Search results for " format"
showing 10 items of 2156 documents
Discrete-ring vortex solitons
2010
We study analytically and numerically the existence and stability of discrete vortex solitons in the circular arrays of nonlinear optical waveguides, governed by the discrete nonlinear Schrodinger equation. Stable vortex breathers with periodically oscillating topological charge are identified and a continuous interpolating map is constructed which allows to recover trajectories of individual phase dislocations in the form of hyperbolic avoided crossings.
Long-Range interaction of temporal incoherent solitons
2014
Contrary to conventional solitons, temporal incoherent solitons are sustained by a defocusing nonlinearity with anomalous dispersion and exhibit a non-mutual attractive-repulsive interaction. We explain these results by a long-range Vlasov formalism.
Breather compactons in nonlinear Klein-Gordon systems
1999
We demonstrate the existence of a localized breathing mode with a compact support, i.e., a stationary breather compacton, in a nonlinear Klein-Gordon system. This breather compacton results from a delicate balance between the harmonicity of the substrate potential and the total nonlinearity induced by the substrate potential and the coupling forces between adjacent lattice sites.
Solitons in Nonlinear Transmission Lines
1996
Although solitary waves and solitons were originally discovered in the context of water waves and lattice dynamics, consideration of these physical systems (which will be considered in Chaps.5 and 8) leads to calculations far too involved for pedagogical purposes. Thus, for an introduction to the soliton concept, we therefore consider simple wave propagation in electrical nonlinear transmission lines and electrical networks.
Dynamical Aspects of Generalized Palatini Theories of Gravity
2009
We study the field equations of modified theories of gravity in which the Lagrangian is a general function of the Ricci scalar and Ricci-squared terms in Palatini formalism. We show that the independent connection can be expressed as the Levi-Civitagrave connection of an auxiliary metric which, in particular cases of interest, is related with the physical metric by means of a disformal transformation. This relation between physical and auxiliary metric boils down to a conformal transformation in the case of f(R) theories. We also show with explicit models that the inclusion of Ricci-squared terms in the action can impose upper bounds on the accessible values of pressure and density, which m…
Hidden Dirac Monopoles
2008
Dirac showed that the existence of one magnetic pole in the universe could offer an explanation of 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. I proposed a universe with magnetic poles which are not observed free because they hide in deeply bound monopole--anti-monopole states named monopolium. I discuss the realization of this proposal and its consistency with known cosmological features. I furthermore analyze its implications and the experimental signatures that confirm…
Generalized bottom-tau unification, neutrino oscillations and dark matter: Predictions from a lepton quarticity flavor approach
2017
We propose an $A_4$ extension of the Standard Model with a Lepton Quarticity symmetry correlating dark matter stability with the Dirac nature of neutrinos. The flavor symmetry predicts (i) a generalized bottom-tau mass relation involving all families, (ii) small neutrino masses are induced a la seesaw, (iii) CP must be significantly violated in neutrino oscillations, (iv) the atmospheric angle $\theta_{23}$ lies in the second octant, and (v) only the normal neutrino mass ordering is realized.
Revisiting pseudo-Dirac neutrinos
2001
We study the pseudo-Dirac mixing of left and right-handed neutrinos in the case where the Majorana masses M_L and M_R are small when compared with the Dirac mass, M_D. The light Majorana masses could be generated by a non-renormalizable operator reflecting effects of new physics at some high energy scale. In this context, we obtain a simple model independent closed bound for M_D. A phenomenologically consistent scenario is achieved with M_L,M_R ~ 10^{-7} eV and M_D ~ 10^{-5}-10^{-4} eV. This precludes the possibility of positive mass searches in the planned future experiments like GENIUS or in tritium decay experiments. If on the other hand, GENIUS does observe a positive signal for a Major…
The reactor mixing angle and CP violation with two texture zeros in the light of T2K
2012
We reconsider the phenomenological implications of two texture zeros in symmetric neutrino mass matrices in the light of the recent T2K result for the reactor angle and the new global analysis which gives also best fit values for the Dirac CP phase delta. The most important results of the analysis are: Among the viable cases classified by Frampton et al. only A1 and A2 predict the reactor mixing angle to be different from zero at 3 sigma. Furthermore these two cases are compatible only with a normal mass spectrum in the allowed region for the reactor angle. At the best fit value A1 and A2 predict 0.024 >= sin^2(theta13) >= 0.012 and 0.014 <= sin^2(theta13) <= 0.032, respectively…
Flavour-violating charged lepton decays in seesaw-type models
1994
Analytic expressions of lepton-flavour- and lepton-number-violating decays of charged leptons are derived in the context of general $SU(2)_L\otimes U(1)_Y$ seesaw scenarios that are motivated by grand unified theories (GUT's) or superstring models, in which left-handed and/or right-handed neutral singlets are present. Possible constraints imposed by cosmology and low-energy data are briefly discussed. The violation of the decoupling theorem in flavour-dependent graphs due to the presence of heavy neutral leptons of Dirac or Majorana nature is emphasized. Numerical estimates reveal that the decays $\tau^-\to e^-e^-e^+$ or $\tau^-\to e^-\mu^-\mu^+$ can be as large as $\sim 10^{-6}$, which may…