Prezentacja programu PowerPoint

1
New Resonances at Belle Jolanta Brodzicka INP
Kraków For the Belle Collaboration XLIV
Cracow School of Theoretical Physics,
Zakopane May 28 - June 6, 2004

• Topics
• heavy-light mesons
• cs DSJ in e e- ? cc continuum and B
  exclusive decays
• cu D in B ? D() ? ?- decays
• charmonium-like state X(3872)

2
The Belle Collaboration
A World-Wide Activity 300 People from 50
Institiutions
Jolanta Brodzicka, INP Kraków
, Belle Coll.
3
KEK-B Factory

• KEKB Asymmetric ee- collider
• Two separate rings
• e (LER) 3.5 GeV
• e- (HER) 8.0 GeV
• CM energy 10.580 GeV at ?(4S)
• ee- ? ?(4S) ? BB
• Parameters
• 3016 m circumference
• 11 mrad crossing angle
• History Physics run since June 1999
• Luminosity peak 1.3x1034 cm-2s-1
• (achieved 20May2004)
• Integrated Luminosity 250 fb-1
• 260 x 10 6 BB
• 300 x 10 6 cc continuum events

Jolanta Brodzicka, INP Kraków
, Belle Coll.
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Belle Detector
Aerogel Cherenkov Counter

• Event reconstruction
• ? Charged track
• ? Central Drift Chamber (CDC)
• ? Silicon Vertex Detector (SVD)
• ? Electron and photon
• ? Electromagnetic Calorimeter (ECL)

Time of Flight Counter
Central Drift Chamber

• Particle identification
• ? K/? separation
• ? CDC dE/dx
• ? Aerogel Cherenkov Counter (ACC)
• ? Time of Flight Counter (TOF)
• ? electron identification
• ? ECL
• ? KL and ? identification
• ? KL and muon detector (KLM)
• Vertexing
• ? SVD

SC Solenoid 1.5T
Silicon Vertex Detector
KL /? Detector
Electromagnetic Calorimeter
Jolanta Brodzicka, INP Kraków
, Belle Coll.
5
New observations at B-Factories

• BaBar with 91 fb-1 on/off ?(4S) discovered
  resonance
• DSJ(2317) ? DS ?0
• isospin violating decay , narrow state ( ? lt
  10MeV )
• BaBar also saw peak in DS ? ?0 mass
  distribution _at_ 2460 MeV
• Interpreted as cross-feed from 2317 (DS
  from 2317 random ? )
• CLEO (13.5 fb-1) confirmed DSJ(2317)
  established DSJ(2463) ? DS ?0
• Belle (87 fb-1) saw both DSJ(2317) DSJ(2457)
  states in cc continuum
• in B decays

Topic of this talk
Interpretations

• DSJ(2317) DSJ(2457) identified with 0 , 1
  orbitally excited P-wave cs states

• more exotic assignments DK molecule,
  multiquark state, mixing P-wave cs states with
  4-quark csqq states (? masses shifted below D()K
  )

Jolanta Brodzicka, INP Kraków
, Belle Coll.
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Potential Model for Q q
Godfrey-Isgur (1985)

• Basic hypotheses of constituent quark model
• mesons valence-quark configuration
• dynamics described by a Hamiltonian
• relativized
• confinement with running ?s
• one gluon exchange dominates at short distance

VQq ? Hconf Hspin-spin (color-hyperfine)
Hspin-orbit (1-gluon-exch)
Hspin-orbit (Thomas precession)
Inter-quark potential
Heavy Quark Symmetry mQ ? ?
Q at rest (no chromomagnetic field, static
source of chromoelectric field) , Q decouples
from q
(hydrogen atom)
dynamics of the q ? meson properties
separately conserved
Jolanta Brodzicka, INP Kraków
, Belle Coll.
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Predictions for cu and cs mesons
based on Heavy Quark Symmetry

• L 1 Parity
• jq ³/2 J 2
• J 1
• jq ½ J 1
• J 0
• L 0 Parity -
• jq ½ J 1
• J 0

DSJ(2573) DS1(2536) DS1 2.53 GeV DS 0
2.48 GeV
D2 (2462) D1 (2421) D1 2.44 GeV D0
2.40 GeV
Missing doublets till last summer
Ds (2112) Ds (1968)
D (2007) D (1865)

• P-wave states with jq ½ expected to be broad
  (S-wave decays)
• ? difficult to identify
  experimentally (jq ³/2 states narrow)
• Also some predictions that m( jq ½ ) gt m(jq
  ³/2 )

Jolanta Brodzicka, INP Kraków
, Belle Coll.
8
DSJ(2317) _at_ Belle

• data sample 87 fb-1
• ee- ? cc ? Ds ?0 X (inclusively-produced)
• Ds ? ? (?K- K )? p (Ds ?0 ) gt 3.5 GeV (p
  in CMS) (to reduce combinatorial
  background)

DK threshold
Fitted signal 761 ? 44 (stat) ? 30 (syst)
Events/5MeV
?0 /DS sidebands
M( DS ?0 ) - M( DS ) GeV/c 2
M( DS ?0 ) - M( DS ) GeV/c 2
Small peak feed-down from DSJ(2457)
M(DSJ(2317)) 2317.2 0.5 (stat) 0.9 (syst)
MeV/c 2
? lt 4.6 MeV/c 2 (90 C.L.)
Jolanta Brodzicka, INP Kraków
, Belle Coll.
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DSJ(2457) _at_ Belle

• ee- ? cc ? Ds ?0 X ( Ds ?0
  inclusively produced )
• Ds ? Ds ? Ds ? ? (?K- K )? p (Ds
  ?0 ) gt 3.5 GeV

Fitted signal 126? 25 (stat) ? 12 (syst)
Events/5MeV
DS sideband
M( DS ?0 ) - M( DS ) GeV/c 2
M( DS ?0 ) - M( DS ) GeV/c 2
M(DSJ(2457)) 2456.5 1.3(stat) 1.3(syst)
MeV/c 2
Sideband-subtracted distribution
? lt 5.5 MeV/c 2 (90 C.L.)

• Peaking background sources
• Signal feeddown from DSJ(2317) random soft ?
• Broken DSJ(2457) signal Ds with bad ?

Test of nature of DSJ search for other decay
modes
Jolanta Brodzicka, INP Kraków
, Belle Coll.
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Decay modes of DSJ
DSJ(2457) ? DS ? ?-
DSJ(2457) ? DS ?
DSJ(2317) region
59 ? 11
152 ? 18
DS1 (2536)
Events/3MeV
Events/5MeV
M( DS ? ) - M( DS ) GeV/c 2
M( DS ? ?- ) - M( DS ) GeV/c 2
Dipion mode 1st time observed
(DS1 assumption 0.62 )
(DS1 assumption 0.16 )
Godfrey,Phys.Lett.B 568, 254 (2003)
DSJ(2457) JP ? 0 ,0- favours JP 1
DSJ(2317) favours JP 0

• No signal observed in
• DSJ(2457) ? Ds ? , Ds ?0
• DSJ(2317) ? Ds ? , Ds ? , DS ? ?-

From conservation of angular mom. and parity
Jolanta Brodzicka, INP Kraków
, Belle Coll.
11
-
DSJ in cc continuum - summary

• Belle observed DSJ(2317) ? DS ?0
• and
  DSJ(2457) ? DS ?0
• inclusively produced in ee- ? cc continuum
• radiative and dipion decay modes of DSJ(2457)
  observed
• the spin-parities 0 (DSJ(2317)) and 1
  (DSJ(2457)) are favoured

Jolanta Brodzicka, INP Kraków
, Belle Coll.
12
DSJ in B exclusive decays
Motivations

• Assignments of DSJ(2317) and DSJ(2457) being
• orbitally excited cs
  mesons need confirmation
• If DSJ(2317) and DSJ(2457) are cs states
• can be observed in B ? D DsJ
  decays
• expected BF 10-2 ? 10-3 , quite
  large
• States cs with j q ½ easier produced in B
  decays than those with j q ³/2 (HQET)
• States produced in B decay can be polarized
  from angular distributions ? J P
• In B decays background reduction

Tree type diagram processes
Jolanta Brodzicka, INP Kraków
, Belle Coll.
13
Method of full B reconstruction

• Experimental conditions

ee- ? ?(4S) ? BB m? ? (mBmB)

• For B decay to specific final state B ?
  f 1 f 2 f n

In ?(4S) frame Energy-Momentum conservation
Kinematical constraints are used

• Kinematical Variables
• Energy difference
• Beam-constrained
• mass

resolution improvement, background separation
Jolanta Brodzicka, INP Kraków
, Belle Coll.
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B ? D DsJ decays
data sample 115 fb-1
Signal extracted in ?E, Mbc and M(DSJ) Plot one
of them with cuts on the others
Reconstructed modes
B0 ? D- DsJ
B ? D0 DsJ
Both isospin related modes
Events/10MeV
M( DSJ ) GeV/c 2
?E GeV
DS decay angle of in DSJ (2457) ? DS ?
(B ? D DSJ )
Jolanta Brodzicka, INP Kraków
, Belle Coll.
15
DSJ in exclusive B decays summary
BR(B?DDSJ) ? BR(DSJ) comparison
? 0.4

• first observation of DSJ states in B decay in
  Belle
• no new DSJ decay modes in comparison to
  inclusive production
• masses and widths consistent
• DSJ (2457) angular analysis consistent with J1
• measured BRs do not exclude cs states
  assignments

Jolanta Brodzicka, INP Kraków
, Belle Coll.
16
New D0 states
expected decay modes D- ? , D- ?

• data sample 60 fb-1
• Dalitz analysis for
• B ?D- ? ? (1100 signal events) and
  B ?D- ? ? (600 events)

both with good S/B

• unbinned likelihood fit performed with signal
  density function
• S (M 12, M22 ) ? ? Ai exp(i?i ) BWi (M1
  2, M2 2 ) Aexp(i? ) ? 2 ? R(M2)

• coherent sum of the amplitudes of D states
  which can contribute and phase space term
• convolution with experimental resolution

Jolanta Brodzicka, INP Kraków
, Belle Coll.
17
D0 mesons
Dalitz plot projections with fit results
Background
M ( D ?min ) GeV/c 2
M ( D ?min ) GeV/c 2
Background
M ( D ?min ) GeV/c 2
M ( D ?min ) GeV/c 2
First observation of D0 and D10
, Belle Coll.
Jolanta Brodzicka, INP Kraków
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D0 - summary

• Belle observed for the first time broad D0
  and D10 states in B decays
• (observed also
  by FOCUS, poor agreement in measured masses)
• Identified as 0 and 1 orbitally excited cu
  doublet (with j q ½ )
• Narrow 1 , 2 states D10 and D2 0 also
  seen
• (already observed by CLEO)
• Masses and widths of four D states were
  measured

Jolanta Brodzicka, INP Kraków
, Belle Coll.
19
Measured masses versus model predictions

• In cu spectrum masses of D, D,D consistent
  with model expectations
• In cs case masses of new DSJ (2317) and DSJ
  (2457) inconsistent

Model expectation M(cs ) M(cu) ? 100 MeV
Chiral symmetry broken ? chiral partners split
off (states with opposite parity)
DSJ (2317) and DSJ (2457) interpreted as chiral
partners of DS and DS ?
? Nowaks talk
Jolanta Brodzicka, INP Kraków
, Belle Coll.
20
Discovery of X(3872)

• Belle data sample 140 fb-1
• in B decay B ? K ? ?- J/? J/? ? l l-

For B signal extracted in ?E, Mbc
M( ? ?- l l- ) - M( l l- ) GeV
M( ? ?- l l - ) - M( l l - )
New state is not reflection from any known
state
new narrow charmonium-like state X(3872) ? J/?
? ?-
Jolanta Brodzicka, INP Kraków
, Belle Coll.
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X(3872)

• Signal B ? X(3872)K extracted in ?E, Mbc
  and M( J/? ? ?- )
• Plot one of them with cut on the others
• Simultaneous fit in 3 variables

S 35.7? 6.8 (10? )
Events/5MeV
Events/5MeV
Events/15MeV
?E GeV
Mbc GeV
M ( J/? ? ?- ) GeV
MX 3872.0 0.6(stat) 0.5(syst) MeV
?X lt 2.3 MeV (90 C.L.)

• MX gt M(D D ) open-charm decay possible, why
  so narrow ?
• X produced in B decays J cannot be high
• Is it charmonium state?
• One of the unobserved higher charmonium states
  13DJ 11D2 23P1 21P1 ?
• 
  
  (predicted masses _at_ X mass region)
• MX ? M(D0 D0 ) loosely bounded
  molecular or hybrid state?

Jolanta Brodzicka, INP Kraków
, Belle Coll.
22
Properties of X(3872)

• Checking hypothesis that X(3872) is charmonium
  state
• ? radiative X decays should be observed
  (Eichten,Lane,Quigg)

3Dc 2 3Dc 3 ? X(3872) ? ? ?c1 , ? ?c2
Theory

• B ? K ? ?c1 ?c1(1P) ? ? J/?

Events/4MeV
Events/8MeV
M (? ?c1 ) GeV
No signal in X(3872) region
Mbc GeV

• B ? K ? ?c2 ?c2(1P) ? ? J/?

Events/10MeV
Events/5MeV
M (? ?c2 ) GeV
Mbc GeV
3Dc 2 3Dc 3 ruled out
Jolanta Brodzicka, INP Kraków
, Belle Coll.
23
Properties of X(3872)
23P1 ? X(3872) ? ? J/?
Theory
B ? K ? J/?
? 11keV / 0.3keV ? 30
Absence of X(3872)
?c1 ( 23P1 ) ruled out
M (? J/? ) - M ( J/? ) GeV
hc ( 21P1 ) ?
Prediction for 1 ? 1- cos2? (J/? )
J/? decay angle in
X(3872) ? J/? ? ?- (B ? K X(3872) )
cos ?(J/? )
hc1 ( 21P1 ) ruled out
Jolanta Brodzicka, INP Kraków
, Belle Coll.
24
X(3872) summary

• New unexpected state X(3872) observed by Belle
• 
  (also seen at Fermilab in pp
  collisions and BaBar )
• Still no obvious charmonium assignment
• Is it D0 D0 molecule?

MX 3872.0 0.6(stat) 0.5(syst) MeV
?X lt 2.3 MeV (90 C.L.)
Jolanta Brodzicka, INP Kraków
, Belle Coll.
25
Summary

• Many charm results from Belle.
• Some of them
• unexpected or/and inconsistent with
  theoretical expectations.
• B-Factory is a Charm Factory, too.
• In adition B decays are good and clear ground
  
• to study charm spectroscopy.

Jolanta Brodzicka, INP Kraków
, Belle Coll.
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Jolanta Brodzicka, INP Kraków
, Belle Coll.
27
Ds mesons
D mesons
L1
L1
Jolanta Brodzicka, INP Kraków
, Belle Coll.
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Jolanta Brodzicka, INP Kraków
, Belle Coll.