Charmed Hadron Spectroscopy At
Robert K. KutschkeFermilab
FCP01 March 7, 2001
1. Introduction
2. D**
3. DS**
4. C , C*
5. C*
R. K. Kutschke Frontiers in Contemporary Physics, 2001.
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At FermilabBeO charm
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FOCUS: The Successor to E687
• Segmented BeO Target interleaved with SMDs.• Upgraded:
– EM Calorimetry.– Cerenkov system.– Muon ID capability.
• Data taken in 1996-1997.• More than 10 times the Luminosity
• >106 reconstructed “Golden Mode” Decays: D0K-K-and D+K-
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Candidate Driven Vertexing
•Find charm candidate: good vertex, good particle ID.
•Seed primary vertex finder with the charm candidate.
•Require isolated secondary. One measure: L/L> cut.
•Add tracks from primary to form ccombinations.
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P-wave Charmed Mesons
c D*, D
c
q
q-
(K, K*)u,d,s
---
• L=1 between c and light quark ( q=u,d,s ).
• jlight = Slight + L , approximately good Q number if mC >> QCD Rosner: “the hydrogen atom of QCD”
• Idealized picture is a “doublet of doublets”.
• Strong decays to D(*) ( or D(*)K for DS )
u,d,s---
R. K. Kutschke Frontiers in Contemporary Physics, 2001.
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Idealized Picture of P-wave Charmed Mesons
Observed?
D2*+, D2
*0, Ds2*
D1+, D1
0, Ds1
No confirmed
candidates
(MeV/c2)
20
>100
Decays
D*, D
D*
D*
D
JP
2+
1+
1+
0+
jlight
3/2
1/2
mc mc>>QC
DNo spins
Heavy quark symmetry:
jl=3/2 dominant decays are D-wave
jl=1/2 dominant decays are S-wave
Reminder:
D : JP = 0-
D*: JP = 1-Jlight
P
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Angular Momentum and Parity Selection Rules
Decay L Decay L
2
2
2
0 , 2
0
0
All 5 decays in the multiplet are described by 2 parameters, the S wave and D wave amplitudes (x Wigner 6-j, x
phase space)
1+3/2 Decays via D-
wave
1+1/2 Decays via S-
wave
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What’s Overly Simplified in the Ideal Picture?
• Doublets may overlap ( which 1+ is more massive?)
• Is suppression of S wave widths complete?
• Ds1 right at threshold for D*:
• Very narrow, < 2.3 MeV/c2 @ 90% CL.
• Data suggests mostly S-wave!
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S-Wave Charm States at FOCUS
D0 K
D0 K
D+ K
For S/B > 7,> 330,000 D candidates
Entr
ies
/ 5
MeV
/c2
D*+ D0
K
K
Entr
ies
/ 0
.5
MeV
/c2
30000
2000010000
0.140M(D0+)-M(D0)(GeV/c2)
0.144 0.148
For S/B > 5, 70,000 D*+ candidates
(GeV/c2)
D+D0
M(Kor K3)
M(K)
D*+
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D0and D+ Mass Distributions
Wrong sign Wrong sign
Feed down from D2*, D1 partial
reconstruction
Feed down from D2*, D1 partial
reconstruction
M(D0+)-M(D0)+1.8646 (GeV/c2)
M(D+-)-M(D+)+1.8693 (GeV/c2)[ Shorthand: MF(D0) MF(D+) ]
Entr
ies
/ 1
0 M
eV
/c2
Entr
ies
/ 1
0 M
eV
/c2
FOCUS
FOCUS
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Get Feed-down Line Shapes from Monte Carlo
D1
Do
D*o ++
, Do D2
Do
D*o +*+
, Do
MF(D0) (GeV/c2)
300
3.02.62.42.22.0 2.8 3.02.62.42.22.0 2.8
200
100
600
400
200
400
Entr
ies
/ 1
0 M
eV
/c2
Entr
ies
/ 1
0 M
eV
/c2
MF(D0) (GeV/c2)
MC MC
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Beyond Signal Region all Shapes are Exponential
Side band: e-2.670.04
Wrong sign: e-2.380.01
Right sign: e-2.350.01
D2*0
D+-
Side band: e-2.650.03
Wrong sign: e-2.270.01
Right sign: e-2.530.01
D2*+
Do+
MF(D0) (GeV/c2) MF(D+) (GeV/c2)
Entr
ies
/ 1
0 M
eV
/c2
Entr
ies
/ 1
0
MeV
/c2
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Fitting the D0 Mass Distribution (1)Entr
ies
/ 1
0 M
eV
/c2
=724 MeV/c2
2 / dof= 3.1
MF(D0) (GeV/c2)
Fit Results: Terms in the Fit:
1. Signal: D-wave Rel. BW, convoluted with a gaussian, = 7 MeV/c2.
2. Exponential extrapolated from 2.4 – 4.5 GeV/c2.
3. MC D1 Feed-down.
4. MC D2 Feed-downGet horrible fit!
FOCUS
( PDG(D2*+) = 25 8 MeV/c2 )
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Fitting the D0 Mass Distribution (2)
MF(D0) (GeV/c2)
=724 MeV/c2
2 / dof= 3.1Fit Results:
Entr
ies
/ 1
0 M
eV
/c2
MF(D0) (GeV/c2)
M=2468.21.5 MeV/c2
2 / dof= 1.8= 28.6±1.3 MeV/c2
Add 5th term to the fit: S-wave Rel. BW
FOCUS
FOCUS
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D2 Do+*+
D*+ Do +
Pion momentum (GeV/c)
Reducing BG from Soft From D*+ Decays
M = 2468.5 2.1 MeV/c2
= 30.3 3.6 MeV/c2 D2
*+
p> 10 GeV/c
MF(D0) (GeV/c2)
Entr
ies
/ 1
0 M
eV
/c2
FOCUS
MC
MC
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Fitting the D+- Mass Distribution
2 / dof = 0.9
MF(D+) (GeV/c2)
= 55 3 MeV/c2
2 / dof= 2
PDG ( D2*0 ) = 23 5 MeV/c2
MF(D+) (GeV/c2)
Signal + Exp + D1 + D2
+ S-Wave Rel. BW
Entr
ies
/ 1
0 M
eV
/c2
Entr
ies
/ 1
0 M
eV
/c2
= 30.5 1.9 MeV/c2
M = 2463.5 1.5 MeV/c2
FOCUS
FOCUS
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L/<
30
L/>
30
Par
ticl
eA
nti
par
ticl
eP
< 1
8 G
eV/c
P
> 1
8 G
eV/c
PD<
70
GeV
/cP
D>
70
GeV
/c
D2*+
Width
D2* Mass and Width
Systematics
L/<
30
L/>
30
Par
ticl
eA
nti
par
ticl
eP
< 1
8 G
eV/c
P
> 1
8 G
eV/c
PD<
70
GeV
/cP
D>
70
GeV
/c
D2*+
Mass
FOCUS D2* Results
Mass (MeV/c2) (MeV/c2)D2
*+ 2468.2 1.5 1.4 28.6 1.3 3.8
D2*0 2463.5 1.5 1.5 30.5 1.9
3.8
Prelim
inar
y
D2
*+ M
ass
M
eV
/c2
D2
*+ W
idth
M
eV
/c2
PDG 2000: M+=24594, M0=2458.92.0, +=258, =235 MeV/c2.
R. K. Kutschke Frontiers in Contemporary Physics, 2001.
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D*+- Mass Distribution
Wrong sign
D10 Yield = 889
92 D2*0 Yield = 977
101
M((D0+))-M(D0)+2.0100
2.72.42.1
[ Shorthand: MF(D*+)]
800
600
Entr
ies
/ 1
0 M
eV
/c2
(GeV/c2)
200
400
Prelim
inar
y
1200
2.7
R. K. Kutschke Frontiers in Contemporary Physics, 2001.
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Observation of the DS2* and DS1
c D*, D
c
u
qDS
**q-
u-
-K, K*
DS2* D0 K+
D+ KS0
D0 K-+, K- ++-
D+ K-++
DS1 D*+ KS0
D*+ D0 +
R. K. Kutschke Frontiers in Contemporary Physics, 2001.
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Observation of the Ds2* at Focus
Prelim
inar
y
FOCUS
First observation of the D+KS
0 mode!
D0K+ D+KS0
There are some real KS0 in
the sideband sample.
R. K. Kutschke Frontiers in Contemporary Physics, 2001.
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Simultaneous Fits to D0K+ and D+KS0
Spectra
1. DS2 Signal: D-wave Rel. BW
2. Smooth background shape
3. MC DS1 feeddown shape
4. MC DS2 feeddown shape. Significance is not stable with cut variations!
Terms in the fit:
• Simultaneous: M and same.• Errors are statistical only PDG:
M = 2573.5 ± 1.7 MeV/c2
= ± 5 MeV/c2
Prelim
inar
y
First observation of D+KS0
mode
R. K. Kutschke Frontiers in Contemporary Physics, 2001.
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Observation of the DS1 at FOCUS
Prelim
inar
y
1. DS1 Signal: Non Rel BW, convoluted with a gaussian.
2. Smooth background shape.
3. DS2* Signal: D-wave Rel
BW.
Terms in the fit:
• Errors are statistical only
PDG:
= 525.35 ± 0.34 MeV/c2
< 2.3 MeV/c2 @ 90 % CL.
M(D*+Ks0)-
M(D*+)
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Some Charmed Baryons:
cdd
cud
cuu
c*+
c0
c*++
JP 3/2-c(2625)
c+
c*0
1/2+c++
c+
c(2593)
c*c
c(*) c
cud
JP
3/2+
1/2-
Definition: : I=0: I=1
P-Wave Baryon
c*c
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Selection of cfor c++and c
0Studies
4000
2000
3000
1000
5000
Entr
ies
/ 5
MeV
/c2
2.1 2.2 2.3 2.4M(p+K-) (GeV/
c2)
• L/L > 6.
• Isolated secondary vertex.
• affirmative Id for p and K
• consistency for
• For c+study
•L/ > 4, Looser .
•Yield = 18346 248
• S/B = 1.19
c+p+ K-
Č
Č
Č
Yield=12410 180
S/B = 1.7
7.890.11 MeV/c2
Cut 2
Sidebands
FOCUS
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M(c0) – M(c
+) =
167.38 0.21 MeV/c2
M(c++) – M(c
+) =
167.35 0.19 MeV/c2
c++and c
0Masses
C++C
+
C0C
+
En
trie
s /
500
KeV
/c2
Yield = 362 36
Yield = 461 39
0.15
0.17
0.19
(GeV/c2)
0.15
0.17
0.19
(GeV/c2)M(C
+) – MC+
FOCUS
60
40
20
60
40
20
( CLEO 2.5 ICHEP 2000167.20.10.2 MeV/c2 )
( CLEO 2.5 ICHEP 2000167.40.10.2 MeV/c2 )
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Source Systematic Error (MeV/c2)
c++c
+ c0c
+ c++c
0
Momentum Scale
0.05 0.05 0.00
Fitting 0.02 0.06 0.04Recon. Bias 0.04 0.04 0.00Analysis Cuts 0.10 0.10 0.10
Total 0.12 0.13 0.11
M(c++) – Mc
0=-0.03 0.28 0.11 MeV/c2
Systematic Errors
Phys. Lett. B488, 218-224, 2000.
M(c0) – M(c
+ ) = 167.38 0.21 0.13
MeV/c2M(c ) – M(c ) = 167.35 0.19 0.12 MeV/c2
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R. K. Kutschke Frontiers in Contemporary Physics, 2001.
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Observation of c+ c
+0
(GeV/c2)
100
200
150
50
0.2 0.4 0.16
0.20
0.3 0.18
0.14Mc
+ – Mc+
20
80
60
40
N /
1 M
eV
/c2
N /
3 M
eV
/c2
Mc+ –Mc
+168.0 1.0 0.3 MeV/c2
( CLEO hep_ex/0007041: Mc+ – Mc
+166.4 0.2 0.3 MeV/c2 )
Mc+ –Mc
00.6 1.0 0.3 MeV/c2
Yield =118 40
0Reconstructed in EMCAL.
Prelim
inar
y
FOCUS 3.040.84 MeV/c2
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Isospin Mass Differences
Mass Difference (MeV/c2)Particles PDG 1998 CLEO 2.5 FOCUS
N-P 1.293318 ± 0.000009
2.6 ± 0.4 8.08 ± 0.08 6.4 ± 0.6c
c 4.7 ± 0.6
cc
-0.57 ± 0.23 0.03±0.28±0.11
cc
-1.4 ± 0.6 0.7 ± 0.5 -0.6±1.0±0.3
Prelim
inar
y
Theory has canceling contributions: quark masses, strong potential, Coulomb interaction, hyperfine ( EM + QCD ).
R. K. Kutschke Frontiers in Contemporary Physics, 2001.
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Natural Widths (MeV/c2)
c02.58
0.79
+0.51 -0.55 c
++2.53 0.77
+0.51 -0.56
0.200.180.160.140.160.14 0.18(GeV/c2)
0.20
80
60
40
20
80
60
40
20
Mc+ – McMc
+ – Mc
Signal Shape: BW convoluted with a gaussian.
Prelim
inar
y
MeV/c2
Entr
ies
/ 0
.5 M
eV
/c2
FOCUS
( CLEO 2.5 ICHEP 2000: MeV/c2 )
MeV/c2
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c++and c
0
Theoretical PredictionsAuthor ‡ (MeV/c2)
c0 c
++
Ivanov 2.65 ± 0.19 2.85 ± 0.19Tawfig 1.57 1.64Huang 2.4 2.5Pirjol 1.0 - 3.0 1.1 - 3.1Rosner 1.32 ± 0.04 1.32 ± 0.04‡ References at end of talk.
Focus Preliminary Results2.58 ± 0.79
2.53 ± 0.77
+0.51 -0.56
+0.51 -0.55
R. K. Kutschke Frontiers in Contemporary Physics, 2001.
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Observation of c*++ and c
*0
0.30
0.25
0.15
0.20
0.30
0.20
0.25
0.15 (GeV/c2)Mc
+ – Mc Mc+ – Mc
300
200
100
300
200
100
Entr
ies
/ 1
.0 M
eV
/c2
Mc0232.7 1.2
MeV/c2
Mc++234.21.5
MeV/c2
Prelim
inar
y
9.4 3.7 MeV/c2 = 23.6 4.5 MeV/c2
Mc*0Mc
*++ = -1.5 1.9 MeV/c2
Yield = 1284 225
Yield = 593 146
FOCUS
( CLEO II: M0=232.61.00.8 M+
+)
Stat
errs on
ly
R. K. Kutschke Frontiers in Contemporary Physics, 2001.
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Observation of Excited c States
(GeV/c2)
0.30
0.35
0.40
0.45
250
200
150
100
50
M(c+) – M(c
+)
c(2625):
M = 341.6 ± 0.3 MeV/c2
c(2593):
M = 308.1 ± 0.7 MeV/c2
Entr
ies
/ 2
MeV
/c2
Prelim
inar
y
Errors are Stat only.
FOCUS
( PDG 2000: 341.7 0.6 )Yield = 371 ± 32
Yield = 100 ± 20( PDG 2000: 308.9 0.6 )
R. K. Kutschke Frontiers in Contemporary Physics, 2001.
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Summary and Conclusions
• Preliminary masses and widths in D** and DS** sectors.
• First observation of DS2* D+KS
0.
• Confronting a new level of systematics in the D** sector
• We require something like the expected broad state to fit the mass difference spectrum successfully.
• Measurements of C++ and C
0 Masses and Widths
• Published: M(c++) – Mc
0=-0.03 0.28 0.11 MeV/c2
• Confirm C+, C
*++C*0 previously seen only by CLEO II.
• A good start on C*
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References for Theory on Page 30
1. M.A. Ivanov et al., Phys. Lett. B442, 435 (1998).
2. M.A. Ivanov et al., Phys. Rev. D60, 094002 (1999).
3. S. Tawfig et al., Phys. Rev. D58, 054010 (1998).
4. M.-Q. Huang et al., Phys. Rev. D52, 3986 (1995).
5. D. Pirol and T.-M. Yan, Phys. Rev D56, 5483 (1997).
6. J.L. Rosner, Phys. Rev. D52, 6461 (1995).