<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>J</mml:mi><mml:mo>/</mml:mo><mml:mi>ψ</mml:mi></mml:math> photoproduction and polarization in <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline">

We calculate the production and polarization of direct <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"><a:mi>J</a:mi><a:mo>/</a:mo><a:mi>ψ</a:mi></a:math> in the improved color evaporation model in <c:math xmlns:c="http://www.w3.org/1998/Math/MathML" display="inline"><c:mi>e</c:mi><c:mo>+</c:mo><c:mi>p</c:mi></c:math> photoproduction. We present the production as functions of transverse momentum, mass of the hadronic final state, and inelasticity. We also present the polarization parameters <e:math xmlns:e="http://www.w3.org/1998/Math/MathML" display="inline"><e:msub><e:mi>λ</e:mi><e:mi>ϑ</e:mi></e:msub></e:math>, <g:math xmlns:g="http://www.w3.org/1998/Math/MathML" display="inline"><g:msub><g:mi>λ</g:mi><g:mi>φ</g:mi></g:msub></g:math>, and <i:math xmlns:i="http://www.w3.org/1998/Math/MathML" display="inline"><i:msub><i:mi>λ</i:mi><i:mrow><i:mi>ϑ</i:mi><i:mi>φ</i:mi></i:mrow></i:msub></i:math> in the helicity and the Collins-Soper frames, as well as the frame-invariant polarization parameter <k:math xmlns:k="http://www.w3.org/1998/Math/MathML" display="inline"><k:mover accent="true"><k:mi>λ</k:mi><k:mo stretchy="false">˜</k:mo></k:mover></k:math> as a function of transverse momentum and inelasticity. We find agreement with both <o:math xmlns:o="http://www.w3.org/1998/Math/MathML" display="inline"><o:mi>J</o:mi><o:mo>/</o:mo><o:mi>ψ</o:mi></o:math> unpolarized cross sections and the invariant polarization parameters as a function of <q:math xmlns:q="http://www.w3.org/1998/Math/MathML" display="inline"><q:msub><q:mi>p</q:mi><q:mi>T</q:mi></q:msub></q:math>. Published by the American Physical Society 2024