Related papers: On Axion Reheating in the String Landscape
If nature is described by string theory, and if the compactification radius is large (as suggested by the unification of couplings), then the theory is in a regime best described by the low energy limit of $M$-theory. We discuss some…
We consider the class of effective supergravity theories from the weakly coupled heterotic string in which local supersymmetry is broken by gaugino condensation in a hidden sector, with dilaton stabilization achieved through corrections to…
It is well-known that heterotic string compactifications have, in spite of their conceptual simplicity and aesthetic appeal, a serious problem with precision gauge coupling unification in the perturbative regime of string theory. Using both…
Late-decaying string moduli dilute the baryon asymmetry of the universe created in any previous era. The reheat temperature for such moduli is below a GeV, thus motivating baryogenesis at very low temperatures. We present an extension of…
We study the contribution to the QCD axion dark matter abundance that is produced by string defects during the so-called scaling regime. Clear evidence of scaling violations is found, the most conservative extrapolation of which strongly…
One cannot yet point to any firm string prediction. While many approximate string ground states are known with interesting properties, we do not have any argument that one or another describes what we observe around us, and for reasons…
We have studied numerically the evolution and decay of axion strings. These global defects decay mainly by axion emission and thus contribute to the cosmological axion density. The relative importance of this source relative to misalignment…
The quest to understand the nature of dark matter and dark energy motivates a deep exploration into axion physics, particularly within the framework of string theory. Axions, originally proposed to solve the strong CP problem, emerge as…
We argue that the striking similarity between the cosmic abundances of baryons and dark matter, despite their very different astrophysical behavior, strongly motivates the scenario in which dark matter resides within a rich dark sector…
The current cosmological constraints on a dark matter axion are reviewed. We describe the basic mechanisms by which axions are created in the early universe, both in the standard thermal scenario in which axion strings form and in…
We study preheating in theories where the inflaton couples derivatively to scalar and gauge fields. Such couplings may dominate in natural models of inflation, in which the flatness of the inflaton potential is related to an approximate…
Low scale string models naturally have axion-like pseudoscalars which couple directly to gluons and photons (but not $W$s) at tree level. We show how they typically get tree level masses in the presence of closed string fluxes, consistent…
Inflationary models driven by a large number of axion fields are discussed in the context of type IIB compactifications with N=1 supersymmetry. The inflatons arise as the scalar modes of the R-R two-forms evaluated on vanishing two-cycles…
String theory has been claimed to give rise to natural fuzzy dark matter candidates in the form of ultralight axions. In this paper we revisit this claim by a detailed study of how moduli stabilisation affects the masses and decay constants…
We examine the effects of the axion coupling to $R\tilde{R}$ on the evolution of cosmic structures. It is shown that the evolutions of the scalar- and vector-type perturbations are not affected by this axion coupling. However the axion…
We show that quantum systems of extended objects naturally give rise to a large class of exotic phases - namely topological phases. These phases occur when the extended objects, called ``string-nets'', become highly fluctuating and…
The axion is a well-motivated candidate for the inflaton, as the radiative corrections that spoil many single-field models are avoided by virtue of its shift symmetry. However, axions generically couple to gauge sectors. As the axion…
String theories suggest the existence of a plethora of axion-like fields with masses spread over a huge number of decades. Here we show that these ideas lend themselves to a model of quintessence with no super-Planckian field excursions and…
We propose that gaugino condensation in the hidden sector may dynamically induce intermediate gauge symmetry breaking and specify the compactification scale. We also show that this scheme makes possible affine level one grand unified string…
We study the production of dark matter and dark radiation after reheating in string inflation models where the Calabi-Yau has a fibred structure and the visible sector lives on D3 branes. We show how the interplay between different physical…