Z(4430) and related results at Belle

Z(4430) and related results Z(4430) and related results at Belleat Belle

Jolanta Brodzicka Jolanta Brodzicka (KEK)(KEK) 20/11/2007 KEK20/11/2007 KEK

Outline Observation of Z+(4430)→ψ’π+ in B→ψ’π+K decays Z(4430) interpretation within 4-quark model Recent results on X(3872) Summary

Recent KEK press releaseRecent KEK press release

Jolanta Brodzicka Z(4430) and related KEK 20/11/2007 2

KEK B FactoryKEK B Factory

Jolanta Brodzicka for Belle New charmed particles JPS/DPF 2006 3 Jolanta Brodzicka for Belle New charmed particles JPS/DPF 2006 3

Asymmetric e+e- collider

e+: 3.5 GeV e-: 8.0 GeV

CM energy: 10.58 GeV at (4S)

e+e- (4S) BB Advantages:

exclusive source of BB pairs useful kinematical constraints high signal-to-background ratio separation of B decay vertices

Record luminosity peak:1.711034cm-2s-1

Integrated luminosity: ~742 fb-1

~ 780 * 106 BB

Beauty Factory

Tsukuba

Belle DetectorBelle Detector

Jolanta Brodzicka for Belle New charmed particles JPS/DPF 2006 4 Jolanta Brodzicka for Belle New charmed particles JPS/DPF 2006 4

Particle identificationParticle identificationK/ separation Central Drift Chamber: dE/dx Aerogel Cherenkov Counter Time of Flight Counter Electron identification Electromagnetic Calorimeter

KL and identification KL and muon detector

VertexingVertexing Silicon Vertex Detector

Event reconstructionEvent reconstruction Charged tracks Central Drift Chamber Silicon Vertex DetectorElectrons and photons Electromagnetic Calorimeter

Silicon Vertex Detector KL / Detector

SC Solenoid 1.5T

Central Drift Chamber

Aerogel Cherenkov Counter

Electromagnetic Calorimeter

Time of Flight Counter

8 GeV e-

3.5 GeV e+

Following B decays used:

Advantages: b→cW→ccs is Cabbibo-favored process (not rare) background reduction is possible JPof parent B is known → JPof the child particles can be

determined from angular analysis

Charmonium(-like) factoryCharmonium(-like) factory


b c u, d c

s K(*)

u, d

B charmonium (-like)

W Good place for spectroscopy study! Cabbibo-favored

vertices

Study of BStudy of B→→ψψ’’ππ++KK B0 →ψ’π+K- and B+→ψ’π+K0

s studied using 657·106 BB data

ψ’→ e+e-, μ+μ- or J/ψπ+π- J/ψ →e+e-, μ+μ- K0s→π+π-

secondary particles combined to B→ψ’π+K candidates B signal identification takes advantage of Υ(4S)→BB kinematics:

EB=Ebeam=√s/2 in cms kinematical variables used in B factories

Mbc= √E2beam- p2

B beam-constrained mass (signal at mB~5.28GeV)

ΔE=EB- Ebeam cms energy difference (signal peaks at 0)

clear

B signal

seen


hep-ex/0708.1790

Submitted to PRL

in addition to expected B→ψ’K* components

a clear band seen at M2(ψ’π+)~20GeV2

to study ψ’π+ structure we apply K*veto (both K* regions excluded)

M(ψ’π+) fitted with Breit-Wigner + phase-space like function

prominent peak

(K* veto applied)

3-body decays

non-B

background

BB→→ψψ’’ππ++KK Dalitz plotDalitz plot


M(ψ’π+)

Nsig =121 ± 30 (6.5σ)

M= 4433 ± 4 MeV Γ= 45+18-13 MeV

M2 (

ψ’π

+)

M2(Kπ+)

K*(890)

K2*(1430)

???

Z+(4430)

Is Z(4430) signal robust?Is Z(4430) signal robust? data subsets checked, K* veto changed → consistent Z parameters interference between different (S,P,D) Kπ partial waves

→ cannot produce such narrow peak in ψ’π+ B generic MC studied → Z(4430) is not a reflection interference with 3-body → does not affect Z parameters much anything else contributed besides vetoed K*’s? no

conclusion: Z(4430) signal is robust


M(Kπ) for Z(4430) signal regionwithout K* veto

we cannot determine its JP with present statistics

First candidate for a charged charmonium-like state!

Must be exotic! It could be a tetraquark state

either diquark [cu][cd] or molecular (cd)(cu)

(Charged states naturally appear within multiquark models)

ZZ++(4430) properties (4430) properties


hep-ex/0708.1790

Submitted to PRL

M(ψ’π+)

Z+(4430)

Within 4-quark modelWithin 4-quark model (by Maiani, Polosa et al.)

Z+(4430)→Ψ’π+ can be diquark-antidiquark state [cu][cd]

charged member of JPC=1+- multiplet it can be radial excitation of lowest lying

4-quarks with JPC=1++ : X0u[cu][cu] X0

d[cd][cd]

X(3872) is candidate for such 4-quark state (but doublet needed)

Mass splitting:

M(Xu ) - M(Xd) ~2(md – mu)=8 ± 3 MeV (but mixing possible)

Production rates in charged B larger than in neutral B Jolanta Brodzicka Z(4430) and related KEK 20/11/2007 10

Maiani, Polosa et al.

PRD 71, 014028 (2005)

hep-ph/0707.3354

hep-hp/0708.3997

u cuc

Xu=d c

dcXd=

B+→K+Xu B0→K0Xd

Reminder on X(3872)Reminder on X(3872) X(3872)→J/Ψπ+π- observed B+→X(3872)K+ by Belle confirmed by BaBar, CDF, D0 PDG06: M=3871.2 ± 0.5MeV Γ<2.3MeV other decay modes: X(3872)→J/Ψγ, J/Ψω, DDπ favored spin-parity: 1++ (by the decay modes

and angular analysis by CDF/Belle)

What is X(3872)? does not match any cc state predicted by quark models DD* molecule? MX-(MD*0+ MD0)= -0.6±0.6 MeV 4-quark? Would explain small width. Charged X should exist

X(3872) properties still under investigation

(mass, width, line shape, decay modes…)


PRL 91, 262001 (2003)

M(J/Ψππ)

New X(3872)New X(3872)→J/ψπ+π- resultsresults Motivated by 4-quark model predictions B+→X(3872)K+ and B0→X(3872)K0

s X(3872)→J/ψπ+π- with 657M BB control sample: B→ψ’K ψ’→J/ψπ+ π- (to calibrate mass & resolution)

look at ΔM= M(J/ψπ+ π-) - M(J/ψ)+mJ/ψ

models predicting different properties for X(3872) from

neutral and charged B decays are disfavored


BELLE-CONF-0711

B0→XK0s

Ns=30±7 (6.5σ)

B+→XK+ Ns=125±14 (12σ)

First observation!

Surprises from X(3872)Surprises from X(3872)→→DD*D*D X(3872) is very close to D*0D0 mass threshold BaBar: B+→D*0D0K K=K+or K0 D*0 →D0π0,D0γ (with 383·106 BB) Belle: B+→ D0D0 π0K K=K+or K0 (with 447·106 BB)

mass ~4σ away from X →J/Ψπ+π- are there two states X(3872) and X(3875)?


hep-ex/0708.1565 PRL 97, 162002(2006)

Ns=33 ± 7 (4.9σ)M(X)=3875.1+0.7

-0.5 ±0.5 MeVΓ=3.0+1.9

-1.4 ± 0.9 MeV

Ns=24 ± 6 (6.4σ)M(X)=3875.4 ± 0.7+0.4

-1.7 ±0.9 MeVΓ=3.0+1.9

-1.4 ± 0.9 MeV

Still within 4-quark model?Still within 4-quark model? (by Maiani, Polosa et al.)

Model revised:

Xu state decaying to D0D0π0 / D*0D0 = X(3875)

Xd state decaying to J/Ψπ+π- = X(3872)

(why Xd lighter than Xu?) predictions on rates in B decays:

neutral Z partner should exist

M~ M(Z+(4430))+few MeV

decay modes: Ψ’π0,Ψ’η or ηc(2S)ρ0, ηc(2S)ω charged partner for X(3872)/X(3875)

M~3880MeV, decay modes: J/Ψπ+ or ηc(1S)ρ+ Jolanta Brodzicka Z(4430) and related KEK 20/11/2007 14

Maiani, Polosa et al.

hep-ph/0707.3354

hep-hp/0708.3997

u cuc

Xu=

d cdc

Xd=

SummarySummary Z+(4430)→ψ’π+ observed in B→ψ’π+K by Belle First candidate for charged charmonium-like state.

It is exotic! Tetraquark interpretation favored

X(3872) →J/ψπ+π- ,DD* in B decays studied Recent results disfavor models that predict different

properties between B+→XK+ and B0→XK0


Z(4430) and related results at Belle

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