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31
Recombination of intersecting Dbranes by local tachyon condensation
 JHEP 0306
"... We provide a simple low energy description of recombination of intersecting Dbranes using super YangMills theory. The recombination is realized by condensation of an offdiagonal tachyonic fluctuation localized at the intersecting point. The recombination process is equivalent to braneantibrane a ..."
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Cited by 36 (1 self)
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We provide a simple low energy description of recombination of intersecting Dbranes using super YangMills theory. The recombination is realized by condensation of an offdiagonal tachyonic fluctuation localized at the intersecting point. The recombination process is equivalent to braneantibrane annihilation, thus our result confirms Sen’s conjecture on tachyon condensation, although we work in the super YangMills theory whose energy scale is much lower than α ′. We also discuss the decay width of nonparallelly separated Dbranes.
Overproduction of cosmic superstrings
"... Abstract: We show that the naive application of the Kibble mechanism seriously underestimates the initial density of cosmic superstrings that can be formed during the annihilation of Dbranes in the early universe, as in models of braneantibrane inflation. We study the formation of defects in effec ..."
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Cited by 16 (2 self)
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Abstract: We show that the naive application of the Kibble mechanism seriously underestimates the initial density of cosmic superstrings that can be formed during the annihilation of Dbranes in the early universe, as in models of braneantibrane inflation. We study the formation of defects in effective field theories of the string theory tachyon both analytically, by solving the equation of motion of the tachyon field near the core of the defect, and numerically, by evolving the tachyon field on a lattice. We find that defects generically form with correlation lengths of order M −1 s rather than H−1. Hence, defects localized in extra dimensions may be formed at the end of inflation. This implies that braneantibrane inflation models where inflation is driven by branes which wrap the compact manifold may have problems
Adding a brane to the brane antibrane action
 in BSFT,” JHEP 0310, 002
, 2003
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Spectral flow and boundary string field theory for angled dbranes
 JHEP
"... Abstract: Dbranes intersecting at an arbitrary fixed angle generically constitute a configuration unstable towards recombination. The reconnection of the branes nucleates at the intersection point and involves a generalization of the process of brane decay of interest to nonperturbative string dyn ..."
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Cited by 10 (1 self)
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Abstract: Dbranes intersecting at an arbitrary fixed angle generically constitute a configuration unstable towards recombination. The reconnection of the branes nucleates at the intersection point and involves a generalization of the process of brane decay of interest to nonperturbative string dynamics as well as cosmology. After reviewing the string spectrum of systems of angled branes, we show that worldsheet twist superfields may be used in the context of Boundary Superstring Field Theory to describe the dynamics. Changing the angle between the branes is seen from the worldsheet as spectral flow with boundary insertions flowing from bosonic to fermionic operators. We calculate the complete tachyon potential and the low energy effective action as a function of angle and find an expression that interpolates between the braneantibrane and the DiracBornInfeld actions. The potential captures the mechanism of Dbrane recombination and provides for interesting new
SeibergWitten monopole equations on noncommutative R 4
 J. Math. Phys
"... It is well known that, due to vanishing theorems, there are no nontrivial finite action solutions to the Abelian SeibergWitten (SW) monopole equations on Euclidean fourdimensional space 4. We show that this is no longer true for the noncommutative version of these equations, i.e. on a noncommutati ..."
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Cited by 7 (0 self)
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It is well known that, due to vanishing theorems, there are no nontrivial finite action solutions to the Abelian SeibergWitten (SW) monopole equations on Euclidean fourdimensional space 4. We show that this is no longer true for the noncommutative version of these equations, i.e. on a noncommutative deformation 4 θ
Worldsheet Description of Tachyon Condensation in Open String Theory
, 2003
"... In this thesis we review the fundamental framework of boundary string field theory (BSFT) and apply it to the tachyon condensation on nonBPS systems in the superstring theory. The boundary string field theory can be regarded as a natural extension of the nonlinear sigma model. By using this theory ..."
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In this thesis we review the fundamental framework of boundary string field theory (BSFT) and apply it to the tachyon condensation on nonBPS systems in the superstring theory. The boundary string field theory can be regarded as a natural extension of the nonlinear sigma model. By using this theory we can describe the tachyon condensation exactly and also obtain the effective actions on nonBPS systems consisting of the DiracBornInfeld type action and the WessZumino type action. Especially the WessZumino action is written by superconnection and coincides with the mathematical argument by Ktheory. Moreover we also discuss the tachyon condensation keeping the conformal invariance (onshell). The exact argument by using the boundary state formalism gives a good support to the conjecture of the tachyon condensation and it is also
A Quantum Analysis on Recombination Process and Dynamics of Dpbranes at one angle”, [arXiv:hepth/0304237
"... A quantummechanical technique is used within the framework of U(2) superYangMills theory to describe recombination processes of two Dpbranes at one angle; how tachyons condense starting from certain initial conditions, and how (curved) shapes of the recombined branes develop. Two types of initi ..."
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A quantummechanical technique is used within the framework of U(2) superYangMills theory to describe recombination processes of two Dpbranes at one angle; how tachyons condense starting from certain initial conditions, and how (curved) shapes of the recombined branes develop. Two types of initial conditions are considered: branes at one angle made put from parallel ones at the initial moment, and the ones approaching each other slowly, which is important as a candidate of inflation mechanism. An interesting behavior of the branes ’ shapes is shown to appear, each of which comes to have multiple (three) extremes due to localization of tachyon condensation but not the effect of compact spaces. Blowingup behavior of paircreations of stings connecting the recombined branes are also observed. The above two behaviors means that the branes in the process have a relatively stronger tendency than naively expected, to dissipate their energy into radiations of gravitational and (RR and NSNS) gauge fields. This implies that the tachyonic preheating era might be rather short if this setup is applied to the braneworld scenarios.
BPS limit of multi D and DFstrings in boundary string field theory,” arXiv:hepth/0703144
"... A BPS limit is systematically derived for straight multi D and DFstrings from the D3 ¯ D3 system in the context of boundary superstring field theory. The BPS limit is obtained in the limit of thin D(F)strings, where the Bogomolnyi equation supports singular static multiD(F)string solutions. Fo ..."
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Cited by 1 (1 self)
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A BPS limit is systematically derived for straight multi D and DFstrings from the D3 ¯ D3 system in the context of boundary superstring field theory. The BPS limit is obtained in the limit of thin D(F)strings, where the Bogomolnyi equation supports singular static multiD(F)string solutions. For the BPS multistring configurations with arbitrary separations, BPS sum rule is fulfilled under a Gaussian type tachyon potential and reproduces exactly the descent relation. For the DFstrings ((p,q)strings), the distribution of fundamental string charge density coincides with its energy density and the Hamiltonian density takes the BPS formula of squareroot form. 1 1
Cosmology of the Tachyon in Brane Inflation
, 2006
"... Abstract: In certain implementations of the brane inflationary paradigm, the exit from inflation occurs when the branes annihilate through tachyon condensation. We investigate various cosmological effects produced by this tachyonic era. We find that only a very small region of the parameter space (c ..."
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Abstract: In certain implementations of the brane inflationary paradigm, the exit from inflation occurs when the branes annihilate through tachyon condensation. We investigate various cosmological effects produced by this tachyonic era. We find that only a very small region of the parameter space (corresponding to slowroll with tiny inflaton mass) allows for the tachyon to contribute some efolds to inflation. In addition, nonadiabatic density perturbations are generated at the end of inflation. When the brane is moving relativistically this contribution can be of the same order as fluctuations produced 55 efolds before the end of inflation. The additional contribution is very nearly scaleinvariant and enhances the tensor/scalar ratio. Additional nongaussianities will also be generated, sharpening current constraints on DBItype
COSMIC STRINGS IN BRANE INFLATION AND SUPERSTRING THEORY
, 2004
"... Observable predictions of Superstring theories are rare and important. Recent theoretical advances and upcoming experimental measurements of cosmological physics make the testing of generic predictions of string theories possible. Brane antibrane models of inflation within superstring theory are pr ..."
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Observable predictions of Superstring theories are rare and important. Recent theoretical advances and upcoming experimental measurements of cosmological physics make the testing of generic predictions of string theories possible. Brane antibrane models of inflation within superstring theory are promising as string theory descriptions of the physics of the early universe, and while varied in their construction, they can have the generic and observable consequence that cosmic strings will be abundant in the early universe. This leads to possible detectable effects in the cosmic microwave background, gravitational wave physics, gravitational lensing and pulsar timing. The string theory physics involved in the production of these defects at the phase transition at the end of inflation is reviewed herein. Detailed calculations of cosmic string interactions within string theory are also presented, in order to distinguish these cosmic strings from those in more conventional theories. It is found that cosmic strings are stable and have tensions compatible with current upper bounds and which are detectable in upcoming experiments. Interaction probabilities of these strings are found to be very different from conventional strings, providing the possibility of experimental tests of string theory.