Statistical description with anisotropic momentum distributions for hadron production in nucleus-nucleus collisions

The various experimental data at AGS, SPS and RHIC energies on hadron particle yields for central heavy ion collisions are investigated by employing a generalized statistical density operator, that allows for a well-defined anisotropic local momentum distribution for each particle species, specified by a common streaming velocity parameter. The individual particle ratios are rather insensitive to a change in this new intensive parameter. This leads to the conclusion that the reproduction of particle ratios by a statistical treatment does not imply the existence of a fully isotropic local momentum distribution at hadrochemical freeze-out, i.e. a state of almost complete thermal equilibrium.Comment: 14 pages, revtex, 3 figures accepted version, to be published in Journal of Physics

Collective correlations in C12

The strong coupling of the giant resonance to the surface vibrations in C12 results in the splitting of the single one-particle, one-hole, 1- collective state into several components, thus improving the agreement between theory and experiment to a very large extent

Collective correlations in spherical nuclei and the structure of giant resonances

The theory of collective correlations in nuclei is formulated for giant resonances interacting with surface vibrations. The giant dipole states are treated in the particle-hole framework, while the surface vibrations are described by the collective model. Consequently, this treatment of nuclear structure goes beyond both the common particle-hole model (including its various improvements which take ground-state correlations into account) and the pure collective model. The interaction between giant resonances and surface degrees of freedom as known from the dynamic collective theory is formulated in the particle-hole language. Therefore, the theory contains the particle-hole structures and the most important "collective intermediate" structures of giant resonances. Detailed calculations are performed for 12C, 28Si, and 60Ni. A good detailed agreement between theory and experiment is obtained for all these nuclei, although only 60Ni is in the region where one would expect the theory to work well (50< A <110)

Top-spin analysis of new scalar and tensor interactions in e^+ e^- collisions with beam polarization

We utilize top polarization in the process e+ e-\rightarrow t\bar{t} at the ILC with transverse beam polarization to probe interactions of the scalar and tensor type beyond the standard model and to disentangle their individual contributions. 90% confidence level limits on the interactions with realistic integrated luminosity are presented and are found to improve by an order of magnitude compared to the case when the spin of the top quark is not measured. Sensitivities of the order of a few times 10^{-3} TeV^{-2} for real and imaginary parts of both scalar and tensor couplings at \sqrt{s}=500 and 800 GeV with an integrated luminosity of 500 fb^{-1} and completely polarized beams is shown to be possible. A powerful model-independent framework for inclusive measurements is employed to describe the spin-momentum correlations and their C, P and T properties is presented in a technical appendix.Comment: 14 pages, 10 figures, uses revtex; replaced with version accepted for publication in Physical Review D; significantly rewritten and reformulated, section added, inclusive section moved to appendix, reference adde

A Note on a Particle-Antiparticle Interaction

We develop an iso spin like formulation with particles and their anti particle counterparts. This leads to a new shortlived interaction between them, valid at very high energies and mediated by massive particles. We point out that evidence for this is already suggested by the very recent observations by the CDF team at Fermi Lab.Comment: 8 pages latex; Int.J.Mod.Phys E, 201