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<tt>Theory Center Seminar</tt><tt><br>
</tt><tt>Monday, June 22, 2015</tt><tt><br>
</tt><tt>1:00 p.m. (coffee at 12:45 p.m.)</tt><tt><br>
CEBAF Center, Room L102<br>
<br>
</tt><tt><br>
</tt><tt>Cintia Willemyns (JSA/HUGS International Fellow)<br>
University of Buenos Aires <br>
<br>
<b>New </b><b>M</b><b>ass Relations for L=1 Excited Baryons </b><b><br>
</b><br>
It will be shown how the non-relativistic quark model, with both
flavor dependent <br>
and flavor independent effective quark-quark interactions, matches
to the $1/N_c$ <br>
quark operator basis. Analytic expressions in terms of radial
integrals are obtained <br>
for the $1/N_c$ operator coefficients. Several new, parameter free
relations between<br>
the masses and the two mixing angles of the negative parity $L=1$
excited baryons <br>
will be presented. They can discriminate between quark-quark
interactions with <br>
different spin-flavor structures. Within the present experimental
uncertainties,<br>
consistency with the best values of the mixing angles, as
determined by a recent <br>
global fit to masses and decays, does not exclude any of the two
most extreme <br>
possibilities of flavor dependent (independent) quark-quark
interactions, as <br>
generated by pion (gluon) exchange models.</tt><br>
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