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Theory Center Seminar<br>
Monday, March 25, 2013<br>
1:00 p.m. (coffee at 12:45 p.m.)<br>
CEBAF Center, Room L102<br>
<br>
Nathan Hall <br>
University of Adelaide<br>
<br>
<b>Interference Radiative Corrections to the Proton's Weak Charge </b><br>
<br>
Low energy precision experiments provide crucial tests of our
understanding of the Standard Model of particle physics. QWEAK is
one such experiment, aiming to measure the proton's weak charge,
QWp, to within 4%. Unfortunately, the theoretical prediction of QWp
has been difficult to pin down owing to disagreements over the
precise nature of certain higher-order radiative corrections and
this has left the interpretation of future results subject to
unwanted ambiguity. In this presentation, we examine the radiative
corrections arising specifically from gammaZ interference and show
that in fact, by using recent electron-deuteron parity-violating
asymmetries, together with well-determined parton distribution
functions, we can dramatically reduce the uncertainties associated
with these corrections. Having removed such concerns, we provide a
new estimate of both the gammaZ interference contribution and the
revised theoretical uncertainties associated with it.
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