Update on Update on aa00(980)(980)

P.Gauzzi

2

Main problem• From event counting:

Br(0) = (6.70 0.26) 10-5 with Br(0) = (7.22 0.52) 10-5 with +0

Compatible at 2 level (excluding the common uncertainty)

• Combined fit to the spectra:Br()/Br()= 1.58 0.04 (free parameter) Br()/Br()=1.73 0.03 from PDGMarginally compatible ( 8-9% discrepancy 3 )

Checks on efficiencies OK Checks on background subtraction procedure OK

Check the normalization: 1) check integrated luminosity 2) Bhabha lumin. vs 30

3

Check on bad runsCheck on bad runs

N5/L

Nfinal/L

• Criterion: reject runs 5 far from the average (N5/L = 1.7)

2001 2002

2001: from 161.509 to 161.134 pb-1 2002: from 263.550 to 252.292 pb-1

4

Final sampleFinal sample• datadata

ωω00 77

ff00 33

2001 2002 2001+2002

DATA 11314 18287 29601

7 2746 24.3% 4406 24.1 % 7152 24.2 %

ω0 1489 13.2% 2291 12.5% 3780 12.8 %

00 (f0 ) 1955 17.3% 3149 17.2% 5104 17.2 %

3 92 0.8% 110 0.6% 202 0.7 %

5 38 0.3% 60 0.3% 98 0.3 %

Tot. Bckg. 6320 55.9% 10016 54.8% 16336 55.2 %

0 events 4994 8271 13265

2001 2002

(-101 evts.)

5

Final sampleFinal sample

2001+2002

6

Branching ratioBranching ratio

2001 2002

• N - iBi = 4994 ; 8271

= 38.5 % ; 38.8 %

• L = 161.1 pb-1 ; 252.5 pb-1 = 3090 nb from () = (40.2 1.0) nb (M.Dreucci – Capri

’03)

• Br() = (39.38 0.26) %

• Br = 6.61 10-5 ; 6.93 10-5 ( 5% difference)

[ Weighted average: (6.80 0.09 0.24) 10-5 ]

γγ)Br(η σ L ε

BNγ)ηπBr( i i0

7

Normalization to Normalization to 3300 events events

ηγ7

0ηγ7i i0

N

)3πηγ)Br(ηBr(ε

γγ)Br(η ε

BNγ)ηπBr(

2001 2002

• N7 = 1.5 106 ; 2.6 106

(contam. = 1.5 % ; 1.2 % ) 7 (MC) 73.1 % ; 81.2 %

• Br() = 1.3%

• Br(30) = 32.51 %

• Br = 6.90 10-5 ; 6.98 10-5

(1% difference)

• Weighted average : (6.95 0.09 0.22) 10-5 s (MeV)

2002

2001

nb 3017

)3πηγ)Br(ηBr(ε L

N σ effective

0ηγ7

ηγ7

8

Kaon loop fitKaon loop fit

Fit value Uncert.

Ma 0 (MeV) 983.5 2

ga KK2/(4) (GeV

2) 0.373 0.027

ga /ga KK 1.299 0.038(°) 208 12Br()-VDM 1.51E-06 6.12E-072

94.17ndf 76

P(2) 0.08

• Neutral

2

• Br(0) = 7.0 10-5

• Br(a0) = 6.8 10-5 (only scalar part)

9

Kaon loop fitKaon loop fit

Fit value Uncert.

Ma0 (MeV) 983.9 1.2

ga KK2/(4) (GeV2) 0.380 0.016

ga/ga KK 1.306 0.023(°) 211 12Br()-VDM 9.5E-07 4.1E-07

Br( )/Br( 0) 1.687 0.0392 148.7ndf 136.0

P(2) 0.216

• Combined fit

(Br()/Br()=1.73 0.03 from PDG)

now discrepancy 2-3% (instead of 8-9%)

()

(π+ππ0)

Including last point of the charged spectrum

2 181, P(2) 0.6%

2

2

10

No structure fit No structure fit

Fit value Uncert.

Ma0 (MeV) 983.9 Fixed

ga KK (GeV) 1.227 0.045

ga(GeV) 2.045 0.036

g a(GeV-1) 1.482 0.033

|c0| 13.9 1.2

arg(c0) ( 46.24 0.61

|c1| 23.8 2.8

arg(c1) ( 66.6 2.6

2 83.6ndf 74

P(2) 0.209

• If mass free non reasonable values: M < 900 MeV

2

• Br(0) = 7.1 10-5

• Br(a0) = 6.6 10-5 (only scalar part)

11

No structure fit No structure fit

Fit value Uncert.

Ma 0 (MeV) 983.9 fixed

ga KK (GeV) 1.36 0.15

ga(GeV) 2.098 0.035

g a(GeV-1) 1.557 0.038

|c0| 14.57 0.39

arg(c0) ( 47.53 0.77

|c1| 24.2 1.3

arg(c1) ( 73.0 1.2

Br( )/Br( ) 1.699 0.0332 146.9ndf 134

P(2) 0.211

()

(π+ππ0)

2

2

12

Conclusions on normalizationConclusions on normalization

Two effects:

1) Bad runs: 10 pb-1 2.5% increase in Br (neutral)

2) Spread in s (especially for 2001) 2.5% increase in Br

Br from 6.7 10-5 to 7.0 10-5

difference with respect to the charged channel 3%

(compatible with the uncertainties on Br() and Br())

13

SU(3) couplingsSU(3) couplings• KL and NS models do not make predictions on the structure

• Relations among couplings can be derived from SU(3)

• These relations are different for the qqbar and 4q cases

• For example, for the a0(980):

39.7 assuming

0.90 sin 2 g

g

: s)sddu(u2

1

1.54 cos 2g

g

:)ddu(u2

1

P

PKK

ηπ

PKK

ηπ

0

0

0

0

a

a

a

a

• KL

• NS

)q(q

)qq(qq

(LM)

ga0/ga0KK

14

ff00// couplings couplings• Complicated by mixing

SS

S

KK

ππ

SS

SS0

sincos2

2sin

g

g

sin sscos )ddu(u2

1σ

cos sssin )ddu(u2

1

:case qq

0

0

f

f

f

SKK

ππ

SS

SS0

cot 2g

g

sin dduu cos s)sddu(u2

1σ

cos dduusin s)sddu(u2

1

:case qqqq

0

0

f

f

f

Achasov: S = 0 or 90° for qqbar; S = 90° for 4q (no mixing)

Bugg: 17.3° or -29° “ ; 15.7° “

(gf0/gf0KK from BES, J/+, K+K)

Escribano: -8°

C.Gatti: -13°

15

• Claudio’s suggestion: S can be derived from the ratio gf0/ga0

• It could work for 4q, but ...

• In the qqbar case does not couple

to a0

OZI violating contributions have to

be taken into account ?

SU(3)SU(3) couplings for couplings for ff00 and and

)ss (assuming sin3

1

g

gS

γ

γ

0

0

a

f

s

s

q

q a0

gf0/ga0

KL NS

16

SU(3)SU(3) couplings for couplings for ff00 and and

• Exercise: get S from couplings, fixed in KL fit to Dalitz plot,

taken from Achasov-Kiselev paper

gππ = 2.4 GeV; gKK = 0.55 GeV

72 tan 2 g

g : qqqq

-21 sin 2cos

cos 2

g

g :qq

SSσKK

σππ

S

SS

S

σKK

σππ

17

ff00 couplings couplings

KL π0π0 NS π0π0 KL π+π─ NS π+π─

0 qq S

90 qq S

(Escribano LM)

72 with0.46 g

g : qqqq

-21 with0.43 g

g :qq

SKK

ππ

SKK

ππ

0

0

0

0

f

f

f

f

gf0π/gf0KK

(BES data:

J/π+π─, K+K─ 0.49)

18

ff00//aa00 ratio ratiogf0KK/ga0KK

Kaon loop

No Structure 9072 qqqq S

21 qq S

90 qq S

0 qq S

(f000)

(f0+)

(f000)

(f0+)

19

ggSSKKKK

• KL

• NS

ga0KK

)qq (Achasov

)qqqq (Achasov

)KK (Achasov

)KK ova(Kalashnik

(Escribano LM)

Not SU(3) predictions

KL π0π0 NS π0π0 KL π+π─ NS π+π─

)90 q(q S 0) q(q S

20

Br(Br(00))

Br(0)

-410 2-1 qqqq

-510 2-1 qq

)(10 al.)et Close (Achasov, KK -5O

al.)et ova(Kalashnik KK

• CMD-2

• SND

• KLOE ’00

• KLOE ’01-02

• Event counting

• Kaon Loop

• No Structure

• KLOE ’00

(Not SU(3) predictions)

21

ggSS

• The coupling gS can be related to the strange quark contents of the mesons

Meson gM (GeV-1)

0 0.13

0.71

´ 0.75

a0(980) 1.5 – 1.8

f0(980) 1.2 – 4.1

Increasing s-quark content

)MγΓ(mm

2m

α

3g

3

2M

2

φ2Mγ

<gf0/ga0> 2

22

Conclusions on couplingsConclusions on couplings

• Data do not seem incompatible with an SU(3) picture

• This can be used to discriminate between qqbar and 4q

(at the moment qqbar model seems slightly preferred, but no conclusions can be drawn)

• A trial to fit all f0 and a0 spectra together within SU(3) can be done:

all the couplings can be written in terms of few parameters: gSPP, S, gVS, and P (already measured in / decays)

• However the KL fit on a0 (neutral spectrum only), by fixing the ratio ga0π/ga0KK, does not converge