ELPH研究会 The measurement of in-medium modification of η’ meson properties at LEPS2/BGOegg experiment (LEPS2/BGOegg 実験における原子核中での η’ メソンの性質変化測定) Yuji Matsumura for the LEPS2/BGOegg collaboration Research Center for Electron Photon Science , Tohoku Univ. Dec 2, 2016
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The measurement of in-medium modification of...BGOegg calorimeter ・1320 BGO crystals ・polar angle : 24 144 azimutial angle : 360 ・homogenious ・no housing material ・energy
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ELPH研究会
The measurement of in-medium modification ofη’ meson properties at LEPS2/BGOegg experiment
(LEPS2/BGOegg 実験における原子核中でのη’ メソンの性質変化測定)
Yuji Matsumura
for the LEPS2/BGOegg collaboration
Research Center for Electron Photon Science , Tohoku Univ.
Dec 2, 2016
ELPH研究会
Contents
・physics motivation
・calibration
・mass resolution
・summary
・LEPS2/BGOegg experiment
・ mass
An meson has larger mass than otherpseudo scalar mesons due to UA(1) anomaly.→ The mass of meson is expected to
decrease at the nuclear density.
・line shape analysisA direct measurement of mass spectra
c.f.
physics motivation
ELPH研究会
Nagahiro et al., PRC74, 045203(2006)
(based on NJL model + KMT interaction) ee 0
R.Muto et al. PRL98, 042501(2007) M.Thiel et al. Eur.Phys.J.A49, 132(2013)
・ width
in a vacuum
in-medium width : from the measurement of transparency ratio @ CBELSA
→ decay mainly inside nuclei
・・no hadrons in the final state → pure information of
in-medium mass・
・distortion by final state interaction・higher mass resolution by kinematical fit
physics motivation
ELPH研究会
fm 10 , keV 200 3 c
MeV 2515)( 0
(M.Nanova et al. PLB710, 600(2012))
-4
0 10)(/
00
SPring-8/LEPS2 beamline
・ 1.3 – 2.4 GeV tagged photon beam→ nearly recoilless can be produced