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<font color="#000099"><b><font color="#3333ff">Physics Seminar<br>
</font></b></font><font color="#3333ff"><b>April 6, 2012<br>
11:00 AM<br>
CEBAF Center AUD.<br>
Cookies and Coffee 10:45AM<br>
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<font color="#cc0000"><b>Jin Huang
<br>
Los Alamos National Laboratory</b>
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<font color="#990000"><b><font color="#cc0000">"Clues to New Quark
Behavior"</font>
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New measurements of novel spin phenomena in deep inelastic
electron-neutron scattering (DIS) provide the first experimental
indication of a longitudinal quark polarization inside a transversely
polarized nucleon. Such a polarization, known as transversal helicity,
can only be observed if the quarks undergo orbital motion inside the
nucleon. In the first measurement of its kind, transversal helicity was
accessed at Hall A 6 GeV Transversity Experiment, through the
beam-target double spin asymmetry for charged pion electroproduction in
DIS on a transversely polarized He-3 target. A state-of-the-arts
polarized He-3 target was used as an effective polarized neutron
target, which is sensitive to the d-quark distributions in the nucleon.
Systematic uncertainties were minimized due to the frequent reversal of
both the beam helicity and the target spin. This result was recently
published in PRL. Related future experiments will also be discussed.
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