Decays Working Group Activities

1. systematics studies concerning the had

measurement

2. first results in Dalitz plot parameters

3. background and a new upper

limit

GENERAL MEETING

Federico Nguyen - October 10th 2002

GENERAL MEETING

Trackmass, Acceptance and

Filfo studies for the had

measurement

Trackmass, Acceptance and

Filfo studies for the had

measurement

Federico Nguyen

October 10th 2002 General Meeting

Mtr

ack (M

eV)

Trackmass Systematics (I)

M2 (GeV2)

m

0)(M||M||M 2γ

221

22trk

22

2trk

21φ qpppp

some sources of background can be seen in the Mtrk - distribution:

- :at high values of Mtrk

which is M2 dependent

- :at Mtrk 104 MeV

MeV220M.AND1.MeV105

MeV250M

GeV0.85

M.AND.MeV120M trk

2

trk

2

2

2ππ

trk

Federico Nguyen

October 10th 2002 General Meeting

Trackmass Systematics (II)

2 MC samples differingonly for Fvalues

β1

βBWα1

)αBW(1BW

Fρ'

ωρ

π

0.145β

101.85α

MeV150.7Γ

MeV768.5M

FZK

3

ρ

ρ

0.1473β

101.48α

MeV143.7Γ

MeV772.6M

LNF

3

ρ

ρ

FZK(M) LNF(M)

at the level 2% Switched OFF PPGTAG and PPFILTSwitched OFF PPGTAG and PPFILT

Federico Nguyen

October 10th 2002 General Meeting

Geometrical Cuts Systematics (I)

our acceptance selection:

400 < +,-<1400 and

(pt>160 MeV or |pz| >90 MeV)

00 < < 150 or 1650 < < 1800

E > 10 MeV

we studied acceptance

cuts dependence on F

parameters by generating

stand alone MC samples

(NTOT=106 events) with

different M orvalues

covering the

whole phase space

there is no significant dependence on F

parameters in acceptance studies

there is no significant dependence on F

parameters in acceptance studies

Federico Nguyen

October 10th 2002 General Meeting

Geometrical Cuts Systematics (II)

[(772.6)-(770)]/(772.6)

[(772.6)-(780)]/(772.6)

geomgeom

MM2 2 (GeV(GeV22))

MM2 2 (GeV(GeV22))

MM2 2 (GeV(GeV22))

dependence on M - we fixed the other parameters

Federico Nguyen

October 10th 2002 General Meeting

Geometrical Cuts Systematics (III)

[(143.7)-(140)]/(143.7)

[(143.7)-(150)]/(143.7)

Q2

Q2

geomgeom

MM2 2 (GeV(GeV22))

MM2 2 (GeV(GeV22))

MM2 2 (GeV(GeV22))

dependence on - we fixed the other parameters

Federico Nguyen

October 10th 2002 General Meeting

Filfo Systematics (I)

o Filfo efficiency is evaluated from

DATA by reprocessing RAW

without using Filfo as a filter

o to overcome the long

reconstruction time, a prefilter,

based on CALORIMETER and

PATTERN RECOGNITION, is used,

then TRACK, VERTEX modules are

called...

FILFO/par=5: FILFO/par=5: ~ 2000 refiltered files~ 2000 refiltered files 6 pb-1 6 pb-1from different periods of 2001 DATA takingfrom different periods of 2001 DATA taking

Overall efficiency:Overall efficiency:DATADATA FILFO, SMAFILFO, SMA= (94.82±0.07) %= (94.82±0.07) %

errors errors ~~ 0.5-1% per bin0.5-1% per bin

MM2 2 (GeV(GeV22))

MM2 2 (GeV(GeV22))

Federico Nguyen

October 10th 2002 General Meeting

Filfo Systematics (II)

MB[205 events]

COS[659 events]

BHABHA[3955events]

4734 events

MM2 2 (GeV(GeV22))

signal events vetoed by FILFO/par=5

by the following:• Bhabha-filter (83.5%)• Cosmic-filter (13.9%)• Machine Background

filter (4.3%)

Federico Nguyen

October 10th 2002 General Meeting

Filfo Systematics (III)

o we wanted to know the

difference in applying Filfo at the

beginning or at the end of our

analysis chain

o resulting systematic correction:

= (-0.71 ± 0.07)%

FILFO/par=5: FILFO/par=5: 2 2 10 105 5 stand alone MC eventsstand alone MC events

Overall efficiency (Filfo at the end):Overall efficiency (Filfo at the end):MCMC FILFO, SMAFILFO, SMA= (97.37±0.07) %= (97.37±0.07) %

Overall efficiency (Filfo at first):Overall efficiency (Filfo at first):MCMC FILFO, SMAFILFO, SMA= (96.66±0.07) %= (96.66±0.07) %

MM2 2 (GeV(GeV22))

MM2 2 (GeV(GeV22))

systematic Filfo checks havebeen performed

we plan to study Filfo changesin different periods

of DATA taking

systematic Filfo checks havebeen performed

we plan to study Filfo changesin different periods

of DATA taking

GENERAL MEETING

resolutio

n, fit procedure and results

resolutio

n, fit procedure and results

Federico Nguyen

October 10th 2002 General Meeting

Dalitz Plot Parameters: Definition

1Q

T3Y

Q

TT3X

0

-

1;0.895Y

1;1X

Ti kinetic energy of the i

Q m - 2m - m

usual decay rate in termsof slope parameters:

() |M(X,Y)|2

|M(X,Y)|2 1 + aY + bY2 + cX2

Federico Nguyen

October 10th 2002 General Meeting

Dalitz Plot Parameters: Resolution (I)

corecore = 0.042 = 0.042corecore = 0.034 = 0.034

Y resolution has been obtained by using 1.3105 MC events

it can be estimated either from or from from0

0πππηπ0 mEEmT

0

0

πγγπ0 mET

Federico Nguyen

October 10th 2002 General Meeting

Dalitz Plot Parameters: Resolution (II)

corecore = 0.028 = 0.028

Federico Nguyen

October 10th 2002 General Meeting

Fit Procedure and Results (I)

as a 1st approximation b c 0, , that

has

to be fitted on:

aY1|(Y)M| 2 the

PS(Y)X

2dX

Y)ε(X,

Y)N(X,(Y)M /obs

where:

N(X,Y) = # of events in the Dalitz plot

(X,Y) = efficiency (from an independent MC sample)

PS(Y) = phase space as a function of Y bins

Federico Nguyen

October 10th 2002 General Meeting

Fit Procedure and Results (II)

dN/dY dN/dY ~ 1 ~ 1 + aY+ aY

YY

16 pb-1 from 2000 DATAhave been studied (the same selection for the mixing angle analysis, Kloe Memo 266)

Federico Nguyen

October 10th 2002 General Meeting

Fit Procedure and Results (III)

dN/dY dN/dY ~ 1 ~ 1 + aY + bY+ aY + bY22

YY

resolution studies have been optimized,1st glance at DATA shows sensitivity to the quadraticslope parameter

resolution studies have been optimized,1st glance at DATA shows sensitivity to the quadraticslope parameter

GENERAL MEETING

selection cuts, possible background and

preliminary limit

selection cuts, possible background and

preliminary limit

Federico Nguyen

October 10th 2002 General Meeting

Analysis Requirements

Pre-selection:4 prompt clustersAngle between two clusters > 15°

Etot(clusters) > 900 MeV; Ptot < 110 MeV

Final Selection:

• Pkin-fit() > 0.01

• |M - 140| > 30 MeV

• E vs. cos plane cut

• |M – 550| < 45 MeV

after kin. fitafter kin. fit

before kin. fitbefore kin. fit

kinematic fit has been

studied on MC

(Ntot=3104 events)

EE (MeV) (MeV) EE (MeV) (MeV)

Federico Nguyen

October 10th 2002 General Meeting

Background Problem

Data2001 (59.933 pb-1) Cut Type

tot (

Pre-cuts 1345779

Pre-selection 4499 (0.3%)

Final Selection 179 (4 %)

All. 179 (0.013%)

inconsistent with MC estimated

background 59 events

perhaps a missing background:

4 e+ e-

0 2

MMrecoilrecoil of of 1 1 (MeV)(MeV)

MMMeVMeV

1 non 0 least energetic

can be rejected by can be rejected by 00 cut, cut,still we must know the tailsstill we must know the tails

peak peak

Federico Nguyen

October 10th 2002 General Meeting

Preliminary Results on 2001 DATA

MM (MeV) (MeV) MM (MeV) (MeV)

PAW raw fPAW raw fit:it:a+bx+cxa+bx+cx22+N+Nsignalsignal*Gauss*Gauss

Nsignal = 9 26, corresponding to 616 events out of 142 pb-1

Nupper (90% C.L.) = Nsignal + 1.28*Nsignal = 42, TOT = 21%

BR() < Nupper/(L**BR()*TOT) = 3.5 10-5

Nsignal = 9 26, corresponding to 616 events out of 142 pb-1

Nupper (90% C.L.) = Nsignal + 1.28*Nsignal = 42, TOT = 21%

BR() < Nupper/(L**BR()*TOT) = 3.5 10-5

from MC:from MC:GaussGauss = 13 MeV = 13 MeV

Federico Nguyen

October 10th 2002 General Meeting

Summary and Outlook

had:NO significant Fparameters dependence both in acceptance and trackmass,filfo efficiency has been studied,we started evaluating trackmass efficiency from DATA.

:resolution and fit procedure have been checked,work ahead: genuine 2D fit, 2001-2002 DATA analysis.

: background has been studied, but a MC code is needed,reachable limit (~ 500 pb-1): BR() < 2 10-5 .