update of analysis ~leps collaboration meeting in taiwan
DESCRIPTION
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 - PowerPoint PPT PresentationTRANSCRIPT
Update of Analysis ~LEPS Collaboration Meeting in Taiwan
Nuclear Physics Group, Academia Sinica
Bo-Ru, Lin2006/01/12
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
Φ-photoproduction using LD2 target.
p, n, or D ?
• 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
η: isoscalar
π: isovector
D : isoscalar
: isoscalar
Allowed
Forbidden
By isospin conservation we should be able to separate π from the whole exchanging channels.
Conjecture :
Pseudo-scalar Exchange
MMd of LD2, and LH2Missing mass distributions provide us a tool.
22 )()( PPEmEMM dd
LD2 LH2
Validity of momentum Calculation
Accredited Md = 1.875 GeV Accredited MΛ = 1.520 GeV
Validity of momentum Calculation
Accredited Mp = 0.938 GeV
Validity of momentum Calculation
Accredited MΦ = 0.938 GeV
Determination of appropriate MC Eγ smearing
15 Mev Smearing
MMp fitting of LH2 real data using different Eγ smearing
Determination of appropriate Eγ smearing
10 Mev SmearingTwo component (11.64 MeV)
Smearing
Determination of Appropriate mass offshell effect
Use MC Incoherent MMd fit LD2 MMd (in the region 1.9~2.1)
Do subtraction and fit with gaussian distribution. Compare the result with coherent distribution
Determination of Appropriate mass offshell effect
Determination of Appropriate mass offshell effect
Determination of Appropriate mass offshell effect
t - resolution ~ sigma plot
The t-resolution is better than 0.02 GeV
Fit (t-in) – (t-out) with gaussian distribution to get σ value
t-in : from event generator
t-out : deduced in the way the same as real data
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
Cross check of MMd, and MMp Fitting
MMd
MMp
Coherent LD2 dN/dt Fitting
min||exp||min
ttbttdt
d
dt
d
Fitting Formula :
min||exp||min
ttbttdt
d
dt
d
||minttdt
d
b
intercept
slope
Coherent LD2 dN/dt Fitting
t bin : 30 MeV
t bin : 20 MeV
t bin : 40 MeV
Coherent LD2 Common slope dN/dt Fitting
t bin : 30 MeV
t bin : 20 MeV
t bin : 40 MeV
Slope : 20~23
Slope with last Eγbin removed : 17 ~19
Incoherent LD2 dN/dt Fitting
Incoherent LD2 Common slope dN/dt Fitting
dN/dt Fitting of coherent, incoherent, LH2 results
LH2
Incoherent
Coherent
Coherent Slope : ~18.5
Incoherent Slope : ~4.0
LH2 Slope : ~3.6
Background Estimation
10 Mev cut
MC Backgrounds
None-resonant KKn
Λ(1520)
None-resonant KKd
Invm-kk MMpMMd
Multidimensional Fitting
Invm-KK MMd MMp
LD2 Data
Incoherent
Coherent
Sum of all
Fit invm-KK, MMd, MMp simultaneously without background.
Multidimensional Fitting
Invm-KK MMd MMp
LD2 Data
Incoherent
Coherent
Sum of BG
Sum of all
KKd
Sum of BG
Λ(1520)
KKn
Multidimensional Fitting
Invm-KK MMd MMp
LD2 Data
Incoherent
Coherent
Sum of BG
Sum of all
Next step : Apply the same procedure with t-binning
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
Backup Slides
MMd
MMd, using smaller binning
Determination of Appropriate mass offshell effect ~ Results of other Ntuples
Determination of Appropriate mass offshell effect ~ Results of other Ntuples
Determination of Appropriate mass offshell effect ~ Results of other Ntuples
Determination of Appropriate mass offshell effect ~ Results of other Ntuples
Determination of Appropriate mass offshell effect ~ Results of other Ntuples