Found 10 result(s)
Regular Seminar Chris Hull (IC)
at: 10:30 room Online  abstract: Live Tutorial. This lecture provides an introduction to duality symmetries in string theory. String theory was originally formulated as a theory of strings propagating in space time with interactions governed by the string coupling constant g. Scattering amplitudes for small g were constructed as a perturbation theory in g. Five consistent supersymmetric string theories were found, all in 10 spacetime dimensions with five distinct perturbation theories. This left many questions unanswered, such as why there should be five apparently consistent quantum theories of gravity and what happens to these theories as the coupling constant is increased. Such questions were answered by the developments in the mid1990s that have been called the 2nd superstring revolution. Dualities proved to be the key to uncovering the nonperturbative structure of superstring theory and in particular its strong coupling behaviour. When g is large, one can analyse the theory as a perturbation theory in 1/g and seek a "dual theory" with coupling constant g' whose perturbative expansion in g' matches the behaviour of the original theory as a perturbation theory in 1/g on identifying g'=1/g. In some cases the dual theory is again a string theory, which might be a different string theory from the original one. In other cases, the dual theory isn't a string theory at all, but a new theory  Mtheory. This leads to a picture in which all 5 string theories are related by dualities and so are all seen as different limits of Mtheory. Duality transformation provide new symmetries of string/M theory and T,S and Udualities. Remarkably, the theory that emerges is no longer just a theory of strings but one which includes both strings and branes which are higher dimensional extended objects. As the branes are related to strings by duality symmetries, they should be regarded as being on the same footing as the strings and of equal importance. The lecture explores all of these issues and discusses some examples. Please register at https://lonti.weebly.com/registration.html to receive joining instructions for this live session which will be held via Zoom. 
Regular Seminar Chris Hull (IC)
at: 10:00 room Youtube  abstract: This lecture provides an introduction to duality symmetries in string theory. String theory was originally formulated as a theory of strings propagating in space time with interactions governed by the string coupling constant g. Scattering amplitudes for small g were constructed as a perturbation theory in g. Five consistent supersymmetric string theories were found, all in 10 spacetime dimensions with five distinct perturbation theories. This left many questions unanswered, such as why there should be five apparently consistent quantum theories of gravity and what happens to these theories as the coupling constant is increased. Such questions were answered by the developments in the mid1990s that have been called the 2nd superstring revolution. Dualities proved to be the key to uncovering the nonperturbative structure of superstring theory and in particular its strong coupling behaviour. When g is large, one can analyse the theory as a perturbation theory in 1/g and seek a "dual theory" with coupling constant g' whose perturbative expansion in g' matches the behaviour of the original theory as a perturbation theory in 1/g on identifying g'=1/g. In some cases the dual theory is again a string theory, which might be a different string theory from the original one. In other cases, the dual theory isn't a string theory at all, but a new theory  Mtheory. This leads to a picture in which all 5 string theories are related by dualities and so are all seen as different limits of Mtheory. Duality transformation provide new symmetries of string/M theory and T,S and Udualities. Remarkably, the theory that emerges is no longer just a theory of strings but one which includes both strings and branes which are higher dimensional extended objects. As the branes are related to strings by duality symmetries, they should be regarded as being on the same footing as the strings and of equal importance. The lecture explores all of these issues and discusses some examples. Please register at https://lonti.weebly.com/registration.html to receive joining instructions for this live session which will be held via Zoom. The lecture is available here: https://youtube.com/playlist?list=PLlva4MroGKHsP0WGLxRk9ZWsmAHUklMT 
Regular Seminar Chris Hull (Imperial College)
at: 14:00 room G.O. Jones 610  abstract: One of the ways in which string theory differs from conventional field theories is that it has duality symmetries, which allow the construction of socalled nongeometric backgrounds, such as Tfolds which have Tduality transition functions. String theory on a torus requires the introduction of dual coordinates conjugate to string winding number. This leads to physics and novel geometry in a doubled space, with nontrivial dynamics in the full doubled spacetime. The geometry and physics of doubled spacetime will be developed and discussed. 
Regular Seminar Christopher Hull (Imperial College London)
at: 13:15 room 423  abstract:

String Theory & Geometry Seminar Chris Hull (Imperial)
at: 14:00 room Blackett 630  abstract:

String Theory & Geometry Seminar Chris Hull (IC)
at: 13:00 room H408  abstract: String Theory and Geometry Seminar 
String Theory & Geometry Seminar Chris Hull (Imperial College)
at: 13:00 room 408 Huxley building  abstract:

String Theory & Geometry Seminar Chris Hull (Imperial College)
at: 13:00 room CLORE LECTURE THEATRE, Huxley building  abstract:

Regular Seminar Chris Hull (IC)
at: 14:00 room 112  abstract:

Regular Seminar Christopher Hull (Imperial College London)
at: 17:00 room H503  abstract:
