charmed hadron spectroscopy at

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.

2

At FermilabBeO charm


3

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-


4

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.


5

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---


6

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


7

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


8

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!


9

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*+


10

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


11

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


12

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


13

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 )


14

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


15

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


16

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


17

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.


18

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


19

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 +


20

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.


21

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


22

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*+)


23

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


24

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


25

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 )


26

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


27


28

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


29

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 ).


30

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


31

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


32

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


33

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 )


34

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*


35

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).

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