28 July 2020 to 6 August 2020
virtual conference
Europe/Prague timezone

Production of $\nu_{\tau}$ neutrinos and ${\overline \nu}_{\tau}$ antineutrinos - elaborate calculation for a fixed target experiment SHiP

31 Jul 2020, 11:15
virtual conference

virtual conference

Talk 02. Neutrino Physics Neutrino Physics


Rafal Maciula (Institute of Nuclear Physics PAN) Antoni Szczurek (Institute of Nuclear Physics)


We discuss how to calculate cross sections as well as rapidity, transverse momentum and energy distributions of $\nu_{\tau}$ and ${\overline \nu}_{\tau}$ produced from the direct $D_s^{\pm} \to \nu_{\tau}/{\overline \nu}_{\tau}$ and chain $D_s^{\pm} \to \tau^+/\tau^- \to \nu_{\tau}/{\overline \nu}_{\tau}$ decays in $p\!+^{96}\!\mathrm{Mo}$ scattering with proton beam $E_{\mathrm{lab}}$ = 400 GeV \textit{i.e.} at $\sqrt{s}_{NN}$ = 27.4 GeV. Both direct neutrinos and neutrinos from $\tau$ lepton decays (chain decays) are included. The $\tau$ decays are simulated with the help of the \textsc{Tauola} code and include large number of decay channels. In our calculations we include $D_s^{\pm}$ from charm fragmentation ($c \to D_s^{+}$ and $\bar c \to D_s^-$) as well as those from
subleading fragmentation of strange quarks/antiquarks $s \to D_s^-$ and $\bar s \to D_s^+$. The $s \ne \bar s$ asymmetry of the strange quark content of proton is included. The different contributions to $D_s^{\pm}$ and $\nu_{\tau} / {\overline \nu}_{\tau}$ are shown explicitly. We discuss and quantify a not discussed so far effect of asymmetries for production of $\nu_{\tau}$ and ${\overline \nu}_{\tau}$ caused by (helicity) polarization of $\tau^{\pm}$ from the first (weak) decay $D_s^{\pm} \to \tau^{\pm}$. We try to estimate also effect of the production asymmetry caused by subleading fragmentation mechanism and discuss related uncertainties. A potential measurement of the asymmetry is discussed. Estimates of a number of observed $\nu_{\tau} / \overline{\nu}_{\tau}$ in the $\nu_{\tau} / \overline{\nu}_{\tau} +^{208}\!\mathrm{Pb}$ reaction, with 2m long target are given with the help of the NuWro program. We refer also to the production of the high-energy (anti)neutrinos in the atmosphere.

R. Maciuła, A. Szczurek, J. Zaremba and I. Babiarz,
"Production asymmetry of $\nu_{\tau}$ neutrinos and ${\overline \nu}_{\tau}$ antineutrinos from a fixed target experiment SHiP"
J. High Energy Phys. 01, 116 (2020).

Primary authors

Rafal Maciula (Institute of Nuclear Physics PAN) Antoni Szczurek (Institute of Nuclear Physics)

Presentation materials