Perturbative T -odd asymmetries in the Drell-Yan process revisited

We calculate the perturbative <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"><a:mi>T</a:mi></a:math>-odd contributions to the lepton angular distribution in the Drell-Yan process. Using collinear factorization, we work at the first order in QCD perturbation theory where these contributions appear, <c:math xmlns:c="http://www.w3.org/1998/Math/MathML" display="inline"><c:mi mathvariant="script">O</c:mi><c:mo stretchy="false">(</c:mo><c:msubsup><c:mi>α</c:mi><c:mi>s</c:mi><c:mn>2</c:mn></c:msubsup><c:mo stretchy="false">)</c:mo></c:math>, and address both <h:math xmlns:h="http://www.w3.org/1998/Math/MathML" display="inline"><h:msup><h:mi>W</h:mi><h:mo>±</h:mo></h:msup></h:math> and <j:math xmlns:j="http://www.w3.org/1998/Math/MathML" display="inline"><j:mi>γ</j:mi><j:mo>/</j:mo><j:msup><j:mi>Z</j:mi><j:mn>0</j:mn></j:msup></j:math> boson exchange. A major focus of our calculation is on the regime where the boson’s transverse momentum <l:math xmlns:l="http://www.w3.org/1998/Math/MathML" display="inline"><l:msub><l:mi>Q</l:mi><l:mi>T</l:mi></l:msub></l:math> is much smaller than its mass <n:math xmlns:n="http://www.w3.org/1998/Math/MathML" display="inline"><n:mi>Q</n:mi></n:math>. We carefully expand our results up to next-to-next-to-leading power in <p:math xmlns:p="http://www.w3.org/1998/Math/MathML" display="inline"><p:msub><p:mi>Q</p:mi><p:mi>T</p:mi></p:msub><p:mo>/</p:mo><p:mi>Q</p:mi></p:math>. Our calculation provides a benchmark for studies of <r:math xmlns:r="http://www.w3.org/1998/Math/MathML" display="inline"><r:mi>T</r:mi></r:math>-odd contributions that employ transverse-momentum dependent parton distribution functions. In the neutral-current case we compare our results for the <t:math xmlns:t="http://www.w3.org/1998/Math/MathML" display="inline"><t:mi>T</t:mi></t:math>-odd structure functions to available ATLAS data. Published by the American Physical Society 2024