Results 1 - 10 of 6342
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[en] We study topological as well as dynamical properties of BPS nonabelian magnetic monopoles of Goddard-Nuyts-Olive-Weinberg type in G = SU(N), USp(2N) and SO(N) gauge theories, spontaneously broken to nonabelian subgroups H. We find that monopoles transform under the group dual to H in a tensor representation of rank determined by the corresponding element in π1(H). When the system is embedded in a N = 2 supersymmetric theory with an appropriate set of flavors with appropriate bare masses, the BPS monopoles constructed semiclassically persist in the full quantum theory. This result supports the identification of 'dual quarks' found at r-vacua of N = 2 theories with the nonabelian magnetic monopoles. We present several consistency checks of our monopole spectra
[en] We consider the monopole contamination of the normal sequence, ca.1 Msun companion star of the fast binary pulsar PSR 1953 + 29. We find that the photosphere of this star is practically monopole free,i.e. the number ratio r of photospheric monopoles to nucleons is r < 3 x 10-29. If the Rubakov effect exists at the predicted level, the much stronger limit r < 1.2 x 10-42 is obtained and the Galactic isotropic flux is bounded by F < 1.3 x 10-20 cm-2 sr-1 s-1. 43 refs. (author)
[en] The present work discusses the classical electromagnetic theory in the presence of magnetic monopoles. We review the connection between such objects and the long standing problem of charge quantization and the main theoretical difficulties in formulating the classical dual electromagnetic theory in terms of an action principle. We show that a deeper understanding of the source of such difficulties leads naturally to the construction of a variational principle for a non-local Lagrangian from which all the (local) dynamical equations for electric, magnetic charges and fields can be obtained. (author)
[en] The hyperspherical harmonics which appear in the analysis of the planar three-body problem are explicitly expressed in terms of the harmonics of importance in the theory of magnetic monopoles. This connection is achieved by transforming the eigenvalue equations which define hyperspherical harmonics into the eigenvalue equations for monopole harmonics. This transformation requires the recognition of a gauge potential which arises in the three-body problem and which has the same form as that of a magnetic monopole. In this manner, explicit formulas for the two standard representations of the three-body harmonics are derived. The coupling coefficients between the two representations follow naturally from the derivation. Emphasis is placed on the gauge theoretical aspects of the derivations and the significance of gauge transformations is discussed. copyright 1997 The American Physical Society
[en] Recent claims of magnetic monopoles and strings in the Nano physics of spin-ice lattices are revised and analyzed. We start with a through explanation of the main features of the fundamental gauge monopoles and the related Dirac strings. After a careful analysis of the results and simulations we conclude that the observed excitations do not share any properties with the Dirac monopoles. We then critically examine the fascinating problem of the nature and interactions of the new objects, concluding that they are more subtle than claimed. (Author) 16 refs.
[en] A model consisting of a SO3 gauge field interacting with an isovector Higgs field is considered. When the original Higgs field mass parameter is imaginary, real-valued, static, radially symmetric, finite-energy magnetic-monopole solutions have been found to exist at the tree level of the classical theory. It is speculated that no such solutions exist at the one-loop level of this model
[en] Complete text of publication follows. High-speed video recordings of two lightning flashes confirm that positive cloud-to-ground (CG) strokes can be produced by extensive horizontal intracloud (IC) discharges within and near the cloud base. These recordings constitute the first observations of CG leaders emanating from IC discharges of either polarity. In one case, the discharge began with a negative leader that propagated horizontally, went upward and produced an IC discharge. After the beginning of the IC discharge, a positive leader emanated from the lowest portion of the IC discharge, and initiated a positive return stroke. In the other case, the IC discharge began with a positive leader and then initiated a downward-propagating positive leader that contained recoil processes and produced a bright return stroke followed by a long continuing luminosity. These observations help to understand the complex genesis of positive CG flashes, why IC lightning commonly precedes them and why extensive horizontal channels are often involved. The association of complex intracloud discharges with positive flashes suggests that positive discharges cannot always be modeled as the neutralization of simple, vertically stacked monopoles [Rakov, 2003]. Moreover, it can be helpful to studies on sprite morphology [Mika and Haldoupis, 2008] and to studies on why sprites are more common above some particular kind of storms [Lyons et al., 2008].
[en] It is suggested that the existence of gravitomagnetic monopoles may imply not only the quantisation of mass-energy but also the quantisation of frequency (and other rate-like quantities). It is possible that the magnitude of the poles may be determined by cosmological consideration and whilst it is unlikely that they can exist except at large distances from the Earth, their detection is, in principle, possible using gyroscopic rings. It is shown that these detection processes may involve an effect in which gyro-particles are created or destroyed. (author)