4,500 research outputs found
Single Leptoquark Production at and Colliders
We consider single production of leptoquarks (LQ's) at and
colliders, for two values of the centre-of-mass energy,
GeV and 1 TeV. We find that LQ's which couple within the first
generation are observable for LQ masses almost up to the kinematic limit, both
at and colliders, for the LQ coupling strength equal to
. The cross sections for single production of - and
-generation LQ's at colliders are too small to be observable.
In collisions, on the other hand, -generation LQ's with
masses much larger than can be detected. However,
-generation LQ's can be seen at colliders only for
masses at most , making their observation more probable via the
pair production mechanism.Comment: plain TeX, 14 pages, 6 figures (not included but available on
request), some minor changes to the text, one reference added, figures and
conclusions unchanged, UdeM-LPN-TH-93-152, McGill-93/2
Field-dependent diamagnetic transition in magnetic superconductor
The magnetic penetration depth of single crystal
was measured down to 0.4 K in dc fields up
to 7 kOe. For insulating , Sm spins order at the
N\'{e}el temperature, K, independent of the applied field.
Superconducting ( K) shows a
sharp increase in diamagnetic screening below which varied from
4.0 K () to 0.5 K ( 7 kOe) for a field along the c-axis. If the
field was aligned parallel to the conducting planes, remained
unchanged. The unusual field dependence of indicates a spin freezing
transition that dramatically increases the superfluid density.Comment: 4 pages, RevTex
An Introduction to Breakdown Phenomena in Disordered Systems
The rupture of a medium under stress typifies breakdown phenomena. More
generally, the latter encompass the dynamics of systems of many interacting
elements governed by the interplay of a driving force with a pinning disorder,
resulting in a macroscopic transition. A simple mean-field formalism
incorporating these features is presented and applied to systems representative
of fracture phenomena, social dilemmas, and magnets out of equilibrium. The
similarities and differences in the corresponding mathematical structures are
emphasized. The solutions are best obtained from a graphical method, from which
very general conclusions may be drawn. In particular, the various classes of
disorder distribution are treated without reference to a particular analytical
or numerical form, and are found to lead to qualitatively different
transitions. Finally, the notion of effective (or phenomenological) theory is
introduced and illustrated for non-equilibrium disordered magnets.Comment: Pedagogical article published as part of a special issue on
thermodynamics and statistical physics; 20 page
Electron cyclotron maser emission mode coupling to the z-mode on a longitudinal density gradient in the context of solar type III bursts
Copyright 2012 American Institute of Physics. This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Institute of Physics. This article appeared in Physics of Plasmas 19, 110702 (2012) and may be found at .supplemental material at http://astro.qmul.ac.uk/~tsiklauri/sp.htmlsupplemental material at http://astro.qmul.ac.uk/~tsiklauri/sp.htm
The effect of electron beam pitch angle and density gradient on solar type III radio bursts
Copyright 2012 American Institute of Physics. This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Institute of Physics. This article appeared in Physics of Plasmas 19, 112903 (2012) and may be found at .supplemental material at http://astro.qmul.ac.uk/~tsiklauri/sp.htmlsupplemental material at http://astro.qmul.ac.uk/~tsiklauri/sp.htm
Evolution of Universe to the present inert phase
We assume that current state of the Universe can be described by the Inert
Doublet Model, containing two scalar doublets, one of which is responsible for
EWSB and masses of particles and the second one having no couplings to fermions
and being responsible for dark matter. We consider possible evolutions of the
Universe to this state during cooling down of the Universe after inflation. We
found that in the past Universe could pass through phase states having no DM
candidate. In the evolution via such states in addition to a possible EWSB
phase transition (2-nd order) the Universe sustained one 1-st order phase
transition or two phase transitions of the 2-nd order.Comment: 19 pages, 3 figure
Higgs Boson Interference in
We study interference effects between resonant and nonresonant amplitudes for
the process at a backscattered
photon-photon collider. We show that a Higgs boson with > 200 GeV is
manifest as a resonant dip in the invariant mass spectrum and we
investigate its statistical significance.Comment: 8 pages (LaTeX) + 5 PostScript figures in accompanying file
(uuencoded), figures also available by fax upon request to
[email protected], UCLA/TEP/93/3
Evolution of Universe to the present inert phase
We assume that current state of the Universe can be described by the Inert
Doublet Model, containing two scalar doublets, one of which is responsible for
EWSB and masses of particles and the second one having no couplings to fermions
and being responsible for dark matter. We consider possible evolutions of the
Universe to this state during cooling down of the Universe after inflation. We
found that in the past Universe could pass through phase states having no DM
candidate. In the evolution via such states in addition to a possible EWSB
phase transition (2-nd order) the Universe sustained one 1-st order phase
transition or two phase transitions of the 2-nd order.Comment: 19 pages, 3 figure
Softer than normal, but not as soft as one might think: Spontaneous flux lattices in ferromagnetic spin-triplet superconductors
A theory is developed for the spontaneous vortex lattice that is expected to
occur in the ferromagnetic superconductors ZrZn_2, UGe_2, and URhGe, where the
superconductivity is likely of spin-triplet nature. The long-wavelength
fluctuations of this spontaneous flux lattice are predicted to be huge compared
to those of a conventional flux lattice, and to be the same as those for
spin-singlet ferromagnetic superconductors. It is shown that these fluctuations
lead to unambiguous experimental signatures which may provide the easiest way
to observe the spontaneous flux lattice.Comment: 4pp, 1 eps fi
Complete description of polarization effects in e^+e^- pair production by a photon in the field of a strong laser wave
We consider production of a e^+e^- pair by a high-energy photon in the field
of a strong laser wave. A probability of this process for circularly or
linearly polarized laser photons and for arbitrary polarization of all other
particles is calculated. We obtain the complete set of functions which describe
such a probability in a compact invariant form. Besides, we discuss in some
detail the polarization effects in the kinematics relevant to the problem of
electron-photon conversion at photon-photon and electron-photon colliders.Comment: 14 pages, 8 figure
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