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DMRG Studies on the Spin Liquid Ground State of the Kagome Model

Stefan Depenbrock Ludwig-Maximilians-Universität München (LMU)
February 26, 2013

PIRSA:13020147
Condensed Matter
FERMI 130 GeV Line: Dark Interpretations

Matthew McCullough Massachusetts Institute of Technology (MIT)
February 26, 2013

PIRSA:13020150
Particle Physics
12/13 PSI - Cosmology Review Lecture 6

Latham Boyle University of Edinburgh
February 26, 2013

PIRSA:13020106
Cosmology
Newton’s Method in Cosmology Today

Bill Harp Western University
February 26, 2013

PIRSA:13020151
Cosmology
12/13 PSI - Quantum Information Review Lecture 6

Andrew Childs University of Waterloo
February 26, 2013

PIRSA:13020116
Quantum Information
12/13 PSI - Beyond the Standard Model Lecture 6
- Itay Yavin McMaster University
- Natalia Toro Stanford University
February 26, 2013

PIRSA:13020096
Particle Physics
Bounding the purification rank of mixed states

Gemma De Las Cuevas Universität Innsbruck
February 25, 2013

PIRSA:13020149
Quantum Information
12/13 PSI - Cosmology Review Lecture 5

Latham Boyle University of Edinburgh
February 25, 2013

PIRSA:13020105
Cosmology
Beyond Massive Gravity

Rachel Rosen Carnegie Mellon University
February 25, 2013

PIRSA:13020134
Cosmology
12/13 PSI - Quantum Information Review Lecture 5

Andrew Childs University of Waterloo
February 25, 2013

PIRSA:13020115
Quantum Information
12/13 PSI - Beyond the Standard Model Lecture 5
- Itay Yavin McMaster University
- Natalia Toro Stanford University
February 25, 2013

PIRSA:13020095
Particle Physics
Closing Summary Talks
- Peter Loch University of Arizona
- Michael Spannowsky Durham University
- Brian Shuve Harvey Mudd College
February 23, 2013

PIRSA:13020145

DMRG Studies on the Spin Liquid Ground State of the Kagome Model

Stefan Depenbrock Ludwig-Maximilians-Universität München (LMU)
February 26, 2013

PIRSA:13020147
Condensed Matter
I will present a density-matrix renormalization group (DMRG) study of the S=1/2 Heisenberg antiferromagnet on the kagome lattice to identify the conjectured spin liquid ground state. Exploiting SU(2) spin symmetry, which allows us to keep up to 16,000 DMRG states, we consider cylinders with circumferences up to 17 lattice spacings and find a spin liquid ground state with an estimated per site energy of -0.4386(5), a spin gap of 0.13(1), very short-range decay in spin, dimer and chiral correlation functions and finite topological entanglement consistent with the logarithm of 2, ruling out gapless, chiral or non-topological spin liquids. All this would provide strong evidence for a gapped topological Z_2 spin liquid.
FERMI 130 GeV Line: Dark Interpretations

Matthew McCullough Massachusetts Institute of Technology (MIT)
February 26, 2013

PIRSA:13020150
Particle Physics
Last year strong evidence was claimed for a 130 GeV gamma ray line from the galactic center in the FERMI telescope data. In the first half of the talk I will review the status of the evidence, including recent suggestions which call it into question. In the second half of the talk, under the bold assumption that the line is a genuine signature of dark matter, I will review some of the properties required of dark matter to explain the line and the general features of models proposed to explain it. This second half will include material from recent work with Francesco D'Eramo and Jesse Thaler (arxiv:1210.7817), which suggests that the line is readily explained by dark matter "semi-annihilation" rather than the standard annihilation interpretation.
12/13 PSI - Cosmology Review Lecture 6

Latham Boyle University of Edinburgh
February 26, 2013

PIRSA:13020106
Cosmology
Newton’s Method in Cosmology Today

Bill Harp Western University
February 26, 2013

PIRSA:13020151
Cosmology
Newton’s inferences from phenomena realize an ideal of empirical success that’s richer than prediction. To realize Newton’s richer conception of empirical success a theory needs to do more than to accurately predict the phenomena it purports to explain: in addition it needs to have the phenomena accurately measure parameters of the theory. Newton’s method aims to turn theoretical questions into ones which can be empirically answered by measurements from phenomena. Propositions inferred from phenomena are provisionally accepted as guides to further research. Newton’s ideal of empirical success as agreeing measurements from diverse phenomena is appealed to in support of the radical inference to dark energy in cosmology today. Robert Kirshner (two of his PhDs share one half of 2011’s Nobel Prize in physics) gave an account of the role of cosmic microwave background measurements, to back up the supernova measurements and measurements from galaxy clustering in supporting the transition of dark energy from a wild hypothesis into an accepted background assumption that guides further research in cosmology today. This illustrates a feature of agreeing measurements from diverse phenomena that is especially important for turning data into evidence. To the extent that the sources of systematic error of the different measurements can be regarded as independent, their agreement contributes additional support for counting them as accurate rather than as mere artifacts of systematic error.
12/13 PSI - Quantum Information Review Lecture 6

Andrew Childs University of Waterloo
February 26, 2013

PIRSA:13020116
Quantum Information
12/13 PSI - Beyond the Standard Model Lecture 6
- Itay Yavin McMaster University
- Natalia Toro Stanford University
February 26, 2013

PIRSA:13020096
Particle Physics
Bounding the purification rank of mixed states

Gemma De Las Cuevas Universität Innsbruck
February 25, 2013

PIRSA:13020149
Quantum Information
A mixed state can be expressed as a sum of D tensor product matrices, where D is its operator Schmidt rank, or as the result of a purification with a purifying state of Schmidt rank D', where D' is its purification rank. The question whether D' can be upper bounded by D is important theoretically (to establish a description of mixed states with tensor networks), as well as numerically (as the first decomposition is more efficient, but the second one guarantees positive-semidefiniteness after truncation). Here we show that no upper bounds of the purification rank that depend only on operator Schmidt rank exist, but provide upper bounds that also depend on the number of eigenvalues. In addition, we formulate the approximation problem as a Semidefinite Program.
Joint work with N. Schuch, D. Perez-Garcia, and J. I. Cirac.
12/13 PSI - Cosmology Review Lecture 5

Latham Boyle University of Edinburgh
February 25, 2013

PIRSA:13020105
Cosmology
Beyond Massive Gravity

Rachel Rosen Carnegie Mellon University
February 25, 2013

PIRSA:13020134
Cosmology
In the last few years there has been a burst of progress in the field of massive gravity. The construction of consistent theories in which the graviton has a small mass has in turn led to the development a new family of compelling, consistent low-energy modifications of General Relativity. These theories improve our understanding of the interplay between gravity and particle physics and provide new approaches to solving the cosmological constant problem. In this talk I will review these recent developments. I will discuss the search among these new theories for a symmetry that has the potential to address the cosmological constant problem.
12/13 PSI - Quantum Information Review Lecture 5

Andrew Childs University of Waterloo
February 25, 2013

PIRSA:13020115
Quantum Information
12/13 PSI - Beyond the Standard Model Lecture 5
- Itay Yavin McMaster University
- Natalia Toro Stanford University
February 25, 2013

PIRSA:13020095
Particle Physics
Closing Summary Talks
- Peter Loch University of Arizona
- Michael Spannowsky Durham University
- Brian Shuve Harvey Mudd College
February 23, 2013

PIRSA:13020145

Title	Date	Collection	Type	Info
DMRG Studies on the Spin Liquid Ground State of the Kagome Model	2013‑02‑26	Quantum Matter	Scientific Series	View details
FERMI 130 GeV Line: Dark Interpretations	2013‑02‑26	Particle Physics	Scientific Series	View details
12/13 PSI - Cosmology Review Lecture 6	2013‑02‑26	12/13 PSI - Cosmology Review	Course	View details
Newton’s Method in Cosmology Today	2013‑02‑26	Cosmology and Gravitation	Scientific Series	View details
12/13 PSI - Quantum Information Review Lecture 6	2013‑02‑26	12/13 PSI - Quantum Information Review	Course	View details
12/13 PSI - Beyond the Standard Model Lecture 6	2013‑02‑26	12/13 PSI - Beyond the Standard Model	Course	View details
Bounding the purification rank of mixed states	2013‑02‑25	Perimeter Institute Quantum Discussions	Scientific Series	View details
12/13 PSI - Cosmology Review Lecture 5	2013‑02‑25	12/13 PSI - Cosmology Review	Course	View details
Beyond Massive Gravity	2013‑02‑25	Colloquium	Scientific Series	View details
12/13 PSI - Quantum Information Review Lecture 5	2013‑02‑25	12/13 PSI - Quantum Information Review	Course	View details
12/13 PSI - Beyond the Standard Model Lecture 5	2013‑02‑25	12/13 PSI - Beyond the Standard Model	Course	View details
Closing Summary Talks	2013‑02‑23	Applications of Jet Substructure 2013	Conference	View details

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