93 research outputs found
Monopolium production from photon fusion at the Large Hadron Collider
Magnetic monopoles have attracted the attention of physicists since the founding of the electromagnetic theory. Their search has been a constant endeavor which was intensified when Dirac established the relation between the existence of monopoles and charge quantization. However, these searches have been unsuccessful. We have recently proposed that monopolium, a monopole-antimonopole bound state, so strongly bound that it has a relatively small mass, could be easier to find and become an indirect but clear signature for the existence of magnetic monopoles. In here we extend our previous analysis for its production to two photon fusion at LHC energies
Permeability of Microporous Carbon Preforms
The permeability of microporous amorphous carbon preforms with varying pore size and pore distributions has been experimentally examined. The porous structures have been characterized by mercury porosimetry and by quantitative metallography of pressure-infiltration-cast metal matrix composites based on the carbon preforms. The permeability shows a linear correlation with the fraction porosity and the square of the pore diameter
Monopolium: the key to monopoles
Dirac showed that the existence of one magnetic pole in the universe could offer an explanation for the discrete nature of the electric charge. Magnetic poles appear naturally in most Grand Unified Theories. Their discovery would be of greatest importance for particle physics and cosmology. The intense experimental search carried thus far has not met with success. Moreover, if the monopoles are very massive their production is outside the range of present day facilities. A way out of this impasse would be if the monopoles bind to form monopolium, a monopole- antimonopole bound state, which is so strongly bound, that it has a relatively small mass. Under these circumstances it could be produced with present day facilities and the existence of monopoles could be indirectly proven. We study the feasibility of detecting monopolium in present and future accelerators
Peak grain forecasts for the US High Plains amid withering waters
ACKNOWLEDGMENTS. This paper stems from discussions during the Ettersburg Ecohydrology Workshop in Germany (October 2018), with the corresponding manuscript preparation ensuing in subsequent months. The workshop was funded by the UNIDEL Foundation, Inc. and the University of Delaware. Accordingly, partial support for this paper derived from funding for the workshop. A.M. was supported by the US NSF (Grants NSF-AGS-1644382 and NSF-IOS-175489).Peer reviewedPublisher PD
Black Hole, Jet, and Disk: The Universal Engine
In this paper I review the results of our ongoing project to investigate the
coupling between accretion disk and radio jet in galactic nuclei and stellar
mass black holes. We find a good correlation between the UV bump luminosity and
the radio luminosities of AGN, which improves upon the usual [OIII]/radio
correlations. Taking mass and energy conservation in the jet/disk system into
account we can successfully model the correlation for radio-loud and radio-weak
quasars. We find that jets are comparable in power to the accretion disk
luminosity, and the difference between radio-loud and radio-weak may correspond
to two natural stages of the relativistic electron distribution -- assuming
that radio weak quasars have jets as well. The distribution of flat- and
steep-spectrum sources is explained by bulk Lorentz factors gamma_j ~ 5-10. The
absence of radio-loud quasars below a critical optical luminosity coincides
with the FR I/FR II break and could be explained by a powerdependent,
``closing'' torus. This points towards a different type of obscuring torus in
radio-loud host galaxies which might be a consequence of past mergers (e.g. by
the temporary formation of a binary black-hole). Interaction of the jet with
the closing torus might in principle also help to make a jet radio-loud.
Turning to stellar-mass black holes we find that galactic jet sources can be
described with the same coupled jet/disk model as AGN which is suggestive of
some kind of universal coupling between jet and accretion disk around compact
objects.Comment: to appear in ``Jets from Stars and Galactic Nuclei'', Springer
Lecture Notes, plain TeX, 16 pages, also at
http://www.astro.umd.edu/~hfalcke/publications.htm
Relação entre acidez e outros atributos quĂmicos em solos com teores elevados de matĂ©ria orgĂąnica
Recuperação da qualidade estrutural, pelo sistema plantio direto, de um Argissolo Vermelho
Benthic macroinvertebrate assemblages structure in two headwater streams, south-eastern Brazil
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