We obtain static self-gravitating solitonic 3-brane solutions in the Einstein-Skyrme model in 7D. These solitons correspond to a smooth version of the previously discussed cosmic p-brane solutions. We show how the energy-momentum tensor of the Skyrme field is able to smooth out the singularities found in the thin wall approximation and falls fast enough with the distance from the core of the object so that it asymptotically approaches the flat cosmic p-brane metric.

We investigate the mass-radius relation of neutron star (NS) with hyperons inside its core by using the Eddington-inspired Born-Infeld (EiBI) theory of gravity. The equation of state of the star is calculated by using the relativistic mean field model under which the standard SU(6) prescription and hyperons potential depths are used to determine the hyperon coupling constants. We found that, for 4×10 6 m 2 κ 6×10 6 m 2 , the corresponding NS mass and radius predicted by the EiBI theory of gravity is compatible with observational constraints of maximum NS mass and radius. The corresponding κ value is also compatible with the κ range predicted by the astrophysical-cosmological constraints. We also found that the parameter κ could control the size and the compactness of a neutron star.

We review the Bogomol'nyi equations and investigate an alternative route in obtaining it. It can be shown that the known Bogomol'nyi-Prasad-Sommerfield equations can be derived directly from the corresponding Euler-Lagrange equations via the separation of variables, without having to appeal to the Hamiltonian. We apply this technique to the Dirac-Born-Infeld solitons and obtain the corresponding equations and the potentials. This method is suitable for obtaining the first-order equations and determining the allowed potentials for noncanonical defects.

We construct instanton solutions describing the decay of flux compactifications of a 6d gauge theory by generalizing the Kaluza-Klein bubble of nothing. The surface of the bubble is described by a smooth magnetically charged solitonic brane whose asymptotic flux is precisely that responsible for stabilizing the 4d compactification. We describe several instances of bubble geometries for the various vacua occurring in a 6d Einstein-Maxwell theory namely, AdS 4 × S 2 , R 1,3 × S 2 , and dS 4 × S 2 . Unlike conventional solutions, the bubbles of nothing introduced here occur where a two-sphere compactification manifold homogeneously degenerates.

Abstract:We use a recent on-shell method, developed in [1], to construct Bogomol'nyi equations of the three-dimensional generalized Maxwell-Higgs model [2]. The resulting Bogomol'nyi equations are parametrized by a constant C 0 and they can be classified into two types determined by the value of C 0 = 0 and C 0 = 0. We identify that the Bogomol'nyi equations obtained by Bazeia et al. [2] are of the (C 0 = 0)-type Bogomol'nyi equations. We show that the Bogomol'nyi equations of this type do not admit the Prasad-Sommerfield limit in its spectrum. As a resolution, the vacuum energy must be lifted up by adding some constant to the potential. Some possible solutions whose energy equal to the vacuum are discussed briefly. The on-shell method also reveals a new (C 0 = 0)-type Bogomol'nyi equations. This non-zero C 0 is related to a non-trivial function f C 0 defined as a difference between energy density of the scalar potential term and of the gauge kinetic term. It turns out that these Bogomol'nyi equations correspond to vortices with locally non-zero pressures, while their average pressure P remain zero globally by the finite energy constraint.

Within the framework of the recent Eddingtoninspired Born-Infeld (EiBI) theory we study gravitational field around an SO(3) global monopole. The solution also suffers from the deficit solid angle as in the Barriola-Vilenkin metric but shows a distinct feature that cannot be transformed away unless in the vanishing EiBI coupling constant, κ. When seen as a black hole eating up a global monopole, the corresponding Schwarzschild horizon is shrunk by κ. The deficit solid angle makes the space is globally not Euclidean, and to first order in κ (weak-field limit) the deflection angle of light is smaller than its Barriola-Vilenkin counterpart.

Within the framework of flux compactifications, we construct an instanton describing the quantum creation of an open universe from nothing. The solution has many features in common with the smooth 6d bubble of nothing solutions discussed recently, where the spacetime is described by a 4d compactification of a 6d Einstein-Maxwell theory on S 2 stabilized by flux. The four-dimensional description of this instanton reduces to that of Hawking and Turok. The choice of parameters uniquely determines all future evolution, which we additionally find to be stable against bubble of nothing instabilities.

We study the theory of a (global) texture with DBI-like Lagrangian, the higher-dimensional generalization of the previously known chiral Born-Infeld theory. This model evades Derrick's theorem and enables the existence of solitonic solutions in arbitrary (N + 1)-dimensions. We explicitly show the solutions in spherically-symmetric ansatz. These are examples of extended topological solitons. We then investigate the coupling of this theory to gravity, and obtain the static self-gravitating solitonic p-brane solutions. These non-singular branes can be identified as the smooth versions of cosmic p-branes which, in the thin-wall limit, suffers from naked singularities. † Present affiliation.