MSSM Higgs Bosons decaying in SUSY cascade with ATLAS
description
Transcript of MSSM Higgs Bosons decaying in SUSY cascade with ATLAS
Simonetta Gentile, Charged Higgs, 2008,Uppsala, Sweden.
MSSM Higgs Bosons decaying in SUSY
cascade with ATLAS
Simonetta Gentile Università di Roma, La Sapienza, INFN
on Behalf of ATLAS Collaboration
Simonetta Gentile, Charged Higgs, 2008,Uppsala, Sweden.
OutlineMotivationMSSM Higgs in SUSY cascade search
limits at LHCBench mark pointsDetection MSSM Higgs in ATLASAnalysis: first results on neutral & charged
Higgs discovery potentialConclusionsThe results presented are preliminary.
Simonetta Gentile, Charged Higgs, 2008,Uppsala, Sweden.
SUSY & Higgs interplayIf SUSY kinematically accessible, then real production of
sparticles.
Higgs can decay directly to or come from decay of SUSY particles
Associated production modes: e.g, squark-squark-Higgs SUSY particles suppress or enhance loop induced
production or decays Higgs into sparticle decay modes can compete with SM modes:
H/A →0
202→ 4 ± X
H± →±
1→ 3 ± X
[1] ATLAS Coll., ATLAS detector and Physics Perfomance, Vol.2 p766[2] F. Moortgat, S. Abdullin, D. Denegri”. hep-ph/0112046[3] M.Bisset, F. Moortgat and S. Moretti “Eur.Phys.J.C30:419-434,2003.[4] C. Hansen, N. Gollub, K. Assamagan, T. Ekelof Eur.Phys.J.C44S2:1-9,2005.
[5] CMS Coll., CMS detector and Physics Perfomance, Vol.1
Pioneering papers:
Simonetta Gentile, Charged Higgs, 2008,Uppsala, Sweden.
Signature
4 isolated leptons (e,)+ ET miss
powerful signature against theSM + SUSY backgrounds at LHC
Assume a classical production Mechanism
Decays
Simonetta Gentile, Charged Higgs, 2008,Uppsala, Sweden.
A/H susy decaysA,H →
2,3,4 0
2,3,4→4 ±+ Emiss T
A,H →+2-
1,2 →4 ±+ Emiss T
M.Bisset,N.Kersting,F.Moortgat,S.Moretti,arXi:0709.10029[hep –ph]
=eμ
(pp →H/A) Br(A,H →4 ±+N)
tan = 20 MA=500GeV
M2[
GeV
]
[GEV]
202
0
3,403,4
0
Simonetta Gentile, Charged Higgs, 2008,Uppsala, Sweden.
Search in a LHC detector
Representive points studied: MSSM representative Points MSugra representative Points
Discovery potential in a typical LCH detector investigated with this selections:
4 leptons > 7.4 GeV
lepton Isolation 2pairs of opposite sign |MZ ±10 GeV| veto GeV
< 80 GeV
jet < 50 GeV
Point A M0=125 GeV tan=20Point B M0=400 GeV tan=20M½=165GeV sign()=+1 A0=0
Simonetta Gentile, Charged Higgs, 2008,Uppsala, Sweden.
Reach for MSSM Higgs bosons in 0
2,3,402,3,4or 1,2
+2- pairs
Point 1 MA=500 GeV tan=20M1=90GeV M2=180 GeV =-500GeVMl=M= 250GeV mg=Mq=1000GeV
Point 2 MA=600 GeV tan=35M1=100GeV M2=200 GeV =-200GeVMl=150GeVM= 250GeV mg=800GeV Mq=1000GeV
M.Bisset,N.Kersting,F.Moortgat,S.Moretti,arXi:0709.10029[hep –ph]
Simonetta Gentile, Charged Higgs, 2008,Uppsala, Sweden.
Choice of Bench mark points
mtop= 175 GeV mb= 4.25 GeV tan β= 10 mA= 500 GeV Msquark= 1 TeV Atau= 0 Aℓ= 0 mℓ=mτsoft= 250 GeV
“High” branching ratio in
02,3,4
“High” branching ratio in0
2 → 01 + -
To choose representative points in the search A/H→i
0i0→ 4
The following characteristics
Simonetta Gentile, Charged Higgs, 2008,Uppsala, Sweden.
Branching ratio
M2 = 180 GeV = -500 GeV
Point1
M2 = 200 GeV = -200 GeV
Point2 Point2
<0
Simonetta Gentile, Charged Higgs, 2008,Uppsala, Sweden.
Br( 2
0 →
10 2
)
Br( 2
0 →
10 2
)
Br(
A/H
→ 2
0 20 )
Br(
A/H
→ 2
0 20 )
A/H→202
0→101
0 4 negative
Simonetta Gentile, Charged Higgs, 2008,Uppsala, Sweden.
Sample of events
~
~,~
Standard Model Background•bbZ → 4 • tt → 4 •ZZ → 4
Reference points: ( same BKMM)1) MSSM Point 1 MA=500 GeV tan=202) MSSM Point 2 MA=600 GeV tan=353) MSUGRA Point A tan=204) MSUGRA Point B tan=20
Signal H → 4 A → 4
MSSM Background
• → 4
..
~~/~,~~
~,~
~,~
cctH
gq
gq
Simonetta Gentile, Charged Higgs, 2008,Uppsala, Sweden.
Point 1 [GeV]
Point 2 [GeV]
Point A [GeV]
Point B [GeV]
MA 500.0 600.0 257.4 439.5
MH 503.4 603.9 259.1 442.5
89.7 93.9 61.1 62.3
176.3 155.5 109.4 111.9
507.0 211.9 235.9 241.9
511.0 262.6 259.8 265.4
176.3 153.1 108.7 111.6
514.0 263.6 260.2 265.9
01
~02
~03
~04
~
1~
2
~
MSSM particle masses
Simonetta Gentile, Charged Higgs, 2008,Uppsala, Sweden.
ATLAS detector response has been full simulated taking into account the effetcts of energy loss, multiple scattering and showering in the detector through ATHENA interface.
SM background cross section , as signal are considered at LO approximation
Study at Lint =300 fb-1 scenario .( → Lint =100 fb-1 ) The statistics used corrisponds to AT LEAST this
luminosity. In some delicate points the statistics is increased up a factor 2, with exception tt background.
Simulation & reconstruction in ATLAS detector
Simonetta Gentile, Charged Higgs, 2008,Uppsala, Sweden.
Muons
For A Sample in events A/H→2
020→ .......
preliminary
preliminary
preliminary
Simonetta Gentile, Charged Higgs, 2008,Uppsala, Sweden.
Electrons & E Tmiss
For A Sample in events A/H→2
020→ e...... preliminary
preliminarypreliminary
preliminary
Simonetta Gentile, Charged Higgs, 2008,Uppsala, Sweden.
ZZ and tt samplepreliminary
preliminary
preliminary
Simonetta Gentile, Charged Higgs, 2008,Uppsala, Sweden.
Selection 1 part
Preselection cuts: Trigger one:1 electron isolated E > 22 GeV or a isolated > 20 GeV (120i or 1e22i)pT
> 5GeVIsolation pT< 6 GeV in cone R=0.2Medium electron definition considered
Selection Lepton pair charge and flavour constrains 1
-1+2 2
+
Generation Event Filter: 4 → and || < 2.7, pT > 5GeV
reconstru
ction
Simonetta Gentile, Charged Higgs, 2008,Uppsala, Sweden.
Selection 2 part
~~/~,~~
~,~
gq
gq
~~/~,~~
~,~
gq
gq ~,~
Selection cuts:Impact significance parameter for 4 and e > 6pT
1 > 8 GeV 35 GeV< ET
miss < 130 GeVZ veto : |Minv (+ -) –Mz| > 6 GeV
Zbb, ZZ
1st high energy lepton pT1, 2nd high energy lepton pT
2 25 GeV < pT
1 < 110 GeV pT
1 < 100 GeV and pT2 > 60 GeV
pT2 > 60 GeV ( only Set2 & SetA)
tt
PTMin > 20 GeV
Njet 5 PTjet >20 GeV (with 1 track)
Minv (+ - + -) < 125 GeV (SetA)
~~/~,~~
~,~
gq
Simonetta Gentile, Charged Higgs, 2008,Uppsala, Sweden.
Reference Point 1 Sample Particle e
[pb]
BR4lepNev
(300 fb-1)
Sample
Used
00)
N Sel
(300 fb-1)
A 1.18 0.0051 1800 2250
30
H 1.16 0.0049 1700 2500
14
Zbb 60.5 0.00942 171000 44500 2
tt 500 0.00728 1092000 570555 82
ZZ 0.21 0.219* 13500 115700 10
1.49 0.034 15000 17000 1
0.15 0.15 1100 1500 44
2.97 0.019 1700 2500 7
0.136 0.0078 315 500 0
SM
MS
SM
Back
SIG
NA
L
* x br without box diagram 34.8 fb (weight 1.49)
..
~~/~,~~
~,~
~,~
cctH
gq
gq
Simonetta Gentile, Charged Higgs, 2008,Uppsala, Sweden.
Set1:Cross Section & Br A,H
Br4
( || < 2.5, pT > 5GeV) x Br 4
A A A
H H H
preliminary preliminary preliminary
Simonetta Gentile, Charged Higgs, 2008,Uppsala, Sweden.
Background effective cross section x Br 4
x Br 4
x Br 4
x Br 4
gq ~,~~,~
~~/~,~~ gq..cctH
preliminary preliminary
Simonetta Gentile, Charged Higgs, 2008,Uppsala, Sweden.
Set 1-MSSM Background
..
~~/~,~~
~,~
~,~
cctH
gq
gq
x Br 4 not depending from MA, as
expected. The events processed at each tan at MA= 500 GeV are used.
tH events studied at each point (tan,MA)
Explored region:
•tan 5,8 and 10-40 step 5•MA 375-900 GeVstep 25 GeV
Simonetta Gentile, Charged Higgs, 2008,Uppsala, Sweden.
Set 1 Discovery plots at L = 300 fb-1
02
02
~~ 0
20
2~~
preliminary preliminary
Simonetta Gentile, Charged Higgs, 2008,Uppsala, Sweden.
Set 1 Discovery plots at L = 100 fb-1
02
02
~~ The discovery region for A/H→2
020→4 + ET
miss
can be accessible only after L=300fb-1.
No clear discovery possibilty at lower luminosity
The background are mainly ZZ and slepton pair and tt pair.
preliminary
Simonetta Gentile, Charged Higgs, 2008,Uppsala, Sweden.
Set 2 :Cross Section & Br A,H
Br4
( || < 2.5, pT > 5GeV) x Br 4
A A A
H H H
preliminary preliminary preliminary
Simonetta Gentile, Charged Higgs, 2008,Uppsala, Sweden.
Background effective cross section
• low tan regionSignal dominated A→2
020
tH background not anymore neglegible LL background neglegible
x Br 4
..cctH A
H
x Br 4
x Br 4
tan =3
tan =3
preliminary
preliminary
preliminary
Explored region:•Tan 3 and 5-50 step 5•MA 375-900 GeVstep 25 GeV
Simonetta Gentile, Charged Higgs, 2008,Uppsala, Sweden.
Set2 Discovery plots at L = 300 fb-1
02
02
~~ 043
0 ~~ 043
0 ~~ 0
20
2~~
preliminary preliminary
Simonetta Gentile, Charged Higgs, 2008,Uppsala, Sweden.
Set2 Discovery plots at L = 100 fb-1
02
02
~~ 043
0 ~~ 0
20
2~~ 0
430 ~~
preliminary preliminary
Simonetta Gentile, Charged Higgs, 2008,Uppsala, Sweden.
Conclusion of Set2The detection region ofA/H→0
2,3,4 02,3,4→4 + ET
miss
andA,H →+
2 -1,2 →4 ±+ E T
miss
is accessible also with L=100fb-1.The remaing background are mainly ZZ and tt pair,
direct tH± production is not neglegible.
Preliminary study also on MSUGRA has been performed, SetA, In this scenario the copious background is tt pair
The point at MA= 257 GeV and tan = 20
has been studied . The significance achieved is after L =300fb-1 is 5 .
~~/~,~~,~,~
gq
Simonetta Gentile, Charged Higgs, 2008,Uppsala, Sweden.
Charged Higgs involvement
Final state: Only 3 lepton +another lepton from a top decay
Is not the best final state for a dedicated H- search…..
Simonetta Gentile, Charged Higgs, 2008,Uppsala, Sweden.
Charged Higgs role
The range of discovery is enlarged, extending the search to all MSSM Higgs(H/A/H±) respect to neutral H/A..
preliminary
Simonetta Gentile, Charged Higgs, 2008,Uppsala, Sweden.
Charged Higgs role
The range of discovery is enlarged, extending the search to all MSSM Higgs(H/A/H±) respect to neutral H/A..
preliminary preliminary
Simonetta Gentile, Charged Higgs, 2008,Uppsala, Sweden.
Conclusion Discover potential study in MSSM neutral Higgs boson, A/H→
4 + ETmiss in ATLAS has provided the first results.
A scan in (MA,tan plane with the the points dominated by 2
020 decays (Set1) and 2,3
02,3,40
decays (Set2) has been performed using full simulation of ATLAS detector
With Set1 parameters the possibilty of discovery of neutral MSSM Higgs are after L=300 fb-1,
With Set 2 the perspective are more encouraging even with L=100fb-1
The inclusion of charged Higgs decay extends the possibility of discovery a MSSM Higgs even with L=100fb-1.
I would like to thank Stefano Moretti and Filip Mortgart for discussions and informations.
Many thanks to Karl Jakobs , who coming back from Uppsala2006 suggested me this interesting topic. MANY THANKS to JUNICHI TANAKA