Speaker
Description
The ηd threshold structure has been experimentally studied in the γd→π0ηd reaction at incident photon energies ranging from the reaction threshold to 1.15 GeV. An enhancement is observed near the ηd threshold in dσ/dMηd. The measured angular distribution of deuteron emission dσ/dΩd<\sub> is rather flat, which cannot be reproduced by the calculations based on the kinematics of quasi-free π0η production with deuteron coalescence even if the ηd final-state interaction is incorporated. The spin-parity of 1− is consistent for the enhancement with the π0 and η angular distributions for the events with Mηd<2.47 GeV.Its Breit-Wigner mass and width are limited to 2.34~2.35 and 0~0.06 GeV, respectively, at 99% confidence level, suggesting a possible ηd bound state. In this talk, we present the ηd threshold enhancement, and its properties.
