Self-Dual Fields Harbored by a Kerr-Taub-bolt Instanton

We present a new exact solution for self-dual Abelian gauge fields living on the space of the Kerr-Taub-bolt instanton, which is a generalized example of asymptotically flat instantons with non-self-dual curvature, by constructing the corresponding square integrable harmonic form on this space.Comment: 7 page

Managing Spider Mites in corn: A review

Corn is one of the three most important cereal crops in the world. The mites that attack maize belong to the family Tetranychidae, and the species Tetranychus urticae. Koch TSM and Oligonychus pratensis BGM (primary pests of cereals) are particularly formidable. Although high populations of spider mites frequently cause significant damage to corn (grain, silage, and sweet), the level of economic loss varies from season to season. Several factors influence population dynamics from year to year, including temperature, humidity, precipitation, soil type, pesticide applications, proximity to the host, and natural enemies. High temperatures and drought stress usually accelerate the accumulation process of high mite populations. This is compounded by the application of neonicotinoid pesticides, dust accumulation on corn leaves, and sandy soils as these soils are typically drought stressed, even with irrigation. Mites are responsible for severe yield losses of up to 40% of dry matter for silage. With the extensive and unsustainable use of pesticides, including acaricides and insecticides, management of mites currently commercially available miticides has become increasingly difficult, as these arthropods have developed resistance to over 95 active ingredients. The use of drought-tolerant corn plants can help reduce spider mite outbreaks and losses associated with these pests. Natural enemies, including predatory mites of the phytoseiidae family (Phytoseiulus persimilis Athias, Neoseiulus californicus), thrips (Scolothrips sexmaculatus), the tiny pirate bug (Orius sp), and the small black lady beetle (Stethorus punctillum) can keep spider mite numbers below the economic damage threshold. However, the effectiveness of these natural enemies is reduced by hot, low humidity conditions, pesticide use and dust accumulation on leaves. Proper irrigation can help reduce the risk of plant drought and the environment in which spider mites thrive. Eliminating alternate hosts for grasses can reduce their population potential. These biological and cultural control practices can be beneficial but often unreliable, which is why spider mite management on corn relies heavily on synthetic chemicals. New active ingredients such as etoxazole, dimethoate and fenpyroximate have been recentlyintroduced in the market to control spider mites more effectively. Preventive treatments at the beginning of the season can bring significant economic advantage. This effectiveness is greatly enhanced by aerial treatments.  Electrostatic nozzles, for example, have been shown to be 3 times more effective than conventional hydraulic nozzles in controlling corn spider mites. Keywords: Phytophagous mites, maize, natural enemies, synthetic chemicals, aerial treatmen

The Dirac field in Taub-NUT background

We investigate the SO(4,1) gauge-invariant theory of the Dirac fermions in the external field of the Kaluza-Klein monopole, pointing out that the quantum modes can be recovered from a Klein-Gordon equation analogous to the Schr\" odinger equation in the Taub-NUT background. Moreover, we show that there is a large collection of observables that can be directly derived from those of the scalar theory. These offer many possibilities of choosing complete sets of commuting operators which determine the quantum modes. In addition there are some spin- like and Dirac-type operators involving the covariantly constant Killing-Yano tensors of the hyper-K\" ahler Taub-NUT space. The energy eigenspinors of the central modes in spherical coordinates are completely evaluated in explicit, closed form.Comment: 20 pages, latex, no figure

Explicit Construction of Yang-Mills Instantons on ALE Spaces

We describe the explicit construction of Yang-Mills instantons on ALE spaces, following the work of Kronheimer and Nakajima. For multicenter ALE metrics, we determine the abelian instanton connections which are needed for the construction in the non-abelian case. We compute the partition function of Maxwell theories on ALE manifolds and comment on the issue of electromagnetic duality. We discuss the topological characterization of the instanton bundles as well as the identification of their moduli spaces. We generalize the 't Hooft ansatz to SU(2) instantons on ALE spaces and on other hyper-Kahler manifolds. Specializing to the Eguchi-Hanson gravitational background, we explicitly solve the ADHM equations for SU(2) gauge bundles with second Chern class 1/2, 1 and 3/2.Comment: 59 pages, epsf.tex, 2 figures included, uuencoded fil

Instanton-Meron Hybrid in the Background of Gravitational Instantons

When it comes to the topological aspects, gravity may have profound effects even at the level of particle physics despite its negligibly small relative strength well below the Planck scale. In spite of this intriguing possibility, relatively little attempt has been made toward the exhibition of this phenomenon in relevant physical systems. In the present work, perhaps the simplest and the most straightforward new algorithm for generating solutions to (anti) self-dual Yang-Mills (YM) equation in the typical gravitational instanton backgrounds is proposed and then applied to find the solutions practically in all the gravitational instantons known. Solutions thus obtained turn out to be some kind of instanton-meron hybrids possessing mixed features of both. Namely, they are rather exotic type of configurations obeying first order (anti) self-dual YM equation which are everywhere non-singular and have finite Euclidean YM actions on one hand while exhibiting meron-like large distance behavior and carrying generally fractional topological charge values on the other. Close inspection, however, reveals that the solutions are more like instantons rather than merons in their generic natures.Comment: 33pages, Revtex, typos correcte

Finite energy/action solutions of p1p_1 Yang-Mills equations on p2p_2 Schwarzschild and deSitter backgrounds for dimension d≥4d \ge 4

Physically relevant gauge and gravitational theories can be seen as special members of hierarchies of more elaborate systems. The Yang-Mills (YM) system is the first member of a hierarchy of Lagrangians which we will index by $p_1$, and the Einstein-Hilbert (EH) system of general relativity is the first member of another hierarchy which we index by $p_2$. In this paper, we study the classical equations of the $p_1 = 1,2$ YM hierarchy considered in the background of special geometries (Schwarzschild, deSitter,anti-deSitter) of the $p_2=1,2,3$ EH hierarchy. Solutions are obtained in various dimensions and lead to several examples of non-self-dual YM fields. When $p_1=p_2$ self-dual solutions exist in addition. Their action is equal to the Chern-Pontryagin charge and can be compared with that of the non-self-dual solutions.Comment: LaTeX, 25 pages, 2 figures, new title, minor change

Anti-de-Sitter regular electric multipoles: Towards Einstein-Maxwell-AdS solitons

We discuss electrostatics in Anti-de-Sitter (AdS) spacetime, in global coordinates. We observe that the multipolar expansion has two crucial differences to that in Minkowski spacetime. First, there are everywhere regular solutions, with finite energy, for every multipole moment exceptfor the monopole. Second, all multipole moments decay with the same inverse power of the areal radius, 1/r, as spatial infinity is approached. The first observation suggests there may be regular, self-gravitating, EinsteinMaxwell solitons in AdSspacetime. The second observation, renders a Lichnerowicz-type no-soliton theorem inapplicable. Consequently, we suggest Einstein-Maxwell solitons exist in AdS, and we support this claim by computing the first order metric perturbations sourced by test electric field multipoles, which are obtained analytically in closed form

Yang-Mills Solutions on Euclidean Schwarzschild Space

We show that the apparently periodic Charap-Duff Yang-Mills `instantons' in time-compactified Euclidean Schwarzschild space are actually time independent. For these solutions, the Yang-Mills potential is constant along the time direction (no barrier) and therefore, there is no tunneling. We also demonstrate that the solutions found to date are three dimensional monopoles and dyons. We conjecture that there are no time-dependent solutions in the Euclidean Schwarzschild background.Comment: 12 pages, references added, version to appear in PR

The Dirac equation in Taub-NUT space

Using chiral supersymmetry, we show that the massless Dirac equation in the Taub-NUT gravitational instanton field is exactly soluble and explain the arisal and the use of the dynamical (super) symmetry.Comment: An importatn misprint in a reference is corrected. Plain Tex. 8 page