Βdecays to open charm and charmonium from BaBar’decays to open charm and charmonium from BaBar...

Β decays to open charm and charmoniumfrom BaBarStefania RicciardiRoyal Holloway, University of LondonOn behalf of the BaBar Collaboration

32nd International Conference on High Energy Physics Beijing, August 16-22nd,2004

ICHEP04Stefania Ricciardi, BaBar2

OutlineTesting models of hadronic Β decays

Inclusive charm production in Β decaysΒ0 → Ds*+ D*− [and Ds → φ π+]Β0 → D(*)−ppπ+, Β0 → D(*) 0ppExclusive Β → (cc) K(*), where cc = J/ψ,ψ(2S),χc

Charm and Charmonium Spectroscopy: Β decays to DsJ (2317) and DsJ (2460)X(3872)

For new results on Β→ D(*)K(*) and Β→ Ds+ρ −

see L.Cavoto’s talk in the CP violation session

All results are PRELIMINARY


Inclusive charmHadronization models (Heavy Quark Expansion)predict average charm multiplicity in B decays, nc ≈ 1.2-1.3

[Bagan et al. PLB351(1995)Buchalla and Dunietz, PLB364(1995)Neubert and Sachrajda, Nucl.Phys.B483(1997)]

We define:• Flavor correlated charmcorrelated charm

production from dominant b→c transition

• Flavor antianti--correlated charmcorrelated charmproduction from W− → cs’ decay

b cu u

W −

B−

s’c

) ( Nc

c XXB cX

→−∑= B

[charge-conjugationimplied everywhere]

)(,,,, ,0 ccDDDX ccc S ΞΛ= +++

) ( Nc

c XXB cX

→−∑= B

ccc N N n +=)(,,,, 0 ccDDDX cc S−−− Λ=


Inclusive charm: a new experimental method

Full reconstruction of one B = BrecoCharm hadron searched for in rest of event, fully reconstructed and correlated with charge of parent B = Brecoil

We correct for: mixing in the B0 sample and background from B0 (B+) in the B+ (B0) sample

**

**

BrecoBrecoil

BrecoBrecoil

recorecoil

pp

EE

BB

−=

=

=Y(4S)→ Β Β :

e− e+

Y(4S)B+

B−

Kπ

D0

X

D+, D0, Ds,Λc

π, ρ,a1

Brecoil

Breco

(#)

(# at the time of Brecodecay only, for neutral B)

→ →


Inclusivecharm

Data sample: 89 million B pairs

D0

D+

D+S

D0

D−

D−S

Λ−c

B−

corr

elat

ed

B−

anti-

corr

elat

ed

BaBar Preliminary

Λ+c Signal

41±9Signal33±9

Signal11±5

Signal82±11

Signal262±29

Signal98±20

Signal1273±42

Signal160±16

Blue-shaded areas: true charm particlesfrom background of misreconstructed B

• Significant production ofcorrelated D0 and D+

• Ds correlated production small. Anti-correlated dominant.


Inclusive charm: branching fraction

correlated anti-correlated

Xc B(B−→ XcX) % B(B−→ XcX) %

D0 51.1 ± 3.1 ± 2.5+1.3-1.3 6.3 ± 1.9 ± 0.5+0.2

-0.2

D+ 39.7 ± 3.0 ± 2.8+2.8-2.5 2.3 ± 1.8 ± 0.3+0.2

-0.2

< 5.1 at 90% CL

D+s 3.9 ± 1.7 ± 0.4+1.3

-0.8

< 8.7 at 90% CL10.9 ± 2.1 ± 0.8+3.8

-2.3

Λ+c 4.9 ± 1.7 ± 0.4+1.8

-1.0 2.0 ± 1.2 ± 0.2+0.7-0.4

<3.9 at 90%CL

correlated anti-correlated

Xc B(B−→ XcX) % B(B−→ XcX) %

D0 79.3 ± 2.5 ± 4.0+2.0-1.9 9.8 ± 0.9 ± 0.5+0.3

-0.3

D+ 9.8 ± 1.2 ± 1.2+0.8-0.7 3.8 ± 0.9 ± 0.4+0.3

-0.3

D+s 0.5 ± 0.6 ± 0.2+0.2

-0.1

<2.2 at 90% CL14.3 ± 1.6 ± 1.5+4.9

-3.0

Λ+c 3.5 ± 0.8 ± 0.3+1.3

-0.8 2.9 ± 0.8 ± 0.3+1.1-0.6

B− recoil

N(B+RECO) = 85840 ± 1910

B0 recoil

N(B0RECO) = 48322 ± 590

• First measurement ofD+

s correlated• Sizeable Λc

production


Inclusive charm: nc0

, nc−

We find no evidence ofB− →Λc

+ Λc− K

looking at the missing mass distribution (obtained from the B 4-momentum, a K and a reconstructed Λc or Λc)

We estimate B(B− →Ξc X) = B(B− →Λc

− X) - B(B− →Λc+ Λc

− K) ≅ B(B− →Λc− X)

B(B− →Ξc X) neglectedUsing B(B− →(cc) X) = (2.3 ± 0.3) %,

we determine separately for the first time:

058.0 0.0621.276n 062.0 0.0371.313n

012.0 0.0360.237N 020.0 0.0220.330 N

049.0 0.0511.039N 046.0 0.0300.983 N

066.0046.0

0c

063.0042.0c

039.0024.0

0c

051.0031.0c

039.0031.0

0c

028.0023.0c

+−

+−

−

+−

+−

−

+−

+−

−

±±=±±=

±±=±±=

±±=±±=

Previous results (hep-ex/0112028)1.175 ± 0.042 (CLEO)1.230 ± 0.042 (LEP+SLD) 1.206 ± 0.033 (Average)

=cn

B− B0


Β0 → Ds*+ D*−

New measurement of B(Β0 → Ds*+ D*−)Experimental test of factorization at high q2 values:q2~m2(Ds*+)

New measurement of B(Ds+→ φ π+)

used to normalize other Ds+ branching fractions

The present ~25% uncertainty

B (Ds+→φ π+ ) = (3.6 ± 0.9)% (CLEO)

propagates to all analyses where a Ds(*) is

reconstructed


Β0 → Ds*+ D*−: method

With a partial reconstruction technique, determine

B1 = B (B0 → Ds*+ D*-)

Fully reconstruct final state with Ds+→ φ π+

and measure

B2 = B (B0 → Ds*+ D*-) x B (Ds

+→ φ π+)

B (Ds+→ φ π+) = B2/B1.

Many systematics cancel in the ratio.


Β0 → Ds*+ D*− : partial reconstruction

hep-ex/0408040124 million B pairs

0B∗D

0D

∗SD

)( SD

−π

−+−+−+

−+−+

πππππ

πππ

SKKKK

,,, 0

γ

Ds+ from Ds

*+ → Ds+γ is not reconstructed

Pair D*- (→ D0 π-) and γ , assuming they come from B0→ Ds

*+D∗−

This BaBar Resultindependent of B(Ds

+→ φπ+) :

B(B0→ Ds*+D*-) = (1.85 ± 0.09(stat) ± 0.16(syst) )%

B(B0→ Ds*+D*-) theor= (2.4 ± 0.7)%

in agreement with previous:

and theory (Luo and Rosner,2001):

Signal: 7414 ± 345

B(B0→ Ds*+D*-) = (1.9 ± 0.5)% (PDG2004)

22 )()( ** γγ pppEEEm DBDbeammiss ++−−−= → → →


Ds+→ φ π+ :ResultsD* and γ selection analogous to inclusive analysisDs+→ φ (→K+K−) π+ fully reconstructed

measure branching fraction product:

Signal 212 ±19

2*4/ BES psm −= Dividing by our measurement of B(B0→ Ds

*+D*-), we obtain

B(Ds+→ φ π+) = (3.6 ± 0.9)% (CLEO)

to be compared with

Readjustment of many results needed!Not used yet for other results in this talk

B (B0 → Ds*+ D*−) x B (Ds

+→ φ π+) = (8.71 ± 0.78(stat)) x10-4

B(Ds+→ φ π+) = (4.71 ± 0.47(stat) ±0.35(syst))%


B0→D(*)−ppπ+ and B0→ D(*)0pp

Decay B (10-4) Reference B (10-4)

B0→D*−ppπ+ 5.61 ± 0.59 ± 0.73 6.5+1. 3-1.2 ± 1.0 (CLEO)

B0→D−ppπ+ 3.80 ± 0.35 ± 0.46 −

B0→D*0pp 0.67 ± 0.21 ± 0.09 1.20+0.33-0.29 ± 0.21 (Belle)

B0→D0pp 1.24 ± 0.14 ± 0.12 1.18 ± 0.15 ± 0.16 (Belle)

hep-ex/0408035124 millions B pairs

BB00→→DD**−−ppppππ++

130 ± 14BB00→→DD−−ppppππ++

238 ± 22

BB00→→DD**00pppp13 ± 4

BB00→→DD00pppp96 ± 11

• Full reconstruction• Explore dynamics of decays

involving baryons• Multi-body decays to baryons

sizeable, as found by CLEO& predicted

I.Dunitez, PRD (1998)Hou and Soni, PRL (2001)Chua, Hou and Tsai, PRD (2002)

No evidence of θ0c+ @ 3.1 GeV

BB00→→DD**−−ppppππ++


Β → (cc) K(*)

Exploring heavy quark dynamics by measurements of exclusive Βdecay rates to modes allowed in the factorization scheme (charmonium JPC=1−− or 1++) [12 decay modes]:

B → J/ψ K(*)B → ψ(2S) K(*)

B → χc1 K(*)

and suppressed (⇒ measure size of non-factorizable contributions)(JPC=0++ or 2++) [8 decay modes]:

B → χc0 K(*)

B → χc2 K(*)

Measurement of CP asymmetriesin the charged modes to search for effects due to “New Physics”

[Diehl and Hiller, JHEP 0106 (2001)]

Charmoniumreconstructed in

• J/ψ(ψ(2S)) → l+l-

• χc→ J/ψγ


B (Β → (cc) K(*)) Resultshep-ex/0408036124 million B pairs

Channel BR (10-4) PDG2004B+ → J/ψ K+ 10.55 ± 0.15 ± 0.48 10.0 ± 0.4B0 → J/ψ K0 8.73 ± 0.23 ± 0.30 8.5 ± 0.5

B+ → J/ψ K*+ 14.34 ± 0.36 ± 0.94 13.5 ± 1.0

B0 → J/ ψ K*0 12.92 ± 0.25 ± 0.75 13.1 ± 0.7

B+ → ψ (2S) K+ 6.31 ± 0.33 ± 0.44 6.8 ± 0.4

B0 → ψ(2S) K0 6.60 ± 0.60 ± 0.46 6.2 ± 0.7

B+ → ψ (2S) K*+ 6.03 ± 0.85 ± 0.91 9.2 ± 2.2

B0 → ψ (2S) K*0 6.65 ± 0.57 ± 1.00 8.0 ± 1.3

B+ → χc1 K+ 5.72 ± 0.24 ± 0.64 6.8 ± 1.2

B0 → χc1 K0 4.56 ± 0.39 ± 0.51 4.0 +1.2-1.0

B+ → χc1 K*+ 2.89 ± 0.69 ± 0.93 new

B0 → χc1 K*0 3.19 ± 0.37 ± 0.64 4.1 ± 1.5

0

10

20

30

5.2 5.225 5.25 5.275 5.3

mES (GeV/c2)mES (GeV/c2)mES (GeV/c2)mES (GeV/c2)

Even

ts/2

MeV

mES (GeV/c2)mES (GeV/c2)

Babar Preliminary

mES (GeV/c2)mES (GeV/c2)mES (GeV/c2)

BB00 →→ χχc1 c1 KK*0*0

BB++ →→ χχc1 c1 KK*+*+

0

20

40

60

80

5.2 5.225 5.25 5.275 5.3

mES (GeV/c2)mES (GeV/c2)mES (GeV/c2)mES (GeV/c2)Ev

ents/

2 M

eVmES (GeV/c2)mES (GeV/c2)

Babar Preliminary

mES (GeV/c2)mES (GeV/c2)mES (GeV/c2)


Β → (cc) K(*): Other Results

03.002.014.1) )cc(.(.) )cc(.(.

(*)00

(*)

±±=→→ ++

KBFBKBFBCharged/Neutral Ratio

assuming equal production of charged and neutral at Y(4S) (i.e., R+/0 =1)R+/0 (assuming isospin invariance and τB+/ τB0=1.086 ± 0.017 from PDG2004)

03.002.005.1))4S(())4S((

00

0/

±±=→ΥΓ→ΥΓ

=−++

BBBBR Final state Asymmetry

J/ψ K+ -0.029 ± 0.014 ± 0.010J/ψ K*+ 0.045 ± 0.025 ± 0.011ψ(2S)K+ 0.059 ± 0.051± 0.021ψ(2S)K*+ -0.063 ± 0.137 ± 0.050

χc1 K+ 0.011 ± 0.042 ± 0.017χc1 K*+ -0.403 ± 0.309 ± 0.237

Charge CP Asymmetries

))(.(.))(.(.))(.(.))(.(.

(*)(*)

(*)(*)

−−++

−−++

→+→→−→

=KccBFBKccBFBKccBFBKccBFBACP

All measurements compatible with no direct CP asymmetry.


Factorization suppressed decaysB+ → χc0 (→ ππ,KK) K+ observed by Belle and BaBar with

B.F. >10-4, i.e., comparable to factorization allowed decays

hep-ex/0408033124 million B pairs

Radiative BF relatively large for χc2:• B (χc0 → J/ψ γ) = (1.18 ± 0.14)%• B (χc1 → J/ψ γ) = (31.6 ± 3.3)%• B (χc2 → J/ψ γ) = (20.2 ± 1.7)%

χc2 BF (10-4) (90% CL)

K+ <0.36K0 <0.44K*+ <0.14K*0 <0.22

Upper limits for B → χc2 K(*)

an order of magnitude smallerthan B.F. for factorization allowed modes and B → χc0 K(*)

χc1χc1

χc2 χc2χc0

No statistical significant signal

χc0

m(llγ) – m(ll)

Spectroscopy

Β Mesons Heavenly Gateways

to Forbidden States…


Study of B → DsJ(*)+D(*)

Godfrey-Isgur model

S-wave P-wave

Ds+

Ds*+

Ds1(2536)+

DsJ (2573)+

Ds0(2317)

Ds1(2460)

DsJ*(2317)+, DsJ (2460)+

Observed by BaBar, Belle and CLEO Unexpectedly below threshold for DK and D*K, respectively Consistent with P-wave csstates but other interpretations not ruled outIf cs, observed decays

• DsJ*(2317)+ → Ds

+ π0

• DsJ (2460)+ → Ds*+ π0

are isospin violating ⇒ narrow DsJ (2460)+ → Ds

+ γalso observed (and used hereto determine J)


B → DsJ(*)+ D(*) hep-ex/0408041

Data sample: 122 million B pairs

DDsJsJ**(2317)(2317)++→→ DDssππ00

DDsJsJ(2460)(2460)++→→ DDss**ππ00

DDsJsJ(2460)(2460)++→→ DDssγγ

mmESES mm((DDsJsJ)

Full reconstruction of the exclusiveΒ decay

Sum over all D(*)(0) modes

Signal:88 ± 17 events

112 ± 14 events

139 ± 17events

020.0045.0274.0

))2460(.(.))2460(.(.0*

±±=

=→

→++

++

πγ

sDDFBDDFB

sJ

ssJ

We measure:


B → DsJ(*)+D* Results

First measurement of all these modes

m(Ds+π0) m(Ds

*+π0) m(Dsγ )

B.F. (10-3) DsJ*(2317)+ →Dsπ0 DsJ(2460)+→Ds*π0 DsJ(2460)+→ Dsγ

B0 1.5 ± 0.4 ± 0.2(+0.5-0.3)

0.9 ± 0.6 ± 0.2(+0.3-0.2)

2.3 ± 0.3 ± 0.3(+0.8-0.5)5.5 ± 1.2 ± 1.0(+1.9-1.2)

7.6 ± 1.7 ± 1.8(+2.6-1.6)B+ 1.4 ± 0.4 ± 0.3(+0.5-0.3)

B.F. Productsfor B→DsJ

(*)+D*


B → DsJ(*)+D Results

m(Ds+π0) m(Ds

*+π0) m(Dsγ )

B.F. (10-3) DsJ*(2317)+ →Dsπ0 DsJ(2460)+→Ds*π0 DsJ(2460)+→ Dsγ

B0 1.8 ± 0.4 ± 0.3(+0.6-0.4)

1.0 ± 0.3 ± 0.1(+0.4-0.2)

0.8 ± 0.2 ± 0.1(+0.3-0.2)2.8 ± 0.8 ± 0.5(+1.0-0.6)

2.7 ± 0.7 ± 0.5(+0.9-0.6)B+ 0.6 ± 0.2 ± 0.1(+0.2-0.1)

B.F. Productsfor B→DsJ

(*)+D

in good agreement with Belle results


B→DsJ(2460)+D : Helicity J=2J=1

DsJ+ (2460)

Ds

γ

θh

Data points from m(Dsγ) fitscorrected for detector acceptanceand efficiency

J=1 (χ2=4.0/4) preferred to J=2 (χ2=36.4/4)

confirms Belle measurement


X(3872) from B−→J/ψ K−π+π−hep-ex/0406022117 million B pairs

mX(3782)= 3873.4 ±1.4 MeV/c2

B(B-→X(3872)K-) x B(X(3872)→J/ψπ+π-) = (1.28 ± 0.41) x10-5

m(J/ψπ+π−)ψ(2S)

X(3872)

• Discovered by Belle(2003) in B decays• Confirmed by CDF,D0 and BaBaras narrow state decaying to J/ψ π+ π−

• Nature unknown (Charmonium, DD* molecule, ccg hybrid?)

• Most puzzling: mass @ D0D*0 threshold

30.5 ± 5.8 signal events ,after bkg (combinatorial and peaking) subtraction, in 20 MeV:3.862 < mX <3.882 GeV

Accumulation near kinematic limit in m(π+π−)which is ~m(ρ0) for X(3872). Isospin-breaking ? More data needed!

m(π+π−)

ψ(2S)

X(3872)


Search for B→ X −(3872) KData sample:213 million B pairs

• If observed decay is X(3872)→J/ψρ0

⇒ charged partner may exist X(3872) −→ J/ψρ-

• Search for B0 → X−K+, B− → X−K0s

(and charged conjugates) with X− → J/ψ π−π0

• If X isovector, decay rate to X± should be twicethat observed for neutral X [BaBar: (1.28 ± 0.41) x10-5]

B0

m(J/ψπ−π0)

mES for |m(X)-3872| < 12MeV

Consistent with peaking background (estimated from mX sidebands)

Mode B0 → J/ψ π−π0K+ B−→ J/ψ π−π0K0s

n obs. 87 31n bkg. 101.8 ± 10.2 27.6 ± 6.2n signal -14.8 ± 13.9 3.4 ± 8.390%CL < 5.8 x 10-6 < 11 x 10-6

A likelihood ratio test excludes isovector hypothesis (Probability <1/600)

B0

X−?


SummaryNew results on Β decays to open and hidden charm from BaBar:

Powerful application of recoil method for first separate determination of nc

− and nc0

Most precise measurement of Β0 → Ds*+ D*− and Ds branching fractions

Improved measurements of Β0 → D(*)-ppπ+, Β0 → D(*) 0ppImproved results of many exclusive Β decays to charmonium, including:

• measurement of B+ → χc1 K*+

• stringent upper limits on B → χc2 K(*)

First observation of B→ DsJ(*)+D*

New insights on X(3872): isovector hypothesis excluded

B(Ds+→ φ π+) = (4.71 ± 0.47(stat) ± 0.35(syst))%

Additional SlidesAdditional Slides


Ds+→ φ π+

Signal 212 ±192*4/ BES psm −= B(Ds

+→ φ π+) = (3.6 ± 0.9)% PDG2004 (CLEO)

B (B0 → Ds* D*−, Ds→ φ π+) = (8.71 ± 0.78(stat)) x10-4

B(Ds+→ φ π+) = (4.71 ± 0.47(stat) ±0.35(syst))%

22 )()( ** γγ pppEEEmDBDbeammiss ++−−−=

Signal 7414 ± 345

1 - Partial reconstruction:

2 - Full reconstruction:

B(B0→ Ds*+D*-)=(1.85 ± 0.09(stat) ± 0.16(syst) )%

0B∗D

0D

∗SD

)( SD

−π

γ

Partial reconstruction resultindependent of B(Ds

+→ φπ+):→→→

−+−+−+

−+−+

πππππ

πππ

SKKKK

,,, 0Data sample

124 million B pairs

From the ratio BaBar obtains:


Ξc ProductionB(B− →Ξc X) = B(B− →Λc

− X) - B(B− →Λc+ Λc

− K)CKM allowed processes

1

2

3

Anticorrelated Λc productionnot many different ways

Βdecays to open charm and charmonium from BaBar’decays to open charm and charmonium from BaBar...

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