Nuclear Physics Seminar

"Hadronization studies at HERMES"

Presented by Charlotte Van Hulse, University of the Basque Country

Tuesday, September 20, 2016, 11:00 am — Small Seminar Room, Bldg. 510

The HERMES experiment at DESY, Hamburg, collected data using the 27.6 GeV HERA electron/positron beam incident on a variety of gaseous targets, among others transversely
polarized and unpolarized hydrogen as well as unpolarized deuterium, neon, krypton, and xenon. From the data taken with hydrogen and deuterium targets, charge-separated kaon and pion multiplicities in semi-inclusive deep-inelastic scattering were extracted. These allow the study of the spin-independent fragmentation of quarks into the identified hadrons. Hadronization in the nuclear environment studied via the analysis of multiplicities provides additional qualitative information on the space-time evolution of hadron formation. From the analysis of the azimuthal distribution of the produced hadrons, spin effects in hadronization can be studied, in particular the Collins fragmentation function, which
describes the formation of a transversely polarized quark into an unpolarized hadron. The latter fragmentation function can also be accessed independently analyzing semi-inclusive
deep-inelastic scattering events using the transversely polarized hydrogen target. The study of two-pion and two-kaon production from this same data sample provides access to a series of di-hadron fragmentation functions, including those in which the transverse spin of the
fragmenting quark is transferred to the relative orbital angular momentum of the hadron pair. An overview of the results of the mentioned analyses as well as their possible
interpretations will be presented.

Hosted by: Oleg Eyser

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