PRODUCTION OF \(\nu _{\tau }\) AND \(\bar {\nu }_{\tau }\) IN FIXED TARGET SHiP EXPERIMENT*

We discuss production cross sections of \(\nu _{\tau }\) and \(\bar {\nu }_{\tau }\) coming from the direct $D$$_{s}^{±}$ → $\tau$$^{+}$/$\tau$$^{-}$ \(\nu _{\tau }\)/\(\bar {\nu }_{\tau }\) and chain $D$$_{s}^{±}$ → $\tau$$^{+}$/$\tau$$^{-}$ → \(\nu _{\tau }\)/\(\bar {\nu }_{\tau }\) decays in $p$+$^{96}$Mo scattering with proton beam $E$$_{lab}$ = 400 GeV i.e. at $\sqrt{S}$$_{NN}$ = 27.4 GeV. We include two different $D$$_{s}^{±}$ meson production mechanisms: via charm fragmentation $c$ → $D$$_{s}^{+}$ and $\bar{c}$ → $D$$^{−}$ as well as via subleading fragmentation of strange quarks/antiquarks $s$ → $D$$^{−}$ and $\bar{s}$ → $D$$_{s}^{+}$. Estimates of a number of observed \(\nu _{\tau }\)/\(\bar {\nu }_{\tau }\) in the \(\nu _{\tau }\)/\(\bar {\nu }_{\tau }\) +$^{208}$Pb reaction, with 2 m long target are given.