119082818
Instanton moduli and topological soliton dynamics
It has been proposed by Atiyah and Manton that the dynamics of skyrmions in R3+1 may be approximated by motion on a finite dimensional manifold obtained from the moduli space of SU(2) Yang-Mills instantons in R4. Motivated by this work we describe how similar results exist for other soliton and instanton systems. We describe in detail two examples for the approximation of the infinite dimensional dynamics of sine-Gordon solitons in R1+1 by finite dimensional dynamics on a manifold obtained from instanton moduli. In the first example we use the moduli space of CP1 instantons in R2 and in the second example we use the moduli space of SU(2) Yang-Mills instantons in R4. The metric and potential functions on these manifolds are constructed and the resulting dynamics is compared with the explicit exact soliton solutions of the sine-Gordon theory.
9593695
Light Nuclei of Even Mass Number in the Skyrme Model
We consider the semiclassical rigid-body quantization of Skyrmion solutions of mass numbers B = 4, 6, 8, 10, and 12. We determine the allowed quantum states for each Skyrmion and find that they often match the observed states of nuclei. The spin and isospin inertia tensors of these Skyrmions are accurately calculated for the first time and are used to determine the excitation energies of the quantum states. We calculate the energy level splittings, using a suitably chosen parameter set for each mass number. We find good qualitative and encouraging quantitative agreement with experiment. In particular, the rotational bands of beryllium-8 and carbon-12, along with isospin 1 triplets and isospin 2 quintets, are especially well reproduced. We also predict the existence of states that have not yet been observed and make predictions for the unknown quantum numbers of some observed states.
15942904
Schrödinger-Chern-Simons vortex dynamics
We study the motion of vortices in the planar Ginzburg-Landau model with Schrodinger-Chern-Simons dynamics. We compare the moduli space approximation with the results of numerical simulations of the full field theory and find that there is agreement if the coupling constant is very close to the critical value separating type I from type II superconductors. However, there are significant qualitative differences even for modest deviations from the critically coupled regime. Radiation effects produce forces which are of the same order of magnitude as the intervortex force and therefore have a significant impact on vortex motion. We conclude that the moduli space approximation does not provide a good description of the dynamics in this regime.
17219972
Q-balls, Integrability and Duality
This paper is concerned with the dynamics and interactions of Q-balls in (1+1)-dimensions. The asymptotic force between well-separated Q-balls is calculated to show that Q-balls can be attractive or repulsive depending upon their relative internal phase. An integrable model with exact multi-Q-ball solutions is investigated and found to be of use in explaining the dynamics in non-integrable theories. In particular, it is demonstrated that the dynamics of small Q-balls in a generic class of non-integrable models tends towards integrable dynamics as the charge decreases. Long-lived oscillations of a single Q-ball can also be understood in terms of a deformation of an exact breather solution in the integrable model. Finally, we show that any theory with Q-ball solutions has a dual description in which a stationary Q-ball is dual to a static kink, with an interchange of Noether and topological charges.
15963919
Cyclic Monopoles
We study charge k SU(2) BPS monopoles which are symmetric under the cyclic group of order k. Approximate twistor data (spectral curves and Nahm data) is constructed using a new technique based upon a Painlevé analysis of Nahm’s equation around a pole. With this data both analytical and numerical approximate ADHMN constructions are performed to study the zeros of the Higgs field and the monopole energy densities. The results describe, via the moduli space approximation, a novel type of low energy k monopole scattering. ∗This work was supported in part by the Nuffield Foundation
118864310
Discrete breathers in anisotropic ferromagnetic spin chains
We prove the existence of discrete breathers (time-periodic, spatially localized solutions) in weakly coupled ferromagnetic spin chains with easy-axis anisotropy. Using numerical methods we then investigate the continuation of discrete breather solutions as the intersite coupling is increased. We find a band of frequencies for which the one-site breather continues all the way to the soliton solution in the continuum. There is a second band, which abuts the first, in which the one-site breather does not continue to the soliton solution, but a certain multi-site breather does. This banded structure continues, so that in each band there is a particular multi-site breather which continues to the soliton solution. A detailed analysis is presented, including an exposition of how the bifurcation pattern changes as a band is crossed. The linear stability of breathers is analysed. It is proved that one-site breathers are stable at small coupling, provided a non-resonance condition holds, and an extensive numerical stability analysis of one-site and multisite breathers is performed. The results show alternating bands of stability and instability as the coupling increases.
53461882
A double-sided, shield-less stave prototype for the ATLAS Upgrade strip tracker for the High Luminosity LHC
A detailed description of the integration structures for the barrel region of the silicon strips tracker of the ATLAS Phase-II upgrade for the upgrade of the Large Hadron Collider, the so-called High Luminosity LHC (HL-LHC), is presented. This paper focuses on one of the latest demonstrator prototypes recently assembled, with numerous unique features. It consists of a shortened, shield-less, and double sided stave, with two candidate power distributions implemented. Thermal and electrical performances of the prototype are presented, as well as a description of the assembly procedures and tools.
53410002
A double-sided silicon micro-strip Super-Module for the ATLAS Inner Detector upgrade in the High-Luminosity LHC
The ATLAS experiment is a general purpose detector aiming to fully exploit the discovery potential of the Large Hadron Collider (LHC) at CERN. It is foreseen that after several years of successful data-taking, the LHC physics programme will be extended in the so-called High-Luminosity LHC, where the instantaneous luminosity will be increased up to 5 × 1034 cm−2 s−1. For ATLAS, an upgrade scenario will imply the complete replacement of its internal tracker, as the existing detector will not provide the required performance due to the cumulated radiation damage and the increase in the detector occupancy. The current baseline layout for the new ATLAS tracker is an all-silicon-based detector, with pixel sensors in the inner layers and silicon micro-strip detectors at intermediate and outer radii. The super-module is an integration concept proposed for the strip region of the future ATLAS tracker, where double-sided stereo silicon micro-strip modules are assembled into a low-mass local support structure. An electrical super-module prototype for eight double-sided strip modules has been constructed. The aim is to exercise the multi-module readout chain and to investigate the noise performance of such a system. In this paper, the main components of the current super-module prototype are described and its electrical performance is presented in detail.
119115810
A Compact High Energy Camera for the Cherenkov Telescope Array
The Compact High Energy Camera (CHEC) is a camera-development project involving UK, US, Japanese and Dutch institutes for the dual-mirror Small-Sized Telescopes (SST-2M) of the Cherenkov Telescope Array (CTA). Two CHEC prototypes, based on different photosensors are funded and will be assembled and tested in the UK over the next ≈18 months. CHEC is designed to record flashes of Cherenkov light lasting from a few to a hundred nanoseconds, with typical RMS image width and length of ∼ 0.2◦×1.0◦, and has a 9◦ field of view. The physical camera geometry is dictated by the telescope optics: a curved focal surface with radius of curvature 1 m and diameter ∼35 cm is required. CHEC is designed to work with both the ASTRI and GATE SST2M telescope structures and will include an internal LED flasher system for calibration. The first CHEC prototype will be based on multi-anode photomultipliers (MAPMs) and the second on silicon photomultipliers (SiPMs or MPPCs). The first prototype will soon be installed on the ASTRI SST-2M prototype structure on Mt. Etna.