Precision measurement of the Z boson to electron neutrino coupling at the future circular colliders

R. Aleksan (1) , S. Jadach

1 IRFU - Institut de Recherches sur les lois Fondamentales de l'Univers

At the high luminosity electron-positron circular colliders like FCC-ee in CERN and CEPC in China it will possible to measure very precisely e+e−→Zγ process with subsequent Z decay into particles invisible in the detector, that is into three neutrina of the Standard Model and possibly into other weakly coupled neutral particles. Apart from the measurement of the total invisible width (which is not the main subject of this work) this process may be used as a source of Z coupling to electron neutrino – known very poorly. This is possible due to the presence of the t -channel W exchange in the e+e−→νeν¯eγ channel which deforms slightly spectrum of the photon. We are going to show experimental investigation of this effect, for ∼10 inverse atobarn accumulated luminosity, which can provide measurement of the Z−νe coupling with statistical error of order 1%. The estimation of the systematic experimental error will require more work, but most likely it will be of similar size.

Mots clés: electron positron --> Z0 photon; neutrino/e: coupling; precision measurement; CERN Lab; photon: spectrum; neutral particle: final state; Z0: invisible decay; electron positron: scattering; FCC-ee; electron positron --> neutrino antineutrino photon; weak coupling; CEPC; W: exchange; luminosity: high; error: statistical; neutrino: coupling; Z0: coupling; Z0: width: measured

Domaines: Physique des Hautes Energies - Phénoménologie [hep-ph]; Physique des Hautes Energies - Expérience [hep-ex]

R. Aleksan, S. Jadach. Precision measurement of the Z boson to electron neutrino coupling at the future circular colliders. Phys.Lett.B, 2019, 799, pp.135034. ⟨10.1016/j.physletb.2019.135034⟩. ⟨hal-02303031⟩