Search for Dark Photon at NA48/2, and measurement of π0 form factor

10th International Conference on Kaon Physics

Raggi, Mauro^1

Sapienza Universita di Roma, INFN Roma, Piazzale Aldo Moro 5, Roma, Italy^1

关键词: Decay chains;    Electromagnetic transitions;    Final state;    Form factors;    Measured values;    Neutral pions;    Photon mixing;    Slope parameter;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/800/1/012032/pdf
DOI  :  10.1088/1742-6596/800/1/012032

来源: IOP

【 摘 要 】

The NA48/2 experiment at CERN performed a search for the dark photon (A′) via the decay chain π0→ γA′, A′ → e+e-. Using a sample of ∼ 1.7 • 107neutral pions tagged from and decays collected in 2003-04 no signal is observed. The limits in the plane dark photon mixing parameter 2versus its mass mA′are reported. The NA62-RK experiment collected, during the 2007 data taking, a large sample of neutral pion Dalitz decays with a trigger optimised for electrons final states with respect to NA48/2 one. We report the measurement of the π0electromagnetic transition form factor (TFF) slope parameter (a) based on a sample of decays. The preliminary measured value a = (3.70 ± 0.53stat± 0.36syst) • 10-2is compatible with theoretical expectations and previous measurements.