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<b> Theory Center Seminar </b><br>
Monday, Nov. 26, 2012<br>
1:00 p.m. (coffee at 12:45 p.m.)<br>
CEBAF Center, Room F113<br>
<br>
<br>
Igor Akushevich<br>
Duke University/Jefferson Lab<br>
<br>
<b> Exact Calculation of Radiative Corrections in DVCS and SIDIS <br>
</b> <br>
The experimental precision achievable in modern experiments on
ep-scattering allows for measuring the cross section and spin
asymmetries in Bethe-Heitler (BH) and semi-inclusive deep inelastic
scattering (SIDIS) processes with unprecedented accuracies. The QED
radiative correction is one serious source of systematical
uncertainties and therefore must be known with any predetermined
accuracy. Several available calculations provide only leading
logarithm accuracy (for BH), performed only for unpolarized target
(for SIDIS), and/or have certain other limitations. In this report
we present the results of exact calculation of RC for BH process for
unpolarized target as well as for both longitudinally and
transversely polarized targets. Details of the calculations of the
three key components such as i) the calculation of the cross section
of two-photon-emission process and analytic integration over
additional kinematical variables, ii) extraction of infrared
divergence using the dimensional regularization, and iii)
calculation of loop effects with extraction and complete
cancellation of the infrared divergence, are discussed. Also we
present an approach for exact calculation of RC in semi-inclusive
process. The general task of exactly calculated RC in semi-inclusive
processes for arbitrary target polarization requires the calculation
of the covariant SIDIS hadronic tensor, important intermediate
quantity. Recent results for its calculation are presented and
discussed.
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