Renormalization scheme invariant analysis of the DIS structure functionsF 2 andF L

A renormalization scheme invariant analysis of the deep inelastic scattering structure functionF ₂ andF _L is performed. Expressions for the moments are given in this approach. We find a significant improvement of the agreement withR=σ _L /σ _T -SLAC data with respect to the conventional perturvative \((\overline {MS} )\) analysis. Higher twist corrections are also required confirming previous evidence.     

Subthreshold pion production from nucleus-nucleus collisions around 100 MeV/nucleon

Several global variables were tested with the aim to determine the impact parameter in nucleus-nucleus collisions producing pions at incident energies around 100 MeV/nucleon. The experimental set-up includes the MEDEA multidetector, part of which is used as a ⁰ spectrometer, and an additional hodoscope of plastic scintillators to cover very forward angles. A statistical model was used to generate bothinclusive and pion-triggered events. Selection ofwell measured events was made through the measured total parallel momentum. Among the different global variables which were tested, the average parallel velocity was seen to give the best correlation with the impact parameter.