Application of the two-scale model to the HERMES data on nuclear attenuation

The two-scale model and its improved version were used to perform a fit to the HERMES data for the (the virtual photon energy) and z (the fraction of carried by hadron) dependences of the nuclear multiplicity ratios for and mesons electro-produced on two nuclear targets (¹⁴N and ⁸⁴Kr). The quantitative criterion was used for the first time to analyze the results of the model fit to the nuclear multiplicity ratios data. The two-parameter's fit gave satisfactory agreement with the HERMES data. Best values of the parameters were then used to calculate the and z dependences of the nuclear attenuation for , K ⁺ , K^-, and produced on the ⁸⁴Kr target, and also make predictions for , z, and the Q² (the photon virtuality) dependences of the nuclear attenuation data for those identified hadrons and nuclei that will be published by HERMES. Received: 10 February 2005, Revised: 7 July 2005, Published online: 13 September 2005 L. Grigoryan Supported by DESY, Deutsches Elektronen-Synchrotron.