HEP-GR Colloquium Series
Place: Meeting Room 2
Time: Wednesdays, 2:15pm (unless otherwise stated.)
Organisers: Dr Daniele Dorigoni, Dr Sungjay Lee and Dr Tolya Dymarsky.
Please stay for tea, coffee and biscuits in the Central Core!
Easter Term 2013
17th-April-2013: Entanglement entropy and negativity in quantum field theories.
Pasquale Calabrese (Pisa)
Abstract: The study of the entanglement content of many body quantum systems has prompted an
intense research activity at the crossroad of different disciplines such as statistical mechanics,
quantum information, condensed matter, and quantum field theory.The quantification of the entanglement allowed a novel and finer characterization of many extended quantum systems. In this talk I will present systematic methods to calculate the entanglement entropy and negativity in the ground state of 1+1 dimensional quantum field theories, with particular emphasis on conformal invariant ones. I will show how to apply these powerful tools to the calculation of the entanglement of a single interval, and the generalization to different situations such as the case of several disjoint intervals.
Lent Term 2013
16th-Jan-2013: Amplitudes and number theory
Francis Brown (CNRS, Paris)
Abstract: I will give an overview of some recent results on amplitudes in massless phi^4 theory, and explain their connection to algebraic geometry, and multiple zeta values and modular forms in number theory
23rd-Jan-2013: Unoriented D-brane instantons
Massimo Bianchi (Rome)
Abstract: We give a pedagogical introduction to D-brane instanton effects in vacuum configurations with open and unoriented strings. We focus on quiver gauge theories for unoriented D-branes at orbifold singularities and describe in some detail the Z_3 case, where both "gauge" and "exotic" instantons can generate non-perturbative super potentials, and the Z_5 case, where supersymmetry breaking may arise from the combined effect of `gauge' instantons and a FI D-term.
30th-Jan-2013 The Wilkinson Microwave Anisotropy Probe (WWAMP) Observations: The Final Results
Eiichiro Komatsu (Max Planck Institute for Astrophysics)
Abstract: The Cosmic Microwave Background (CMB), the fossil light of the Big Bang, is the oldest light that one can ever hope to observe in our Universe. The CMB provides us with a direct image of the Universe when it was still an "infant" - 380,000 years old. The Wilkinson Microwave Anisotropy Probe (WMAP) has mapped the microwave sky in five frequency bands for nine years since 2001, creating a full-sky CMB map with the unprecedented precision. The WMAP data have enabled us to obtain a wealth of cosmological information, such as the composition, age, geometry, and history of the Universe. Yet, can we go further and learn about the primordial universe, when it was much younger than 380,000 years old, perhaps as young as a tiny fraction of a second? If so, this gives us a hope to test competing theories about the origin of the Universe at ultra high energies. In this talk, we will review the physics of CMB and the WMAP mission, present the basic results from nine years of observations, and discuss their cosmological implications.
6th-Feb-2013: Old and New in Constructive Field Theory
Arthur Jaffe (Harvard)
Abstract: We describe the motivation and background for the theoretical understanding of relativistic field theory (cqft), and summarize major solved and unsolved problems. We highlight reflection positivity and explain some recent discoveries. These apply to symmetries in field theory and also give insight into certain spin chains.
13-Feb-2013: New Observations about Quantum Field Theory
Zohar Komargodski (Weizmann Institute, Israel)
Abstract: We review recent progress in understanding Quantum Field Theory. The new results connect three thorny and fundamental questions: The symmetries of second order phase transitions, monotonicity of the renormalization group flow, and the entanglement entropy of the vacuum. We give examples of various applications for theories ranging from boiling water to Quantum Chromodynamics.
20th-Feb-2013: A holographic view of the very early universe
Kostas Skenderis (Southampton)
Abstract: In this talk I will give an overview of holographic cosmology. I will first discuss standard inflation, show that it is holographic and discuss the new insights that come from this. I will then present new holographic models that describe a universe that that was non-geometric at early times and describe the phenomenology and the observational signatures of these models.
27-Feb-2013 Title TBC
Speaker TBC
6th-March-2013: Cancelled
13th-March-2013: The LHC update
Ben Gripaios (Cavendish Lab, Cambridge)
Abstract: I will describe some recent results from the LHC and the implications for physics Beyond the Standard Model
20th-March-2013: Exploring the infrared properties of gluons and ghosts
John Gracey (Liverpool)
Abstract: We discuss several different field theoretic approaches to explain recent lattice data of the infrared structure of the gluon and ghost propagators. These include effective massive gluons as well as the Gribov approach. Loop calculations using the Gribov-Zwanziger Lagrangian are presented
Michaelmas 2012
24-Oct-2012: Complementarity vs. Firewalls: Are there large quantum effects near black hole horizons?
Don Marolf (UC Santa Barbara)
Abstract: We argue that the following three statements cannot all be true: (i) Hawking radiation is in a pure state, (ii) the information carried by the radiation is emitted from the region near the horizon, with low energy effective field theory valid beyond some microscopic distance from the horizon, and (iii) the infalling observer encounters nothing unusual at the horizon. Perhaps the most conservative resolution is that the infalling observer burns up at the horizon. Alternatives would seem to require novel dynamics that nevertheless cause notable violations of semiclassical physics at macroscopic distances from the horizon.
26-Oct-2012: New Horizons in Black Hole Physics and Holography.
*NB: Friday 26th Oct in 2:30 pm in MR3*
Shamit Kachru (Stanford)
Abstract: tbc.
7-Nov-2012: Simulating black-hole spacetimes on supercomputers.
Ulrich Sperhake (DAMTP, Cambridge)
Abstract: This talk presents a review of numerical relativity, the generation of solutions to the Einstein field equations using numerical methods. After an overview of the numerical techniques, we will summarize results about black-hole systems in the context of astrophysics, gravitational wave physics and high-energy physics. We conclude with a summary of the main future directions of numerical relativity.
14-Nov-2012: Some Properties of String Theory Scattering Amplitudes
Michael Green (DAMTP, Cambridge)
Abstract: tbc
21-Nov-2012: New Superconformal Field Theories From Wrapped Branes.
Brian Wecht (Queen Mary, London)
Abstract: In string/M-theory, it is possible to engineer a wide variety of interesting supersymmetric conformal field theories (SCFTs) by wrapping branes on nontrivial manifolds. In this talk, I will describe a new infinite set of theories which come from M5-branes on Riemann surfaces. The corresponding supergravity solutions interpolate between and extend beyond a famous pair of solutions by Maldacena and Nuñez. Additionally, the dual SCFTs are "non-Lagrangian" theories, which have no weakly coupled UV descriptions, yet can (and will) be described explicitly.
28-Nov-2012: Quark flavour and lattice QCD: investigations into electroweak symmetry
breaking
Matt Wingate (DAMTP, Cambridge)
Abstract: This colloquium will review how theoretical calculations and experimental measurements of weak decays of hadrons are testing the Standard Model and constraining models which would supplant it. The role played by lattice QCD will be a focus of the talk, with an emphasis on the bigger picture rather than specific details.