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Singular Fluxes in Ten and Eleven Dimensions: Sources, Singularities, Fluxes and Spam
Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Physics.
2014 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The energy content of our present universe is dominated by the dark-energy, or vacuum energy, which provides accelerated cosmic expansion. Dark energy has a possible effective explanation through a positive cosmological constant. The problem present in any fundamental theory is to explain the underlying dynamics of what gives rise to the cosmological constant.

In string theory there are several scenarios that could give insight into what is behind the positive cosmological constant. One such construction uses anti-branes to achieve a net positive energy density of the vacuum. Anti-branes refers in this case to branes placed in a background with oppositely charged flux. As backreaction and localisation procedures are considered for anti-brane constructions a certain kind of singularity arise. This new type of singularity is present in the surrounding flux, which is not directly sourced by the brane.

This thesis, and the works contained, considers several aspects of this type of singularity. The first such flux singularity were discovered for the anti-D3-branes, in which the approximations and assumptions of partial smearing and perturbative expansions are used. Included in this thesis are new anti-D6-brane solutions which are placed in oppositely charged flux. It is shown that after the anti-D6-branes are localised, they display the same type of singularity. The strength of this result lies in that it is possible to show the presence of the singularity beyond partial smearing and perturbative expansions. Similar to the anti-D6-brane solutions, new anti-M2-brane solutions are presented. These solutions are also argued to display the same type of singularity.

The investigation into the presence of the singularity is just the first step. The second step is to deduce whether this singularity is acceptable and can somehow be resolved. Included in this thesis are two works that considers exactly this. One way of interpreting the singularity is through the absence of a no-force condition between the brane and the surrounding flux. This interpretation leads to the conclusion that the singularity is present due to the use of static Ansätze in a system that is inherently time dependent. Through an adiabatic approach it is here argued that this interpretation leads to a new type of instability.

Another way of arguing for a possible resolution of this singularity is whether or not the singularity can be cloaked by an event horizon. This condition have been successful in other systems with singularities. It is argued in this thesis that it is not possible to hide the flux singularity behind a horizon. This leads to one out of two conclusions, either the condition is not a necessary one and the singularity can be resolved in a static manner, or the singularity does not have a resolution.

To put these works in context the current singularities from anti-branes program is briefly reviewed to give a full overview of the current situation of these investigations.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2014. , 82 p.
Series
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 1138
National Category
Other Physics Topics
Research subject
Theoretical Physics
Identifiers
URN: urn:nbn:se:uu:diva-221322ISBN: 978-91-554-8925-0 (print)OAI: oai:DiVA.org:uu-221322DiVA: diva2:709512
Public defence
2014-05-23, Å10132 Häggsalen, Ångströmlaboratoriet, Lägerhyddsvägen 1, Uppsala, 13:15 (English)
Opponent
Supervisors
Available from: 2014-04-29 Created: 2014-03-28 Last updated: 2014-06-30
List of papers
1. Smeared versus localised sources in flux compactifications
Open this publication in new window or tab >>Smeared versus localised sources in flux compactifications
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2010 (English)In: Journal of High Energy Physics (JHEP), ISSN 1126-6708, E-ISSN 1029-8479, no 12, 043- p.Article in journal (Refereed) Published
Abstract [en]

We investigate whether vacuum solutions in flux compactifications that are obtained with smeared sources (orientifolds or D-branes) still survive when the sources are localised. This seems to rely on whether the solutions are BPS or not. First we consider two sets of BPS solutions that both relate to the GKP solution through T-dualities: (p + 1)-dimensional solutions from spacetime-filling Op-planes with a conformally Ricci-flat internal space, and p-dimensional solutions with Op-planes that wrap a 1-cycle inside an everywhere negatively curved twisted torus. The relation between the solution with smeared orientifolds and the localised version is worked out in detail. We then demonstrate that a class of non-BPS AdS(4) solutions that exist for IASD fluxes and with smeared D3-branes (or analogously for ISD fluxes with anti-D3-branes) does not survive the localisation of the (anti) D3-branes. This casts doubts on the stringy consistency of non-BPS solutions that are obtained in the limit of smeared sources.

Keyword
Flux compactifications, Superstring Vacua, D-branes
National Category
Physical Sciences
Identifiers
urn:nbn:se:uu:diva-148934 (URN)10.1007/JHEP12(2010)043 (DOI)000285964400003 ()
Available from: 2011-03-15 Created: 2011-03-14 Last updated: 2017-12-11Bibliographically approved
2. The problematic backreaction of SUSY-breaking branes
Open this publication in new window or tab >>The problematic backreaction of SUSY-breaking branes
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2011 (English)In: Journal of High Energy Physics (JHEP), ISSN 1126-6708, E-ISSN 1029-8479, no 8, 105- p.Article in journal (Refereed) Published
Abstract [en]

In this paper we investigate the localisation of SUSY-breaking branes which, in the smeared approximation, support specific non-BPS vacua. We show, for a wide class of boundary conditions, that there is no flux vacuum when the branes are described by a genuine delta-function. Even more, we find that the smeared solution is the unique solution with a regular brane profile. Our setup consists of a non-BPS AdS(7) solution in massive IIA supergravity with smeared anti-D6-branes and fluxes T-dual to ISD fluxes in IIB supergravity.

Keyword
Flux compactifications, Superstring Vacua, D-branes, dS vacua in string theory
National Category
Natural Sciences
Identifiers
urn:nbn:se:uu:diva-161759 (URN)10.1007/JHEP08(2011)105 (DOI)000294901200056 ()
Available from: 2011-11-21 Created: 2011-11-17 Last updated: 2017-12-08Bibliographically approved
3. (Anti-)brane backreaction beyond perturbation theory
Open this publication in new window or tab >>(Anti-)brane backreaction beyond perturbation theory
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2012 (English)In: Journal of High Energy Physics (JHEP), ISSN 1126-6708, E-ISSN 1029-8479, Vol. 2012, no 2, 025- p.Article in journal (Refereed) Published
Abstract [en]

We improve on the understanding of the backreaction of anti-D6-branes in a flux background that is mutually BPS with D6-branes. This setup is analogous to the study of the backreaction of anti-D3-branes inserted in the KS throat, but does not require us to smear the anti-branes or do a perturbative analysis around the BPS background. We solve the full equations of motion near the anti-D6-branes and show that only two boundary conditions are consistent with the equations of motion. Upon invoking a topological argument we eliminate the boundary condition with regular H flux since it cannot lead to a solution that approaches the right kind of flux away from the anti-D6-branes. This leaves us with a boundary condition which has singular, but integrable, H flux energy density.

Keyword
Flux compactifications, dS vacua in string theory, Superstring Vacua, D-branes
National Category
Physical Sciences
Identifiers
urn:nbn:se:uu:diva-174603 (URN)10.1007/JHEP02(2012)025 (DOI)000301451200025 ()
Available from: 2012-05-24 Created: 2012-05-22 Last updated: 2017-12-07Bibliographically approved
4. Resolving anti-brane singularities through time-dependence
Open this publication in new window or tab >>Resolving anti-brane singularities through time-dependence
2013 (English)In: Journal of High Energy Physics (JHEP), ISSN 1126-6708, E-ISSN 1029-8479, no 2, 61- p.Article in journal (Refereed) Published
Abstract [en]

In this note we discuss a possible resolution of the flux singularities associated with the insertion of branes in backgrounds supported by fluxes that carry charges opposite to the branes. We present qualitative arguments that such a setup could be unstable both in the closed and open string sector. The singularities in the fluxes then get naturally resolved by taking the true solution to be a time-dependent process in which flux gets attracted towards the brane and subsequently annihilates.In this note we discuss a possible resolution of the flux singularities associated with the insertion of branes in backgrounds supported by fluxes that carry charges opposite to the branes. We present qualitative arguments that such a setup could be unstable both in the closed and open string sector. The singularities in the fluxes then get naturally resolved by taking the true solution to be a time-dependent process in which flux gets attracted towards the brane and subsequently annihilates.

Keyword
open string, membrane model, singularity, time dependence, flux, background, resolution
National Category
Subatomic Physics
Research subject
Theoretical Physics
Identifiers
urn:nbn:se:uu:diva-196357 (URN)10.1007/JHEP02(2013)061 (DOI)000316272900061 ()
Available from: 2013-03-08 Created: 2013-03-08 Last updated: 2017-12-06Bibliographically approved
5. Antibranes cannot become black
Open this publication in new window or tab >>Antibranes cannot become black
2013 (English)In: Physical Review D, ISSN 1550-7998, E-ISSN 1550-2368, Vol. 87, no 10, 104023- p.Article in journal (Refereed) Published
Abstract [en]

When D-branes are inserted in flux backgrounds of opposite charge, the resulting solution has a certain singularity in the fluxes. Recently it has been argued, using numerical solutions, that for anti-D3 branes in the Klebanov-Strassler background, these singularities cannot be cloaked by a horizon, which strongly suggests they are not physical. In this paper we provide an analytic proof that the singularity of all codimension-three antibrane solutions (such as anti-D6 branes in massive type IIA supergravity or anti-D3 branes smeared on the T-3 of R-3 x T-3 with fluxes) cannot be hidden behind a horizon and that the charge of black branes with smooth event horizons must have the same sign as the charge of the flux background. Our result indicates that infinitesimally blackening the antibranes immediately triggers brane-flux annihilation and strengthens the intuition that antibranes placed in flux with positive charge immediately annihilate against it.

National Category
Natural Sciences
Identifiers
urn:nbn:se:uu:diva-203294 (URN)10.1103/PhysRevD.87.104023 (DOI)000319284100005 ()
Available from: 2013-07-09 Created: 2013-07-08 Last updated: 2017-12-06Bibliographically approved
6. Note on M2-branes in opposite charge
Open this publication in new window or tab >>Note on M2-branes in opposite charge
2014 (English)In: Physical Review D, ISSN 1550-7998, E-ISSN 1550-2368, Vol. 89, no 6, 065004- p.Article in journal (Refereed) Published
Abstract [en]

The flux singularity that arises for branes in oppositely charged fluxes is a widely discussed issue and in this paper the problem is investigated further. New AdS world volume (anti-)M2-brane solutions are constructed using space-filling branes placed in fluxes of opposite dissolved charge that is opposite to that of the brane. A topological obstruction is derived to show how the singularity develops during localization of this solution and any similarly constructed solution. Furthermore it is shown that it is not possible to hide the singularity behind a horizon, which would have given credence to an M theory resolution.

National Category
Other Physics Topics
Identifiers
urn:nbn:se:uu:diva-220841 (URN)10.1103/PhysRevD.89.065004 (DOI)000333106900011 ()
Available from: 2014-03-21 Created: 2014-03-21 Last updated: 2017-12-05Bibliographically approved

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