resent bes results on scalar mesons
DESCRIPTION
Resent BES Results on Scalar Mesons. Zhipeng Zheng (Representing BES Collaboration) Institute of High Energy Physics, CAS GHP-2004, Oct. 25. OUTLINE. Introduction and f 0 (980) f 0 (1370) , f 0 (1500) , f 0 (1710) and f 0 (1790) Summary. Introduction (1). - PowerPoint PPT PresentationTRANSCRIPT
Resent BES Results on Scalar Mesons
Zhipeng Zheng (Representing BES Collaboration)
Institute of High Energy Physics, CAS GHP-2004, Oct. 25
OUTLINE
Introduction and f0(980)
f0(1370), f0(1500), f0(1710) and f0(1790)
Summary
Introduction(1)
Why are light scalar mesons interesting?
The knowledge on the light scalars is very important to the understanding of QCD in nonperturbative region
There have been hot debates on the existence of and .
f0(980): precise parameters m, …. are needed.
Is it a state, or molecular or four quark state?
Lattice QCD predicts the 0++ scalar glueball mass from 1.5 - 1.7 GeV. f0(1500) and f0(1710) are good candidates.
Introduction(2)
ss KK
f0(1370), f0(1500), f0(1710) were found in the fixed target, , e+e- experiments. The confirmation of them is important.
f0(1500), f0(1710) are treated as mixed state of glueball with meson, but we need more information.
The BESII data have much higher statistics and lead to a much more decisive partial wave analysis.
Introduction(3)
pp
0
10
20
30
40
50
60
CBAL MK II MK III DM2 BES I BES II
BESII Detector
VC: xy = 100 m TOF: T = 180 psMDC: xy = 220 m BSC: E/E= 21 % dE/dx= 8.5 % = 7.9 mr p/p=1.78(1+p2) z = 2.3 cm counter: r= 3 cm B field: 0.4 T z = 5.5 cm 0
2
4
6
8
10
12
14
MKI MKII MKIII CBAL BESI BESII CLEOc
J/
(2S)
World J/ and (2S) Samples (×106) BESII
58M J/
BESII 14M (2S)
Introduction(4)
M() M(+-0)
M(+-)
0
The pole in J/+-
f2(1270)
f2(1270)
Fit Method I: (whole mass region)
f0 contribution
b1(1235)Channels fitted to the data:J/f2(1270) f0(980) b1(1235) ’(1450) f2(1565) f2(2240)
f2 contribution
Fit to J/→+ (M < 1.5 GeV)
Channels fitted to the data:
J/f2(1270) f0(980) b1(1235) P.S
f0 contribution
f2 contribution
Fit Method II: (M<1.5GeV)
Breit-Wigner for in the fit:
(1)(2)
(3)
(4)
Averaged pole position:
P. L. B 598 (2004) 149-158
Method I
Method II
Fit Result
MeVi )42252()39541(
in J/K+ - K+ -
K0*(1430), K2*(1430)K*(892)
ρ(770)
K1(1270), K1(1400)
in J/K+ - K+ -
K*0(1430)K*
in KKJ */
f0(980) in J/+-,K+K-
Important parameters from PWA fit:
Large coupling with KK indicates big component in f0(980)
/J
KKJ /
21.025.021.4
1510165
68965
g
g
MeVg
MeVM
KK
ssf0(980)
f0(980)f0(1370)
f2(1525)
BESII preliminary
There has been some debate whether f0(1370) exists or not.
f0(1370) clearly seen in J/ , but not seen in J/ .
/J
/J
f0(1370)
NO f0(1370)
MeV
MeVM
40265
501350
f0(1370) in J/+-, +-
PWA 0++ components
f0(980)
f2(1270)
BESII preliminary
f0(1500) in J/+-, 00
/J
00/ J One scalar with a mass = 1466 6 16 MeV is needed in J / . It’s also needed in the fit of J / , kkNo peak directly seen in , KK, , KK channels.
f2(1270)
f2(1270)
f0(1500)
f0(1500)
f0(1500) f0(1710)
BESII preliminary
KKJ /
00/ ss KKJ
f0(1710) in
PWA analysis showsone scalar.
MeV166
MeV41740155
108
10
25
M
Phys. Rev. D 68 (2003) 052003
f0(1710)
f0(1710)
f2(1525)
f2(1525)
KKJ /
f0(1710) in J/ /J
00/ J
• The scalar around 1710MeV with mass
• Combine the branching ration of and kk, we
obtain:
MeV
MeVm
298145
111765 4
3
22.0
18.0
0
0 41.0))1710((
))1710((
KKfBR
fBR
f2(1270)
f0(1710)
f2(1270)
f0(1710)
BESII preliminary
f0(1710) in J/K+K-, +-
Clear f0(1710) peak in J/ KK.
No f0(1710) observed in J/ !
KKJ /
/J
f0(1710)
NO f0(1710)
MeV
MeVM
20125
301740
f2(1270)
PWA 0++ components
CLKKfBR
))1710((
))1710((
0
0
hep-ex/0409007
A clear peak around 1790 MeV is observed in J/ +-.
No evident peak in J/ KK. If f0(1790) were the same as f0(1710), we would have:
Inconsistent with what we observed in J/ , KK!
/J
f0(1790)
KKJ /
?
MeV
MeVM6030
4030
270
1790
f0(1790) in J/K+K-, +-
f0(1710) 5.1~))1710((
))1790((
0
0
KKfBR
fBR
BESII preliminary
Summary of Scalar Meson at BES
Summary
Clear seen(peak + fit) in the fit
The existence of is confirmed in J/+ - with pole position:
Evidence for the as a peak close to threshold. Pole position:
Summary
MeVi )42252()39541(
MeVi )420~310()840~760(
f0(980) is clearly seen in both +-, K+ K- data, parameters of f0(980) are well determined.
Summary
21.025.021.4
1510165
68965
g
g
MeVg
MeVM
KK
f0(1370) is clearly seen in J/+- , But not evidence in J/+ -
f0(1500) is seen in J/ channel with mass:
f0(1710) is clearly seen in J/ KK with mass and width:
Summary
MeVM 1661466
MeV166
MeV,41740
155
108
10
25
M
f0(1710) is also seen in the J/, and K+K, but not seen in J/ +-
f0(1790) is needed in the fit of J/ +-, and need more study.
Summary