Status of the g10 analyses Review of two PRL papers: gdL0K n and gdpK Kn

1
Status of the g10 analyses Review of two PRL
papersgdL0K(n) and gdpKK-(n)

• Spectroscopy Working Group meeting, January 20,
  2006

2
gdpKK-(n)

• Lead authors
• K. Hicks, B. McKinnon, N. Baltzell, D.S. Carman,
  T. Mibe, M. Mirazita, S. Niccolai, P. Rossi, S.
  Stepanyan, D. Tedeschi
• Reviewers
• W. Brooks, R. Schumacher (chair), E. Smith, D.
  Sober, S. Strauch
• http//www.jlab.org/Hall-B/secure/g10/analysis/rev
  iew/
• eight analysis note
• paper has two parts (1) repeat of g2a analysis
  (2) full analysis of g10 data
• first response from the review committee is
  received -
• many good comments, couple of major ones
• - discussion of the published results
• - discussion of the rescattering mechanism
• revised version of the paper will be send to the
  committee in a week or so

3
MM(pK-) distributions

• The same photon energy range
• The same cuts as in previous analysis
• PID for p, K and K-
• 3s cut on MM(pKK-)-Mn
• M(KK-)gt1.07 GeV, f(1020) cut
• Pngt0.08, spectator cut
• M(pK-)gt1.545 GeV, L(1520) cut
• PKlt1 GeV/c (cut on t-channel production)

Preliminary

• Two distributions statistically consistent with
  each other
• 26 c.l. for null hypothesis from the Kolmogorov
  test (two histograms are compatible).
• Reduced c21.15 for the fit in the mass range
  from 1.47 to 1.77 GeV/c2

4
Analysis of the full statistics of g10

• Top low field data bottom high field data
• MM in the reaction gdpKK-X
• Clean identification of the exclusive reaction
  gdpKK-n
• Invariant mass of pK-
• Prominent peak for the L(1520) and also strength
  for higher mass L resonances at 1.67, 1.69 and
  1.82 GeV/c2

5
The M(nK) distributions and the cross section
upper limits
Low field data High field data
Cross section upper limit for gdQK-p

• The final results on UL are obtained from fits to
  the M(nK) distributions using F(M)
• UL from each data sets were extracted using FC
  method and using fit with F(M) results are
  consistent within 10

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Cross section upper limit for gnQK-

• In the reaction gdpK-Kn the Q is produced on
  the neutron and the proton is a spectator
• In the same reaction L(1520) is produced on the
  proton and the neutron is a spectator
• Detecting the high energy spectator, proton in
  the reaction gdpK-Kn, requires re-scattering
  (FSI)
• Minimum momentum of protons in CLAS is 0.35
  GeV/c
• Production of the L(1520) was taken as a guide to
  account for rescattering
• The Fermi momentum tail can account only for 20
  of the L(1520) cross section in the reaction
  gdL(1520)K(n) with spectator momentum Pngt0.35
  GeV/c
• Rescattering correction for L(1520) case is x10
• For Q one should expect this to less due large
  K-p and possibly Qp scattering cross section

UL of the cross section for gnQK- is obtained
by scaling the UL of the cross section of
gdQK-p by a factor of 10
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gdL0Kn

• Lead authors
• S. Niccolai, M. Mirazita, P. Rossi, N. Baltzell,
  D.S. Carman, K. Hicks, T. Mibe, B. McKinnon, S.
  Stepanyan, D. Tedeschi
• Reviewers
• L. Guo, P. Stoler (chair), M. Dagger
• http//www.jlab.org/Hall-B/secure/g10/analysis/rev
  iew-theta-lambda/
• five analysis note
• first response from the review committee received
• major issue difference between Silvias and
  Marcos analysis. Silvia is repeating Marcos
  analysis
• revised version of the paper will be send to the
  committee in a week or so

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Reaction gdL0KX

• Reaction identification using cuts on the missing
  neutron mass and on the invariant mass of (pp-)
• Search for Q in the (nK) invariant mass

• The background from S-np- is easily removed
  after L0 cut

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M(nK) distributions and cross section UL of
gdL0Q
95 CL Upper Limits

• Upper limits are obtained in similar way as in
  pKK case
• Several models were used to calculate cross
  sections