A.De Santis Radiative Meeting 30/05/07 Cross section e e Antonio De Santis Simona Giovannella.
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Transcript of A.De Santis Radiative Meeting 30/05/07 Cross section e e Antonio De Santis Simona Giovannella.
A.De Santis Radiative Meeting 30/05/07
Cross section ee
Antonio De Santis
Simona Giovannella
A.De Santis - Radiative Meeting 30/05/07 2 of 18
Amplitude
contribution in cross section (b) could be represented as interference with continuum process (a)Interference is parametrized by term (Z) at -resonace peak.
A.De Santis - Radiative Meeting 30/05/07 3 of 18
Data sample
Integrated luminosity onpeak 450 pb-1
Integrated luminosity offpeak 150 pb-1
Data:• drc (DBV-13/14) 01/02
• drc (DBV-24/25) 06
MC sample:• Signal (DBV-26 LSF=1) 01/02 (?)• mrc (DBV-18 all_phys LSF=0.2) 01/02• mrc (DVB-26 all_phys LSF=1(2)) 06
Total Luminosity: 600 pb-1
Scan 01/02
Scan 06
A.De Santis - Radiative Meeting 30/05/07 4 of 18
Analisys strategy
• Acceptance– One vertex at Interaction Point (IP)– Two tracks connected at vertex– Four neutral cluster with:
• Eclu grater than 10 MeV
• ToF compatible with prompt • |cos()| < 0.93
• Kinematic Fit (33 input parameters, 8 constraints) (?)
• Fine selection:– 2 < 50
– m/m
• Slice dataset in function of ECM (100 Kev Bin)
• Signal events counting (fit via HMCMLL) • Cross section fit
A.De Santis - Radiative Meeting 30/05/07 5 of 18
Data vs MC: cos()
2<50 2>50
MC fit
MC sig
Data
Same scale factors are used to normalize MC distributions in both selections
A.De Santis - Radiative Meeting 30/05/07 6 of 18
Data vs MC
2<50 2>50
MC fit
MC sig
Data
Same scale factors are used to normalize MC distributions in both selections
A.De Santis - Radiative Meeting 30/05/07 7 of 18
Data vs MC
2<50 2>50
MC fit
MC sig
Data
Same scale factors are used to normalize MC distributions in both selections
A.De Santis - Radiative Meeting 30/05/07 8 of 18
Data vs MC
2<50 2>50
MC fit
MC sig
Data
Same scale factors are used to normalize MC distributions in both selections
A.De Santis - Radiative Meeting 30/05/07 9 of 18
Data vs MC
2<50 2>50
MC fit
MC sig
Data
Same scale factors are used to normalize MC distributions in both selections
A.De Santis - Radiative Meeting 30/05/07 10 of 18
Data vs MC
ECoM =
1000 MeV
ECoM =
1010 MeV
ECoM =
1030 MeV
MC fit
MC sig
Data
A.De Santis - Radiative Meeting 30/05/07 11 of 18
Efficiency
Conditional efficiency:
tot = 40.07±0.03
A.De Santis - Radiative Meeting 30/05/07 12 of 18
Systematic errors I
Different source of systematic errorsare taken into account.
All of them are summed in quadraturewith statistic error of the counting fit toget the final error on the visible cross section
A.De Santis - Radiative Meeting 30/05/07 13 of 18
Cross section fit
tot
count
L
N
intexp
A.De Santis - Radiative Meeting 30/05/07 14 of 18
Fit result
A.De Santis - Radiative Meeting 30/05/07 15 of 18
Systematic errors II
Systematic errors on the fit parameters are evaluated as r.m.s. of the distributions obtained varying cuts and fitted distribution (counting).
Cross section stability as been checked for each CoM energy.
A.De Santis - Radiative Meeting 30/05/07 16 of 18
Final results
KLOE results:
SND results:
A.De Santis - Radiative Meeting 30/05/07 17 of 18
GoodNews
Referees at work
A.De Santis - Radiative Meeting 30/05/07 18 of 18
Conclusions
Cross section parameters accuracy better than SND results.
Agreement between results due to large errors in SND measurements.
Yesterday was my birthday and Today is exactly one months after my wedding and this work is completed…
…Life is Beautiful
A.De Santis - Radiative Meeting 30/05/07 19 of 18
Spare
A.De Santis - Radiative Meeting 30/05/07 20 of 18
Amplitude: MC generatorAll term which differs for exchange between two 0’s or different charge must be summed. Resulting matrix element (M) could be expressed as modulus squared of current composed by two term(0’s permutation) each composed by tree terms ( charge) 2002
0M
J
)(),,,(),,,(),,,( 3241323412314200
0 pppppptpppptpppptGJ
)()()()(
)()(
)(),,,(
31441324133142214334
431
12
4321
ppppppppppppppp
ppDpPD
pPFppppt
Reference: hep-ex/9904024 v2
A.De Santis - Radiative Meeting 30/05/07 21 of 18
Amplitude current term
Form factor
Inverse propagator
)()(
)()(
)()(
)(),,,(
3144132
4133142214334
431
12
4321
pppppp
ppppppppp
ppDpPD
pPFppppt
A.De Santis - Radiative Meeting 30/05/07 22 of 18
Major change in GEANFI
A.De Santis - Radiative Meeting 30/05/07 23 of 18
Kinematic fit
Input parameters:
0pppPγ γππφ
Constraints:
A.De Santis - Radiative Meeting 30/05/07 24 of 18
Measured visible cross section
tot
count
L
N
intexp
A.De Santis - Radiative Meeting 30/05/07 25 of 18
Tracking efficiency
A.De Santis - Radiative Meeting 30/05/07 26 of 18
Vertex efficiency
A.De Santis - Radiative Meeting 30/05/07 27 of 18
Eta filter and Bhabha filter