New Particles at BELLE

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New Particles at BELLE
There is an impressive list of new particles in
the charm sector discovered by BELLE in the last
few years This talk covers only Not
included in this talk
X(3872)
?c(3753) ? Phys. Rev. Lett. 89 (2002) X(3940)

(2308) Y(3940) ? Phys. Rev. Lett. 94 (2005)
D1(2427) ?c(2800) ? Phys. Rev. Lett. 94 (2005)

? Phys. Rev. D 69 (2004)
Beauty 2005 Assisi
Spectroscopy and new Particles
F. Mandl
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Beauty 2005 Assisi
Spectroscopy and new Particles
F. Mandl
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Beauty 2005 Assisi
Spectroscopy and new Particles
F. Mandl
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• ? History
• Discovery by BELLE
• narrow ??- J/? mass peak
• in excl. B- ? K- ??- J/? decays ? Phys.
  Rev. Lett. 91, 262001 (2003)
• has been confirmed by CDF II, D0, BaBar
• m, ? not compatible with charmonium state
• m??- peaks near upper kinematic limit as
  expected for ? ? ??-
• but charmonium decaying to ?J/? violates
  isospin ? suppressed

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X(3872) observation
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Theoretical Explanation for X(3872)

• ? What could it be?
• Mx (3871.9 0.5) MeV is within error equal to
  the threshold (3871.3 1) MeV
• ? Speculation X might be a molecule - like
  bound state
• Tornquist JPC 0-, 1 C 1
• ??- J/? via ?0J/? intermediate
  state ? m??- concentrated at high masses
• Swanson dynamical model for X as a
  hadronic resonance
• JPC 1 strongly favoured
• appreciable
  admixture of ?J/? small ?J/?
• Decay X(3872) ? ?J/? observation would
  unambiguously establish C 1 for X

Beauty 2005 Assisi
Spectroscopy and new Particles
F. Mandl
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Study of X(3872) ? ?J/?
Study B ? K ?J/? 256 fb-1 data sample (275 M
) Selection J/?, K0 or K?, ? Ptab gt 40 MeV
to reduce continuum events (ee- ? ??q???b)
R2 lt 0.4 (normalized Fox-Wolfram moment)
cos?B lt 0.8 ?B polar angle of B in
cms B ? K?J/? are identified by
Beauty 2005 Assisi
Spectroscopy and new Particles
F. Mandl
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Evidence for X(3872) ? ?J/?
Constraint
Signal Region Mbc gt 5.20 GeV
5.2745 lt Mbc lt 5.2855 GeV ?E lt 0.2
GeV ?E lt 0.035
GeV Prominent peak near 3510 MeV in M(?J/?)
is used for
calibration The only significant B-meson signal
is in the 3872 MeV bin (also for
?E-distribution) Simultaneous fit of Mbc and ?E
and background (ARGUS function for Mbc and first
order polynominal
for ?E) Signal yield 13.6 4.4
events, Significance 4.0 ?
Beauty 2005 Assisi
Spectroscopy and new Particles
F. Mandl
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Beauty 2005 Assisi
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Evidence for X(3872) ? ?????? J/?

• X ? ??????J/?
• similar selection as above
• slightly different signal region
• only significant B-meson signal in 3872 MeV bin
  (not shown)
• Mbc distribution for various ????????inv. mass
  bins
• only significant B meson signal for M(??????) gt
  750 MeV bin
• the same for ?E
• Fit 12.4 4.1 events
  Significance 4.3 ?
• possible background B ? K ? J/? fit
  0.75 0.14 events
• B ?
  K-?????? J/? non res., use left and right side
  bound region
• 
  1.3 1.0 events

Beauty 2005 Assisi
Spectroscopy and new Particles
F. Mandl
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Beauty 2005 Assisi
Spectroscopy and new Particles
F. Mandl
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Beauty 2005 Assisi
Spectroscopy and new Particles
F. Mandl
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triple scalar product
X(3872) ? ???J/?
A ????J/?xprel
Lint
p waves
J/? in ???? rest frame
???? rest frame
Transversity analysis useful for decays to V V
1-p 4, 0.01
Beauty 2005 Assisi
Spectroscopy and new Particles
F. Mandl
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X(3872) ? ???J/?
A ????J/?
Lint
common rest frame of J/? and??0 (relativ momentum
maybe neglected)
1-p 0.3, 5x10-6
Beauty 2005 Assisi
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triple scalar product
X(3872) ? ???J/?
A ?????x?J/?
Lint
in X rest frame (D 0)
neglecting rel.mom. between J/? and ?0 all are
in same CMS
1-p 75, 16
Beauty 2005 Assisi
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centrifugal barrier !
X(3872) ? ???J/?
Beauty 2005 Assisi
Spectroscopy and new Particles
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3 pseudoscalars require D-wave
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I-violating hadr.trans. ?(2S) ? ?? J/?
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X(3940)

• Further analysis of the processes
• History first observation of such processes by
  BELLE
• Phys. Rev. Lett. 89, 142001
  (2002)
• Theoretical calculation
• ? various speculations
  glueball contribution ? etc.
• For the first time seen
• 
  X(3940) new charmonium state
• Look for recoil to J/??and ?(2S)?
  
  etc.

Beauty 2005 Assisi
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F. Mandl
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Study of the decay of reconstructed ?(2S) ?
J/?????? ????search for look for recoil
spectra 3 significant signals seen
(BaBar gets consistent results)
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Using higher statistics (287 fb?)
extend analysis of recoil masses against J/?
above DD threshold
no signal of X(3872)
? find new significant peak at M 3.940 GeV/c2
? X(3940) Fit ?c, ?co, ?c(2S),
X(3940) background ? MX (3.937 0.012)
GeV/c2 ??compatible with 0 (lt 95
MeV/c2) 90 CL lt resolution (32
MeV)
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Beauty 2005 Assisi
Spectroscopy and new Particles
F. Mandl
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? X(3940)
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Charmed baryon spectroscopy
light diquark in the environment of a heavy
quark ? test for theoretical models PDG 2004
4 excited charmed
baryons observed
?c(2455) ground state
?c(2520) Aim find excitations of ?c
Analysis uses data sample 253 fb-1 at ?(4S),
signal window around 8 MeV/c2
xp gt 0.5 for candidates
yield (516 2) x 1013 S/B 2.3
combine with ?? xp gt 0.7
cos?dec gt -0.4 ?dec angle between (? in
rest frame of ) and boost direction of
the system in cms
Beauty 2005 Assisi
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()
(0)
()
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Charmed baryon spectroscopy
?c(2800)0 ?c(2800) ?c(2800)
Isotriplet Enhancement at ?M 0.43 GeV for ?M(
??) and ?M( ?) ? feed-down from decay
?c(2880) ? ??? observed by CLEO next
study ??? clear peaks of ?c(2800) and
?c(2765) seen consistent with
observation of CLEO Fit Isotriplet
feed-down combinatorial background ?(ee- ?
?c(2800)X) x Br(?c(2800) ? ?) 2.04 (0),
2.6 (), 2.36 () pb Theoretical models ?c2
doublet with Jp 3/2- and 5/2- ?c2 ?
? mainly in D wave ?M 500 MeV/c2 as
measured ? 15 MeV smaller as
measured ?c2(JP 3/2-) can mix with ?c1(JP
3/2-) and would produce a wider physical state
Beauty 2005 Assisi
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Summary
seen for the first time (now also BaBar)
? X(3940) new charmonium state
?c(2800) triplet established
tentative identification ?c2, JP 3/2- ?c1,
JP 3/2- admixture
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Spectroscopy and new Particles
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SPARES ?
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Continuum Suppression
Unwanted Background for B-Decays
Continuum
ee- ? qq continuum (3x
BB)
Jet-like
To suppress use event shape variables
BB
spheric
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Continuum Suppression

• To separate spherical BB events from jet-like
  continuum events, topological variables are
  used
• Second Fox-Wolfram moment
• Super Fox-Wolfram
• (six modified Fox-Wolfram moments, Fisher
  discriminant)
• 3) Angle between B meson and
• beam axis direction
• 4) Angle between thrusts of
• selected B meson particles and all other
  particles in event
• Likelihood ratio includes all info.

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Beauty 2005 Assisi
Spectroscopy and new Particles
F. Mandl
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Beauty 2005 Assisi
Spectroscopy and new Particles
F. Mandl
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JPC possibilities for X(3872)

• J 2

• DD allowed P-violating unlikely

• signal for X ? ?J/?
• ? C-1 ruled out

• check of angular distributions
• ? rules out 1-,0,2--

• fits of Mpp
• ? 2- unlikely

• X(3872) ?c1?
• ? unlikely, since mass and BR ratio way off theo.
  expect.