Speaker
Description
Nucleon resonances (N and Δ) have been studied for a long time mostly through
γN→πN. πN→πN, and γN→ππN reactions. However, there are many resonances which
have not been established experimentally, due to a limited number of πN→ππN reaction
data which was mainly measured in 1970’s. Thus, J-PARC E45 has been proposed to
study nucleon resonances in πN→ππN reactions with high-intensity π± beams injected on
the liquid hydrogen target at J-PARC. We aim to establish nucleon resonances with the
mass up to 2 GeV/c2 using πN→ππN reactions in higher statistics than the world’s existing
data by two-orders of magnitude. We will measure reactions of π−
p→π+π−
n, π0π−
p and
π+p→π0π+p, π+π+n, as well as π−
p→K0Λ and π+p→K+Σ+ in a large acceptance Time
Projection Chamber (HypTPC) inside a superconducting Helmholtz magnet. We will
measure these reactions in small momentum steps in the center-of-mass energy range of
1.5-2.1 GeV. Then, we perform partial wave analysis to extract properties of resonances.
The first physics run of E45 is planned in Nov. 2026 in the energy range of 1.66-1.75 GeV.
In this presentation, we will show the preliminary results of the commissioning run, and the
preparation status for the physics run.
