Measurement of the highly Lorentz-boosted Higgs boson cross section in the decay mode of a pair of $\tau$ leptons in proton-proton collisions at $\sqrt{s}=13~\mathrm{TeV}$

A measurement of the highly Lorentz-boosted Higgs boson cross section is presented, where the Higgs boson decays to a pair of $\tau$ leptons and its transverse momentum is greater than 250 GeV. It is based on proton-proton collision data collected by the CMS experiment at the CERN LHC at a center-of-mass energy of 13 TeV. The data sample corresponds to an integrated luminosity of 138 fb$^{-1}$. The $\tau$ leptons are required to be spatially close, and a dedicated algorithm is used to reconstruct and identify them. The product of the production cross section and branching fraction is measured to be $1.64^{+0.68}_{-0.54}$ times the standard model expectation, which corresponds to an observed (expected) significance of 3.5 (2.2) standard deviations. The fiducial differential cross section of the Higgs boson is also measured as a function of the Higgs boson and leading jet transverse momenta.