Time-dependent orbifolds and string cosmology
نویسندگان
چکیده
منابع مشابه
Time–dependent Orbifolds and String Cosmology
In these lectures, we review the physics of time–dependent orbifolds of string theory, with particular attention to orbifolds of three–dimensional Minkowski space. We discuss the propagation of free particles in the orbifold geometries, together with their interactions. We address the issue of stability of these string vacua and the difficulties in defining a consistent perturbation theory, poi...
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We continue and extend our earlier investigation " Strings in a Time-Dependent Orbifold " (hep-th/0204168). We formulate conditions for an orbifold to be amenable to perturba-tive string analysis and classify the low dimensional orbifolds satisfying these conditions. We analyze the tree and torus amplitudes of some of these orbifolds. The tree amplitudes exhibit a new kind of infrared divergenc...
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In this note we observe that, contrary to the usual lore, string orbifolds do not describe strings on quotient spaces, but rather seem to describe strings on objects called quotient stacks, a result that follows from simply unraveling definitions, and is further justified by a number of results. Quotient stacks are very closely related to quotient spaces; for example, when the orbifold group ac...
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In this short review we outline some recent developments in understanding string orbifolds. In particular, we outline the recent observation that string orbifolds do not precisely describe string propagation on quotient spaces, but rather are literally sigma models on objects called quotient stacks, which are closely related to (but not quite the same as) quotient spaces. We show how this is an...
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In order to include nontrivial spatial topologies in the problem of quantum creation of a universe, it seems to be necessary to generalize the sum over compact, smooth 4-manifolds to a sum over finitevolume, compact 4-orbifolds. We consider in detail the case of a 4spherical orbifold with a cone-point singularity. This allows for the inclusion of a nontrivial topology in the semiclassical path ...
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ژورنال
عنوان ژورنال: Fortschritte der Physik
سال: 2004
ISSN: 0015-8208
DOI: 10.1002/prop.200310123