Related papers: On The Warped Heterotic Axion
The QCD axion can successfully solve the strong CP problem under the condition that the Peccei-Quinn symmetry is respected to extremely high standard. We explore a class of gauge theories that accommodate a high-quality axion, known as the…
The axion decay into charged fermion-antifermion pair $a ~\to f ~\tilde f$ is studied in external crossed and magnetic fields. The result we have obtained can be of use to re-examine the lower limit on the axion mass in case of possible…
We consider a family of perturbative heterotic string backgrounds. These are complex threefolds X with c_1 = 0, each with a gauge field solving the Hermitian Yang-Mill's equations and compatible B and H fields that satisfy the anomaly…
We construct a new model of four-dimensional relativistic strings with integrable dynamics on the worldsheet. In addition to translational modes this model contains a single massless pseudoscalar worldsheet field - the worldsheet axion. The…
We consider twisted tachyons on C/Z_N orbifolds of bosonic closed string theory. It has been conjectured that these tachyonic instabilities correspond to decays of the orbifolds into flat space or into orbifolds with smaller deficit angles.…
In this paper we describe the heterotic dual of the type IIB theory compactified to four dimensions on a toroidal orientifold in the presence of fluxes. The type IIB background is most easily described in terms of an M-theory…
In this paper, $E_6$ and especially $E_7$ GUT are considered in the F-theory setting in view of the free fermionic construction of the $4D$ heterotic string. In particular, the NAHE-Based LRS model of \cite{Cleaver:2000ds, Cleaver:2002ps}…
A new term in the p-adic world-sheet action is proposed, which couples a constant B-field to the boundary of the world-sheet at disk level. The induced deformation of tachyon scattering amplitudes by star-products is derived. This is in…
Inspired by the string axiverse idea, it has been suggested that the recent transition from decelerated to accelerated cosmic expansion is driven by an axion-like quintessence field with a sub-Planckian decay constant. The scenario requires…
The near-horizon metric for a black brane in Anti-de Sitter (AdS) space and the metric near the AdS boundary both exhibit hydrodynamic behavior. We demonstrate the equivalence of this pair of hydrodynamic systems for the sound mode of a…
We show that a Goedel-like deformation of AdS3 in heterotic string theory can be realized as an exact string background. Indeed this class of solutions is obtained as an exactly marginal deformation of the conformal field theory describing…
We study the stochastic axion dark matter scenario in the axion landscape, where one of the axions is light and stable and therefore explains dark matter. If the axion mass at the potential is a typical value of the curvature along the…
We discuss the stability of an electroweak string with axions in its core, which give to the configuration a quasi-topological property, and compare it with other modifications using instantons in the thin wall approximation.
We investigate a string-inspired axion extension of the standard model obtained from Type II superstrings using quiver method. In the first part, we discuss intersecting Type IIA D6-branes wrapping non trivial 3-cycles in the presence of…
The Axion Weak Gravity Conjecture provides one of the most effective quantum gravity tools for constraining particle physics and cosmology, but it has long been thought of as a slightly fuzzy statement: given an axion with decay constant…
This paper revisits the problem of the string decay contribution to the axion cosmological energy density. We show that this contribution is proportional to the average relative increase when axion strings decay of a certain quantity…
Axions, encompassing both QCD axions and axion-like particles, can generate loop-induced quadratic couplings to electromagnetic field strength tensors, resulting in oscillatory shifts of the fine-structure constant. Near a Kerr black hole,…
The compactification of the heterotic string on six-dimensional orbifolds is reviewed. Some important technical aspects of their construction are clarified and new parameters, called generalized discrete torsion, are introduced and related…
Dynamical mechanisms to generate an ultralight axion of mass $\sim 10^{-21}-10^{-22}$ eV in supergravity and strings are discussed. An ultralight particle of this mass provides a candidate for dark matter that may play a role for cosmology…
We describe how 4d de Sitter vacua might emerge from 11d heterotic M-theory. Non-perturbative effects and $G$-fluxes play a crucial role leading to vacua with F-term supersymmetry breaking and a positive energy density. Charged scalar…