The RHIC high energy collision of species ranging from p+p, p(d)+A to A+A provide access to the small-x component of the hadron wave function. The RHIC program has brought renewed interest in that subject with its ability to reach values of the parton momentum fraction smaller than 0.01 with studies of particle production at high rapidity. Furthermore, the use of heavy nuclei in the p(d)+A collisions facilitates the study of saturation effects in the gluonic component of the nuclei because t8he appropriate scale for that regime grows as A i . We review the experimenta,l results of the RHIC program that have relevance to small-x emphasizing the physics extractled from d+Au collisions and their comparison to p+p collisions at the same energy.

No abstract

No abstract

We propose the necessary and sufficient condition for the presence of quantum entanglement in arbitrary symmetric pure states of two-level atomic systems. We introduce a parameter to quantify quantum entanglement in such systems. We express the inherent quantum fluctuations of a composite system of two-level atoms as a sum of the quantum fluctuations of the individual constituent atoms and their correlation terms. This helps to separate out and study solely the quantum correlations among the atoms and obtain the criterion for the presence of entanglement in such multiatomic systems.

Abstract. We discuss generic spin squeezing operators (quadratic in angular momentum operators) capable of squeezing out quantum mechanical noise from a system of two-level atoms (spins) in a coherent state. Such systems have been considered by Kitagawa and Ueda (Refs. 2) in this context and a Hamiltonian of this nature governs the Lipkin model (Ref. 14) which is relevant to nuclear physics.