Exotic charmonium-like states in B decays

Roman Mizuk, ITEP

ITEP Seminar, 18 Nov 2009

c cConventional Charmonium

in Quark Model

Above open charm threshold broad states are expected

Below open charm threshold most states are narrow

n(2S+1)LJ

n radial quantum number

J = S + LP = (–1)L+1 parity

C = (–1)L+S charge conj.

B-factoriese+e–→(4S) and

nearby continuum:Ecms ~ 10.6 GeV

L ~ 1034/cm2/s

950 + 530 fb-1 in total

cc production at B factories

Outline

• X(3872)

• States near 3940 MeV

• Z(4430) and Z1(4050) & Z2(4250)

• In (4S) decays B are produced almost at rest.

• ∆E = Ei - ECM/2 Signal peaks at 0.

• Mbc = { (ECM/2)2 - (Pi)2}1/2 Signal peaks at B mass (5.28GeV).

∆E, GeV

Mbc, GeV

Reconstruction of B decays

B0J/ KS

6th anniversary!

Phys.Rev.Lett.91 262001, (2003)

CP

Belle citation count

B→Xsγ

451

479

330

X(3872)

Swanson, CharmEx09

PRL91,262001 (2003)

X(3872) was observed by Belle in

B+ → K+ X(3872)′

→ J/ψ π+ π-

…recent signals of X(3872) → J/ψ π+ π-

X(3872)

Confirmed by CDF, D0 and BaBar.

B+ → K+ X(3872)

pp collisions

PRL93,162002(2004)

arXiv:0809.1224 PRD 77,111101 (2008)

PRL103,152001(2009)

Mass & Width

M = 3871.550.20 MeV,Γ < 2.3 MeV (90% C.L.)

Close to D*0D0 threshold:m = -0.250.40 MeV.

Branching Fraction

Br(X(3872) J/ + -) > 2.5%

90%C.L.

B K Xcc studied using missing mass technique.

reconstructed B

reconstructed K

Xcc

missing massB

(4S)

PRL96,052002(2006)

Radiative Decays & J/

CX = +1

m (J/ ), MeV m (′ ), MeV

J/

J/ ′

Evidence for X(3872) → J/ +-0

M(+-0) is peaked at kinematic boundary

subthreshold production of

also CX = +1

+-0

hep-ex/0505037

hep-ex/0505037

PRL102,132001(2009)

CX = + C(+-) = –

(|+1,-1 – |-1,+1) ( r )

1. Isospin (+-) = 12. L(+-) = 1

M (+-) is well described by 0→+- (CDF: + small interfering →+- ).

Large isospin violation.

+- system has IJPC quantum numbers of 0.

B(X(3872) J/ )B(X(3872) J/ ) ~1

PRL96,102002(2006)

hep-ex/0505038

L=1

L=0

Mass of +-

+- system from X(3872) J/ +-

Angular analyses by Belle and CDF excluded JP =

Only two possibilities JP = 1++ and 2-+.

2-+ is disfavored by

1++ are favorite quantum numbers for X(3872)

0++, 0+-, 0-+,1-+ ,1+-, 1--, 2++, 2-- , 2+-,3--, 3+-

Spin & Parity

1. Observation of D*D decay centrifugal barrier at the threshold2. Br(X → ′ γ) / Br(X → J/γ) ~3 multipole suppression

2-+ is not excluded.

PRL98,132002(2007)

0++

1--

1++

2-+

X(3875) X(3872)?PRL 97,162002,2006

B K D0D00

6.4σ

PRD77,011102,2008

B+& B0 D0D*0K4.9σ

347fb-1

PDG

New Belle vs. BaBar: ~2σ difference

1.4σ

B K D0D*0

605 fb-1

D*→Dγ

D*→D0π0

Flatte vs BW similar result: 8.8σ

arXiv:0810.0358

X(3872) Experimental Summary

JPC = 1++ (2-+ not excluded)

MJ/ = 3871.550.20 MeVΓ < 2.3 MeV (90% C.L.)

Close to D*0D0 threshold:m = -0.250.40 MeV.

J/ J/ J/

D*0D0

Decay modes: Br(X(3872) J/ 0) > 2.5%

Br(X D*0D0)Br(X J/+-)

~10

0.14 0.05

3872

JPC = 1++ c1′ (23P1)

X(3872) is not conventional charmonium.

Interpretation: Charmonium?

Γ ( c1′ → J/ψ γ) / Γ ( c1′ → J/ψ π+π- ) • expect 30• measure 0.140.05

JPC = 2-+ η c2 (11D2)

Expected to decay into light hadronsrather than into isospin violating mode.

[cq][cq]

Tetraquark?Maiani, Polosa, Riquer, Piccini; Ebert, Faustov, Galkin; …

No evidence for X–(3872) J/ –0 excludes isovector hypothesis

X(3872)–

M(J/π–π0) M(J/π–π0)

X(3872)–

PRD71,031501,2005

B0 B-

PRD71,014028(2005)

1. Charged partners of X(3872) should exist.2. Two neutral states ∆M=(83)MeV,

one populate B+ decay, the other B0.

B0 vs. B+

No evidence for X(3872) neutral partner in B0 decay.

= (2.7 ± 1.6 ±0.4) MeV

B0→XK0s

5.9

M(J/)

2.3σ

M(J/)

arXiv:0809.1224 605 fb-1

PRD 77,111101 (2008) [413 fb-1]

Two overlapping peaks in J/ +- mode?

No evidence for two peaks m < 3.2 MeV at 90% C.L.

Tetraquarks are not supported by any experimental evidence for existence of X(3872) charged or neutral partners.

PRL103,152001(2009)

D0D*0 molecule? March 1976

November 1976

MX = 3871.55 0.20 MeV(MD*0 + MD0) = 3871.80 0.35 MeV

BES III canimprove on this

Weakly bound S-wave D*0D0 system

Swanson, Close, Page; Voloshin; Kalashnikova, Nefediev; Braaten; Simonov, Danilkin ...

m = -0.250.40 MeV

D*0D0 molecule can reconcile X(3872) signals in D*0D0 and J/+- modes.

Bound stateVirtual state

J/+-D0D00

D*0D0 J/+-

D0D00

If EX goes positive …

D0D*0 molecule

Yu.S.Kalashnikova, A.V.Nefediev arXiv:0907.4901

Analysis of dataBound or virtual?c1 admixture?

Belle data: bound state with ~ 30% admixture of c1.BaBar : virtual state with ~ no c1 admixture.

~2 difference

Present statistics is insufficient to constrain theory?

B(X(3872) J/ )B(X(3872) J/ ) ~1

Large isospin violation due to 8MeV differencebetween D*+D- and D*0D0 thresholds.

B(X(3872) )B(X(3872) J/ ) ~3

Similar ratio is expected for c1 decays c1 admixture?

Large production rate in B decays and at TEVATRON c1 ?

theorists here should agree on the proper form & thenexperimenters should use it in a proper unbinned fit

Steve Olsen “Charmed Exotics 2009”

There are other similar analyses which differ in the fit functions:

Braaten, StapletonZhang, Meng, Zheng

arXiv: 0907.31670901.1553

~90 events

Very weak K

*(892)

Br(BJ/ K*0)

Br(BJ/ KNR)~4

B K X(3872)

signal

bg

arXiv:0809.1224 605 fb-1

DD* molecular models for the X(3872) attribute its production& decays charmonium to an admixture of c1′ in the wave fcn.

But BKX(3872) is very different from BK charmonium.

BaBar PRD 71 032005

Belle arXiv 0809.0124

Belle arXiv 0809.0124

Belle PRD 74 072004

K′

KJ/

Kc1

Kc

Belle F.Fang Thesis

KX3872

M(K)

M(K)

M(K)

M(K)

M(K)

States near 3940 MeV

The states near 3940 MeV-circa 2005-

M = 3942 +7 ± 6 MeV

tot = 37 +26 ±12 MeV

Nsig =52 +24 ± 11evts

-6

-15

-16

PRL 100, 202001

e+e- J/ DD*

M(DD*)

M≈3940 ± 11 MeV≈ 92 ± 24 MeV

PRL94, 182002 (2005)

M(J/)

BKJ/

M = 3929±5±2 MeV

tot = 29±10±2 MeV

Nsig =64 ± 18evts

DD

M(DD)

PRL 96, 082003

Z(3930)

Probably the c2’

X(3940) Y(3940)

Y(3940) DD* ?BKDD*

3940

MeV

3940

MeV

X(3940)J/?

e+e-J/ + ( J/)

PRL 98, 082001

X(3940) ≠ Y(3940) @ 90% CL

Y(3940) confirmed by BaBar

B±K±J/

B0KSJ/

J)

ratio

Some discrepancy in M & ; general features agree

PRL 101, 082001

Belle will update with the complete (4S) date set later this Fall

Same binning(Belle publishedresult : 253 fb-1)492fb-1

Belle-BaBar direct comparison

Y(3915)J/ from Belle

7.7 M: 3914 3 2 MeV,

: 23 10 +2 -8 MeV, Nres = 55 14 +2 -14 events

Signif. = 7.7,

prel

imin

ary

Probably the same as the Belle/BaBar Y(3915)

cc assignments for X(3940) & y(3915)?

3940MeV

•Y(3915) = co’? (J/) too large?•X(3940) = c”? mass too low?

c

”

c’’’

3915MeVc0’

_

ucd

c

Z(4430) and Z1(4050) & Z2(4250)

Smoking guns for charmed exotics:

BK ’ (in Belle)

K*(892)K+-

M2(K+-)

M2

(+’)

K*(1430)K+-?

??

The Z(4430)± ±’ peak

M(

±’)

Ge

V

BK +’

Z(4430)

M () GeV

evts near M(’)4430 MeV

M2

(

±’)

GeV

2

M2() GeV2

“K* Veto”

Shows up in all data subsamples

Could the Z(4430) be due to a reflection from the K channel?

Cos vs M2(’)

16 GeV2

22 GeV2 +1.0

-1.0

cos

M (’) & cosare tightly correlated;a peak in cos peak in M(’)

0.25

’

K

(4.43)2GeV2M

2(

’)

S- P- & D-waves cannot make a peak (+ nothing else) at cos≈0.25

not without introducing other, even more dramatic features at other cos (i.e., other M’) values.

But…

BaBar doesn’t see a significant Z(4430)+

“For the fit … equivalent to the Belle analysis…we obtain mass

& width values that are consistent with theirs,… but only ~1.9from zero; fixing mass and width increases this to only ~3.1.”

Belle PRL: (4.1±1.0±1.4)x10-5

Reanalysis of Belle’s BK’ data using Dalitz Plot

techniques

2-body isobar model for K’

KZ+

K2*’

K*’

K’

Our default model

’

K*(890)’

K*(1410)’

K0*(1430)’

K2*(1430)’

K*(1680)’

KZ+

Results with no KZ+ term

fit CL=0.1%

12

3 4

5

1 2 3 4 5

A

B

C

A B

C

Results with a KZ+ term

fit CL=36%

1

1

2 3

2

34 5

4

A5

B

A

C

B

C

Compare with PRL results

Signif: 6.4Published results

Mass & significance similar,width & errors are larger

With Z(4430)

WithoutZ(4430)

Belle: = (3.2+1.8+9.6 )x10-5 0.9-1.6

BaBar:

No big contradiction

K* veto applied

Variations on a theme

Others: Blatt f-f term 0r=1.6fm4fm; Z+ spin J=0J=1; incl K* in the bkg fcn

Z(4430)+ significance

The Z1(4050)+ & Z2(4250)+ +c1 peaks

PRD 78,072004 (2008)

Dalitz analysis of B0K-+c1

K*(

89

0)

K*(

14

00

)’s

K*(

16

80

)

K3*(

17

80

)

M (J) GeV

E GeV ???

BKc1 Dalitz-plot analyses

KZ+

K2*c1

K*c1

Kc1

Default Model

c1

K*(890)c1

K*(1410)c1

K0*(1430)c1

K2*(1430)c1

K*(1680)c1

K3*(1780)c1

KZ+

Fit model: all low-lying K*’s (no Z+ state)

a b

c d

e f

g

a b c d g

f

e

C.L.=310-10

Fit model: all K*’s + one Z+ state

a b

c d

e f

g

a b c d g

f

e

C.L.=0.1%

Are there two?

a b c d

? ?? ?

Fit model: all K*’s + two Z+ states

a b

c d

e f

g

a b c d g

f

e

C.L.=42%

Two Z-states give best fit

Projection with K* veto

Systematics of B0 → K- π+ c1 fit

Significance of Z1(4050)+ and Z2(4250)+ is high.

Fit assumes JZ1=0, JZ2=0; no signif. improvement for JZ1=1 &/or JZ2=1.

M=1.04 GeV; G=0.26 GeV

• Z(4430)+ signal in BK’ persists with a more complete amplitude analysis.– signif. ~6, product Bf ~3x10-5 (with large errors)

• No significant contradiction with the BaBar results – signif. = 2~3, Product Bf<3x10-5

• Z1(4050) & Z2(4250), seen in BKc1, have similar properties (i.e. M & ) & product Bf’s– signif. (at least one Z+)>10; (two Z+ states)>5

Summary

•The X3872 mass keeps getting closer & closer to MD0 + MD*0

•BK X3872 is very different from BK charmonium

•The X(3940) & Y(3940) seem to be distinct states

•Y(3940)Y(3915)?

•Belle’s Z(4430)++’ signal is not a reflection from the K channel

•Z1(2050)+ & Z2(2050)++c1 peaks further evidence for charmed exotics

•Most XYZ states have large partial widths to hidden charm final states

e+e-J/X3940 BKY3940DD* J/

by charmonium standards

Summary

In contrast”(3770) only above-open-charm threshold state with an established +-J/ mode

•Discovered 1977 (Lead Glass wall)

•2003 1st evidence for ”+-J/ (BESII)

•2006 ”+-J/ established (CLEOc)

Bf=(1.9+-0.3)x10-3; (+-J/) 50keV

~30 yrs later

PRL96, 082004 (2006)

PRB 605, 63 (2005)

Rapidis et al PRL39, 526 (1977)

~230 evts

~25 evts

3rd generation expt

Back-up

Improvement to M(D0)?

iiKK

ii KEMME

S2

Best single measurement from CLEOc:

MD0 = 1864.847±0.150 (stat) ±0.095 (syst) MeV

CLEOc uses invariant mass:

large MD0

dominatesthe error

small 0not a bigcontrib.

& only uses D0KS(K+K-) decays:

i i

iiinv pEM 22 )()(

well known

±2x16keV±22keV

0.1 MD0

measured

Bf0.002319 evtsstat errordominates

M(D0) measurement @ BESIII

i

ibeambc pEM 22 )(

Use “beam constrained mass @ ”:

need toknow Ebeam preciselyUse backscattered laser beam at

the unused X-ing region to measureEbeam (&MD0) to better than ±100 keV

Approved, funded,& under construction

Signal of B0→c1K+-

605fb-1 c1 → J/, J/ → +- (e+e-)

c1 s.b.

Formalism

B0 → c1K+-, c1 → J/, J/ → +-

described by 6 variables: M(c1), M(K), (c1), (c1), (J/), (J/)

Justification: efficiency is ~constant in (c1), (J/)

after integration over (c1), (J/) interference terms drop out.

Efficiency vs. (c1) Efficiency vs. (J/)

different parts

of Dalitz

plot

range = (0, 2) range = (0, 2)

perform Dalitz analysis w/o considering angular variables, assume no interference between different c1 helicity states.

Formalism (2)

Amplitude

, K*(892), K0(1430), K2(1430), K*(1680), K*3(1780),

Z+ → +c1

Fit function

Signal component

c1 helicity

Binned likelihood fit

(see next slide for details on amplitude of Z+)

E s.b.Efficiency

B meson and R resonance decay form-factors Angular part

Amplitude of Z

c1 rest frame

pK

pc1 spin quantization axisin B → c1 K*(→K) decays

c1 spin quantization axisin B → Z(→c1) K decays

cosTransformation of basis vectors

The same relation for amplitudes

Comparison with BaBar

BaBar paper: Belle and BaBar data are statistically consistent.

peak in M(π+ψ) is present also in BaBar data with similar to Belle shape:

BaBarBelle

Comparison with BaBar

BaBar paper: Belle and BaBar data are statistically consistent.

peak in M(π+ψ) is present also in BaBar data with similar to Belle shape:

BaBarBelle

Why different significances are reported? (6.4σ Belle vs. 1.9–3.1σ BaBar)

assumption about background is crucial.

BaBar method is a simplification of amplitude analysis with a lot of (unphysical?) freedom in description of background.

Dalitz analysis is preferable.

Result of Dalitz fitscaled down by 1.18 to account for smaller statistics @ BaBar.