22ndnd Kloe Physics Workshop Kloe Physics WorkshopJune 10June 10thth-12-12thth, 2002 Otranto (LE), 2002 Otranto (LE) Status report on Status report on
physicsphysics
F. Ambrosino, T. Capussela,C. Di Donato, F.Perfetto
Status report on Status report on physicsphysics
• Correction factor to the observed cross sections (- paper)
• Dalitz plot
• Study of
• Correction factor to the observed cross sections (- paper)
• Dalitz plot
• Study of
ee++ee-- PP
The correction factor to the observedcross sections due to the interference between the amplitudes A() and A() at s = m
The correction factor to the observedcross sections due to the interference between the amplitudes A() and A() at s = m
R.R.Akhmetshin et al., Phys. Lett. B 434 426 (1998)
ee++ee-- PP
P(s)=
(0)
P(s)=
(0)
VV
FFP(s) s3/2 3
BBPP + + AAVV
22
V
mm33VV mmVV VV e eiiVV
FFP(mm22VV) mm22
VV-s-is VV(s) ••AV=
The Born cross section of the process:
ee++ee-- PP
(0)V = m2
V
12BVe+e-BVP
m2V
(0)V = m2
V
12BVe+e-BVP
m2V
==
e+e-VP
For meson see Gounaris-Sakurai model (Phys. Rev. Lett. 21 (1968) 244)
ee++ee-- PP
P(s)=C•|A+A|2 with P=
P(s)=C•|A+A|2 with P=
= K K=0,95
meas
meas
BR() = (6.100.610.43)•10-5 ++- - 33
(6.700.58 )•10-5 ++- - 77
BR() = (6.100.610.43)•10-5 ++- - 33
(6.700.58 )•10-5 ++- - 77+0.89
-0.92
Dalitz plot Dalitz plot
•
• Topological selection• Kinematic fit
• Fit to dalitz plot: efficiency and resolution study
•
• Topological selection• Kinematic fit
• Fit to dalitz plot: efficiency and resolution study
already done(- paper)
Dalitz variableDalitz variable
X=3(T+-T-)/Q
Y=(3T0/Q)-1
Q = T++T-+T0
X=3(T+-T-)/Q
Y=(3T0/Q)-1
Q = T++T-+T0
X
|M(x,y)|2= N0f(x,y)
Nij=N0ij|M(xi,yj)|2dxidyj
|M(x,y)|2= N0f(x,y)
Nij=N0ij|M(xi,yj)|2dxidyj
Study on resolutionStudy on resolution
X
Study on resolutionStudy on resolution
Y
Relevant for the box anomaly: /decays are dominated by the meson; chiral theory expects an anomalous contribution
Relevant for the box anomaly: /decays are dominated by the meson; chiral theory expects an anomalous contribution
Careful spectral shape measurement
in order to study the anomalous
contribution (Holstein hep-ph/0112150)
BR = 6.16•10-4
• PDG’00: 18K events (’73) L = 200 pb-1 means ~385K events
Careful spectral shape measurement
in order to study the anomalous
contribution (Holstein hep-ph/0112150)
BR = 6.16•10-4
• PDG’00: 18K events (’73) L = 200 pb-1 means ~385K events
Topological selectionTopological selection
• One charged vertex r<4 cm and |z|<8 cm • two prompt neutral clusters
• One charged vertex r<4 cm and |z|<8 cm • two prompt neutral clusters
EE (MeV) (MeV)
=56%=56%
MM (MeV)(MeV)
Main backgroundMain background
EE (MeV) (MeV)
• BR = 15.31%• = 63% S/B = 3.5x10-3
• BR = 15.31%• = 63% S/B = 3.5x10-3
MM (MeV)(MeV)
S/B comparison S/B comparison
EE (MeV) (MeV)
EE (MeV) (MeV)
MM (MeV)(MeV)
MM (MeV)(MeV)
prompt prompt
MM (MeV)(MeV)
cos
cos
coscos
coscos
Background rejectionBackground rejection
M> 500 MeV cos < 0.20
M> 500 MeV cos < 0.20
M M tracks tracks
MM (MeV)(MeV)
= 45%S/B=0.14
= 45%S/B=0.14
Ncut/Ntop
MM (MeV)(MeV)
Background rejectionBackground rejection
MM (MeV) (MeV)
MM (MeV) (MeV)
MM (MeV) (MeV)
M > 200 MeV M < 560 MeV M > 200 MeV M < 560 MeV
MM
(M
eV
) (
MeV
)
M M tracks tracks
MM (MeV)(MeV)
= 45%S/B=2
= 45%S/B=2
Ncut/Ntop
MM (MeV)(MeV)
•A first look at the final statefinal state•Kinematic fit•likelihood to improve S/B without deforme the shape of the distributions
•A first look at the final statefinal state•Kinematic fit•likelihood to improve S/B without deforme the shape of the distributions
ConclusionsConclusions
• - paper submitted
• first look at dalitz plot
• likelihood function either to
improve S/B either to have distribution with shape not biased
• - paper submitted
• first look at dalitz plot
• likelihood function either to
improve S/B either to have distribution with shape not biased
M M tracks tracks
MM (MeV)(MeV)
= 45%S/B=2
= 45%S/B=2