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SUMMARY:$\\eta N$ scattering parameters and possible $\\eta' d$ bound stat
 e from $\\eta$ photoproduction on the deuteron
DTSTART;VALUE=DATE-TIME:20190624T122000Z
DTEND;VALUE=DATE-TIME:20190624T124500Z
DTSTAMP;VALUE=DATE-TIME:20260804T034626Z
UID:indico-contribution-61@indico.koza.if.uj.edu.pl
DESCRIPTION:Speakers: Takatsugu Ishikawa (Research Center for Electron Pho
 ton Science\, Tohoku University)\nAmong the two-body dynamics of the meson
 -nucleon systems\, the interaction between the eta meson ($\\eta$) and nuc
 leon ($N$) is not well known although it has been found to be attractive. 
 An experiment [1] is conducted to determine the low-energy $\\eta N$ scatt
 ering parameters using a special kinematics at the Research Center for Ele
 ctron Photon Science (ELPH)\, Tohoku University. The energy and momentum o
 f the emitted proton ($p$) are measured at 0 degrees for $\\eta$ photoprod
 uction on the deuteron at incident energies around 0.94 GeV\, which gives 
 the low relative momentum between $\\eta$ and  neutron ($n$) in the final 
 state. Low-energy $\\eta n$ scattering is likely to take place in this con
 dition\, and the scattering parameters can be determined from the differen
 tial cross section as a function of the $\\eta n$ invariant mass (correspo
 nding to the relative $\\eta n$ momentum) [2]. We present the current stat
 us of the experiment.\n\nRecently\, a possible $\\eta'd$ bound state is th
 eoretically investigated [3]. A structure corresponding to the state can b
 e observed via the $\\gamma d\\to \\eta d$ at incident energies around 1.2
  GeV. In case of backward $\\eta$ emission\, the structure becomes promine
 nt because a background contribution coming from quasi-free single-step $\
 \eta$ emission is highly suppressed. $\\eta$ photoproduction on the deuter
 on has been experimentally studied at ELPH below incident energies of 1.15
  GeV. The angular differential  cross sections are determined at backward 
 $\\eta$ emission angles. We also present the preliminary results for the e
 nergy dependence and discuss a possible $\\eta'd$ bound state.\n\n[1] T. I
 shikawa et al.\, Acta Phys. Polon. B 48\, 1801 (2017).\n[2] S.X. Nakamura\
 , H. Kamano\, T. Ishikawa\, Phys. Rev. C 96\, 042201 (R) (2017).\n[3] T. S
 ekihara\, H. Fujioka\, T. Ishikawa\, Phys. Rev. C 97\, 045202 (2017).\n\nh
 ttps://indico.koza.if.uj.edu.pl/event/1/contributions/61/
LOCATION:Collegium Maius
URL:https://indico.koza.if.uj.edu.pl/event/1/contributions/61/
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