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<font color="#000099"><b><font color="#3333ff">Physics Seminar<br>
Friday, May 28, 2010<br>
11:00AM<br>
CEBAF Center AUD.<br>
Cookies & Coffee at 10:45AM<br>
<font color="#cc0000"><br>
</font></font></b></font><b><font color="#cc0000"><big>"Gauge
Invariance, Canonical Quantization in Nucleon Internal Structure"</big></font></b><br>
<br>
<b><font color="#cc0000"><big>Guorong Wang<br>
Nanjing University, China</big><br>
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I will discuss the old proton spin crisis caused by the DIS
measurement of quark spin and
the new spin crisis caused by the measurement of quark orbital angular
momentum. I will
show that the misidentification of the measured quark spin and orbital
angular momentum
disturbs the nucleon spin structure study. The three different
decompositions of nucleon total angular momentum and the related gauge
invariance and canonical quantization principles will also be
discussed. I suggest that a Lattice QCD calculation of the matrix
elements of the proper quark orbital angular momentum might lighten the
nucleon spin structure study.</tt><br>
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