July 7, 2008 SLAC Annual Program Review Page 1

New Charmonium-like States

Arafat Gabareen Mokhtar

SLAC Group-EC (BABAR)

DOE Review Meeting

July 8th, 2008

July 7, 2008 SLAC Annual Program Review Page 2

Outline

* Charmonium spectroscopy from Initial State Radiation (ISR) processes:– e+e-→ γISRY(4260)→J/ψπ+π-

– e+e-→ γISRY(4350)→ψ(2S)π+π-

* Charmonium spectroscopy from B-meson decay:– B→KX(3872), X(3872) →J/ψπ+π-, D0D0*, J/ψγ– B→KY(3940), Y(3940) →J/ψω

– B→KZ-(4430), Z-(4430)→ψ(2S)π-

* Summary and outlook

July 7, 2008 SLAC Annual Program Review Page 3

Charmonium spectroscopy from ISR processes

* Initial State Radiation (ISR) can lead to the production of charmonium states at lower c.m. energy (i.e. via radiative

return) e.g. ~18M J/ψ events and ~6M ψ(2S) events have been produced by ISR

e+

e- γISR

γ*

J/ψ,ψ(2S),ψ(3770), etc

July 7, 2008 SLAC Annual Program Review Page 4

The Y(4260)

* Observed in ISR events

– γISR detection is not required

– JPC = 1--

mY=4259 ± 8+2-6 MeV/c2

ΓY =88 ± 23+6-4 MeV

* ГY,ee . BF(Y(4260)→J/ψπ+π-) =

(5.5±1.0 +0.8-0.7) eV

e+e-→γISRJ/ψππ

233 fb-1

BABAR: PRL 95, 142001 (2006)

ψ(2S)

Background from J/ψ mass sideband• Confirmed by:

CLEO-c (scan): PRL 96, 162003 (2006) The observed rate to J/ψπ0π0 confirms I=0 CLEO III (ISR) : PRD 74, 091104 (2006) BELLE (ISR): PRL 99, 142002 (2007)

No evidence for Y(4260)→ππφ, DD, pp

July 7, 2008 SLAC Annual Program Review Page 5

The Y(4350)

* After the Y(4260)→J/ψπ+π- discovery, it was natural to search for the decay e+e-→γISRY(4260), Y(4260)→ψ(2S)π+π-

* However, the BABAR analysis found a new peak that does not match the Y(4260) mass/width– m = 4324 ± 24 MeV/c2

– Γ = 172 ± 33 MeV* e+e- requires this state to have

JPC=1--

* Seems impossible to assign both as charmonium; however, there are two towers of

cc 1-- states, which might mix to yield the observed spectrum

BABAR: PRL 98, 212001 (2007)

Y(4350) has been confirmed (BELLE): PRL 99, 142002 (2007)

July 7, 2008 SLAC Annual Program Review Page 6

Charmonium spectroscopy from B-meson decay

* Many conventional Charmonium states observed; J/ψ, ψ(2S), ψ(3770), c,, c(2S), c0, c1,

* In addition, new “charmonium-like” states observed with a recoil K:– X(3872)

– Y(3940)

– Z-(4430)

J/ψ, ψ(2S), c,c, . . .

Typical BF ~(0.5 – 1.0) x 10-3

K-, K0, K*(890),K1(1270),K1(1410),. . .

Color suppressed

July 7, 2008 SLAC Annual Program Review Page 7

The X(3872) (I)

* Discovered by BELLE: PRL 91, 262001 (2003)

* Confirmed by:

– CDF: PRL 93, 072001 (2004)

– D0: PRL 93, 162002 (2004)

– BABAR: PRD 71, 071103 (2004) (data: 117 fb-1)

– BABAR: PRD 73, 011101 (2006) (data: 211 fb-1)

– BABAR: PRD 77, 111101 (2008) (full data set: 413 fb-1, final result)

B+X(3872)K+ B0X(3872)KS

8.6 2.3

413 fb-1 413 fb-1

July 7, 2008 SLAC Annual Program Review Page 8

m(J/ψγ) (GeV/c2)

The X(3872) (II)

* X(3872) decays into J/ψγ: BABAR (PRD 74, 071101 (2006)) implies positive C-parity: C=+1

– being updated to full statistics;

– Search for decay ψ(2S)γ under internal review

* No evidence for charged partner (X-)

BR(B0→X-(J/ψπ0π-)K+)<5.4x10-6 @ 90% C.L.

B+ B0

BABAR: PRD 71, 031501 (2005)212 fb-1 212 fb-1 I = 0

July 7, 2008 SLAC Annual Program Review Page 9

The X(3872) (III)

BABAR: PRD 77, 011102 (2008) 347 fb-1

No X

D

D

ψ(3770)X(3872)

Evidence for X(3872)→D0D0*

BF(B0→X(3872)K0, X(3872)→D0D0*) = (2.22±1.05±0.42)x10-4

BF(B+→X(3872)K+, X(3872)→D0D0*) = (1.67±0.36±0.47)x10-4

This, and absence in DD, consistent with unnatural JP

July 7, 2008 SLAC Annual Program Review Page 10

The X(3872) (IV)

* The mass of X(3872) from the D0D0* is ~4.5σ higher than that from J/ψπ+π-

* The quantum numbers of the X(3872) are

either 1++ or 2-+ (CDF)

* The shift in the mass can be explained if

X(3872) is 2-+ (Dunwoodie & Zeigler PRL 100, 062006 (2008))

* The nature of X(3872) is not completely understood. Is it charmonium state? (mass

is ok for 2-+ ground state) Molecule? Tetraquark? Hybrid (cc+gluon)?

July 7, 2008 SLAC Annual Program Review Page 11

The Y(3940) (I)

* The Y(3940) was discovered (BELLE: PRL 94, 182002 (2005)) in the decay B→Y(3940)K, Y(3940)→J/ψω

* Confirmation of Y(3940) in BABAR: arxiv:0711.2047 (accepted for publication in PRL)

* The BABAR data sample is ~1.4 times larger than BELLE’s data sample

* Separate treatment for B+ and B0

* Branching fractions for B→Y(3940)K, and B →J/ψωK are obtained separately for B+ and B0

BABAR preliminary

July 7, 2008 SLAC Annual Program Review Page 12

The Y(3940) (III)

* The B+ and B0 signals are fitted simultaneously (χ2 fit) with an S-wave Breit-Wigner for the resonant term and a Gaussian function for the non-resonant contribution

* Lower mass and narrower width (relative to BELLE results) are obtained:

– m = 3914.6+3.8-3.4(stat) ± 2.0(syst) MeV/c2

– Γ = 34+12-8(stat) ± 5(syst) MeV

(BELLE: m = 3943±11±13MeV/c2; Γ = 87 ±22 ±26 MeV)

* The ratio between B0 and B+ candidates in the Y(3940) region and in the non-resonant contributions are measured:

– RY =0.27+0.28-0.23(stat)+0.04

-0.01 (syst)

3σ below the isospin expectation

– RNR=0.97+0.23-0.22(stat)+0.03

-0.02 (syst)

B+→J/ψωK+

B0→J/ψωK0

BABAR preliminary

July 7, 2008 SLAC Annual Program Review Page 13

The BELLE Z-(4430)

* BELLE reported (PRL 100, 142001 (2008)) a resonance-like structure in ψ(2S)π±; m=4433 ± 4(stat) ± 2(syst);

Γ=45+18-13(stat)+30

-13(syst)

* If this resonance is confirmed first evidence for a genuine ccud “tetraquark” state, since it is an isovector and carries hidden charm

BELLEBELLE

K*(892) and K*

2(1430) veto used

July 7, 2008 SLAC Annual Program Review Page 14

Remarks/questions on the Z-(4430)

* How does the ψ(2S)π- distribution look for the events in the K*(890) and K*

2(1430) region?

* The assumption that the background under the Z-(4430) signal is polynomial is not realistic

* No report on the decay Z-→J/ψπ- from BELLE

* BF(B0→Z-K+, Z-→ψ(2S)π-)= (4.1 ± 1.0(stat) ± 1.4(syst))x10-5

* In BABAR, we use the full dataset (413 fb-1) to search for the

Z-(4430)* The analysis is under internal review and the BABAR

collaboration will release the results soon

July 7, 2008 SLAC Annual Program Review Page 15

Summary and outlook

* The B-factories have played a leading role in the discovery of unexpected states, especially in the charmonium and charm (meson and baryon) sectors

* Several new charmonium-like states have been discovered above open-charm threshold, but their nature is not yet understood

* BABAR will soon release new results on charmonium physics (including the

search for the Z-(4430))

July 7, 2008 SLAC Annual Program Review Page 16

Backup I: The Y(3940) (IV)

* BF(B+→Y(3940)K+, Y(3940)→J/ψω)=(4.9+1.0-0.9(stat) ± 0.5(syst))x10-5

* BF(B0→Y(3940)K0, Y(3940)→J/ψω)=(1.3+1.3-1.1(stat) ± 0.2(syst))x10-5

<3.9x10-5 @ 95% C.L.

BELLE: BR(B→Y(J/ψω)K)=(7.1 ± 1.3(stat) ± 3.1(syst))x10-5

* Both BABAR and BELLE agree well on the branching fraction of (B)

BABAR provides the first measurements on the total branching fractions:

* BF(B+→J/ψωK+) = (3.5 ± 0.2(stat) ± 0.6(syst) ) x 10-4

* BF(B0→J/ψωK0) = (3.1 ± 0.6(stat) ± 0.3(syst) ) x 10-4