Download - Progress for search of neutral Supersymmetric Higgs boson h/A bb h 0 /A (h 0 /A m + m - )
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Halina Bilokon, Vitaliano Chiarella, Simonetta Gentile, Giovanni NicolettiHiggs Meeting 14 December 2005,CERN.
Progress for search of neutralSupersymmetric Higgs boson h/A
bb h0/A (h0/A Halina Bilokon, Vitaliano Chiarella, Simonetta Gentile, Giovanni Nicoletti
Laboratori Nazionali di Frascati, Università di Roma
La Sapienza, INFN
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Halina Bilokon, Vitaliano Chiarella, Simonetta Gentile, Giovanni NicolettiHiggs Meeting 14 December 2005,CERN.
OutlinePreselectionSelection :• b-tag• muons• b-jets • Invariant mass • -isolation
Conclusions & planning
Background: •bb Z→•tt → bb •ZZ → bb
• Top decay: 100% t bW
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Halina Bilokon, Vitaliano Chiarella, Simonetta Gentile, Giovanni NicolettiHiggs Meeting 14 December 2005,CERN.
SelectionPreselection cuts: At least a pair of opposite muons with pt > 10 GeV and || < 2.5At least a pair of jets with ET > 10 GeV and < 2.5SelectionAt least 1 b-jets (pT > 15 GeV & b-tag weight>1) ET miss < 45 GeV 25 GeV < PT 1 < 95 GeV 20 GeV < PT 2 < 60 GeV for tt background
Final CutMinv( +-) +/- M (A0, h0, m) ( m= exp. mass res.)
Isolation PTtrack < 5 GeV around a cone R<0.2
PTb2 < 40 GeV
PTb1 < 70 GeV
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Halina Bilokon, Vitaliano Chiarella, Simonetta Gentile, Giovanni NicolettiHiggs Meeting 14 December 2005,CERN.
Sample particle L =30 fb-1 sample
h0 6000 5999
A0 7000 7000
Zbb 6.8 x 105 340502*
tt 1.7 104 170110
ZZ 3.8 x 103 3788
130 fbLdt
*Corresponding to half luminosity
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Halina Bilokon, Vitaliano Chiarella, Simonetta Gentile, Giovanni NicolettiHiggs Meeting 14 December 2005,CERN.
Number of muons: no cut MC distributions Reconstracted
Distribution
h0 A
bbZ→ tt ZZ
x 0.5
N 2
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Halina Bilokon, Vitaliano Chiarella, Simonetta Gentile, Giovanni NicolettiHiggs Meeting 14 December 2005,CERN.
PT of muons: no cut MC , reconstructed distributions
tt :
peaked at
lower PT values
h0
tt ZZ
x 0.5
bbZ→
pT > 10 GeV
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Halina Bilokon, Vitaliano Chiarella, Simonetta Gentile, Giovanni NicolettiHiggs Meeting 14 December 2005,CERN.
particle L =30 fb-1 sample pair
h0 6000 5999 3643(61%)
A0 7000 7000 4332(62%)
Zbb 6.8 x 105 340502* 206629 (61%)
tt 1.7 104 170110 114718(67%)
ZZ 3.8 x 103 3788 1780(47%)
*Corresponding to half luminosity
•At least a pair of + - with pt > 10 GeV < 2.5
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Halina Bilokon, Vitaliano Chiarella, Simonetta Gentile, Giovanni NicolettiHiggs Meeting 14 December 2005,CERN.
Number of jets: after 1 cut MC distributions Reconstructed
distribution
x 0.5
Ah0
ttbbZ→
x 0.5
ZZ
Njet 2
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Halina Bilokon, Vitaliano Chiarella, Simonetta Gentile, Giovanni NicolettiHiggs Meeting 14 December 2005,CERN.
particle L =30 fb-1 sample pair jets
h0 6000 5999 3643(61%)
1758(29%)
A0 7000 7000 4332(62%)
2178(31%)
Zbb 6.8 x 105 340502* 206629 (61%)
127099(37%)
tt 1.7 104 170110 114718(67%)
107075(63%)
ZZ 3.8 x 103 3788 1780(47%)
1470(39%)
*Corresponding to half luminosity
•A pair of jetswith pt > 10 GeV |η| < 2.5
PRESELECTION
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Halina Bilokon, Vitaliano Chiarella, Simonetta Gentile, Giovanni NicolettiHiggs Meeting 14 December 2005,CERN.
After preselection: Number of Jets (R=0.7)
tt
Ah0
bbZ→
Nev
Nev
Nev
Nev
Njet
Njet
Njet
Njet
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Halina Bilokon, Vitaliano Chiarella, Simonetta Gentile, Giovanni NicolettiHiggs Meeting 14 December 2005,CERN.
After preselection: jets pT (R=0.7)
h0 A
bbZ→
tt
Nev
Nev Nev
Nev
PT(MeV) PT(MeV)
PT(MeV) PT(MeV)
<pT> ~25 MeV <pT> ~26 MeV
<pT> ~35 MeV <pT> ~53 MeV
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Halina Bilokon, Vitaliano Chiarella, Simonetta Gentile, Giovanni NicolettiHiggs Meeting 14 December 2005,CERN.
particle initial preselect
ionb-tag
h0 5999 1758(29%)
572(9.5%)
A0 7000 2178(31%)
751(10.7%)
Zbb 340502* 127099(37%)
62812(18.4%)
tt 170110 107075(63%)
89684(52.7%)
ZZ 3788 1470(39%)
1042(27.5%)
*Corresponding to half luminosity
•At least 1 b-jets (pT > 15 GeV & b-tag weight>1)
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Halina Bilokon, Vitaliano Chiarella, Simonetta Gentile, Giovanni NicolettiHiggs Meeting 14 December 2005,CERN.
After b-tag cut: ETmiss
h0 A
bbZ→
tt
ET miss < 45 GeV<ET>= 21.8 GeV
<ET>= 27.5 GeV
<ET>= 23.7 GeV
<ET>= 67.1 GeV
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Halina Bilokon, Vitaliano Chiarella, Simonetta Gentile, Giovanni NicolettiHiggs Meeting 14 December 2005,CERN.
particle initial preselect
ionb-tag ET
miss
h0 5999 1758(29%)
572(9.5%)
526(8.8%)
A0 7000 2178(31%)
751(10.7%)
675(9.6%)
Zbb 340502* 127099(37%)
62812(18.4%)
52012(15.2%)
tt 170110 107075(63%)
89684(52.7%)
24180(14.2%)
ZZ 3788 1470(39%)
1042(27.5%)
885(23.3%)
*Corresponding to half luminosity
• ETmiss < 45 GeV
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Halina Bilokon, Vitaliano Chiarella, Simonetta Gentile, Giovanni NicolettiHiggs Meeting 14 December 2005,CERN.
After ETmiss:
the most energetic PT1
h0
bbZ→ tt
x 0.5
25 GeV<pT 1 < 95 GeVA
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Halina Bilokon, Vitaliano Chiarella, Simonetta Gentile, Giovanni NicolettiHiggs Meeting 14 December 2005,CERN.
particle initial preselect
ionb-tag ET
miss pT1
h0 5999 1758(29%)
572(9.5%)
526(8.8%)
464(7.7%)
A0 7000 2178(31%)
751(10.7%)
675(9.6%)
597(8.5%)
Zbb 340502* 127099(37%)
62812(18.4%)
52012(15.2%)
43100(12.6%)
tt 170110 107075(63%)
89684(52.7%)
24180(14.2%)
17928(10.5%)
ZZ 3788 1470(39%)
1042(27.5%)
885(23.3%)
690(18.2%)
*Corresponding to half luminosity
• 25 GeV<pT1 < 95 GeV
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Halina Bilokon, Vitaliano Chiarella, Simonetta Gentile, Giovanni NicolettiHiggs Meeting 14 December 2005,CERN.
After PT1 :the
2nd most energetic PT2
h0
ttbbZ→
x 0.5
20 GeV<pT 1 < 60 GeV
Ah0
tt
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Halina Bilokon, Vitaliano Chiarella, Simonetta Gentile, Giovanni NicolettiHiggs Meeting 14 December 2005,CERN.
particle initial presele
ctionb-tag ET
miss pT1 pT
2
h0 5999 1758(29%)
572(9.5%)
526(8.8%)
464(7.7%)
427
(7.1%)
A0 7000 2178(31%)
751(10.7%)
675(9.6%)
597(8.5%)
536 (7.6%)
Zbb 340502* 127099(37%)
62812(18.4%)
52012(15.2%)
43100(12.6%)
36212 (10.6%)
tt 170110 107075(63%)
89684(52%)
24180(14.2%)
17928(10.5%)
13545 (7.9%)
ZZ 3788 1470(39%)
1042(27.5%)
885(23.3%)
690(18.2%)
589
(15.5%)*Corresponding to half luminosity
• 20 GeV<pT1 < 60 GeV
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Halina Bilokon, Vitaliano Chiarella, Simonetta Gentile, Giovanni NicolettiHiggs Meeting 14 December 2005,CERN.
After PT cut:
2nd most energetic b PTb2
pT b < 40 GeV
bbZ→
x 0.5
Ah0
tt
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Halina Bilokon, Vitaliano Chiarella, Simonetta Gentile, Giovanni NicolettiHiggs Meeting 14 December 2005,CERN.
particle
initial preselection
b-tag ETmiss pT
pTb2
h0 5999 1758(29%)
572(9.5%)
526(8.8%)
427
(7.1%)
386 (6.5%)
A0 7000 2178(31%)
751(10.7%)
675(9.6%)
536 (7.6%)
492 (7.0%)
Zbb 340502*
127099(37%)
62812(18.4%)
52012(15%)
36212 (10.6%)
24067 (7.0%)
tt 170110 107075(63%)
89684(52%)
24180(14%)
13545 (7.9%)
3983 (2.3%)
ZZ 3788 1470(39%)
1042(27.5%)
885(23%)
589(15.5%)
406 (10.7%)*Corresponding to half luminosity
• pTb < 40 GeV
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Halina Bilokon, Vitaliano Chiarella, Simonetta Gentile, Giovanni NicolettiHiggs Meeting 14 December 2005,CERN.
After PTb cut:
most energetic b PTb1
pT b < 70 GeV
h0 A
x 0.5
bbZ→ tt
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Halina Bilokon, Vitaliano Chiarella, Simonetta Gentile, Giovanni NicolettiHiggs Meeting 14 December 2005,CERN.
particle
initial preselection
b-tag ETmiss pT
pTb2 pT
b1
h0 5999 1758(29%)
572(9.5%)
526(8.8%)
427
(7.1%)
386 (6.5%)
356 (6.0%)
A0 7000 2178(31%)
751(10.7%)
675(9.6%)
536 (7.6%)
492 (7.0%)
441 (6.3%)
Zbb 340502*
127099(37%)
62812(18.4%)
52012(15%)
36212 (10%)
24067 (7.0%)
20473 (6.0%)
tt 170110 107075(63%)
89684(52%)
24180(14%)
13545 (8.0%)
3983 (2.3%)
2438 (1.4%)
ZZ 3788 1470(39%)
1042(27.5%)
885(23%)
589(15.5%)
406 (10.7%)
334 (8.8%)
*Corresponding to half luminosity
• pTb < 70 GeV
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Halina Bilokon, Vitaliano Chiarella, Simonetta Gentile, Giovanni NicolettiHiggs Meeting 14 December 2005,CERN.
After tt cuts:Invariant mass distributions
bbZ→
x 0.5
h0
tt
A
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Halina Bilokon, Vitaliano Chiarella, Simonetta Gentile, Giovanni NicolettiHiggs Meeting 14 December 2005,CERN.
Mass selection window
Fit results are consistent with detector mass resolution and natural with of particle
k = -820 MeV measured at Z mass f = standard deviation fraction corresponding to chosenprobability: (e.g. f =2) Where tot
h0 =3.31 GeV totA = 4.28 GeV
m= 2.6% measured at Z mass
21
2
2
/ 36.2/0
0
m
TOT
Ah
Ahfkm
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Halina Bilokon, Vitaliano Chiarella, Simonetta Gentile, Giovanni NicolettiHiggs Meeting 14 December 2005,CERN.
Invariant mass
Fit results are consistent with detector mass resolution and natural with of particle
h0 A
bbZ→x 0.5
tt
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Halina Bilokon, Vitaliano Chiarella, Simonetta Gentile, Giovanni NicolettiHiggs Meeting 14 December 2005,CERN.
particle
initial preselection
b-tag tt cut Minv
h0 5999 1758(29%)
572(9.5%)
356 (6.0%)
245(4.0%)
A0 7000 2178(31%)
751(10.7%)
441 (6.3%)
293(4.1%)
Zbb 340502*
127099(37%)
62812(18.4%)
20473 (6.0%)
490(0.1%)
tt 170110 107075(63%)
89684(52.7%)
2438 (1.4%)
323(0.2%)
ZZ 3788 1470(39%)
1042(27.5%)
334 (88.8%)
9(0.02%)
*Corresponding to half luminosity
• |Minv|< |Mh/A± window|
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Halina Bilokon, Vitaliano Chiarella, Simonetta Gentile, Giovanni NicolettiHiggs Meeting 14 December 2005,CERN.
After invariant mass cut:isolationPT for tracks in R < 0.2
PT < 5 GeVsee Louis FloresPresentation Atlas week 28.10.05
h0
tt
PT < 5 GeV
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Halina Bilokon, Vitaliano Chiarella, Simonetta Gentile, Giovanni NicolettiHiggs Meeting 14 December 2005,CERN.
particle
initial preselection
b-tag tt cut Minv isol
h0 5999 1758(29%)
572(9.5%)
356 (6.0%)
245(4.0%)
243 (4.0%)
A0 7000 2178(31%)
751(10.7%)
441 (6.3%)
293(4.1%)
291 (4.1%)
Zbb 340502*
127099(37%)
62812(18.4%)
20473 (6.0%)
490(0.4%)
465 (0.1%)
tt 170110 107075(63%)
89684(52%)
2438 (1.4%)
323(0.3%)
306 (0.2%)
ZZ 3788 1470(39%)
1042(27.5%)
334 (8.8%)
9(0.02%)
8 (0.02%)
*Corresponding to half luminosity
• Isolation PT < 5 GeV
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Halina Bilokon, Vitaliano Chiarella, Simonetta Gentile, Giovanni NicolettiHiggs Meeting 14 December 2005,CERN.
Conclusions
The possibility for a discovery of the neutral MSSM Higgs in bb A/h0 →has been investigated in a test point of MSSM parameter space (tan, mA): mA=110.3 GeV, mh0
=109.25 GeV
A study with considering Zbb, tt, and ZZ background led to a significance
130 fbLdt
15B
S
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Halina Bilokon, Vitaliano Chiarella, Simonetta Gentile, Giovanni NicolettiHiggs Meeting 14 December 2005,CERN.
Next future Background subtraction method using
bbZ→ e+ e- sample Consider other possible discriminator variable Develop an estimator in order to approach a near possible the
Z peak Scan (tan, mA) plane
b-tag improvement (difficult)
Credit to Giovanni Nicoletti.without him this work can never done
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Halina Bilokon, Vitaliano Chiarella, Simonetta Gentile, Giovanni NicolettiHiggs Meeting 14 December 2005,CERN.
Riserve
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Halina Bilokon, Vitaliano Chiarella, Simonetta Gentile, Giovanni NicolettiHiggs Meeting 14 December 2005,CERN.
after 1 cut
x 0.5
bbZ→ bbZ→
x 0.5tt
tt
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Halina Bilokon, Vitaliano Chiarella, Simonetta Gentile, Giovanni NicolettiHiggs Meeting 14 December 2005,CERN.
Study of sample: JetsZ → + -h0→ + -
<ET gen> ~ 20 GeV <ET gen> ~ 26 GeV
Number of jets Number of jets
ET jets ET jets