Sparticle reconstruction Sparticle reconstruction methods in the CMS methods in the CMS detector detector Massimiliano Chiorboli Universita’ and INFN Catania
Mar 28, 2015
Sparticle reconstruction methods Sparticle reconstruction methods in the CMS detectorin the CMS detector
Sparticle reconstruction methods Sparticle reconstruction methods in the CMS detectorin the CMS detector
Massimiliano Chiorboli
Universita’ and INFN Catania
18-20 Apr 2002Euro-GDR Meeting Massimiliano Chiorboli
OutlineOutlineOutlineOutline
Past studies on SUSY in CMS
Recent studies: sparticle recontruction
Decay chain
Sparticles reconstruction: 2200 l l++ll- - 11
0 0 dilepton edge
Sbottom recontstruction
Gluino reconstruction
measurement
Conclusions
)bM(-)gM(~~ )bM(-)gM(~~
18-20 Apr 2002Euro-GDR Meeting Massimiliano Chiorboli
Sparticle searches in CMSSparticle searches in CMSSparticle searches in CMSSparticle searches in CMS
Up to now…
Inclusive studies:
Excess over the SM
Now…
Sparticle reconstruction
18-20 Apr 2002Euro-GDR Meeting Massimiliano Chiorboli
The CMS detectorThe CMS detectorThe CMS detectorThe CMS detector
18-20 Apr 2002Euro-GDR Meeting Massimiliano Chiorboli
99.610 = LSP
186.01±145.8lR
379.72±211.4lL
186.820549qR
358.830570qL
379.140549.7bR
600.5tR522.5bL
412.5tL643.3g
Proposed Post-LEP Benchmarks for Supersymmetry Proposed Post-LEP Benchmarks for Supersymmetry (hep-ph/0106204)(hep-ph/0106204)Proposed Post-LEP Benchmarks for Supersymmetry Proposed Post-LEP Benchmarks for Supersymmetry (hep-ph/0106204)(hep-ph/0106204)
pb 41.41TOTSUSY
PYTHIA 6.152
18-20 Apr 2002Euro-GDR Meeting Massimiliano Chiorboli
Decay chainDecay chainDecay chainDecay chain
p
p
g~
b~
b
b
01
~
02
~ ~
0A
)( sign
10β tan
100m
250m
0
0
21
bb~
g~ pp
b~02
01
~
(15% bL, 10% bR)
(35 % bL, 22% bR)
(0.2 %)
01
~ ~
(60 %)
Event final state:
• 2 high pt isolated leptons OS
• 2 high pt b jets
• missing Et
18-20 Apr 2002Euro-GDR Meeting Massimiliano Chiorboli
Event productionEvent productionEvent productionEvent production
2 isolated leptons, pT>15 GeV, ||<2.4
2 b-jets, pT>20 GeV, ||<2
• PYTHIA 6.152• CMSJET 4.801: fast simulation, parametrization of
the detector
SM bkg: tt, Z+jet, W+jet, ZZ, WW, ZW
18-20 Apr 2002Euro-GDR Meeting Massimiliano Chiorboli
First step: First step: 2200 l l++ll- - 11
00First step: First step: 2200 l l++ll- - 11
00
02
~ 01
~
~p
p
g~
b~
b
b
01
~
02
~ ~
SUSY SUSY + SM
10 fb-1
)μM(μ )eM(e -
Z+jet
tt
~
2
χ~2~
2~
2
χ~max
M
)M)(MM(MM
01
02
18-20 Apr 2002Euro-GDR Meeting Massimiliano Chiorboli
)μM(μ )eM(e -
Etmiss > 50 GeV
10 fb-1
)μM(e -)μM(e - )μM(μ )eM(e --
18-20 Apr 2002Euro-GDR Meeting Massimiliano Chiorboli
Dilepton EdgeDilepton EdgeDilepton EdgeDilepton Edge
GeV 85.32 M
)M)(MM(MM
2
χ
222
χmax01
02
~
~~~~
GeV 0.91 85.48 Mmax
Fit result:
18-20 Apr 2002Euro-GDR Meeting Massimiliano Chiorboli
Sbottom reconstructionSbottom reconstructionSbottom reconstructionSbottom reconstruction
p
p
g~
b~
b
b
01
~
02
~ ~
Assuming M(10)
known!
p
M
M1p
01
02
~
~
GeV 92 M GeV 75
18-20 Apr 2002Euro-GDR Meeting Massimiliano Chiorboli
Sbottom reconstructionSbottom reconstructionSbottom reconstructionSbottom reconstruction
Etmiss > 50 GeV Et
miss > 100 GeV Etmiss > 150 GeV
I choose the most energetic b-jet
p
M
M1p
01
02
~
~MC true
18-20 Apr 2002Euro-GDR Meeting Massimiliano Chiorboli
Sbottom massSbottom massSbottom massSbottom mass
55.8
GeV 8.1516.4b)~M( 02
Result of fit:
GeV 7.549)b~
M(
GeV 5.522)b~
M(
R
L
Generated masses:
10 fb-1
18-20 Apr 2002Euro-GDR Meeting Massimiliano Chiorboli
Gluino reconstructionGluino reconstructionGluino reconstructionGluino reconstruction
p
p
g~
b~
b
b
01
~
02
~ ~
b)b~
( angle
Etmiss > 150 GeV
18-20 Apr 2002Euro-GDR Meeting Massimiliano Chiorboli
Gluino massGluino massGluino massGluino mass
9.54σ
GeV 7.2631.8bb)χ~M( 02
Result of fit:
GeV 643.3)gM( ~Generated mass:
10 fb-1
18-20 Apr 2002Euro-GDR Meeting Massimiliano Chiorboli
Combinatorial suppressionCombinatorial suppressionCombinatorial suppressionCombinatorial suppression
tt~ g~ 1
t~ b,~ (2.7%), b~ 0221
(8%)
%) (3.5t ~ b~ 11
%) (1W t~ b~ 11
t~ b,~ (2.7%), b~ 0221
%) (1.6t ~ b~ 12
%) (1.2W t~ b~ 12
t~ b,~ (2.7%), b~ 0221
GeV 60 t)t~M(-)g~M(
GeV 200 b)~M(-)t~M(
GeV 170 t)~M(-)b~
M(
GeV 20 W)t~M(-)b~
M( GeV 330 b)~M(-)b
~M( 0
2
b-jets from sbottoms of real decay chain have a harder spectrum
18-20 Apr 2002Euro-GDR Meeting Massimiliano Chiorboli
Combinatorial suppressionCombinatorial suppressionCombinatorial suppressionCombinatorial suppression
Eb-jet 1 > 250 GeV
Sbottom Gluino
10 fb-1
18-20 Apr 2002Euro-GDR Meeting Massimiliano Chiorboli
Combinatorial suppressionCombinatorial suppressionCombinatorial suppressionCombinatorial suppression
Sbottom Gluino
10 fb-1Eb-jet 1 > 250 GeV
18-20 Apr 2002Euro-GDR Meeting Massimiliano Chiorboli
Sbottom massSbottom massSbottom massSbottom mass
68.8
GeV 7.7515.9b)~M( 02
Result of fit:
GeV 7.549)b~
M(
GeV 5.522)b~
M(
R
L
Generated masses:
10 fb-1
18-20 Apr 2002Euro-GDR Meeting Massimiliano Chiorboli
Gluino massGluino massGluino massGluino mass
GeV 643.3)gM( ~Generated mass:
9.04σ
GeV 8.3639.3bb)χ~M( 02
Result of fit:10 fb-1
18-20 Apr 2002Euro-GDR Meeting Massimiliano Chiorboli
Dependence on M(Dependence on M())Dependence on M(Dependence on M())
M(10) true
M(10) = M(ll)
M(10) = M edge
p2p
M
M1p
01
02
~
~
I assumed M(10) known: we cannot detect the neutralinos!
Sbottom
Gluino
18-20 Apr 2002Euro-GDR Meeting Massimiliano Chiorboli
Realistic situationRealistic situationRealistic situationRealistic situation
Sbottom
Gluino
GeV 9.489)b~
(M M)~(M
GeV 9.515)b~
(M )true~(M)~(Mmax0
1
01
01
5%
GeV 7.619)g~(M M)~(M
GeV 3.639)g~(M )true~(M)~(Mmax0
1
01
01
3%
18-20 Apr 2002Euro-GDR Meeting Massimiliano Chiorboli
estimationestimation estimationestimation
doesn’t depend on M(10) !
)b~
M(-)g~M(
GeV 30)~M( 01
)bM(-)gM(~~ )bM(-)gM(~~
18-20 Apr 2002Euro-GDR Meeting Massimiliano Chiorboli
estimationestimation estimationestimation
6.32σ
GeV 6.387.5b)χ~M(bb)χ~M( 02
02
Result of fit:
)bM(-)gM(~~ )bM(-)gM(~~
GeV 6.93)b~
M(-)g~M(
GeV 8.120)b~
M(-)g~M(
R
L
Generated values:
10 fb-1
18-20 Apr 2002Euro-GDR Meeting Massimiliano Chiorboli
Dependence on M(ll)Dependence on M(ll)Dependence on M(ll)Dependence on M(ll)
GeV 92 M GeV 75 GeV 92 M GeV 60
GeV 92 M GeV 80
Sbottom
Gluino
18-20 Apr 2002Euro-GDR Meeting Massimiliano Chiorboli
With 60 fbWith 60 fb-1-1With 60 fbWith 60 fb-1-1
Sbottom
7.45
GeV 9.39.521b)~M( 02
GeV 88 M GeV 82
1.41σ
GeV 4.38.296bb)χ~M( 02
Gluino
18-20 Apr 2002Euro-GDR Meeting Massimiliano Chiorboli
Sbottoms separationSbottoms separationSbottoms separationSbottoms separation
1b~
2b~
38
36bb~bb~bb~
g~ ,g~q~ 01
021
bb~bb~bb~
g~ ,g~q~ 01
022
106
106
Detector resolution prevents the two sbottom separation
18-20 Apr 2002Euro-GDR Meeting Massimiliano Chiorboli
152.510 = LSP
294.51±193.4lR
546.12±299.6lL
294.820780qR
532.430814qL
545.340771.3bR
800.8tR723.0bL
589.4tL919.8g
Point GPoint GPoint GPoint G
pb 6.00TOTSUSY
18-20 Apr 2002Euro-GDR Meeting Massimiliano Chiorboli
tt~ g~ 1
t~ b,~ %), (2.7 %) (8.5 b~ 0221
(16%) (8 %)
Decay chainDecay chainDecay chainDecay chain
bb~
g~ pp
b~02
(16% bL, 10% bR)
(15 % bL, 28% bR)
01
~ ~
(8 %) (60 %)
%) (3.5 %) (7t ~ b~ 11
(1%) %) (3W t~ b~ 11
%) (1.6 %) (2.6t ~ b~ 12
%) (1.2 %) (3.2W t~ b~ 12
Less good events
More “fake” events
18-20 Apr 2002Euro-GDR Meeting Massimiliano Chiorboli
Dilepton EdgeDilepton EdgeDilepton EdgeDilepton Edge
60 fb-1
)μM(μ )eM(e -
SUSY only l
slepton l
E(ll) > 160 GeV
18-20 Apr 2002Euro-GDR Meeting Massimiliano Chiorboli
Dilepton EdgeDilepton EdgeDilepton EdgeDilepton Edge
Etmiss > 100 GeVEt
miss > 50 GeV Etmiss > 150 GeV
E(ll) > 160 GeV
18-20 Apr 2002Euro-GDR Meeting Massimiliano Chiorboli
Dilepton EdgeDilepton EdgeDilepton EdgeDilepton Edge
)μM(μ )eM(e - )μM(e -)μM(e - )μM(μ )eM(e --
E(ll) > 160 GeV Etmiss > 250 GeV
GeV 140 M GeV 105
18-20 Apr 2002Euro-GDR Meeting Massimiliano Chiorboli
Peaks reconstructionPeaks reconstructionPeaks reconstructionPeaks reconstruction
Etmiss > 250 GeV
Sbottom Gluino M(g)-M(b)
18-20 Apr 2002Euro-GDR Meeting Massimiliano Chiorboli
Peaks reconstructionPeaks reconstructionPeaks reconstructionPeaks reconstruction
Etmiss > 250 GeV Eb-jet 1 > 300 GeV
Sbottom Gluino M(g)-M(b)
18-20 Apr 2002Euro-GDR Meeting Massimiliano Chiorboli
Point G with 500 fbPoint G with 500 fb-1-1Point G with 500 fbPoint G with 500 fb-1-1
No Pile Up!
GeV 136.84 M
)M)(MM(MM
~
2
χ~2~
2~
2
χ~max01
02
GeV 2.9 138.6 Mmax
Fit result:
)μM(μ )eM(e -
)μM(e -)μM(e - )μM(μ )eM(e --
Etmiss > 250 GeV
18-20 Apr 2002Euro-GDR Meeting Massimiliano Chiorboli
Sbottom at point GSbottom at point GSbottom at point GSbottom at point G
1.51
GeV 13.5 5.738b)~M( 02
Result of fit:
GeV 3.771)b~
M(
GeV 0.723)b~
M(
R
L
Generated masses:
500 fb-1
18-20 Apr 2002Euro-GDR Meeting Massimiliano Chiorboli
Gluino at point GGluino at point GGluino at point GGluino at point G
9.54σ
GeV 10.1 2.913bb)χ~M( 02
Result of fit:
GeV 8.199)g~M(
Generated mass:
500 fb-1
18-20 Apr 2002Euro-GDR Meeting Massimiliano Chiorboli
at point Gat point G at point Gat point G
2.30σ
GeV 6.6175.2b)χ~M(bb)χ~M( 02
02
Result of fit:
GeV 5.148)b~
M(-)g~M(
GeV 8.196)b~
M(-)g~M(
R
L
Generated values:
)bM(-)gM(~~ )bM(-)gM(~~
500 fb-1
18-20 Apr 2002Euro-GDR Meeting Massimiliano Chiorboli
ConclusionsConclusionsConclusionsConclusions
• estimation of M(l+l-)max
• sbottom reconstruction with Resol. ~ 13 %, but 2 sbottoms not resolved
• gluino reconstruction with Resol. 6 %
• M(g) - M(b) estimation, independent of M(10), with Err ~ 4 %
Point B (tan =10, low masses), with 10 fb-1
~2~
2~
2~
2~ M)MM)(MM( 0
102
In some mSUGRA regions CMS will be able to obtain information about the mass spectrum of sparticles from dilepton edges and to reconstruct some sparticles mass peaks:
18-20 Apr 2002Euro-GDR Meeting Massimiliano Chiorboli
ConclusionsConclusionsConclusionsConclusions
Point G (tan =20, higher masses), with 500 fb-1
• estimation of M(l+l-)max
• sbottom reconstruction with Resol. ~ 7%
• gluino reconstruction with Resol. 6 %
• M(g) - M(b) estimation, independent of M(10), with Err ~ 4 %
~2~
2~
2~
2~ M)MM)(MM( 0
102