Resumo

DI NEZZA, Pasquale. Medium modification of fragmentation functions. Nucleus [online]. 2007, n.42, pp. 56-61. ISSN 0864-084X.

ABSTRACT The influence of the nuclear medium on lepto-production of hadrons was studied in semi-inclusive deep-inelastic scattering off several nuclear targets. In particular, at the HERMES experiment at DESY, the differential multiplicity for krypton relative to that of deuterium has been measured for the first time for various identified hadrons (p+, p-, p0, K+, K-, p and anti-p) as a function of the virtual photon energy n, the fraction z of this energy transferred to the hadron, and the hadron transverse momentum squared pt2. The distribution of the hadron transverse momentum is broadened towards high pt2 in the nuclear medium, in a manner resembling the Cronin effect previously observed in collisions of heavy ions and protons with nuclei. Moreover, by studying the hadron attenuation of the leading and sub-leading hadrons, it will be shown, for the first time, an additional tool for studying modifications of hadronization in nuclear matter.

Palavras-chave : deep inelastic scattering; functions; heavy ion reactions; nuclear fragmentation; elementary particles; inelastic scattering; interactions; nuclear reactions; particle interactions; postulated particles; scattering; lepton-baryon interactions; lepton-hadron interactions.

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