Novel Method for the Direct Measurement of the<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:mi>τ</mml:mi></mml:mrow></mml:math>Lepton Dipole Moments

A novel method for the direct measurement of the elusive magnetic and electric dipole moments of the $\ensuremath{\tau}$ lepton is presented. The experimental approach relies on the production of ${\ensuremath{\tau}}^{+}$ leptons from ${D}_{s}^{+}\ensuremath{\rightarrow}{\ensuremath{\tau}}^{+}{\ensuremath{\nu}}_{\ensuremath{\tau}}$ decays, originating in fixed-target collisions at the LHC. A sample of polarized ${\ensuremath{\tau}}^{+}$ leptons is kinematically selected and subsequently channeled in a bent crystal. The magnetic and electric dipole moments of the ${\ensuremath{\tau}}^{+}$ lepton are measured by determining the rotation of the spin-polarization vector induced by the intense electromagnetic field between crystal atomic planes. The experimental technique is discussed along with the expected sensitivities.