Φ-photo-production from deuteron

M. Miyabe

Outlook

• Physics overview

• Study for FSI

• Improvement of Eγ

• Summary

3

Φ photo production of proton near the threshold

• High energy– Pomeron exchange– Increase with energy.

• Low energy– Pseudo scalar meson

exchange– Decrease with energy.

Discriminate natural-parity mode from meson exchange using Decay angular distribution.

P, glueball, , f2’

p

Pure naturalparity exchange

Pure unnaturalparity exchange

0 0

Decay angular distribution

φ-Φ

φ : photon pol. AngleΦ : K decay angle.

4

Results of proton target

Peak structure around 2GeV.Natural parity exchange is dominant　→　 0+ glueball ?T. Mibe, et al. nucl-ex/0506015

2005/09/21 HAW05 5

Φ photo production of deuteron

1. Coherent production– Interact with deuteron

itself.

2. Incoherent production– Interact with proton or

neutron in deuteron.

2005/09/21 HAW05 6

Incoherent production

• Due to isospin effect,– gπnn and gηnn has opposite sign. →unnatural parity exchange process is suppressed in

neutron case. Information of unnatural (π/η) exchange process

Φ photo-production from neutron

• Exclude coherent contribution

• Final state interaction estimation

• Fermi motion effect

Final State Interaction (FSI)

• Enhancement in low PN relative momentum region.

• Try to make up the difference MC from Real data with FSI

γ

np

n

p

φ

FSI

Theoretical calculation• Enhancement factor

– Triplet

• κ: deuteron binding parameter

• r1: NP effective radius– Singlet

• a0: NP scattering length• r0: NP effective radius

• Ref: A.I. Titov arXiv:nucl-th/0001027v1

000

000

22

22

121

121

rra

rra

k

kkFs

111

22

21

2

/)2( rrk

kkFt

Singlet term has stronger dependent then triplet one

pn relative momentum

Real data MC(incoherent)

γ

np

np

φ

Ppn→ k^2

Pφ

Exposion FSI effect

K^2 distribution 　 |qfmin|<0.1 After coherent exclusion

Coherent

RealMC(incohernt)

FSI?

Real-MC(co)

Comparison with theoretical function

• Ft(k)–　ｒ 1 ← parameter fit

• Fit result–ｒ 1 = 1.755 +/- 0.07 fm

• Past experiment results–ｒ 1 = 1.759 fm

Real/MC

Singlet contribution

• F(k)= ε*Fs(k) + (1-ε)*Ft(k)

Prefer triplet function to singlet one?

FSI effect

MMd W/O FSI MMd with FSI

With FSI effect, ratio of coherent and incoherent was modified.

result

χ^2 Ratio of number of φ

Proton case Deuteron case

γ

np

n

p

φγ

p p

φ

Fermi motion correction

Eγ is directly related with s Eγ is not directory related with s Because of fermi motion

• Minimum momentum for spectator nucleon

• Re-calculate Eγ variable in neutron rest frame

γ

np

n

p

φn

p

CM

n

p

Eγ 　 in neutron rest frame

Scattered particle momentum

Scattered particle momentumResidual of scattered nucleus in MC

qfmin<0.1

MC(incoherent)

Improvement of Eγ resolution

• MC simulation for incoherent

• Resolution of Eγ in the n rest frame value improve from 114MeV to 59MeV

ΔEγ

Result

Slope & dσ/dt in original Eγ Slope & dσ/dt in the n rest Eγ

Preliminary

Preliminary

Summary

• Φ photo-production from neutron was unique tool for study unnatural parity exchange process.

• FSI contribution was found.• Improvement resolution of γ energy in the n

rest frame