Comparison of the signal selection with past results

C. Di Donato, M. Jacewicz

Signal/BackgroundReaction: 0

ee0

ee0

X-section [b]:2.04 10-3

9.87 10-3

0.30 10-3

0. 460.14 10-3

• Most frequent charged decays:BR() = (22.73±0.28) 10-2

BR(0) = (4.60±0.16) 10-2

BR(ee) = (6.8±0. 8) 10-3

New VS Old• RAD Stream• 2 pnc• 1 charged vertex

rxy<4cm & |z|<8cm• 2 tracks balanced charge• Kinematic fit:

quadrimomentum conservation with 2 clusters compatible with photon hypothesys

• Cut on M(recoil) to reject +-0

• RAD + RPI + KPM• At least 2pnc one of them

with E>250MeV• Two tracks with balanced

charge and closest to IP using info at pca

• 2 neutral cluster in time, with most energetic assumed to originate from

• E(recoil) calculated from 2 body kinematics

• Using eta decay kinematic we correct E()

• Cut on E() to reject background

Analysis versus EVCL

• Stream correlation for MC charged RAD investigated: run RAD, RPI & RAD, KPM & RAD & RPI

ALLRADRPIKPM

Using new approach

MC 2005: All Phys, runs 34410-34499 (12.7pb-1) Only RAD stream

Total

(1194777)Event Signature |Et-Pt|<10MeV OpAn<0.2

(22131)

10904(49%) 9771(44%) 9271(42%)

0

(105791)59489 (56%) 1429 (1.3%) 75

0

(651153)238261(36%) 47723(7%) 10814(2%)

TrackTrack Selection VS VertexVertex Selection• Best Results from track selection using

PCA at IP parametersTotal:22131 Preselection Event Signature |Et-Pt|<10MeV OpAn<0.2

ALL 17619 (80%) 12553(57%) 10321(47%) 9629(43%)

RAD 10916 (49%) 9430(43%) 8284(37%) 7877(36%)

KPM 1210(5.5%) 595(2.7%) 255(1.1%) 186(0.8%)

RPI 1665(7.5%) 1524(6.8%) 1415(6.4%) 1336(6.0%)

Total:22131 Preselection Event Signature |Et-Pt|<10MeV OpAn<0.2

ALL 17619 (80%) 15335(69%) 12499(56%) 11550(52%)

RAD 10916 (49%) 10904(49%) 9771(44%) 9271(42%)

KPM 1210(5.5%) 998(4.5%) 475(2.1%) 359(1.6%)

RPI 1665(7.5%) 1665(7.5%) 1575(7.1%) 1493(6.7%)

Tra

ckT

rack

Ver

tex

Ver

tex

Event Signature in RADPreselection and Event Signature

M(MeV)M(MeV)

MOLD: 2 PNC + VTX

=46%

Lint(2001) =95.7pb-1

NEW: 2 PNC + 2 TRK

=49%

Lint(MC2005) =12.7pb-1

Signal/background

cos2

22

PE

mmE recoilrecoil MassInvcalc .

recoilcalc

Signal/background

MeVPE ttcalc 10

recoilcalc

Signal/background

Opening angle between calculated and selected neutralcluster from pnc, rejects background

calc

recoil

calc

recoil

Signal Selection

ALL0

0

ALL0

0

ALL0

0

ALL0

0

Two photons invariant massMeasured Corrected

Measured Corrected

Before cuts

After cuts

Two photons invariant mass corrected variables

ALL0

0

100 MeV < M< 170 MeV

Bg=1%

()=39%

Control Sample 0

recoilcalc 0. MMassInvcalc

MeVMMcalc 15|().| 0

Control Sample 0

0. MMassInvcalc

MeVMMcalc 15|().| 0

ALL0

0

BG

recoilcalc

95.0

clu

i

recoil

Frac

E

EEE

cal

Outlooks

• Analysis in RAD stream:– Ilaria’s cuts to reject BG– Evaluate efficiency– Control sample

• Analysis in KPM+RPI stream:– Evaluate efficiency