Update results on use of 0 discriminator
on Hgamma gamma analysis
Z. ZHANG IHEP-Beijing
G.M Chen IHEP-Beijing
J. Tao
IHEP-Beijing
Outline
• I. Show results of last Presentation at Higgs
meeting in May
• II. Introduce 0 discriminator(Aris) which
works only on unconverted photon and our
progress on pion0 and converted photon
discrimination
• III. Apply them on signal and backgrounds,
update the results in last presentation
• IV Conclusion and outlook
I. Global relative performance improvement in
case 2 interval 120+- 5GeV for 1fb-1
channel
A) Events passing cut based
analysis with Applying
NN on unconverted
photons as Aris’ suggested.
The passing cut-based analysis
events show in parentheses
B) Events passing cutbased analysis + additional
no-pass events: Photons
with Et>25, 40GeV and
NN on unconverted
photons as Aris’ suggestion
and NN>0.05 on converted
photons.
C) Total events
Case A + additional nopass events: Photons
with Et>25, 40GeV and
NN on unconverted
photons as Aris’
suggestion and NN>0.05
on converted photons.
Signal
25.5+2.9+1.6 (31.5)
30.0+3.7+2.0
28.7+3.6+1.9
ppγγ(born)
371.7
(397.3)
437.7
412.1
pp γγ(box)
293.5
(309.4)
353.5
337.6
pp γ+jet
666.3
(793.3)
1017.7
890.7
pp jets
374.6
(444.6)
580.5
510.7
Total
1706.1
(1944.6)
2389.4
2151.1
S/sqrt(B)_
0.726
(gg, IVB,
ZWttH)
(0.713)
1.018
0.730
1.024
0.737
1.033
II. Pion0 discrimination (Aris)
II. converted photon and pion0
discrimination(our work progress )
0.77
III. Apply the two methods on
H120_ggfusion
15064
16663
 90.4%
III. Apply the two methods on
H120_WZttH&H120_ VBF
11942
13427
 88.9%
32243
35959
 89.7%
III. Apply the two methods on
jets samples
616
1090
 56.5%
S
0.904

 120%
B
0.565
III. Apply the two methods on
Gamma jet samples
13019
19803
 65.7%
S
0.904

 111.5%
B
0.657
III. Born and Box samples
35361
40339
 87.6%
S
0.904

 96.5%
B
0.876
61098
69103
 88.4%
S
0.904

 96.1%
B
0.884
Higgs mass resolution
signal and background distributions after
pi0 discrimination
S 
c1
30.0
1747
 0.717
S 
c1
27.3
1257
 0.770
The numbers of signal and background needed for the estimator of significance
derived from event counting methods Sc1  S determined in a region of +3
B
around the central of the peak. The significance increase by(0.77/0.717=107.4%)
7.4%.
Release photons’ Et threshold to
Et1>40 GeV and Et2>25GeV
Signal improvement
H120_ggfusion
19105
 1.146%
16663
Signal improvement
H120_VBF & H120_WZttH
45069
 1.253%
35959
16784
 1.250%
13427
background improvements
49783
 1.234%
40337
32769
 1.655%
19803
108789
 1.574%
69103
1815
 1.665%
1090
signal and backgrounds distribution after
applying the two discrimination methods
S 
c1
30.0
1747
 0.717
S 
c1
31.2
1594
 0.782
0.782/0.717=109.2%, so the significance increase by nearly 10%.
Global relative performance improvement
in interval 120+- 5GeV for 1fb-1
Channel
Events passing cut- Events passing cut- Events passing cutbased analysis
based analysis and based analysis and
0 discrimination
0 discrimination
Et>25.40
H120_gg
25.3
23.1
26.05
H120_VBF
3.0
2.7
3.3
H120_WZttH
1.7
1.5
1.9
Born
356
315
345
Box
250
223
252
gamma jet
738
497
660
jets
403
222
337
S/B
30.0/ 1747=0.717 27.3/ 1257=0.770 31.2/ 1594=0.783