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Measurement of single spin asymmetry and fifth structure function for the proton(electron vec, electron Kaon+)Lambda reaction with CEBAF Large Acceptance Spectrometer (CLAS) (open access)

Measurement of single spin asymmetry and fifth structure function for the proton(electron vec, electron Kaon+)Lambda reaction with CEBAF Large Acceptance Spectrometer (CLAS)

The single spin asymmetry, A{sub LT} ?, and the polarized structure function, ?{sub LT}?, for the p(e,e?K{sup +})? reaction in the resonance region have been measured and extracted using the CEBAF Large Acceptance Spectrometer (CLAS) at Jefferson Lab. Data were taken at an electron beam energy of 2.567 GeV. The large acceptance of CLAS allows for full azimuthal angle coverage over a large range of center-of-mass scattering angles. Results were obtained that span a range in Q{sup 2} from 0.5 to 1.3 GeV{sup 2} and W from threshold up to 2.1 GeV and were compared to existing theoretical calculations. The polarized structure function is sensitive to the interferences between various resonant amplitudes, as well as to resonant and non-resonant amplitudes. This measurement is essential for understanding the structure of nucleons and searching for previously undetected nucleon excited states (resonances) predicted by quark models. The W dependence of the ?{sub LT} ? in the kinematic regions dominated by s and u channel exchange (cos q{sup cm} k = ?0.50, ?0.167, 0.167) indicated possible resonance structures not predicted by theoretical calculations. The ?{sub LT} ? behavior around W = 1.875 GeV could be the signature of a resonance predicted by the quark …
Date: August 31, 2005
Creator: Nasseripour, Rahksha
System: The UNT Digital Library
Measurement of the 3He Spin Structure Functions in the Resonance Region: A Test of Quark-Hadron Duality on the Neutron (open access)

Measurement of the 3He Spin Structure Functions in the Resonance Region: A Test of Quark-Hadron Duality on the Neutron

One of the biggest challenges in the study of the nucleon structure is the understanding of the transition from partonic degrees of freedom to hadronic degrees of freedom. In 1970, Bloom and Gilman noticed that structure function data taken at SLAC in the resonance region average to the scaling curve of deep inelastic scattering (DIS). Early theoretical interpretations suggested that these two very different regimes can be linked under the condition that the quark-gluon and quark-quark interactions are suppressed. Substantial efforts are ongoing to investigate this phenomenon both experimentally and theoretically. Quark-hadron duality has been confirmed for the unpolarized structure function F{sub 2} of the proton and the deuteron using data from the experimental Hall C at Jefferson Lab (JLab). Indications of duality have been seen for the proton polarized structure function g{sub 1} and the virtual photon asymmetry A{sub 1} at JLab Hall B and HERMES. Because of the different resonance behavior, it is expected that the onset of duality for the neutron will happen at lower momentum transfer than for the proton. Now that precise spin structure data in the DIS region are available at large x, data in the resonance region are greatly needed in order to …
Date: August 31, 2006
Creator: Solvignon, Patricia
System: The UNT Digital Library