Triangle Seminars
Tuesday, 27 May 2014
(Non)-Integrability of Geodesics in D-brane Backgrounds
Oleg Lunin
(Unveristy of Albany)
Abstract:
Motivated by the search for new backgrounds with solvable string theories, the talk classifies the D-brane geometries leading to integrable geodesics. This analysis gives severe restrictions on the potential candidates for integrable string theories.
It is demonstrated that the Hamilton-Jacobi equation for massless geodesics can only separate in elliptic or spherical coordinates, all known integrable backgrounds are covered by this separation, and new examples are constructed. The Killing and Killing-Yano tensors associated with such separation and their transformations under string dualities are also discussed.
Motivated by the search for new backgrounds with solvable string theories, the talk classifies the D-brane geometries leading to integrable geodesics. This analysis gives severe restrictions on the potential candidates for integrable string theories.
It is demonstrated that the Hamilton-Jacobi equation for massless geodesics can only separate in elliptic or spherical coordinates, all known integrable backgrounds are covered by this separation, and new examples are constructed. The Killing and Killing-Yano tensors associated with such separation and their transformations under string dualities are also discussed.
Posted by: IC
Wednesday, 28 May 2014
Higher Spins in Hyperspace
📍 London
Dmitri Sorokin
(INFN Padova)
Abstract:
I will discuss basic features of a formulation of higher-spin field theory in which conventional space-time gets extended to a hyperspace with a number of extra dimensions that effectively describe the spin degrees of freedom of the fields in the ordinary space-time. In this formulation an infinite number of higher spin fields are packed into a single scalar and spinor field propagating in the hyperspace. The dynamics of higher spin fields is encoded in equations of motion of the scalar and spinor hyperfields. The hyperfield equatons on flat and AdS-like hyperspaces are related to each other by a generalized conformal transformation, which also relates two-, three- and four-point functions in the AdS-like hyperspace to the corresponding correlators in the flat hyperspace.
I will discuss basic features of a formulation of higher-spin field theory in which conventional space-time gets extended to a hyperspace with a number of extra dimensions that effectively describe the spin degrees of freedom of the fields in the ordinary space-time. In this formulation an infinite number of higher spin fields are packed into a single scalar and spinor field propagating in the hyperspace. The dynamics of higher spin fields is encoded in equations of motion of the scalar and spinor hyperfields. The hyperfield equatons on flat and AdS-like hyperspaces are related to each other by a generalized conformal transformation, which also relates two-, three- and four-point functions in the AdS-like hyperspace to the corresponding correlators in the flat hyperspace.
Posted by: KCL
Geometric Constraints in Heterotic/F-theory Duality
Lara Anderson
(Virginia Tech)
Abstract:
We systematically analyze a broad class of dual heterotic and F-theory models that give four-dimensional supergravity theories, and compare the geometric constraints on the two sides of the duality. In this talk I will show that F-theory gives new insight into the conditions under which heterotic vector bundles can be constructed. We show that in many cases the F-theory geometry imposes a constraint on the extent to which the gauge group can be enhanced, corresponding to limits on the way in which the heterotic bundle can decompose. We explicitly construct all dual F-theory/heterotic pairs in the class under consideration where the common twofold base surface is toric, and give both toric and non-toric examples of the general results. Finally, we provide evidence for important new aspects of G-flux in four-dimensional compactifications.
We systematically analyze a broad class of dual heterotic and F-theory models that give four-dimensional supergravity theories, and compare the geometric constraints on the two sides of the duality. In this talk I will show that F-theory gives new insight into the conditions under which heterotic vector bundles can be constructed. We show that in many cases the F-theory geometry imposes a constraint on the extent to which the gauge group can be enhanced, corresponding to limits on the way in which the heterotic bundle can decompose. We explicitly construct all dual F-theory/heterotic pairs in the class under consideration where the common twofold base surface is toric, and give both toric and non-toric examples of the general results. Finally, we provide evidence for important new aspects of G-flux in four-dimensional compactifications.
Posted by: IC
Thursday, 29 May 2014
Non-Associative Geometry, Non-Geometric String Backgrounds and Double Field Theory
Dieter Lust
(LMU)
Abstract:
In this talk we discuss the geometric and non-geometric faces of closed string vacua.
The associated closed string geometries are described by new non-commutative as well
as non-associative algebras, which can be characterized by certain 3-cocycles in Lie algebra cohomology.
We present an associated star-product algebra on functions in phase space.
We also discuss some aspects of uncertainty relations, as well as the question,
if the non-associative structures are visible in conformal field theory and in double field theory.
In this talk we discuss the geometric and non-geometric faces of closed string vacua.
The associated closed string geometries are described by new non-commutative as well
as non-associative algebras, which can be characterized by certain 3-cocycles in Lie algebra cohomology.
We present an associated star-product algebra on functions in phase space.
We also discuss some aspects of uncertainty relations, as well as the question,
if the non-associative structures are visible in conformal field theory and in double field theory.
Posted by: QMW