Measuring Hadronization Length in e^+ e^- \rightarrow K^0 {\bar{K}}^0 \gamma

We propose to study the space-time picture of hadronization by looking at the angular distribution of photons emitted in the process e^+ e^- \rightarrow K^0 {\bar{K}}^0 \gamma at DA{\Phi}NE energies. it is shown that the angular distributions are quite sensitive to the hadronization length.Comment: 5 pages, CERN-TH-7200/94, BI-TP 94/04, March 199

On event-by-event fluctuations in nuclear collisions

We demonstrate that a new type of analysis in heavy-ion collisions, based on an event-by-event analysis of the transverse momentum distribution, allows us to obtain information on secondary interactions and collective behaviour that is not available from the inclusive spectra. Using a random walk model as a simple phenomenological description of initial state scattering in collisions with heavy nuclei, we show that the event-by-event measurement allows a quantitative determination of this effect, well within the resolution achievable with the new generation of large acceptance hadron spectrometers. The preliminary data of the NA49 collaboration on transverse momentum fluctuations indicate qualitatively different behaviour than that obtained within the random walk model. The results are discussed in relation to the thermodynamic and hydrodynamic description of nuclear collisions

Nonlinear Gluon Evolution in the Color Glass Condensate: I

We consider a nonlinear evolution equation recently proposed to describe the small-$x$ hadronic physics in the regime of very high gluon density. This is a functional Fokker-Planck equation in terms of a classical random color source, which represents the color charge density of the partons with large $x$. In the saturation regime of interest, the coefficients of this equation must be known to all orders in the source strength. In this first paper of a series of two, we carefully derive the evolution equation, via a matching between classical and quantum correlations, and set up the framework for the exact background source calculation of its coefficients. We address and clarify many of the subtleties and ambiguities which have plagued past attempts at an explicit construction of this equation. We also introduce the physical interpretation of the saturation regime at small $x$ as a Color Glass Condensate. In the second paper we shall evaluate the expressions derived here, and compare them to known results in various limits.Comment: 67 pages, 7 eps figure