Measurement of the Z/gamma* -> tau tau cross section in pp collisions at root s=13 TeV and validation of tau lepton analysis techniques
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Abstract
A measurement is presented of the (Z/{\gamma }^{\ast }\to \tau \tau ) cross section in (\text{pp}) collisions at (\sqrt{s}=13\phantom{\rule{0.333333em}{0ex}}\text{TeV}), using data recorded by the CMS experiment at the LHC, corresponding to an integrated luminosity of (2.3\phantom{\rule{0.333333em}{0ex}}{\text{fb}}^{-1}). The product of the inclusive cross section and branching fraction is measured to be (\sigma \left(\text{pp}\to Z/{\gamma }^{\ast }\text{+X}\right)\phantom{\rule{0.166667em}{0ex}}B\left(Z/{\gamma }^{\ast }\to \tau \tau \right)=1848±12\phantom{\rule{0.166667em}{0ex}}\left(\text{stat}\right)±67\phantom{\rule{0.333333em}{0ex}}\text{(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 (\phantom{\rule{0.166667em}{0ex}}+\phantom{\rule{0.166667em}{0ex}}{\nu }_{\tau }) final states, determined with respective relative uncertainties of 2.2 and 0.9%.