Biagio Di Micco13/02/2003 - Radiative Phi Decays Meeting 1 Biagio Di Micco Università degli Studi di Roma III 2001 - 2002 results

Biagio Di Micco 13/02/2003 - Radiative Phi Decays Meeting

1

Biagio Di Micco

Università degli Studi di Roma III

2001 - 2002 results


2

Background expected from MC study

2 1293 92 (after reproduction

of functional shape) a00 749 4582 f0 0 0 2194 4592 0 0 0 2318 23255 0 197 6083 0 139 34 e+e- 13.6 - 80 (90% C.L.) 4

Expected (in 140 pb-1 of data) MC sample after cuts


3

M0 distribution for MC background

0

MeVMeV

MeV

MeV

MeV

MeV

2 0

0 0 0 f0 0 0

all


4

M0 distribution DATA-MC comparison (2001)

1) Normaliztion problem (bad luminosity estimation)

2) Shape problem, mainly at high values !!

High discrepancy

=783.90 MeV = 14.8 MeV

DATA

MC expected

M0 afterkinematic fitin 0 4 ipotesis.

MeV


5

4c - 3 kinematic fit (2001)1) perform kinamtic fit on 3 constraining the total momentum2) select the set with least 2

Prob(2 > 20)

CUT PROB > 0.05

E combinatorial

2

MeV


6

M 0 comparison DATA-DATA [P(23)>0.05]

Compensation ofthe bad shape

(2001)

MeV

DATA

DATA [P(23)>0.05]


7

E1 vs. E2 distribution (2001)

2

2

? bhabha?

Huge not predicted by MC

E1 MeV

MeV

E2

E2E1

MeVMeV


8

Be aware of the background problem

Upper limit 2001 - 2002

Selection cuts changed again !! (no cut on the number of photon below a given angle)

• Filfo - EVCL RAD• 250 MeV < E < 480 MeV (Erad = 363 MeV)• Ngood = 4 (Good: E > 30 MeV, t < min(5t, 2ns), |cos()| < 0.93 (> 21.6 °)• > 15°, Etot (4) > 900 MeV• |M-135| > 20 MeV M two photon mass after kinematic fit 4• E1 +E2 (two photon more energetic) > 800 MeV• |E-362.2| > 8 MeV, |E-E(0)| > 4.62 (after 3 kinematic fit, in reference frame)• 2

3 > 25, M < 125 MeV M > 152 MeV, •T.D.W.T < 0.4 (wait a bit for explanation), 2

4 < 8


9

M distribution in hypothesis

MeV

MeVM

M

CUT: |M-135| > 20

DATA(2001)


10

Sum of the energy of the most energetic two

photons

MeV

MeVE1+E2

E1+E2

DATA(2001)

MC CUT: E1+E2 < 800 MeV


11

Energy of photons (combinatorial) in the 3 hypothesis

MeV

MeVE

E

DATA(2001)

MC

2

0

CUT:

|E-362.2| > 8 MeV

|E-500| > 4.6 MeV


12

M2 combinatorial in 4 hypothesis

DATA(2001)

MC CUT:

M < 125 M > 155

MeV

MeVM

M


13

M2 combinatorial in 4 hypothesis

DATA(2001)

MC CUT:

M < 125 M > 155

MeV

MeVM

M


14

t between photons and the two photon which have less difference in the time of flight.

DATA(2001)

MC

CUT:

t < 0.4 ns

ns

nst

t


15

2 of the 4 kinematic fit.

DATA(2001)

MCCUT:

2 < 8

MeV

MeVM

M


16

Be aware of the background problem

Upper limit 2001 - 2002

Selection cuts changed again !! (no cut on the number of photon below a given angle)

• Filfo - EVCL RAD• 250 MeV < E < 480 MeV (Erad = 363 MeV)• Ngood = 4 (Good: E > 30 MeV, t < min(5t, 2ns), |cos()| < 0.93 (> 21.6 °)• > 15°, Etot (4) > 900 MeV• |M-135| > 20 MeV M two photon mass after kinematic fit 4• E1 +E2 (two photon more energetic) > 800 MeV• |E-362.2| > 8 MeV, |E-E(0)| > 4.62 (after 3 kinematic fit, in reference frame)• 2

3 > 25, M < 125 MeV M > 152 MeV, •T.D.W.T < 0.4 (wait a bit for explanation), 2

4 < 8


17

MC energy of the most energetic photon in the reference frame

MeV

MeV

Double gaussian fit

Selected range toestimate upper limit300 - 400 MeV


18

Fit result on 2001 data

MeV

MeV

Fitted function:

)(

)1)(()1(),,(

212

1111

GGaN

xaaNaaaxf

N1,N2 normalization constants

Fit results:

a1 = (-3.49 0.04)10-3 MeV-1

a = -0.013 0.017

Ntot=966


19

Upper limit on 2001 data

Total Events: 961log(likelihood)

a

95 % C.L

90 % C.L.

a(95% C.L.) = 0.037

a(90% C.L.) = 0.032

)(

BrL

NaBr tot

Br() = 1.299 0.026 (PDG 2002) = (3.1 0.2) b

L = 166 pb-1 (trgmon lum)

Br(3) < 2.37 10-5 (90% C.L)

Br(3) < 2.74 10-5 (95% C.L.)


20

Upper limit on 2002 data

MeV

MeV

Fitted function:

)(

)1)(()1(),,(

212

1111

GGaN

xaaNaaaxf

N1,N2 normalization constants

Fir results:

a1 = (-3.58 0.04)10-3 MeV-1

a = 0.006 0.014

Ntot=1517


21

Fit result on 2002 data

Total Events: 1512log(likelihood)

a

95 % C.L

90 % C.L. a(95% C.L.) = 0.041

a(90% C.L.) = 0.037

)(

BrL

NaBr tot

Br() = 1.299 0.026 (PDG 2002) = (3.1 0.2) b

L = 280 pb-1 (trgmon lum)

Br(3) < 2.56 10-5 (90% C.L)

Br(3) < 2.86 10-5 (95% C.L.)


22

generator

Biagio Di Micco

Università degli Studi di Roma III

Generator built according the article:

SND: Nucl.Phys.B600:3, 2001

with the model of NgPhys.Rev. D47:4939, 1993


23

E2 overlapped

Phase Space

Quark Box model

GeV

GeV


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vs. E2

Phase Space

Quark Box model

GeV

GeV

GeV

GeV


25

Phase space

Quark Box model

GeV2

GeV2

art = 0.70 eV

gen=0.71 eV

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Biagio Di Micco13/02/2003 - Radiative Phi Decays Meeting 1 Biagio Di Micco Università degli Studi di Roma III 2001 - 2002 results