The time scale $Delta t$ parameter, which appears in the Bose-Einstein Correlations (BEC) treated in term of the Heisenberg uncertainty relations, is reexamined. Arguments are given for the role of $Delta t$ as a measure of the particles emission tim
e rather than representing the strength property of the correlated particles. Thus in the analyzes of the $Z^0$ hadronic the $Delta t$ given value of ~$10^{-24}$ seconds is the particles emission time prescribed by the $Z^0$ lifetime. In heavy ion collisions $Delta t$ measures the emission time duration of the particles produced from a nucleus of atomic number $A$ which is here shown to be equal to $Delta t =(m_{pi}a^2)/(hbar c^2})*A^{2/3}$ where a is about 1 fm, that is, proportional to the nucleus surface area. This dependence agrees rather well with the experimental $Delta t$ values deduced from the BEC analyzes of heavy ion collisions.
Full exploitation of the physics potential of a future International Linear Collider will require the use of polarized electron and positron beams. Experiment E166 at the Stanford Linear Accelerator Center (SLAC) has demonstrated a scheme in which an
electron beam passes through a helical undulator to generate photons (whose first-harmonic spectrum extended to 7.9MeV) with circular polarization, which are then converted in a thin target to generate longitudinally polarized positrons and electrons. The experiment was carried out with a one-meter-long, 400-period, pulsed helical undulator in the Final Focus Test Beam (FFTB) operated at 46.6GeV. Measurements of the positron polarization have been performed at five positron energies from 4.5 to 7.5MeV. In addition, the electron polarization has been determined at 6.7MeV, and the effect of operating the undulator with a ferrofluid was also investigated. To compare the measurements with expectations, detailed simulations were made with an upgraded version of Geant4 that includes the dominant polarization-dependent interactions of electrons, positrons, and photons with matter. The measurements agree with calculations, corresponding to 80% polarization for positrons near 6MeV and 90% for electrons near 7MeV.
In view of the start up of the 14 TeV pp Large Hadron Collider the quark anti-quark reactions leading to the final states W^+W^-, W^+-Z^0 and Z^0Z^0 are studied, in the frame workn of the Standard Model (SM), using helicity amplitudes. The differenti
al and total cross sections are first evaluated in the parton-parton center of mass system. They are then transformed to their expected behavior in pp collisions through the parton-parton Energy Density Functions which are here derived from the known Parton Density Functions of the proton. In particular the single and joint longitudinal polarizations of the final state di-bosons are calculated. The effect on these reactions from the presence of s-channel heavy vector bosons, like the W and Z, are evaluated to explore the possibility to utilize the gauge boson pair production as a probe for these Beyond the SM phenomena.
