Non-strange dibaryons studied in coherent double neutral-meson photoproduction on the deuteron
1 Research Center for Electron Photon Science (ELPH), Tohoku University, Sendai 982-0826 Japan
2 Department of Physics, Yamagata University, Yamagata 990-8560 Japan
3 Department of Physics, Tohoku University, Sendai 980-8578 Japan
4 Department of Information Science, Tohoku Gakuin University, Sendai 981-3193 Japan
5 Department of Physics, University of Tokyo, Tokyo 113-0033 Japan
6 Institute of Particle and Nuclear Studies, High Energy Accelerator Research Organization (KEK), Tsukuba 305-0801 Japan
* Corresponding author: email@example.com
Published online: 22 September 2020
The B = 2 bound/resonance state (dibaryon) is an interesting object, which can be a molecule consisting of two baryons or a spatially compact hexaquark hadron object. The yd ^ n°n°d reaction has been experimentally investigated at incident energies ranging from 0.58 to 1.15 GeV to study non-strange dibaryons. The angular distributions of deuteron emission in the yd center-of-mass energy cannot be reproduced by quasi-free production of two neutral pions followed by deuteron coalescence. Additionally a 2.14-GeV peak is observed in the n°d invariant mass distribution. These suggest a sequential process such as yd ^ RIS ^ n°RIV ^ n°n°d with an isoscalar dibaryon RIS and an isovector dibaryon RIV. Since the mass of the observed isoscalar dibaryons are close to the sum of the nucleon (N) and nucleon resonance (N*) masses, an S-wave NN* molecule may play a role as a doorway to a dibaryon.
© The Authors, published by EDP Sciences, 2020
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