Probing effective field theory operators in the associated production of top quarks with a $\mathrm{Z}$ boson in multilepton final states at $\sqrt{s} = 13~\mathrm{TeV}$

A search for new top quark interactions is performed within the framework of an effective field theory using the associated production of either one ($\mathrm{t}\mathrm{Z}$) or two ($\mathrm{t}\bar{\mathrm{t}}\mathrm{Z}$) top quarks with a $\mathrm{Z}$ boson in multilepton final states. The data sample corresponds to an integrated luminosity of $138~\mathrm{fb}^{-1}$ of proton-proton collisions at $\sqrt{s} = 13~\mathrm{TeV}$, collected by the CMS experiment at the CERN LHC. Five dimension-six operators modifying the electroweak interactions of the top quark are considered. Novel machine-learning techniques are used to enhance the sensitivity to effects arising from these operators. Distributions used for the signal extraction are parameterized in terms of Wilson coefficients (WCs) describing the interaction strengths of the operators. All five WCs are fit to the data and confidence intervals at $95\%$ confidence level are computed. All intervals contain the standard model expectations for the WC values.