Speaker
Description
The Standard Model is a very beautiful model yet there are still some remain questions which we are curious
about. The Large Hadron Collider (LHC) may or may not provide some of the answers to some some of these
questions. The future international electron-positron collide (ILC) with 200-500 GeV (extendable to 1 TeV)
center of mass high luminosity may provide a window into some of the mysteries that we are hoping to solve.
Which state that our Universe lies in is one of the most crucial and interesting topic for physicists, thus the
precise measurement of the top quark properties is important and necessary. In this thesis, we would like to
discuss this process: e+e ! t?t. Using GRACE system with polarization, we present the di?erence between
the total cross section as the function of CM energy of t?t pair production with the left-handed electron and
right-handed positron initial polarization in both tree level and full electroweak correction. The cross section
with e
Le+
R polarization is larger than the cross section with e
Re+
L polarization. Nevertheless, the radiative
correction of e
Le+
R polarization is smaller than the radiative correction of e
Re+
L polarization. The angular
distributions also con?rm this behavior due to the e?ects of the polarization. For the top quark, since the
forward-backward asymmetry AFB of the top quark is considerable among unpolarized case, left-right and
right left polarization, it should be taken into account at ILC. We also show the property of top quark decay
t ! b + ?+ + ?? included the ?nal polarization. We conclude that by using GRACE system with the e?ect
of polarization, we can distinguish the left-right and right-left for the total cross section, angular distribution,
forward-backward asymmetry at tree level and full electroweak correction. Especially for the top quark, we are
able to calculate with both initial and ?nal polarization. In conclusion, polarization e?ects are essential to ?gure
out the properties of fermions especially the top quark at the future ILC. With GRACE system, total cross
section, angular distribution, energy distribution can be calculated with beam initial and ?nal polarization for
both tree level and full electroweak correction.
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