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Selected topics in string field theory and physics of D-branes
Vošmera, Jakub ; Schnabl, Martin (advisor) ; Erler, Theodore (referee) ; Sachs, Ivo (referee)
We discuss certain aspects of string field theory and its applications in exploring the land- scape of classical string theory vacua. We start by giving a brief overview of various tree-level string field theories, as well as of some relevant mathematical background. As a byproduct of our general discussion of observables, we present a new gauge-invariant quantity for the A∞ formulation of open superstring field theory. Putting particular emphasis on perturba- tive methods, we proceed to review in detail the construction of tree-level effective actions governing the dynamics of a certain subset of degrees of freedom. In light of recent devel- opments, we also discuss efficient methods for evaluating certain vertices of zero-momentum effective actions for open superstring and heterotic string field theories in the presence of a global N = 2 worldsheet superconformal symmetry. We show how to apply this perturbative approach to study dynamics of the D(−1)/D3 system (both with and without a B-field), while also discussing a number of more complicated Dp-brane configurations. At generic points in their moduli spaces, such bound states of Dp-branes clearly cannot be described in terms of simple Dirichlet or Neumann boundary conditions. The rest of this thesis is therefore devoted to developing analytic...
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Časově závislé procesy v teorii strun
Jiroušek, Pavel ; Schnabl, Martin (advisor) ; Novotný, Jiří (referee)
String field theory is a second quantized approach to string theory able to describe off-shell processes like transition between vacua, so-called tachyon condensation, and its dynamics. In this work, we review the necessary tools and ingredients needed to formulate such theory for open bosonic string theory. Namely, we introduce elementary conformal field theory methods and some basics of perturbative string theory. We then recognize the kinetic term of string field action from on-shell condition of the perturbative string and axiomatically introduce an algebraic structure on its Hilbert space to construct interaction terms. We briefly discuss the connection of classical string field theory solutions with various string field backgrounds and present means of reconstructing the background from a given solution by calculating the boundary state. We show that such backgrounds act like a source of open string states. We conclude by calculation of such boundary state for a solution representing light-like tachyon rolling. Powered by TCPDF (www.tcpdf.org)
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Selected topics in string field theory and physics of D-branes
Vošmera, Jakub ; Schnabl, Martin (advisor) ; Erler, Theodore (referee) ; Sachs, Ivo (referee)
We discuss certain aspects of string field theory and its applications in exploring the land- scape of classical string theory vacua. We start by giving a brief overview of various tree-level string field theories, as well as of some relevant mathematical background. As a byproduct of our general discussion of observables, we present a new gauge-invariant quantity for the A∞ formulation of open superstring field theory. Putting particular emphasis on perturba- tive methods, we proceed to review in detail the construction of tree-level effective actions governing the dynamics of a certain subset of degrees of freedom. In light of recent devel- opments, we also discuss efficient methods for evaluating certain vertices of zero-momentum effective actions for open superstring and heterotic string field theories in the presence of a global N = 2 worldsheet superconformal symmetry. We show how to apply this perturbative approach to study dynamics of the D(−1)/D3 system (both with and without a B-field), while also discussing a number of more complicated Dp-brane configurations. At generic points in their moduli spaces, such bound states of Dp-branes clearly cannot be described in terms of simple Dirichlet or Neumann boundary conditions. The rest of this thesis is therefore devoted to developing analytic...
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Level Truncation Approach to Open String Field Theory
Kudrna, Matěj ; Schnabl, Martin (advisor) ; Erler, Theodore (referee) ; Kishimoto, Isao (referee)
Given a D-brane background in string theory (or equivalently boundary conditions in a two dimensional conformal field theory), classical solutions of open string field theory equations of motion are conjectured to describe new D-brane backgrounds (boundary conditions). In this thesis we study these solutions in the bosonic open string field theory using the level truncation approach, which is a numerical approach where the string field is truncated to a finite number of degrees of freedom. We start with a review of the theoretical background and numerical methods which are needed in the level truncation approach and then we discuss solutions in several different back- grounds. First we discuss universal solutions, which do not depend on the open string back- ground, then we analyze solutions of the free boson theory compactified on a circle or on a torus, then marginal solutions in three different approaches and finally solutions in theories which in- clude the A-series of Virasoro minimal models. In addition to known D-branes, we find so-called exotic solutions which potentially describe yet unknown boundary states. 1
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Časově závislé procesy v teorii strun
Jiroušek, Pavel ; Schnabl, Martin (advisor) ; Novotný, Jiří (referee)
String field theory is a second quantized approach to string theory able to describe off-shell processes like transition between vacua, so-called tachyon condensation, and its dynamics. In this work, we review the necessary tools and ingredients needed to formulate such theory for open bosonic string theory. Namely, we introduce elementary conformal field theory methods and some basics of perturbative string theory. We then recognize the kinetic term of string field action from on-shell condition of the perturbative string and axiomatically introduce an algebraic structure on its Hilbert space to construct interaction terms. We briefly discuss the connection of classical string field theory solutions with various string field backgrounds and present means of reconstructing the background from a given solution by calculating the boundary state. We show that such backgrounds act like a source of open string states. We conclude by calculation of such boundary state for a solution representing light-like tachyon rolling. Powered by TCPDF (www.tcpdf.org)
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