Excited Nucleon Spectroscopy in 3-Body Hadronic Reactions with HypTPC

The nucleon resonance (N*) spectrum holds fundamental information about non-perturbative QCD. The precise data on both photoproduction and hadronic reactions are needed in order to separate the overlapping nucleon resonances with large widths using a partial-wave analysis (PWA). The J-PARC E45 was proposed to measure the precise nucleon resonance spectrum in the πN→ππN 3-body hadronic reactions in the wide energy range of 1.5 -- 2.15 GeV. The E45 detector is highlighted by a large-acceptance Superconducting Hyperon Spectrometer, which accommodates a GEM-based time projection chamber (HypTPC). This spectrometer was designed to facilitate a high-precision measurement with a high-rate capability up to 1 MHz beam at J-PARC. In this talk, we will present current preparation status and anticipated results of the E45 experiment. This talk also reviews recent advances of GEM detectors, with a focus on design principles, high-rate capability, and operational experience of HypTPC, and discusses the most promising directions in future applications such as active-target TPCs for stellar nucleosynthesis experiments.