Development of lightweight, fire-retardant, low-smoke, high-strength, thermally stable aircraft floor paneling

Extensive fire resistance and mechanical property tests were conducted on sandwich configurations composed of resin-fiberglass laminates bonded with adhesive to Nomex honeycomb and foam core. The test results were used to select a combination of materials that would improve the fire safety of the airplane without sacrificing mechanical performance of the aircraft floor panels. A test panel is being service evaluated in a commercial aircraft

Scalar potential from de Sitter brane in 5D and effective cosmological constant

We derive the scalar potential in zero mode effective action arising from a de Sitter brane embedded in five dimensions with bulk cosmological constant $\Lambda$. The scalar potential for a scalar field canonically normalized is given by the sum of exponential potentials. In the case of $\Lambda=0$ and $\Lambda>0$, we point out that the scalar potential has an unstable local maximum at the origin and exponentially vanishes for large positive scalar field. In the case of $\Lambda<0$, the scalar potential has an unstable local maximum at the origin and a stable local minimum, it is shown that the positive cosmological constant in brane is reduced by negative potential energy of scalar at minimum.Comment: 14 pages, 5 figures, add the section of cosmological implication

On the sign of the dilaton in the soft wall models

We elaborate on the existence of a spurious massless scalar mode in the vector channel of soft-wall models with incorrectly chosen sign of the exponential profile defining the wall. We re-iterate the point made in our earlier paper and demonstrate that the presence of the mode is robust, depending only on the infra-red asymptotics of the wall. We also re-emphasize that desired confinement properties can be realized with the correct sign choice.Comment: 10 page

Quantum phase transition in a Dp-Dq system

Using the top-down approach, we study intersecting Dp-Dq brane configuration in string theory and find examples, where there can be a quantum phase transition at zero temperature induced by the violation of the Breitenlohner-Freedman (BF) bound at IR, which is done essentially by a combination of charge density and magnetic fields. In particular, there exists a Berezinskii-Kosterlitz-Thouless (BKT) type of transition for D3-D5 and D5-D5 systems. The study of the BKT type of transition is initiated by Jensen et al. [Phys. Rev. Lett. {\bf 105}, 041601 (2010) ] for a D3-D5 system with nonzero charge density and a magnetic field. Here, we show that one can have the BKT transition for a D3-D5 system even in the absence of charge density but requires multiple magnetic fields. In this case the field theory lives in 2+1 dimensions, whereas for the D5-D5 type, the transition requires the presence of both the charge density and magnetic fields and the dual field theory lives on a 3+1 dimensional spacetime. We also study the D3-D7 system but it does not show the BKT type of transition.Comment: 1+37 pages; v2 Chern-Simon term for D3-D5 case presented, typos fixed and a reference added; v3 Minor corrections, Chern-Simon term for D2-D4, D4-D6, and D5-D7 added, also an appendix and few references added; v4 Journal versio

Construction of bosonic string theory on infinitely curved Anti-de Sitter space

Free scalar field theory in the sector with a large number of particles can be interpreted as bosonic string theory on anti-de Sitter space of vanishing radius. Different ways of writing the field theory Hamiltonian translate to different ways of reparametrizing the world-sheet sigma coordinate. Adding a mass term in the field theory corresponds to cutting off the warped AdS direction, with cut-off inversely proportional to the mass. The string theory has neither tachyon, nor critical dimension.Comment: 18 pages, latex, using revte

V2:Performance of the solid deuterium ultra-cold neutron source at the pulsed reactor TRIGA Mainz

The performance of the solid deuterium ultra-cold neutron source at the pulsed reactor TRIGA Mainz with a maximum peak energy of 10 MJ is described. The solid deuterium converter with a volume of V=160 cm3 (8 mol), which is exposed to a thermal neutron fluence of 4.5x10^13 n/cm2, delivers up to 550 000 UCN per pulse outside of the biological shield at the experimental area. UCN densities of ~ 10/cm3 are obtained in stainless steel bottles of V ~ 10 L resulting in a storage efficiency of ~20%. The measured UCN yields compare well with the predictions from a Monte Carlo simulation developed to model the source and to optimize its performance for the upcoming upgrade of the TRIGA Mainz into a user facility for UCN physics.Comment: 23 pages, 8 figure

Intersecting D3-branes and Holography

We study a defect conformal field theory describing D3-branes intersecting over two space-time dimensions. This theory admits an exact Lagrangian description which includes both two- and four-dimensional degrees of freedom, has (4,4) supersymmetry and is invariant under global conformal transformations. Both two- and four-dimensional contributions to the action are conveniently obtained in a two-dimensional (2,2) superspace. In a suitable limit, the theory has a dual description in terms of a probe D3-brane wrapping an AdS_3 x S^1 slice of AdS_5 x S^5. We consider the AdS/CFT dictionary for this set-up. In particular we find classical probe fluctuations corresponding to the holomorphic curve wy=c\alpha^{\prime}. These fluctuations are dual to defect fields containing massless two-dimensional scalars which parameterize the classical Higgs branch, but do not correspond to states in the Hilbert space of the CFT. We also identify probe fluctuations which are dual to BPS superconformal primary operators and to their descendants. A non-renormalization theorem is conjectured for the correlators of these operators, and verified to order g^2.Comment: 46 pages, 5 figures, Latex, minor corrections to section 4.2, version published in Phys. Rev.

Open string modes at brane intersections

We study systematically the open string modes of a general class of BPS intersections of branes. We work in the approximation in which one of the branes is considered as a probe embedded in the near-horizon geometry generated by the other type of branes. We mostly concentrate on the D3-D5 and D3-D3 intersections, which are dual to defect theories with a massive hypermultiplet confined to the defect. In these cases we are able to obtain analytical expressions for the fluctuation modes of the probe and to compute the corresponding mass spectra of the dual operators in closed form. Other BPS intersections are also studied and their fluctuation modes and spectra are found numerically.Comment: 58 pages, 3 figures, LaTeX;v2: typos correcte

Sum rules, plasma frequencies and Hall phenomenology in holographic plasmas

We study the AC optical and hall conductivities of Dp/Dq-branes intersections in the probe approximation and use sum-rules to study various associated transport coefficients. We determine that the presence of massive fundamental matter, as compared to massless fundamental matter described holographically by a theory with no dimensional defects, reduces the plasma frequency. We further show that this is not the case when the brane intersections include defects. We discuss in detail how to implement correctly the regularization of retarded Green's functions so that the dispersion relations are satisfied and the low energy behaviour of the system is physically realistic.Comment: 25 pages, 5 figures. v2.minor changes, published versio

Higgs Phenomenon for 4-D Gravity in Anti de Sitter Space

We show that standard Einstein gravity coupled to a free conformal field theory (CFT) in Anti de Sitter space can undergo a Higgs phenomenon whereby the graviton acquires a nonzero mass (and three extra polarizations). We show that the essential ingredients of this mechanism are the discreteness of the energy spectrum in AdS space, and unusual boundary conditions on the elementary fields of the CFT. These boundary conditions can be interpreted as implying the existence of a 3-d defect CFT living at the boundary of the AdS space. Our free-field computation sheds light on the essential, model-independent features of AdS that give rise to massive gravity.Comment: 17 page