Measurement of the $\mathrm{Z}\gamma^{*} \to \tau\tau$ cross section in pp collisions at $\sqrt{s} = $ 13 TeV and validation of $\tau$ lepton analysis techniques

TL;DR

This paper measures the Z/gamma* to tau tau cross section at 13 TeV using CMS data, confirming standard model predictions and validating analysis techniques for future tau lepton studies.

Contribution

It provides a precise measurement of the Z/gamma* to tau tau cross section and validates new analysis methods for tau lepton detection at the LHC.

Findings

Measured cross section: 1848 ± 12 (stat) ± 67 (syst+lumi) pb.

Validated tau reconstruction efficiency and energy scale with uncertainties of 2.2% and 0.9%.

Results agree with next-to-next-to-leading order standard model predictions.

Abstract

A measurement is presented of the $\mathrm{Z}/\gamma^{*} \to \tau\tau$ cross section in pp collisions at $\sqrt{s} = $ 13 TeV, using data recorded by the CMS experiment at the LHC, corresponding to an integrated luminosity of 2.3 fb$^{-1}$. The product of the inclusive cross section and branching fraction is measured to be $\sigma(\mathrm{pp} \to \mathrm{Z}/\gamma^{*}\text{+X}) \, \mathcal{B}(\mathrm{Z}/\gamma^{*} \to \tau\tau) = $ 1848 $\pm$ 12 (stat) $\pm$ 67 (syst+lumi) pb, in agreement with the standard model expectation, computed at next-to-next-to-leading order accuracy in perturbative quantum chromodynamics. The measurement is used to validate new analysis techniques relevant for future measurements of $\tau$ lepton production. The measurement also provides the reconstruction efficiency and energy scale for $\tau$ decays to hadrons+$\nu_{\tau}$ final states, determined with respective relative uncertainties of 2.2% and 0.9%.