Triangle Seminars
Tuesday, 11 Nov 2014
String Compactifications, Dark Radiation and a 0.1-1 keV Cosmic Axion Background
Joseph Conlon
(Oxford U., Theor. Phys.)
Harmony of scattering amplitudes
Gabriele Travaglini
(QMUL)
Wednesday, 12 Nov 2014
The quantum theory of fluids
📍 London
Ben Gripaios
(Cambridge Cavendish)
Abstract:
I discuss the quantization of a perfect fluid. This differs from textbook QFT, because of the presence of vortex modes, which map to an infinite collection of quantum mechanical free particles rather than harmonic oscillators. As a result, there is no Fock space and no S-matrix. I argue that there exists, nevertheless, a consistent effective field theory description, valid at large distances and times.
I discuss the quantization of a perfect fluid. This differs from textbook QFT, because of the presence of vortex modes, which map to an infinite collection of quantum mechanical free particles rather than harmonic oscillators. As a result, there is no Fock space and no S-matrix. I argue that there exists, nevertheless, a consistent effective field theory description, valid at large distances and times.
Posted by: KCL
Galaxy Clusters as Tele-ALP-scopes
📍 London
Joe Conlon
(Oxford)
Abstract:
Galaxy clusters are the most efficient convertors of axion-like particles to photons in the universe.
I discuss the physics and phenomenology of ALPs, and describe their astrophysical implications, with particular reference to the
recently observed 3.5 keV X-ray line that is a candidate for a dark matter decay line.
Galaxy clusters are the most efficient convertors of axion-like particles to photons in the universe.
I discuss the physics and phenomenology of ALPs, and describe their astrophysical implications, with particular reference to the
recently observed 3.5 keV X-ray line that is a candidate for a dark matter decay line.
Posted by: KCL
Thursday, 13 Nov 2014
Holography, Probe Branes and Isoperimetric Inequalities
Frank Ferrari
(Brussels U.)
Abstract:
In many instances of holographic correspondences between a d dimensional boundary theory and a d+1 dimensional bulk, a simple argument in the boundary theory implies that there must exist a direct relation between the on-shell Euclidean gravitational bulk action and the on-shell Euclidean action of a (d-1)-brane probing the bulk geometry. This relation is crucial for the consistency of holography but puzzling from the bulk perspective. We provide a full bulk derivation in the case of pure gravity.
A central role is played by a non-trivial isoperimetric inequality that must be satisfied in a large class of Poincaré-Einstein spaces. Remarkably, this inequality follows from a theorem by John Lee.
In many instances of holographic correspondences between a d dimensional boundary theory and a d+1 dimensional bulk, a simple argument in the boundary theory implies that there must exist a direct relation between the on-shell Euclidean gravitational bulk action and the on-shell Euclidean action of a (d-1)-brane probing the bulk geometry. This relation is crucial for the consistency of holography but puzzling from the bulk perspective. We provide a full bulk derivation in the case of pure gravity.
A central role is played by a non-trivial isoperimetric inequality that must be satisfied in a large class of Poincaré-Einstein spaces. Remarkably, this inequality follows from a theorem by John Lee.
Posted by: QMW