A self-induced transparency (SIT) phenomenon consists in the propagation of a powerful ultrashort pulse (USP) of light through a resonance medium without the distortion and energy loss of this pulse [1–4]. This phenomenon is characterised by the continuous absorption and re-emission of electromagnetic radiation by resonant atoms of medium in such a manner that steady-state optical pulse propagates. In the ideal case the energy dissipation of the USP is invisible, and the state of the resonant medium is not varying. It means that the medium is transparent. The group velocity of a such steady-state pulse, called 2π-pulse or soliton of SIT, is less than the phase speed of light in a medium. The group velocity depends on a 2π-pulse duration: the shorter is the duration, the higher is its speed [2–5]. When two pulses of the different velocities spread in the medium, the second pulse may overtake the first and a collision will take place. After the collision, the solitons keep their shape and velocity (but in general all other parameters of solitons may alter). This fundamental property of the SIT solitons has been studied many times both theoretically and experimentally [3,6,7].

Self-Induced Transparency

Solitons are nonlinear pulses which result from a balance between nonlinearity and dispersion. In this article examples are used to illustrate some connections between physical interacting systems and the solitons which such systems support. In different instances the interaction of an electric field with an assemblage of two-level atoms is shown to yield the solitons of self-induced transparency and the solitons of a nonlinear Schroedinger equation. One case of an electromagnetic wave interacting with a plasma is discussed which yields the solitons of the Kortewegde Vries equation. The interaction of a two-level atomic system with an electric field is used to introduce and to motivate the inverse scattering transform. Finally, connections between this transform, higher conservation laws, and Hamiltonian dynamics are discussed.

Aspects of Soliton Physics

CERN COMPASS plans measurements of γπ and γK interactions using 50–280 GeV pion (kaon) beams and a virtual photon target. Pion (kaon) polarizabilities and radiative transitions will be measured via Primakoff effect reactions such as π− γ → π−′ γ and π− γ → meson. The former can test a precise prediction of chiral symmetry; the latter for πγ → a 1 (1260) is important for understanding the polarizability. The radiative transition of a pion to a low mass two-pion system, π− γ → π−′ π0, can also be studied to measure the chiral anomaly amplitude F3π (characterizing γ → 3π) arising from the effective Chiral Lagrangian. We review here the motivation for the above physics program. We describe the beam, target, detector, and trigger requirements for these experiments. We also describe FNAL SELEX attempts to study related physics via the interaction of 600 GeV pions with target electrons. Data analysis in progress aims to identify the reactions πe → π′e′π0 related to the chiral anomaly, and πe → π′e′γ related to pion polarizabilities.

http://cds.cern.ch/record/342354/files/9801008.pdf

Pion and kaon polarizabilities and radiative transitions

Pion and sigma polarizabilities and radiative transitions

During the past few years there has been an increasing interest in solitons. The soliton and its remarkable properties are well known to those already familiar with the history of coherent optics since one of the earliest examples of a soliton was the 2π pulse of self-induced transparency [1]. In that instance a satisfactory mathematical setting for the soliton was completely provided by the coupled Maxwell and Schroedinger-Bloch equations. The situation is not as satisfactory in regard to the equations that have more recently been shown to exhibit soliton behavior, however. To solve these equations, certain linear equations analogous to the equations for the two-level atom have been introduced [2] in a somewhat ad hoc fashion.

J. Lach

Papers

Search for Ξ - , Σ - , and Ω - production by negative hyperons on nuclei

J. Lach

Papers

Search for Ξ *- , Σ *- , and Ω - production by negative hyperons on nuclei

Search for Ξ - , Σ - , and Ω - production by negative hyperons on nuclei