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Register a new userTheorem: A Static Magnetic N-pole Becomes an Oscillating Electric N-pole in a Cosmic Axion Field
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Added by
Christopher T. Hill
Publication date
2016
fields
Physics
and research's language is
English
Authors
Christopher T. Hill
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We show for the classical Maxwell equations, including the axion electromagnetic anomaly source term, that a cosmic axion field induces an oscillating electric N-moment for any static magnetic N-moment. This is a straightforward result, accessible to anyone who has taken a first year graduate course in electrodynamics.
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A second order pole in the scalar kinetic term can lead to a class of inflation models with universal predictions referred to as pole inflation or $alpha$-attractors. While this kinetic structure is ubiquitous in supergravity effective field theories, realising a consistent UV complete model in e.g. string theory is a non-trivial task. For one, one expects quantum corrections arising in the vicinity of the pole which may spoil the typical attractor dynamics. As a conservative estimate of the range of validity of supergravity models of pole inflation we employ the weak gravity conjecture (WGC). We find that this constrains the accessible part of the inflationary plateau by limiting the decay constant of the axion partner. For the original single complex field models, the WGC does not even allow the inflaton to reach the inflationary plateau region. We analyze if evoking the assistance of $N$ scalar fields from the open string moduli helps addressing these problems. Pole $N$-flation could improve radiative control by reducing the required range of each individual field. However, the WGC bound prohibiting pole inflation for a single such field persists even for a collective motion of $N$ such scalars if we impose the sublattice WGC. Finally, we outline steps towards an embedding of pole N-flation in type IIB string theory on fibred Calabi-Yau manifolds.
In this paper, we apply a method of reducing the dynamics of FRW cosmological models with the barotropic form of the equation of state to the dynamical system of the Newtonian type to detect the finite scale factor singularities and the finite-time singularities. In this approach all information concerning the dynamics of the system is contained in a diagram of the potential function $V(a)$ of the scale factor. Singularities of the finite scale factor manifest by poles of the potential function. In our approach the different types of singularities are represented by critical exponents in the power-law approximation of the potential. The classification can be given in terms of these exponents. We have found that the pole singularity can mimick an inflation epoch. We demonstrate that the cosmological singularities can be investigated in terms of the critical exponents of the potential function of the cosmological dynamical systems. We assume the general form of the model contains matter and some kind of dark energy which is parameterized by the potential. We distinguish singularities (by ansatz about the Lagrangian) of the pole type with the inflation and demonstrate that such a singularity can appear in the past.
We investigate inflation models in Jordan frame supergravity, in which an inflaton non-minimally couples to the scalar curvature. By imposing the condition that an inflaton would have the canonical kinetic term in the Jordan frame, we construct inflation models with asymptotically flat potential through pole inflation technique and discuss their relation to the models based on Einstein frame supergravity. We also show that the model proposed by Ferrara et al. has special position and the relation between the Kahler potential and the frame function is uniquely determined by requiring that scalars take the canonical kinetic terms in the Jordan frame and that a frame function consists only of a holomorphic term (and its anti-holomorphic counterpart) for symmetry breaking terms. Our case corresponds to relaxing the latter condition.
Existing searches for cosmic axions relics have relied heavily on the axion being non-relativistic and making up dark matter. However, light axions can be copiously produced in the early Universe and remain relativistic today, thereby constituting a Cosmic $textit{axion}$ Background (C$a$B). As prototypical examples of axion sources, we consider thermal production, dark-matter decay, parametric resonance, and topological defect decay. Each of these has a characteristic frequency spectrum that can be searched for in axion direct detection experiments. We focus on the axion-photon coupling and study the sensitivity of current and futu
This paper demonstrates a detailed characterization of argon plasma in a variable multi-pole line cusp magnetic field (VMMF). The VMMF has been produced by placing six electromagnets (with embedded profiled vacoflux-50 core) over a large cylindrical volume (1 m axial length and 40 cm diameter). The magnetic field have been measured by hall probe method and compared with simulated magnetic field by performing simulation using FEMM tools. Results from magnetic field simulation indicate that the rate of change of pole magnetic field (maximum magnetic field) with respect to magnet current for vacoflux-50 core is high (7.53 G/A) as compared to the simple air core electromagnet (2.15 G/A). The area of the nearly field free region (null region) in the chamber volume can be controlled without changing a number of pole magnets. From the experimental results, it has been observed that in this field configuration the confinement of the primary electrons increases and leak width of plasma decreases with increasing the magnetic field. Thus the mean density, particle confinement time and the stability of the plasma increase with increasing magnetic field. In addition to this, it has been found that the radial uniformity of the plasma density explicitly depends on the VMMF. It is also shown that the VMMF controls the scavenging of confined primary electrons and confinement of primary electron increased with magnetic field which helps to boost up the plasma density.
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