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.
14764118
A monopole metric
We calculate explicitly in terms of complete elliptic integrals the metric on the moduli space of tetrahedrally-symmetric, charge four, SU(2) monopoles. Using this we verify that in the asymptotic regime the metric of Gibbons and Manton is exact up to exponentially suppressed corrections.
18365450
Instantons and the buckyball
The study of Skyrmions predicts that there is an icosahedrally symmetric charge 17 SU(2) Yang–Mills instanton in which the topological charge density, for fixed Euclidean time, is localized on the edges of the truncated icosahedron of the buckyball. In this paper the existence of such an instanton is proved by explicit construction of the associated ADHM data. A topological charge density isosurface is displayed which verifies the buckyball structure of the instanton.
119481719
SU(N) Monopoles and Platonic Symmetry
We discuss the ADHMN construction for SU(N) monopoles and show that a particular simplification arises in studying charge N−1 monopoles with minimal symmetry breaking. Using this we construct families of tetrahedrally symmetric SU(4) and SU(5) monopoles. In the moduli space approximation, the SU(4) one-parameter family describes a novel dynamics where the monopoles never separate, but rather, a tetrahedron deforms to its dual. We find a two-parameter family of SU(5) tetrahedral monopoles and compute some geodesics in this submanifold numerically. The dynamics is rich, with the monopoles scattering either once or twice through octahedrally symmetric configurations.
15666101
Skyrmions, fullerenes and rational maps
We apply two very different approaches to calculate Skyrmions with baryon number B ≤ 22. The first employs the rational map ansatz, where approximate charge B Skyrmions are constructed from a degree B rational map between Riemann spheres. We use a simulated annealing algorithm to search for the minimal energy rational map of a given degree B. The second involves the numerical solution of the full non-linear time dependent equations of motion, with initial conditions consisting of a number of well separated Skyrmion clusters. In general, we find a good agreement between the two approaches. For B ≥ 7 almost all the solutions are of fullerene type, that is, the baryon density isosurface consists of twelve pentagons and 2B - 14 hexagons arranged in a trivalent polyhedron. There are exceptional cases where this structure is modified, which we discuss in detail. We find that for a given value of B there are often many Skyrmions, with different symmetries, whose energies are very close to the minimal value, some of which we discuss. We present rational maps which are good approximations to these Skyrmions and accurately compute their energy by relaxation using the full non-linear dynamics.
53065799
Hyperbolic vortices with large magnetic flux
There has been some recent interest in the study of non-Abelian Bogomolny-Prasad-Sommerfield (BPS) monopoles in the limit of large magnetic charge. Most investigations have used a magnetic bag approximation, in which spherical symmetry is assumed within an Abelian description. In particular, this approach has been used to suggest the existence of two types of magnetic bags, with differing distributions of the zeros of the Higgs field, together with multilayer structures, containing several magnetic bags. This paper is concerned with the analogous situation of Abelian BPS vortices in the hyperbolic plane, in the limit of large magnetic flux. This system has the advantage that explicit exact solutions can be obtained and compared with a magnetic bag approximation. Exact BPS vortex solutions are presented that are analogous to the two types of magnetic bags predicted for BPS monopoles and it is shown that these structures can be combined to produce exact multilayer solutions.
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.
18410762
DEVELOPMENT OF A POSITRON PRODUCTION TARGET FOR THE ILC POSITRON SOURCE
The future International Linear Collider (ILC) will require of order 10 14 positrons per second to fulfil its luminosity requirements. The current baseline design produces this unprecedented flux of positrons using an undulatorbased source. In this concept, a collimated beam of photons produced from the action of an undulator on the main electron beam of the ILC is incident on a conversiontarget. Positrons producedin the resulting electromagneticshower can then be captured, accelerated and injected into a damping ring. The positron source community is pursuing several alternative technologies to develop a target capable of long-term operation in the intense photon beam. In the design being developed jointly by Lawrence Livermore National Laboratory (LLNL), Stanford Linear Accelerator Center (SLAC), the University of Liverpool and the Cockcroft Institute a thin (0.4 radiation length) watercooled titanium alloy target wheel of diameter 2 m is rotated at approximately 1000 rpm to spread the incident power of each pulse over a wide area. We review the role of the target in the positron source and present the latest target design.