19 research outputs found
The Backreaction of Anti-M2 Branes on a Warped Stenzel Space
We find the superpotential governing the supersymmetric warped M-theory
solution with a transverse Stenzel space found by Cvetic, Gibbons, Lu and Pope
in hep-th/0012011, and use this superpotential to extract and solve the twelve
coupled equations underlying the first-order backreacted solution of a stack of
anti-M2 branes in this space. These anti-M2 branes were analyzed recently in a
probe approximation by Klebanov and Pufu, who conjectured that they should be
dual to a metastable vacuum of a supersymmetric 2+1 dimensional theory. We find
that the would-be supergravity dual to such a metastable vacuum must have an
infrared singularity and discuss whether this singularity is acceptable or not.
Given that a similar singularity appears when placing anti-D3 branes in the
Klebanov-Strassler solution, our work strengthens the possibility that
anti-branes in warped throats do not give rise to metastable vacua.Comment: 28 pages, LaTe
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Robust lineage reconstruction from high-dimensional single-cell data
Single-cell gene expression data provide invaluable resources for systematic characterization of cellular hierarchy in multi-cellular organisms. However, cell lineage reconstruction is still often associated with significant uncertainty due to technological constraints. Such uncertainties have not been taken into account in current methods. We present ECLAIR (Ensemble Cell Lineage Analysis with Improved Robustness), a novel computational method for the statistical inference of cell lineage relationships from single-cell gene expression data. ECLAIR uses an ensemble approach to improve the robustness of lineage predictions, and provides a quantitative estimate of the uncertainty of lineage branchings. We show that the application of ECLAIR to published datasets successfully reconstructs known lineage relationships and significantly improves the robustness of predictions. ECLAIR is a powerful bioinformatics tool for single-cell data analysis. It can be used for robust lineage reconstruction with quantitative estimate of prediction accuracy
Assessing a candidate IIA dual to metastable supersymmetry-breaking
We analyze the space of linearized non-supersymmetric deformations around a
IIA solution found by Cvetic, Gibbons, Lu and Pope (CGLP) in hep-th/0101096. We
impose boundary conditions aimed at singling out among those perturbations
those describing the backreaction of anti-D2 branes on the CGLP background. The
corresponding supergravity solution is a would-be dual to a metastable
supersymmetry-breaking state. However, it turns out that this candidate bulk
solution is inevitably riddled with IR divergences of its flux densities and
action, whose physical meaning and implications for models of string cosmology
call for further investigation.Comment: 33 pages. v2: reference added, clarifications in the introductio
On Metastable Vacua and the Warped Deformed Conifold: Analytic Results
Continuing the programme of constructing the backreacted solution
corresponding to smeared anti-D3 branes in the warped deformed conifold, we
solve analytically the equations governing the space of first-order
deformations around this solution. We express the results in terms of at most
three nested integrals. These are the simplest expressions for the space of
SU(2) \times SU(2) \times \ZZ_2-invariant deformations, in which the putative
solution for smeared anti-D3 branes must live. We also explain why one cannot
claim to identify this solution without fully relating the coefficients of the
infrared and ultraviolet expansions of the deformation modes. The analytic
solution we find is the first step in this direction.Comment: 16 page
On The Inflaton Potential From Antibranes in Warped Throats
We compute the force between a stack of smeared antibranes at the bottom of a
warped throat and a stack of smeared branes at some distance up the throat,
both for anti-D3 branes and for anti-M2 branes. We perform this calculation in
two ways: first, by treating the antibranes as probes in the background sourced
by the branes and second, by treating the branes as probes in the candidate
background sourced by the antibranes. These two very different calculations
yield exactly the same expression for the force, for all values of the
brane-antibrane separation. This indicates that the force between a brane and
an antibrane is not screened in backgrounds where there is positive charge
dissolved in flux, and gives a way to precisely compute the inflaton potential
in certain string cosmology scenarios.Comment: 9 page
The backreaction of anti-D3 branes on the Klebanov-Strassler geometry
We present the full numerical solution for the 15-dimensional space of
linearized deformations of the Klebanov-Strassler background which preserve the
SU(2) X SU(2) X Z_2 symmetries. We identify within this space the solution
corresponding to anti-D3 branes, (modulo the presence of a certain subleading
singularity in the infrared). All the 15 integration constants of this solution
are fixed in terms of the number of anti-D3 branes, and the solution differs in
the UV from the supersymmetric solution into which it is supposed to decay by a
mode corresponding to a rescaling of the field theory coordinates. Deciding
whether two solutions that differ in the UV by a rescaling mode are dual to the
same theory is involved even for supersymmetric Klebanov-Strassler solutions,
and we explain in detail some of the subtleties associated to this.Comment: 41 pages, 5 figures, LaTe
Finite-Temperature Fractional D2-Branes and the Deconfinement Transition in 2+1 Dimensions
The supergravity dual to N regular and M fractional D2-branes on the cone
over \mathbb{CP}^3 has a naked singularity in the infrared. One can resolve
this singularity and obtain a regular fractional D2-brane solution dual to a
confining 2+1 dimensional N = 1 supersymmetric field theory. The confining
vacuum of this theory is described by the solution of Cvetic, Gibbons, Lu and
Pope. In this paper, we explore the alternative possibility for resolving the
singularity - the creation of a regular horizon. The black-hole solution we
find corresponds to the deconfined phase of this dual gauge theory in three
dimensions. This solution is derived in perturbation theory in the number of
fractional branes. We argue that there is a first-order deconfinement
transition. Connections to Chern--Simons matter theories, the ABJM proposal and
fractional M2-branes are presented.Comment: v3: analytic solutions are expose