Related papers: Stringballs and Planckballs for Dark Matter
Velocity-dependent interactions in a fundamental-string dominated universe lead quite naturally, with reasonable assumptions on initial conditions, to an accelerating expanding universe without assuming the existence of a cosmological…
The purpose of this article is twofold. First, by means of Padmanabhan's proposal on the emergence nature of gravity, we recover the $\Lambda$CDM model and the effect of the dark matter in the context of cosmology. Toward this goal, we use…
We point out that the spectrum and interactions of light states of the heterotic string indicate a string scale close to the GUT scale, and a mass generating scale for the gravitationally interacting states around 10^9 GeV if these states…
A large class of four-dimensional supersymmetric ground states of closed superstrings with a non-zero mass gap are constructed. For such ground states we turn on chromo-magnetic fields as well as curvature. The exact spectrum as function of…
It is pointed out that string-loop effects may generate matter couplings for the dilaton allowing this scalar partner of the tensorial graviton to stay massless while contributing to macroscopic gravity in a way naturally compatible with…
Recent theoretical progress indicates that spacetime and gravity emerge together from the entanglement structure of an underlying microscopic theory. These ideas are best understood in Anti-de Sitter space, where they rely on the area law…
Dark matter models with light mediators featuring sizable interactions among dark particles enjoy an increasing attention in the model building community due to the elegance with which they can potentially explain the scaling relations…
In our recently proposed quantum theory of gravity, the universe is made of `atoms' of space-time-matter (STM). Planck scale foam is composed of STM atoms with Planck length as their associated Compton wave-length. The quantum dispersion…
We analyze the behavior of the scalar field as dark energy of the Universe in a static world of galaxies and clusters of galaxies. We find the analytical solutions of evolution equations of the density and velocity perturbations of dark…
We construct a static and spherical excited state without singularities in renormalizable quantum gravity with background-free nature asymptotically. Its diameter is given by a correlation length of the quantum gravity, longer than the…
This is a nontechnical introduction to recent work on quantum gravity using ideas from higher-dimensional algebra. We argue that reconciling general relativity with the Standard Model requires a `background-free quantum theory with local…
It is shown that for small relative angle and kinetic energy two type I $U(1)$ strings can form bound states upon collision instead of the more familiar intercommuting configuration. The velocity below which this may happen is estimated as…
In quantum gravity theories Planckian behavior is triggered by the energy of {\it elementary} particles approaching the Planck energy, $E_P$, but it's also possible that anomalous behavior strikes systems of particles with total energy near…
Theories of dark matter that support bound states are an intriguing possibility for the identity of the missing mass of the Universe. This article proposes a class of models of supersymmetric composite dark matter where the interactions…
It has been suggested that Einstein's theory of General Relativity can be modified to accomodate mismatches between the gravitational field and luminous matter on a wide range of scales. Covariant theories of modified gravity generically…
We study supersymmetry breaking by Scherk-Schwarz compactifications in type I string theory. While in the gravitational sector all mass splittings are proportional to a (large) compactification radius, supersymmetry remains unbroken for the…
We consider a macroscopic model describing a system of self-gravitating particles. We study the existence and uniqueness of non-negative stationary solutions and allude the differences to results obtained from classical gravitational…
The generation of entangled states and their degree of entanglement is studied ab initio in a relativistic formulation for the case of two interacting spin-1/2 charged particles. In the realm of quantum electrodynamics we derive the…
In this paper we investigate the bound state problem of nonrelativistic quantum particles on a conical surface. This kind of surface appears as a topological defect in ordinary semiconductors as well as in graphene sheets. Specifically, we…
If cosmic strings have an irreducible core, then dark matter may consist of entities that are core-sized string remnants. As such they may interact solely by gravity. These talons may be many orders of magnitude more massive than any known…