Intersecting D4-branes Model of Holographic QCD and Tachyon Condensation

We consider the intersecting D4-brane and anti-D4-brane model of holographic QCD, motivated by the model that has recently been suggested by Van Raamsdonk and Whyte. We analyze such D4-branes by the use of the action with a bi-fundamental ``tachyon'' field, so that we find the classical solutions describing the intersecting D4-branes and the U-shaped D4-branes. We show that the ``tachyon'' field in the bulk theory provides a current quark mass and a quark condensate to the dual gauge theory and that the lowest modes of mesons obtain mass via tachyon condensation. Then evaluating the properties of a pion, one can reproduce Gell-Mann-Oakes-Renner relation.Comment: 24 pages, 5 figures; v2: refs. added; v3: discussions on Chern-Simons terms are adde

Note on a non-critical holographic model with a magnetic field

We consider a noncritical holographic model constructed from an intersecting brane configuration D4/$\bar{\rm{D4}}$-D4 with an external magnetic field. We investigate the influences of this magnetic field on strongly coupled dynamics by the gauge/gravity correspondence.Comment: 18 pages, references added and typos revise

Multiple D4-D2-D0 on the Conifold and Wall-crossing with the Flop

We study the wall-crossing phenomena of D4-D2-D0 bound states with two units of D4-brane charge on the resolved conifold. We identify the walls of marginal stability and evaluate the discrete changes of the BPS indices by using the Kontsevich-Soibelman wall-crossing formula. In particular, we find that the field theories on D4-branes in two large radius limits are properly connected by the wall-crossings involving the flop transition of the conifold. We also find that in one of the large radius limits there are stable bound states of two D4-D2-D0 fragments.Comment: 24 pages, 4 figures; v2: typos corrected, minor changes, a reference adde

Quantum Polarization of D4-branes

The low energy effective field theory of type II D4-branes coupled to bulk supergravity fields is used to investigate {\it quantum} effects for D4-branes in the D0 supergravity background. Classically, the D4-branes are unaffected by this background. However, quantum (one-loop) effects are argued to lead to an induced density of D0-brane charge; e.g., D0-multipole moments on the D4-brane. The effect is divergent in field theory, but is expected to be cut-off naturally by stringy corrections.Comment: 15 pages, Some changes in the implications for string theory after discussions with Friedel Eppl

Quantised relativistic membranes and non-perturbative checks of gauge/gravity duality

We test the background geometry of the BFSS model using a D4-brane probe. This proves a sensitive test of the geometry and we find excellent agreement with the D4-brane predictions based on the solution of a membrane corresponding to the D4-brane propagating on this background.Comment: 7 pages, 2 figures, based on a talk, presented by D. O'C. at ISQS 25, 6-10 June, 2017, Prague, Czech Republic; to be published in Journal of Physics: Conference Serie

Exotic polarizations of D2 branes and oblique vacua of (S)YM2+1_{2+1}

We investigate the oblique vacua in the perturbed 2+1 dimensional gauge theory living on D2 branes. The string theory dual of these vacua is expected to correspond to polarizations of the D2 branes into NS5 branes with D4 brane charge. We perturb the gauge theory by adding fermions masses. In the nonsupersymmetric case, we also consider the effect of slight variations of the masses of the scalars. For certain ranges of scalar masses we find oblique vacua. We show that D4 charge is an essential ingredient in understanding D2 -> NS5 polarizations. We find that some of the polarization states which appear as metastable vacua when D4 charge is not considered are in fact unstable. They decay by acquiring D4 charge, tilting and shrinking to zero size.Comment: 15 pages, 3 figures, LaTe

Teleparallel loop quantum cosmology in a system of intersecting branes

Recently, some authors have removed the big bang singularity in teleparallel Loop Quantum Cosmology (LQC) and have shown that the universe may undergo a number of oscillations. We investigate the origin of this type of teleparallel theory in a system of intersecting branes in M-theory in which the angle between them changes with time. This system is constructed by two intersecting anti-D8-branes, one compacted D4-brane and the other a D3-brane. These branes are built by joining M0-branes which develop in decaying fundamental strings. The compacted D4-brane is located between two intersecting anti-D8 branes and glues to one of them. Our universe is located on the D3 brane which wraps the D4 brane from one end and sticks to one of the anti-D8 branes from another one. In this system, there are three types of fields, corresponding to compacted D4 branes, intersecting branes and D3-branes. These fields interact with each other and make the angle between branes oscillate. By decreasing this angle and approaching the intersecting anti-D8 branes towards each other, the D4 brane rolls, the D3 brane wraps around the D4 brane, and t he universe contracts. By separating the intersecting branes and increasing the angle, the D4 brane rolls in the opposite direction, the D3 brane separates from it and the expansion branch begins. Also, the interaction between branes in this system gives us the exact form of the relevant Lagrangian for teleparallel LQC.Comment: 11 page

Declaración ambiental ...

EMASTransport de mercaderíes per carreter

Membranes from Five-Branes and Fundamental Strings from Dp Branes

We argue that M2 brane is realized as a topological soliton on a coincident pair of M5 and anti-M5 branes, as the two five-branes annihilate each other. Topology and quantum numbers of this world-volume soliton are discussed in some detail, and its formation is explained qualitatively. It follows from a compactification that a D4-anti-D4 pair annihilate and produce type II fundamental strings. The phenomenon is best described as the confinement of a world-volume U(1) gauge field on D4-anti-D4, where the confined electric flux string is identified as the fundamental string. This generalizes to other D$p$-anti-D$p$ systems, and solves a puzzle recently pointed out by Witten.Comment: LaTeX, 12 pages (typos corrected and minor changes in the text