Xin Chen, Baosen Cheng, Mousumi Datta,

1
Update on Searches for Charmed Pentaquarks in
B0-gtD()pp(?)

• Xin Chen, Baosen Cheng, Mousumi Datta,
• Haibo Li, Bruce Mellado and Sau Lan Wu
• University of Wisconsin-Madison
• Pentaquark Taskforce Meeting 07/08/04

2
Outline

• Reconstruction Modes and Pre-selection cuts (Beta
  code)
• Overview of pentaquark searches
• Invariant mass spectra
• Upcoming analyses
• Outlook and Plans

3
Reconstruction Modes

• B0 decays involving D, proton, which may be used
  for charmed pentaquark searches
• B0-gtD?ppbar?, D?-gtD0?, D0-gtK?,K3?,K??0,Ks??
• B0-gtD?ppbar?, D?-gtK??,K???0,Ks?,Ks??0
• B0-gtD0ppbar, D0-gtD0?0, D0-gtK?,K3?,K??0,Ks??
• B0-gtD0ppbar, D0-gtK?,K3?,K??0,Ks??
• Xin Chen reports today on branching ratios for
  channels 1-4 with 112.55 fb-1 of data (Run I-III)
• Here we report pentaquark searches and study of
  ppbar invariant mass spectra with 112.5 fb-1 for
  decay channels 1-4
• Most of recent efforts have gone to understanding
  better branching ratios extraction

4
Overview of Pentaquark Searches

• Same minimal quark content as in direct
  combination of channels 3-4 (cbaruuud) may be
  obtained with D-(D-)p? in channels 1-2

5
Overview of Pentaquark Searches (cont)

• With channel 1 and 2 we look for neutral
  pentaquark
• Channel 1 D-p (plus c.c.)
• Channel 2 D-p (plus c.c.)
• H1 observes resonance in D-p at 3.1 GeV
• With channel 3 and 4 we look for a charged
  pentaquark
• Channel 3 D0barp (plus c.c.)
• Channel 4 D0barp (plus c.c.)
• With channel 1 and 2 we look for a charged
  pentaquark using D-p? (channel 3) and D-p?
  (channel 4)

6
Pre-Selection
Cuts at Beta code level based on MC only

• Both Proton and anti-proton from pLhVeryLoose
• K (D daughter) from KMicroNotPion
• ? from GoodTracksVeryLoose
• ?0 from Pi0AllDefault
• Ks from KsDefault
• ? (from B) from ChargeTracks
• D0 mass window 40 MeV (70 MeV for decays with ?0
  )
• D? mass window 70 MeV
• MESgt5.2 GeV and ?Elt0.4 GeV
• Vertex convergence for B0, D0 and D- candidates

7
Final Cuts

• Subdivided into channel independent and channel
  dependent cuts
• Coupled to branching ratio extraction analysis
• Documented in BAD 916 (branching ratio extraction
  analysis)
• BAD 997 to be submitted today
• Continuation of BAD 916
• Todays talk by Xin Chen

8
Constrained Mass for Channels 1-2
Channel 1 (B0-gtD?ppbar?, D-gtD0?)
D0-gtK?
D0-gtK3?
D0-gtK??0
D--gtK-??
Channel 2 (B0-gtD?ppbar?)
9
Constrained Mass for Channels 3-4
Channel 3 (B0-gtD0ppbar, D0-gtD0?0)
D0-gtK?
D0-gtK3?
D0-gtK??0
D0-gtK?
Channel 4 (B0-gtD0ppbar)
10
cduud (direct combination)
Channel 1
Channel 2
11
cduud (indirect combination)
Channel 1
Channel 2
12
cuuud (direct combination)
Channel 3
Channel 4
13
cuuud (indirect combination)
Channel 4
Channel 3
14
Dalitz for Chanels 3-4
Channel 3
Channel 4
15
cuuud (direct combination)
Channel 1
Channel 2
16
cuuud (indirect combination)
Channel 1
Channel 2
17
Upcoming Analyses

• Need to look more into D0(D0)p invariant mass
  spectra
• Exclusive search (with decays not observed
  before)
• B--gtD0ppbar?- (plus c.c.)
• B--gtD0ppbar?- (plus c.c.)
• Beta Ntuples have been generated. To be analyzed
• Hard for a 4 GeV D0(D0)p resonance due to lack
  of phase space
• Inclusive analysis for charged charmed
  pentaquark. Inclusive search of neutral
  pentaquark already done
• D0p (plus c.c.)
• D0p (plus c.c.)
• Beta Ntuples have been generated. To be analyzed

18
Outlook and Plans

• Search of a charmed pentaquark in
  B0-gtD()ppbar(?) decays is reaching maturity
• BAD 916 v5 with details on branching ratio (for
  all 4 B decays) has been submitted
• Will submit BAD 997, continuation of BAD 916 with
  details of pentaquark analysis
• In channels 1 and 2 Dp invariant mass spectra do
  not show significant deviation from phase-space
  hypothesis
• Channels 3 and 4 display differences between
  D0barp (cbaruuud, direct combination) and D0p
  (cbaruubarubardbar, indirect combination)
  invariant mass spectra, inconsistent with phase
  space MC
• Will start looking into
• Exclusive search B--gtD0ppbar?-, B--gtD0ppbar?-
  (plus c.c.)
• Inclusive D0p and D0p (plus c.c.)