Searches and Results in Spectroscopy BaBar

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Searches and Results in Spectroscopy _at_ BaBar

• Jonathon Coleman
• MORIOND QCD 2005

For the collaboration
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OUTLINE

• Study of B?X(3872)K, X(3872)0?J/y p p-
• Charmonia in the recoil hadronic system from
  inclusive B decay to a K meson
• Direct Observation of ee- ? J/y (cc) at
  sqrt(s)10.58 GeV
• Search for the Q(1540) Pentaquark Candidate in
  Electro- and Hadro-Production

All new results are preliminary
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Towards a new spectroscopy(?)

• Recent observations of new states (DsJ,
  X(3872)...)
• several models have been developed
• Are we at a stage where we can start to
  discriminate among them?
• e.g molecular model predicts highly suppressed
  B0?X(3872)Ks
• 4-quark model predicts different masses
  between X(3872) in B0 and B decays
• DMgt5 MeV/c2

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B?X(3872)K
244 fb-1
B?X(3872)K
N5114 6.9s mX(3871.30.6)MeV/c2
B?J/y pp K Signal non B-background Non-resonant
J/y pp background Non-B background Non-B
background

• Statistical errors only

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Search for B0?X(3872)Ks
NEW
B0?X(3872)Ks
N8.44.5 2.7s mX(3868.61.2)MeV/c2
DMM(X,K)-M(X,KS)
Promising Needs more data
DM(2.71.3) MeV/c2
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Search for B?KXcc?
NEW
K-
?
4S

• Fully reconstruct one B, e.g. B?D()0p
• Look for a recoil Kaon get p(K) in the B rest
  frame
• Obtain the absolute branching fraction for any
  state in the recoil system
• Obtain branching fractions for indivdual decay
  modes for such a state

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ee-?BB- K-X0
244 fb-1

• Can measure absolute
• B.F.s of B-?K-X0

J/y
Lower limit on BF(X?J/ypp) gt 4.3 _at_ 90 C.L
cc2
cc1
cc0

• Very clear J/y and hc signals
• N J/y258- 42
• N hc 266 -42

• cc2,cc0ltltcc1
• X(3872) production much lower than for other
  Charmonium states
• can set lower limit on B.F.

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Branching Fraction values for B?K(cc? state)
Preliminary
Recoil
2.4/-2.1
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ee-?J/y cc 2.0ltm(cc)lt3.8 GeV/c2
Reconstruct J/y?ll- and study recoil mass
spectrum
ee-
Dm (GeV/c2)
mm-
Recoil Mass (GeV/c2)
Dmm(ll-)-m(J/y) (GeV/c2)
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Recoil Mass Spectrum
244 fb -1
Observe hc(1S) cc(1P) hc(2S)
C1
C-1

• observe only C1 states

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Preliminary Results
244 fb -1

• Comparison to Belle Theory
• () cross sections in fb , ()
  hep-ex/0412041, hep-ex/0407009
• 1 PRD 67, 054007 (2003), 2 hep-ph/0408141

()
()
()
()
1
()
2
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Inclusive Pentaquark Searchin ee- collisions
124 fb -1
hep-ex/0502004
Large signal for ?c?pKS (100K events) no signal
at 1.54 GeV/c2
Limits on Q5 and X5-- are smaller than expected
for normal baryons
?
BaBar pentaquark production limits
Also searched for other 10 members
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Search for Q5(1540) ?KSp in electro- and
hadro-production
NEW

• Hadroproduction interactions in detector
  material of hadrons produced in ee- annhilations

x

• Electroproduction off-beam e- and e bent into
  Be beampipe in horizontal plane

e
z
off-beam e
e-
off-beam e-
3 GeV
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Target Material
SVT
DCH Be Inner Cylinder
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Detector Tomography with pKS Vertices
244 fb-1
DCH Wall
SVT
Support Tube
e- side
-0.2 lt y lt 0.7 cm -3.1lt x lt -2.2 cm
many other detailed features well reproduced
Ta
Z profile
Ta
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The selected (KS, p) Candidates
plab.(KS)
plab.(proton)
Well defined KS
signal
Excellent S/B behaviour with flight length
sideband
sideband
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pKS mass distributions in the Q(1540) region
KS Signal

• No signal observed

e-Be
(low Q2 or quasi-real)
KS sidebands
All vertices
so associate additional charged tracks
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Combine p or KS with identified p or K
K(892)
K-(892)
p
p-
L(1520)
L(1115)
K-
p-
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but no Q5(1540) All Events e-Be same with
fewer events
p
p-
Remove K(892)
K-
K
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BaBar e-Be Compared to Q(1540) Electroproduction
HERMES, possible acceptance loss at low mass (PID
on proton gt 4.1 GeV/c)
ZEUS fit uses S(1480) PDG, 1 star

• SAPHIR gp ? KnK0
• compare e-Be ? KSpK- X using L(1520) signals
• Implies 2s effect in BaBar m(KSp)
• i.e. no obvious contradiction

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Summary

• X(3872)?J/y pp, 2.7s hint in B?XKS?
• Charmonia in the recoil hadronic system from
  inclusive B decay to a K meson
• Access to absolute B.F.s
• Double cc production in ee- Annihilation
• Larger than expected
• Dominated by even C-parity states against the J/y
• Q5(1540) Searches in electro- and hadro-
  production
• No signal found
• e-Be compared to other electroproduction data
• And to SAPHIR via L(1520)

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Backup Material
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• eta_c exclusive measurement from eta_c -gt KKpi
• J/psi, chi_c1, psi' exclusive from J/psi
  or psi' -gt ll- (plus extra
• gamma from chi_c1 -gt
  J/psi gamma)
• chi_c2 as with chi_c1. There is also an (lt
  8.9) upper limit on chi_c0
• using the same method.
• chi_c0 exclusive measurement from (rarish)
  chi_c0 -gt pipi- and KK-
• PDG value is Belle's measurement of
  the same decay. There are not two sets of errors,
  should read 2.4 / -2.1
• These both "disagree" with Guy's
  upper limit.

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The case of the hc meson

• Measure the absolute BF(B?hcK) PDG value has
  30 error
• PDG2004 BF(B?hcK)(9.0 /- 2.7) x 10-4
• This turn will give a better measurement of the
  BF(hc?KKp)
• This will in turn give a better measurement of
  the BF(J/y?g hc) previously used to normalize the
  exclusive hc decays.

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using MC efficiency BR(B g J/y K) (8.1 m
1.2(stat) m 0.7(sys) 10 -4 BR(B g hc K)MC(8.3
m 1.3(stat) m 0.7(sys)) 10 -4 Using
Intradata BR(B g hc K)/BR(Bg J/yK)1.03 m
0.22(stat) m 0.06(sys) BR(B g hc K)data(10.3 m
2.2(stat) m 0.6(sys) m 0.3(ref))10-4
using the PDG04 BR for the J/y
decay BR(B g hc K)(8.6 m
1.5) 10 -4
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Target Material (ctd)
e
e-
The completed B1/Q1/SVT complex
r.f. shield
SVT mounted between the B1 magnets
Installed in Detector
Stainless Steel (11.7mm)
e-
e
C Fibre (2mm)
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Event Selection

• Candidate KS pp- and proton vertices selected
  using geometry m(pp)-m(KSPDG )lt50 MeV/c2
• Protons selected using dE/dx
• p p- selected using dE/dx

SVT
DCH
DCH
SVT
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Include Additional Vertex-Associated Charged
Tracks
Require DCH dE/dx (94 of tracks) DOCA lt 0.5 cm

• Require
• At least one associated track
• Remove candidates with gt 1 associated baryon
• (gt nuclear breakup, strong rescattering
  etc.)
• Then
• associated p
• associated p-
• associated K
• associated K-

No Signal observed in any Ksp mass distribution