N3N^3 entropy of M5 branes from dielectric effect

We observe that the $N^3$ entropy behavior of near-extermal M5 branes can be reproduced from SYM side with the role of Myers' terms. We start by generalizing the Klebanov-Tseytlin (KT) supergravity solution that displays the $N^3$ entropy behavior. The new feature of the general solution is visibility of the "internal" degrees of the M5 branes, i.e., the M0 branes and the M2 branes. With the rationale provided by the supergravity analysis, we consider a D0 brane quantum mechanical setup with Myers' terms. Using localization technique, we show that the leading $N^3$ behavior of the free energy comes from the "classical contribution" with the rest sub-leading.Comment: latex, 21 pages, missing figure adde

New Examples of Flux Vacua

Type IIB toroidal orientifolds are among the earliest examples of flux vacua. By applying T-duality, we construct the first examples of massive IIA flux vacua with Minkowski space-times, along with new examples of type IIA flux vacua. The backgrounds are surprisingly simple with no four-form flux at all. They serve as illustrations of the ingredients needed to build type IIA and massive IIA solutions with scale separation. To check that these backgrounds are actually solutions, we formulate the complete set of type II supergravity equations of motion in a very useful form that treats the R-R fields democratically.Comment: 38 pages, LaTeX; references updated; additional minor comments added; published versio

Revisiting the S-matrix approach to the open superstring low energy effective lagrangian

The conventional S-matrix approach to the (tree level) open string low energy effective lagrangian assumes that, in order to obtain all its bosonic ${\alpha'}^N$ order terms, it is necessary to know the open string (tree level) $(N+2)$-point amplitude of massless bosons, at least expanded at that order in $\alpha'$. In this work we clarify that the previous claim is indeed valid for the bosonic open string, but for the supersymmetric one the situation is much more better than that: there are constraints in the kinematical bosonic terms of the amplitude (probably due to Spacetime Supersymmetry) such that a much lower open superstring $n$-point amplitude is needed to find all the ${\alpha'}^N$ order terms. In this `revisited' S-matrix approach we have checked that, at least up to ${\alpha'}^4$ order, using these kinematical constraints and only the known open superstring 4-point amplitude, it is possible to determine all the bosonic terms of the low energy effective lagrangian. The sort of results that we obtain seem to agree completely with the ones achieved by the method of BPS configurations, proposed about ten years ago. By means of the KLT relations, our results can be mapped to the NS-NS sector of the low energy effective lagrangian of the type II string theories implying that there one can also find kinematical constraints in the $N$-point amplitudes and that important informations can be inferred, at least up to ${\alpha'}^4$ order, by only using the (tree level) 4-point amplitude.Comment: 34 pages, 3 figure, Submitted on Aug 4, 2012, Published on Oct 15, 201

Critical Collapse in the Axion-Dilaton System in Diverse Dimensions

We study the gravitational collapse of the axion-dilaton system suggested by type IIB string theory in dimensions ranging from four to ten. We extend previous analysis concerning the role played by the global SL(2,R) symmetry and we evaluate the Choptuik exponents in the elliptic case.Comment: LaTeX, 10 pages, no figure

M-theory and Type IIA Flux Compactifications

We consider compactifications of M-theory and type IIA string theory to four dimensions. For Minkowski space-time, a supergravity no-go theorem forbids flux supported in the internal space. We show how to evade this no-go theorem by exhibiting new sources of brane charge: in string theory, the basic physical phenomenon is the generation of new brane charges from D-branes in transverse fluxes. In M-theory, there is a new source of M5-brane charge from novel higher derivative couplings that involve fluxes as well as curvatures. We present some explicit orientifold examples with both N=1 and N=2 space-time supersymmetry. Finally, we explain the status of massive type IIA flux compactifications.Comment: 36 pages, LaTeX; references adde

On-shell Recursion in String Theory

We prove that all open string theory disc amplitudes in a flat background obey Britto-Cachazo-Feng-Witten (BCFW) on-shell recursion relations, up to a possible reality condition on a kinematic invariant. Arguments that the same holds for tree level closed string amplitudes are given as well. Non-adjacent BCFW-shifts are related to adjacent shifts through monodromy relations for which we provide a novel CFT based derivation. All possible recursion relations are related by old-fashioned string duality. The field theory limit of the analysis for amplitudes involving gluons is explicitly shown to be smooth for both the bosonic string as well as the superstring. In addition to a proof a less rigorous but more powerful argument based on the underlying CFT is presented which suggests that the technique may extend to a much more general setting in string theory. This is illustrated by a discussion of the open string in a constant B-field background and the closed string on the level of the sphere.Comment: 36 + 9 pages text, one figure, v3: added discussion on relation to old-fashioned factorization, typos corrected, published versio