three dimensions

Sequestering Lorentz violation in the Lifshitz sector

The Unreasonable Effectiveness Of Quantum Physics in Modern Mathematics

How Much Information Can SUSY QM Conserve About SUSY QFT?

Cosmology Results from the Pan-STARRs Supernova Survey

Nonlocal cosmology

À la recherche du temps perdu - Templeton Frontiers Colloquia

Numerical detection of symmetry protected and symmetry enriched topological phases

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

Probing the Small Scale Structure of Dark Matter with Indirect Detection

Line Defects and Tropicalization

SDSS-III BOSS and Beyond: fundamental physics with galaxy redshift surveys

A one-dimensional action for simplicial gravity in three dimensions

Sequestering Lorentz violation in the Lifshitz sector

The Unreasonable Effectiveness Of Quantum Physics in Modern Mathematics

How Much Information Can SUSY QM Conserve About SUSY QFT?

Cosmology Results from the Pan-STARRs Supernova Survey

Nonlocal cosmology

À la recherche du temps perdu - Templeton Frontiers Colloquia

Numerical detection of symmetry protected and symmetry enriched topological phases

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

Probing the Small Scale Structure of Dark Matter with Indirect Detection