Related papers: Quantum stabilization of a hedgehog type of cosmic…
Recently, a new framework for solving the hierarchy problem has been proposed which does not rely on low energy supersymmetry or technicolor. The gravitational and gauge interactions unite at the electroweak scale, and the observed weakness…
The main goal of this work is to pursue an investigation of cosmic string configurations focusing on possible consequences of the Lorentz-symmetry breaking by a background vector. We analyze the possibility of cosmic strings as a viable…
We study numerically the nonlinear stability of {\it excited} fermion-boson stars in spherical symmetry. Such compound hypothetical stars, composed by fermions and bosons, are gravitationally bound, regular, and static configurations…
We present a critical review and summary of String Gas Cosmology. We include a pedagogical derivation of the effective action starting from string theory, emphasizing the necessary approximations that must be invoked. Working in the…
We study higher-dimensional non-supersymmetric orbifold models where the Higgs field is identified with some internal component of a gauge field. We address two important and related issues that constitute severe obstacles towards model…
We show that the Z-strings of the standard electroweak theory can be stabilized by strong external magnetic fields, provided that $\beta^{1/2} \equiv M_H/M_Z\leq 1$, where $M_H$ and $M_Z$ are the Higgs and Z masses. The magnetic fields…
We study spatial variations of the fine-structure constant in the presence of static straight cosmic strings in the weak-field approximation in Einstein gravity. We work in the context of a generic Bekenstein-type model and consider a gauge…
We study the stability of some classical string worldsheet solutions employed for computing the potential energy between two static fundamental quarks in confining and non-confining gravity duals. We discuss the fixing of the diffeomorphism…
The possibility of the cosmic string creation by the vacuum fluctuations of quantum fields in the self-consistent semiclassical theory of gravity is discussed. We use the approximate method for obtaining vacuum expectation value of the…
We investigate the cosmological constraints on exotic stable matter states which arise in realistic free fermionic superstring models. These states appear in the superstring models due to a ``Wilson--line'' breaking of the unifying…
We evaluate the cross section for electron-positron pair production by a single high energy photon in the space-time of a static, straight cosmic string. Energy and momentum conservation precludes this process in empty Minkowski space. It…
We consider the possibility of a bosonic (meta)stabilization of a cosmic gauge string loop due to the presence of a gas of low mass bosonic particles which become trapped within the string core. This boson gas exerts a pressure which tends…
We examine the stability of classical states with a generic incommensurate spiral order against quantum fluctuations. Specifically, we focus on the frustrated spin-1/2 $XY$ and Heisenberg models on the honeycomb lattice with…
We study the thermodynamics of quantum particles with long-range interactions at T=0. Specifically, we generalize the Hamiltonian Mean Field (HMF) model to the case of fermions and bosons. In the case of fermions, we consider the…
In our previous work, we found new types of the cosmic string solutions in the Abelian-Higgs model with an enhanced $U(1)$ global symmetry. We dubbed those solutions as the compensated/uncompensated strings. The compensated string is…
We extend the recently developed kinematical framework for diffeomorphism invariant theories of connections for compact gauge groups to the case of a diffeomorphism invariant quantum field theory which includes besides connections also…
Presented is a quantum gravity theory that is a quantum mechanical generalization of Einstein's vierbein field-based approach, where the classical metric tensor field is promoted to a quantum mechanical metric tensor field operator. The…
Nielsen-Olesen vortices in the Abelian-Higgs (AH) model are the simplest realisations of cosmic strings in a gauge field theory. Large-scale numerical solutions show that the dominant decay channel of a network of AH strings produced from…
We study the stochastic gravitational wave background sourced by a network of cosmic superstrings and demonstrate that incorporating higher-mass string species, beyond the fundamental string, is crucial for accurately modelling the…
We explore the string spectrum in the Witten QCD model by considering classical string configurations, thereby obtaining energy formulas for quantum states with large excitation quantum numbers representing glueballs and Kaluza-Klein…