Attraction And Repulsion Of Multi-Color Laser Beams In Plasmas: A Computational Study

The nonlinear interaction of high-power multi-color laser beams in plasmas is investigated numerically. Both the relativistic mass increase and the driven plasma wave contribute to the mutual beam-beam interaction and to the development of the electromagnetic cascade. The propagation of the individual cascade sidebands is modelled in the paraxial approximation. The resulting set of coupled nonlinear envelope equations is solved numerically using a newly developed pseudospectral method. We predict that two beams intersecting in the plasma can either attract or deflect each other depending on whether their frequency detuning is slightly below or above the electron Langmuir frequency.Physic

Fluctuations of Xmax and Primary Particle Mass Composition in the Range of Energy 5 10^{17} - 3 10^{19} ev by Yakutsk Data

The experimental distributions of \Xmax obtained with the Yakutsk EAS array at fixed energies of $5 \times10^{17}$, $1\times10^{18}$ and $5\times10^{18}$ eV are analysed. A recent version of the QGSJET model is used as a tool of our analysis. In the framework of this model, the most adequate mass composition of primary particles satisfying the experimental data on \Xmax is selected.Comment: 19th European Cosmic Ray Symposium, Aug 30 - Sep 3 2004, Florence, Italy. 3 pages, 1 figure. Submitted for publication in International Journal of Modern Physics

Hunting long-lived gluinos at the Pierre Auger Observatory

Eventual signals of split sypersymmetry in cosmic ray physics are analyzed in detail. The study focusses particularly on quasi-stable colorless R-hadrons originating through confinement of long-lived gluinos (with quarks, anti-quarks, and gluons) produced in pp collisions at astrophysical sources. Because of parton density requirements, the gluino has a momentum which is considerable smaller than the energy of the primary proton, and so production of heavy (mass ~ 500 GeV) R-hadrons requires powerful cosmic ray engines able to accelerate particles up to extreme energies, somewhat above 10^{13.6} GeV. Using a realistic Monte Carlo simulation with the AIRES engine, we study the main characteristics of the air showers triggered when one of these exotic hadrons impinges on a stationary nucleon of the Earth atmosphere. We show that R-hadron air showers present clear differences with respect to those initiated by standard particles. We use this shower characteristics to construct observables which may be used to distinguish long-lived gluinos at the Pierre Auger Observatory.Comment: 13 pages revtex, 9 eps figures. A ps version with high resolution figures is available at http://www.hep.physics.neu.edu/staff/doqui/rhadron_highres.p

The Affine-Metric Quantum Gravity with Extra Local Symmetries

We discuss the role of additional local symmetries related to the transformations of connection fields in the affine-metric theory of gravity. The corresponding BRST transformations connected with all symmetries (general coordinate, local Lorentz and extra) are constructed. It is shown, that extra symmetries give the additional contribution to effective action which is proportional to the corresponding Nielsen-Kallosh ghost one. Some arguments are given, that there is no anomaly associated with extra local symmetries.Comment: 14 pages in LATEX (The version of paper accepted for publication in Class. Quant. Grav.