Hadron Electro-production in Cold Nuclear Matter at HERMES.

The influence of the nuclear medium on lepto-production of hadrons was studied in the HERMES experiment at DESY using semi-inclusive deep-inelastic scattering of 27.6 GeV positrons off deuterium, helium, nitrogen, neon, krypton, and xenon targets. The differential multiplicity of krypton relative to that of deuterium has been measured for the first time for various identified hadrons (π+, π-, π0, K+, K-, p and p) as a function of the virtual photon energy ν, the fraction z of this energy transferred to the hadron, and the hadron transverse momentum squared pt2. By studying the attenuation of leading and sub-leading hadrons in various nuclei, it is investigated how the hadron absorption and energy loss mechanisms contribute to the formation of hadrons. © 2006 American Institute of Physics [ABSTRACT FROM AUTHOR]