Binned top quark spin correlation and polarization observables for the LHC at 13.6 TeV

We consider top-antitop quark <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"><a:mo stretchy="false">(</a:mo><a:mi>t</a:mi><a:mover accent="true"><a:mi>t</a:mi><a:mo stretchy="false">¯</a:mo></a:mover><a:mo stretchy="false">)</a:mo></a:math> production at the Large Hadron Collider (LHC) with subsequent decays into dileptonic final states. We use and investigate a set of leptonic angular correlations and distributions with which all the independent coefficient functions of the top-spin-dependent parts of the <g:math xmlns:g="http://www.w3.org/1998/Math/MathML" display="inline"><g:mi>t</g:mi><g:mover accent="true"><g:mi>t</g:mi><g:mo stretchy="false">¯</g:mo></g:mover></g:math> production spin density matrices can be experimentally probed. We compute these observables for the LHC center-of-mass energy 13.6 TeV within the Standard Model at next-to-leading order in the QCD coupling including the mixed QCD weak corrections. We determine also the <k:math xmlns:k="http://www.w3.org/1998/Math/MathML" display="inline"><k:mi>t</k:mi><k:mover accent="true"><k:mi>t</k:mi><k:mo stretchy="false">¯</k:mo></k:mover></k:math> charge asymmetry where we take in addition also the mixed QCD-QED corrections into account. In addition we analyze and compute possible new physics (NP) effects on these observables within effective field theory in terms of a gauge-invariant effective Lagrangian that contains the operators up to mass dimension six that are relevant for hadronic <o:math xmlns:o="http://www.w3.org/1998/Math/MathML" display="inline"><o:mi>t</o:mi><o:mover accent="true"><o:mi>t</o:mi><o:mo stretchy="false">¯</o:mo></o:mover></o:math> production. First, we compute our observables inclusive in phase space. Then, in order to investigate which region in phase space has, for a specific observable, a high NP sensitivity, we determine our observables also in two-dimensional <s:math xmlns:s="http://www.w3.org/1998/Math/MathML" display="inline"><s:mo stretchy="false">(</s:mo><s:msub><s:mi>M</s:mi><s:mrow><s:mi>t</s:mi><s:mover accent="true"><s:mi>t</s:mi><s:mo stretchy="false">¯</s:mo></s:mover></s:mrow></s:msub><s:mo>,</s:mo><s:mi>cos</s:mi><s:msubsup><s:mi>θ</s:mi><s:mi>t</s:mi><s:mo>*</s:mo></s:msubsup><s:mo stretchy="false">)</s:mo></s:math> bins, where <y:math xmlns:y="http://www.w3.org/1998/Math/MathML" display="inline"><y:msub><y:mi>M</y:mi><y:mrow><y:mi>t</y:mi><y:mover accent="true"><y:mi>t</y:mi><y:mo stretchy="false">¯</y:mo></y:mover></y:mrow></y:msub></y:math> denotes the <cb:math xmlns:cb="http://www.w3.org/1998/Math/MathML" display="inline"><cb:mi>t</cb:mi><cb:mover accent="true"><cb:mi>t</cb:mi><cb:mo stretchy="false">¯</cb:mo></cb:mover></cb:math>-invariant mass and <gb:math xmlns:gb="http://www.w3.org/1998/Math/MathML" display="inline"><gb:msubsup><gb:mi>θ</gb:mi><gb:mi>t</gb:mi><gb:mo>*</gb:mo></gb:msubsup></gb:math> is the top quark scattering angle in the <ib:math xmlns:ib="http://www.w3.org/1998/Math/MathML" display="inline"><ib:mi>t</ib:mi><ib:mover accent="true"><ib:mi>t</ib:mi><ib:mo stretchy="false">¯</ib:mo></ib:mover></ib:math> zero-momentum frame. Published by the American Physical Society 2024