Final tau-neutrino results from the DONuT experiment

The DONuT experiment collected data in 1997 and published first results in 2000 based on four observed ν_τ charged-current (CC) interactions. The final analysis of the data collected in the experiment is presented in this paper, based on 3.6×10¹⁷ protons on target using the 800 GeV Tevatron beam at Fermilab. The number of observed ν_τ CC events is 9 with an estimated background of 1.5 events, from a total of 578 observed neutrino interactions. We calculate the ν_τ CC cross section as a function of one parameter. Assuming Dₛ mesons are the sole source for ν_τ, the energy-independent part of the total CC cross section can be parametrized as ${{σ}}ᶜᵒⁿˢᵗ({{ν}}_{{τ}})=2.51{n}1.52×{}{10}^{{-}40} {cm}² {GeV}^{{-}1}$ for $n{≥}4$, where $n$ is the parameter controlling the longitudinal part of the ${D}ₛ$ differential cross section of the form $d{σ}/d{x}F{∝}(1{-}|{x}F|{)}ⁿ$. The analysis could not distinguish between ${{ν}}_{{τ}}$ and ${{{ν}}}_{{τ}}$. The value of $n$ obtained from Pythia simulations, $n=6.1$, gives an estimated value of ${{σ}}ᶜᵒⁿˢᵗ({{ν}}_{{τ}})=(0.39±{}0.13±{}0.13)×{}{10}^{{-}38} {cm}² {GeV}^{{-}1}$.