TY - JOUR
T1 - Low-energy η-nucleon interaction studied with η photoproduction off the deuteron
AU - Nakamura, S. X.
AU - Kamano, H.
AU - Ishikawa, T.
N1 - Funding Information:
We thank T. Sato for a useful discussion. This work was supported in part by JSPS KAKENHI Grants No. JP25105010, No. JP25800149, and No. JP26400287, and Fundação de Amparo à Pesquisa do Estado de São Paulo-FAPESP, Process No. 2016/15618-8.
Publisher Copyright:
© 2017 American Physical Society.
PY - 2017/10/26
Y1 - 2017/10/26
N2 - We develop a reaction model for η photoproduction off the deuteron (γd→ηpn) and study the reaction at a special kinematics, where the photon beam energy is ∼0.94 GeV and the scattered proton is detected at ∼0°, for the purpose of determining the η-nucleon scattering length (aηN) and effective range (rηN). In this kinematics, the η-nucleon elastic rescattering is significantly enhanced while other background mechanisms are suppressed. We show that a ratio R, the γd→ηpn cross section divided by the γp→ηp cross section convoluted with the proton momentum distribution in the deuteron, has a very good resolving power of aηN and rηN. We conclude that the R data with 5% error, binned in 1 MeV width of the η-neutron invariant mass, can determine Re[aηN] (Re[rηN]) at the precision of ∼±0.1 fm (∼±0.5 fm), significantly narrowing down the previously estimated ranges of the parameters. To arrive at the conclusion, it is essential to use the γd→ηpn reaction model equipped with elementary amplitudes that are well constrained by πN and γN reaction data through a sophisticated coupled-channel analysis. This result strongly motivates the Research Center for Electron Photon Science (ELPH) at Tohoku University to measure R.
AB - We develop a reaction model for η photoproduction off the deuteron (γd→ηpn) and study the reaction at a special kinematics, where the photon beam energy is ∼0.94 GeV and the scattered proton is detected at ∼0°, for the purpose of determining the η-nucleon scattering length (aηN) and effective range (rηN). In this kinematics, the η-nucleon elastic rescattering is significantly enhanced while other background mechanisms are suppressed. We show that a ratio R, the γd→ηpn cross section divided by the γp→ηp cross section convoluted with the proton momentum distribution in the deuteron, has a very good resolving power of aηN and rηN. We conclude that the R data with 5% error, binned in 1 MeV width of the η-neutron invariant mass, can determine Re[aηN] (Re[rηN]) at the precision of ∼±0.1 fm (∼±0.5 fm), significantly narrowing down the previously estimated ranges of the parameters. To arrive at the conclusion, it is essential to use the γd→ηpn reaction model equipped with elementary amplitudes that are well constrained by πN and γN reaction data through a sophisticated coupled-channel analysis. This result strongly motivates the Research Center for Electron Photon Science (ELPH) at Tohoku University to measure R.
UR - http://www.scopus.com/inward/record.url?scp=85032579359&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85032579359&partnerID=8YFLogxK
U2 - 10.1103/PhysRevC.96.042201
DO - 10.1103/PhysRevC.96.042201
M3 - Article
AN - SCOPUS:85032579359
VL - 96
JO - Physical Review C
JF - Physical Review C
SN - 2469-9985
IS - 4
M1 - 042201
ER -