Update on a 0 (980) P.Gauzzi. 2 Main problem From event counting: Br( 0 ) = (6.70 0.26) 10 -5...
-
Upload
gunner-minett -
Category
Documents
-
view
216 -
download
1
Transcript of Update on a 0 (980) P.Gauzzi. 2 Main problem From event counting: Br( 0 ) = (6.70 0.26) 10 -5...
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