18-22 October 2021
Matsue, Shimane Prefecture, Japan
Asia/Tokyo timezone

Coherent neutral-pion and eta-meson photoproduction on the deuteron

21 Oct 2021, 08:10
20m
Room 401 (Kunibiki Messe)

Room 401

Kunibiki Messe

Parallel Session Presentation Low energy spin physics with lepton, photon and hadron probes Low energy spin physics with lepton, photon and hadron probes

Speaker

Takatsugu Ishikawa (Research Center for Electron Photon Science, Tohoku University)

Description

The $\eta d$ threshold structure $\mathcal{D}_{\eta d}$ with a spin parity of $1^-$ has been experimentally studied in the $\gamma d \to \pi^0 \eta d$ reaction at $E_\gamma \lt 1.15$ GeV. The structure is connected to the isoscalar $S$-wave two-body system between the nucleon $N$ and nucleon resonance $N(1535)1/2^-$, or the chiral partner candidate of $N$. By incorporating the known isovector resonance $\mathcal{D}_{12}$ with a spin-parity of $2^+$ in the $\pi^0 d$ channel, we decompose the $\eta d$ and $\pi^0 d$ invariant-mass spectra into the $\eta \mathcal{D}_{12}$ and $\pi^0 \mathcal{D}_{\eta d}$ contributions. From the analysis of $\pi^0$ and $\eta$ angular distributions, we determine the spin-parity of the first intermediate $\eta \mathcal{D}_{12}$ and $\pi^0 \mathcal{D}_{\eta d}$ systems. The spin-parity of the major component is found to be $0^-$ in the $\pi^0 \mathcal{D}_{\eta d}$ system, suggesting that some nucleon resonance contributes to $\pi^0 \eta$ photoproduction on the nucleon. It should be noted that $\Delta(1700)3/2^-$ is the main contributor for the elementary $\pi^0 \eta$ photoproduction. The talk will be based on [T. Ishikawa et al., arXiv:2105.10887].

Primary author

Takatsugu Ishikawa (Research Center for Electron Photon Science, Tohoku University)

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