Related papers: Relic dilatons in string cosmology
Recent observations of high-redshift supernovae seem to suggest that the global geometry of the Universe may be affected by a `cosmological constant', which acts to accelerate the expansion rate with time. But these data by themselves still…
A strongly-coupled sector can feature a supercooled confinement transition in the early universe. We point out that, when fundamental quanta of the strong sector are swept into expanding bubbles of the confined phase, the distance between…
Brane gas cosmology is a scenario inspired by string theory which proposes a simple resolution to the initial singularity problem and gives a dynamical explanation for the number of spatial dimensions of our universe. In this work we have…
The general constraints on the parameter space of soft-breaking terms, in order to avoid dangerous charge and color breaking minima, are applied to the four-dimensional string scenario where the dilaton is the source of supersymmetry…
We calculate dilaton and axion radiation generated in the collision of two straight initially unexcited strings and give a rough cosmological estimate of dilaton and axion densities produced via this mechanism in the early universe.
Stochastic backgrounds of relic gravitons of cosmological origin extend from frequencies of the order of the aHz up to the GHz range. Since the temperature and polarization anisotropies constrain the low frequency normalization of the…
The scenario that the Universe contracts towards a big crunch and then undergoes a transition to expanding Universe in envisaged in the quantum string cosmology approach. The Wheeler-De Witt equation is solved exactly for an exponential…
We discuss some peculiar properties of the stochastic graviton background predicted by string cosmology. At Planckian times, for the values of the parameters of the model which are more interesting for the detection in gravitational wave…
Cosmic strings are predicted in many models beyond the Standard Model of particle physics. In models which admit strings, a network of strings will inevitably be formed in a phase transition in the early universe and will persist to the…
It has been pointed out recently that the presence of dilaton field in the early Universe can dilute the neutralino dark matter (DM) abundance, if Universe is not radiation dominated at DM decoupling, due to its dissipative-like coupling to…
One of the most interesting predictions of string-inspired cosmological models is the presence of a stochastic background of relic gravitational waves in the frequency band accessible to Earth-based detectors. Here we consider a ``minimal''…
String gas cosmology is rewritten in the Einstein frame. In an effective theory in which a gas of closed strings is coupled to a dilaton gravity background without any potential for the dilaton, the Hagedorn phase which is quasi-static in…
The chameleonic behaviour of the String theory dilaton is suggested. Some of the possible consequences of the chameleonic string dilaton are analyzed in detail. In particular, (1) we suggest a new stringy solution to the cosmological…
We study the production of cosmological axions in the standard scenario in which a global string network forms at the Peccei-Quinn phase transition. We make detailed calculations of the axions produced by string loops (a previously…
Cosmic strings are topological defects possibly formed in the early Universe, which may be observable due to their gravitational effects on the cosmic microwave background radiation or gravitational wave experiments. To this effect it is…
A novel mechanism to produce a cosmic network of fundamental superstrings based on a time-varying string tension has been recently proposed. It has been found that fundamental superstrings can grow in a kinating background driven by the…
An exploratory study of the cosmology of moduli in string theory. Moduli are argued to be natural inflaton fields and lead to a robust inflationary cosmology in which inflation takes place at the top of domain walls. The amplitude of…
We consider the gravitational lensing produced by long cosmic strings formed in a GUT scale phase transition. We derive a formula for the deflection of photons which pass near the strings that reduces to an integral over the light cone…
We study the amplification of the electromagnetic fluctuations, and the production of "seeds" for the cosmic magnetic fields, in a class of string cosmology models whose scalar and tensor perturbations reproduce current observations and…
In theories with cosmic strings, a small fraction of string loops may collapse to form black holes. In this Letter, various constraints on such models involving black holes are considered. Hawking radiation from black holes, gamma and…