Quantum Field Theory Seminar
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Tue, 04/05/2010 12:00 |
Chris Heunen (Comlab) |
Quantum Field Theory Seminar  |
L3 |
| Topology can be generalised in at least two directions: pointless topology, leading ultimately to topos theory, or noncommutative geometry. The former has the advantage that it also carries a logical structure; the latter captures quantum settings, of which the logic is not well understood generally. We discuss a construction making a generalised space in the latter sense into a generalised space in the former sense, i.e. making a noncommutative C*-algebra into a locale. This construction is interesting from a logical point of view, and leads to an adjunction for noncommutative C*-algebras that extends Gelfand duality. | |||
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Tue, 11/05/2010 12:00 |
Katherine Mack (Cambridge) |
Quantum Field Theory Seminar |
L3 |
| The QCD axion is the leading solution to the strong-CP problem, a dark matter candidate, and a possible result of string theory compactifications. However, for axions produced before inflation, high symmetry-breaking scales (such as those favored in string-theoretic axion models) are ruled out by cosmological constraints unless both the axion misalignment angle and the inflationary Hubble scale are extremely fine-tuned. I will discuss how attempting to accommodate a high-scale axion in inflationary cosmology leads to a fine-tuning problem that is worse than the strong-CP problem the axion was originally invented to solve, and how this problem is exacerbated when additional axion-like fields from string theory are taken into account. This problem remains unresolved by anthropic selection arguments commonly applied to the high-scale axion scenario. | |||
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Tue, 18/05/2010 12:00 |
Lars Tuset (Hogskolen i Oslo) |
Quantum Field Theory Seminar |
L3 |
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Tue, 25/05/2010 12:00 |
Tsou Sheung Tsun |
Quantum Field Theory Seminar |
L3 |
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Tue, 01/06/2010 12:00 |
Michael Baker |
Quantum Field Theory Seminar |
L3 |
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Tue, 15/06/2010 12:00 |
Varghese Mathai (Adelaide) |
Quantum Field Theory Seminar |
L3 |
| I will define and discuss the properties of the analytic torsion of twisted cohomology and briefly of Z_2-graded elliptic complexes in general, as an element in the graded determinant line of the cohomology of the complex, generalizing most of the variants of Ray- Singer analytic torsion in the literature. IThe definition uses pseudo- differential operators and residue traces. Time permitting, I will also give a couple of applications of this generalized torsion to mathematical physics. This is joint work with Siye Wu. | |||
