Abstract
We develop a reaction model for photoproduction off the deuteron () and study the reaction at a special kinematics, where the photon beam energy is GeV and the scattered proton is detected at , for the purpose of determining the -nucleon scattering length () and effective range (). In this kinematics, the -nucleon elastic rescattering is significantly enhanced while other background mechanisms are suppressed. We show that a ratio , the cross section divided by the cross section convoluted with the proton momentum distribution in the deuteron, has a very good resolving power of and . We conclude that the data with 5% error, binned in 1 MeV width of the -neutron invariant mass, can determine () at the precision of fm ( fm), significantly narrowing down the previously estimated ranges of the parameters. To arrive at the conclusion, it is essential to use the reaction model equipped with elementary amplitudes that are well constrained by and 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 .
- Received 29 April 2017
- Revised 23 July 2017
DOI:https://doi.org/10.1103/PhysRevC.96.042201
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