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Update of  Analysis ~LEPS Collaboration Meeting in Taiwan. Nuclear Physics Group, Academia Sinica Bo-Ru, Lin 2006/01/12. Outline. Φ photoproduction using LD2 target Validity of momentum calculation Determination of E γ smearing Determination of Appropriate mass offshell effect

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update of analysis leps collaboration meeting in taiwan

Update of Analysis~LEPS Collaboration Meeting in Taiwan

Nuclear Physics Group, Academia Sinica

Bo-Ru, Lin

2006/01/12

outline
Outline
  • Φphotoproduction using LD2 target
  • Validity of momentum calculation
  • Determination of Eγ smearing
  • Determination of Appropriate mass offshell effect
  • t-resolution
  • dN/dt fitting
  • Background estimation
photoproduction using ld2 target

p, n, or D ?

Φ-photoproduction using LD2 target.
  • Incoherent Interaction:Photon interact with constituent nucleon, which is proton or neutron.
  • Coherent Interaction:Photon interact with deuteron as a whole.
isospin effect in coherent production

Pseudo-scalar Exchange

Isospin effect in Coherent production

: isoscalar

η:isoscalar

Allowed

Forbidden

π: isovector

D : isoscalar

Conjecture:

By isospin conservation we should be able to separate πfrom the wholeexchanging channels.

mmd of ld2 and lh2
MMd of LD2, and LH2

Missing mass distributions provide us a tool.

LD2

LH2

validity of momentum calculation
Validity of momentum Calculation

Accredited Md = 1.875 GeV

Accredited MΛ = 1.520 GeV

validity of momentum calculation1
Validity of momentum Calculation

Accredited Mp = 0.938 GeV

validity of momentum calculation2
Validity of momentum Calculation

Accredited MΦ = 0.938 GeV

determination of appropriate mc e smearing
Determination of appropriate MC Eγ smearing

MMp fitting of LH2 real data using different Eγ smearing

15 Mev Smearing

determination of appropriate e smearing
Determination of appropriate Eγ smearing

Two component (11.64 MeV) Smearing

10 Mev Smearing

determination of appropriate mass offshell effect
Determination of Appropriate mass offshell effect

Do subtraction and fit with gaussian distribution. Compare the result with coherent distribution

Use MC Incoherent MMd fit LD2 MMd (in the region 1.9~2.1)

t resolution sigma plot
t - resolution ~ sigma plot

t-in : from event generator

t-out : deduced in the way the same as real data

Fit (t-in) – (t-out) with gaussian distribution to get σ value

The t-resolution is better than 0.02 GeV

mmd fitting to separate coherent from incoherent events
MMd Fitting to Separate Coherent from Incoherent events

Fitting of MMd of LD2 real data using Mote-Carlo generated incoherent, coherent events.

coherent

incoherent

sum

coherent ld2 dn dt fitting
Coherent LD2 dN/dt Fitting

Fitting Formula:

intercept

slope

coherent ld2 dn dt fitting1

t bin : 20 MeV

t bin : 30 MeV

t bin : 40 MeV

Coherent LD2 dN/dt Fitting
coherent ld2 common slope dn dt fitting

t bin : 20 MeV

t bin : 30 MeV

t bin : 40 MeV

Coherent LD2 Common slope dN/dt Fitting

Slope : 20~23

Slope with last Eγbin removed : 17 ~19

dn dt fitting of coherent incoherent lh2 results

Incoherent

LH2

Coherent

dN/dt Fitting of coherent, incoherent, LH2 results

Coherent Slope : ~18.5

Incoherent Slope : ~4.0

LH2 Slope : ~3.6

mc backgrounds
MC Backgrounds

Invm-kk

MMd

MMp

None-resonant KKn

Λ(1520)

None-resonant KKd

multidimensional fitting
Multidimensional Fitting

LD2 Data

Coherent

Invm-KK

MMd

MMp

Incoherent

Sum of all

Fit invm-KK, MMd, MMp simultaneously without background.

multidimensional fitting1

LD2 Data

Coherent

Incoherent

Sum of BG

Sum of all

Sum of BG

KKn

Λ(1520)

Multidimensional Fitting

Invm-KK

MMd

MMp

KKd

multidimensional fitting2

LD2 Data

Coherent

Incoherent

Sum of BG

Sum of all

Multidimensional Fitting

Invm-KK

MMd

MMp

Next step : Apply the same procedure with t-binning

brief summary
Brief Summary
  • Stable results of preliminary dN/dt analysis are acquired.
  • Background estimation in every t, Eγ bin to acquire pure Φ events.

Thank you for paying attention

slide31
MMd

MMd, using smaller binning