Dortmund 2021 – scientific programme

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T: Fachverband Teilchenphysik

T 6: Flavour physics I

T 6.8: Talk

Monday, March 15, 2021, 17:45–18:00, Tf

Rare charm c → uνν dineutrino null test for e⁺ e⁻–machines — •Rigo Bause, Hector Gisbert, Marcel Golz, and Gudrun Hiller — TU Dortmund

Rare |Δ c|=|Δ u|=1 transitions into dineutrinos are strongly GIM-suppressed and constitute excellent null tests of the standard model. While branching ratios of c → u νν transitions are experimentally unconstrained, signals of new physics can be just around the corner.

Signatures of these modes, including D → P  ν ν or D → P⁺ P⁻   ν ν with P=π, K, Λ_c → p  ν ν, contain missing energy and are well suited for experimental searches at e⁺ e⁻–facilities, such as BES III, Belle II and future e⁺ e⁻–colliders, such as the FCC-ee running at the Z.

Using current bounds on c → u  ℓ⁺ ℓ⁻ transitions, model-independent upper limits on branching ratios assuming lepton universality and charged lepton flavour conservation are presented (arxiv:2010.02225). An observation in excess of these upper limits implies a breakdown of the corresponding symmetry.