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Investigation of the Disovery Potential for Higgs Bosons of the MSSM with ATLAS
Markus Schumacher
M. Schumacher, Discovery Potential for Higgs Bosons of the MSSM, ATLAS Physics Workshop, June 05, Roma 2
MSSM: 2 Higgs doublets 5 Bosons: 3 neutral + 2 charged
at Born level:
2 parameters tanv2/v1 and MA (or MH+)
CP conserved 2 neutral CP-even h,H + 1 CP-odd A
mass prediction: Mh < MZ (already excluded by LEP)
The MSSM Higgs Sector in the Nutshell
t b/ W/Z
h cossin -sincos sin()
H sinsin cos/cos cos()
A cot tan -----
gMSSM = gSM
no coupling of A to W/Z
small small BR(h,bb)
large large BR(h,H,A,bb)
= mixing btw. CP-even neutral Higgs bosons
M. Schumacher, Discovery Potential for Higgs Bosons of the MSSM, ATLAS Physics Workshop, June 05, Roma 3
The MSSM Higgs Sector in the Nutshell
mainly influence masses and couplings of h
phenomenology of heavy states very similar
depending on 105 additional MSSM parameters and mtop
too many „constrained“ MSSM: Xt, M0, M2, Mgluino,
mass prediction Mh < 133/136GeV (for Mt=175/178 GeV)
Born effective
benchmark scenarios: fix Xt, M0, M2, Mgluino,
goal: design difficult and challenging scenarios
e.g. low / high values of Mh, suppressed couplings
if Xt,…real Higgs sector CP-conserving h, H, A
complex Higgs sector CP-violating H1, H2, H3
large loop corrections to masses and couplings
M. Schumacher, Discovery Potential for Higgs Bosons of the MSSM, ATLAS Physics Workshop, June 05, Roma 4
MHMAX scenario maximal mh < 133/6 GeV conservative LEP exclusion
Nomixing scenario
Benchmark Scenarios
Carena et al. , Eur.Phys.J.C26,601(2003)
Gluophobic scenario Small scenario
4 CP conserving scenarios
1 CP violating scenario: CPX (Carena et al., Phys.Lett B495 155(2000))
today: discuss only MHMAX and CPX scenario
same tan/MA point:
shift of 17 GeV: MHMAX Nomix
shift in Mt ~ shift in Mh
M. Schumacher, Discovery Potential for Higgs Bosons of the MSSM, ATLAS Physics Workshop, June 05, Roma 5
Signal and Background Rates
LO with CTEQ5L (no K-factors!)
running b-quark mass for bbh(/H/A) and gbtH+
1) SM production cross sections times MSSM correction factors (FH)
2) branching ratios from FeynHiggs
3) efficiencies and background expectations from
documented ATLAS MC studies
M. Schumacher, Discovery Potential for Higgs Bosons of the MSSM, ATLAS Physics Workshop, June 05, Roma 6
4) for part of MSSM parameter space: large tot MSSM = K SM
K =
convolution of BW with Gaussian mass resolution
Corrections to Expected Signal Rates
5) signal overlap due to mass degeneracy of Higgs bosons
count signal in mass window 1
= signal 1 + signal 2 in window 1
h
M. Schumacher, Discovery Potential for Higgs Bosons of the MSSM, ATLAS Physics Workshop, June 05, Roma 7
Discovery Potential in the tanversus MA Plane
LEP tan exclusion: no exclusion for mt larger ~183 GeV !
two expected data volumes
30 fb-1
300 fb-1 = 30 fb-1@ low lumi.
+ 270fb-1 @high lumi
discovery = 5 sigma excess
using Poissonian statistics
main questions for ATLAS:
At least 1 Higgs boson observable in the entire parameter space?
How many Higgs bosons can be observed?
Can the SM be discriminated from extended Higgs sectors?
M. Schumacher, Discovery Potential for Higgs Bosons of the MSSM, ATLAS Physics Workshop, June 05, Roma 8
Discovery potential for light Higgs boson h
observation in entire parameter space ?
several channels observable?
new since February Plenary:
study effect of Mt: 175 178 GeV
of systematic uncertainty on background
For comparison of different benchmark scenarios see talk
at February plenary. Basic conlusions are the same.
M. Schumacher, Discovery Potential for Higgs Bosons of the MSSM, ATLAS Physics Workshop, June 05, Roma 9
h or H observable with 30 fb-1 over allmost whole plane
small effect due to background uncertainty
enlarged coverage for Mt=178, but weaker LEP exclusion
Vector Boson Fusion H
studied for MH>110GeV at low lumi running
effect of BG=10% effect of Mt: 175 vs 178
w/o sys BG
M. Schumacher, Discovery Potential for Higgs Bosons of the MSSM, ATLAS Physics Workshop, June 05, Roma 10
Vector Boson Fusion H WW
studied for MH>110GeV at low lumi running
small effect due to background uncertainty
enlarged coverage for Mt=178, but weaker LEP exclusion
effect of BG=10% effect of Mt: 175 vs 178
M. Schumacher, Discovery Potential for Higgs Bosons of the MSSM, ATLAS Physics Workshop, June 05, Roma 11
H ZZ 4 leptons
effect of Mt: 175 vs 178effect of BG=10%
effect due to background uncertainty decreasing with int. lumi
for Mt=178 GeV observation already possible with 30 fb-1
w/o sys BG
M. Schumacher, Discovery Potential for Higgs Bosons of the MSSM, ATLAS Physics Workshop, June 05, Roma 12
tth hbb
No discovery potential with 300 fb-1 when including BG=10%! (need cross check with 2nd statistic program and for other bechmarks)
SM
strong dependence of significance on Mh
plane covered in „No mixing“ and other scenarios
M. Schumacher, Discovery Potential for Higgs Bosons of the MSSM, ATLAS Physics Workshop, June 05, Roma 13
Light Higgs Boson h: 300 fb-1 (VBF only 30 fb-1)
large area covered by
several channels
sure discovery and
parameter determination
small area uncovered
@ mh = 90 to 100 GeV
(same conclusion in other
3 CPC scenarios)
300 fb-1
30 fb-1
previous channels + H+ bbh, H
(no BGsys,Mt=178GeV)
M. Schumacher, Discovery Potential for Higgs Bosons of the MSSM, ATLAS Physics Workshop, June 05, Roma 14
SM Higgs sector or extended one ?
observation of additional Higgs boson (H/A/H+-)
deviation of properties of h from SM prediction
No systematic uncertainties for background expectation included yet.Only Mt=175 GeV considered. Negligible effect expected forMt=178GeV.
M. Schumacher, Discovery Potential for Higgs Bosons of the MSSM, ATLAS Physics Workshop, June 05, Roma 15
Heavy Neutral Higgs Bosons
large tan
covered by
bbH/A, H/A
~ (tan)2
coverage similar in 3 other scenarios
reminder: tanexclusion depends on mtop, here 175 GeV
running b-quark mass for Xsec. QCD scale = (Mh+mb/4)
intermediate tan maybe
coverable in parts by SUSY
decays: H/A4 l+- ?
M. Schumacher, Discovery Potential for Higgs Bosons of the MSSM, ATLAS Physics Workshop, June 05, Roma 16
Charged Higgs Bosons
gbH+-t
H+-
tbqq
low mass: mH+-< mtop
ggttttH+-bWonly low lumi.
high mass: mH+-> mtop
transition region around mtop needs revised experimental analysis
running bottom quark mass used (Xsec for gbtH+- from T. Plehn‘s program)
intermediate tan maybe coverable in parts by SUSY decays:
H3 l+- ?+-
M. Schumacher, Discovery Potential for Higgs Bosons of the MSSM, ATLAS Physics Workshop, June 05, Roma 17
Overall Discovery Potential: 300 fb-1
at least one Higgs boson
over hole plane
in all four CPC scenarios
significant area where only lightest Higgs boson h is observable
questions for future studies: can SUSY decay modes
provide observation?
can SM be discriminated from
extended Higgs sector by
parameter determination?
similar results in other benchmark scenarios
VBF channels , H/Aonly used with 30fb-1
300 fb-1
M. Schumacher, Discovery Potential for Higgs Bosons of the MSSM, ATLAS Physics Workshop, June 05, Roma 18
BR(h WW) BR(h )
SM or Extended Higgs Sector ?
estimate of sensitivity from rate measurements in VBF channels (30fb-1)
R =
300 fb-1
only statistical errors
assume Mh exactly known
potential for discrimination
seems promising
needs further study incl. sys. errors
compare expected measurement of R in MSSM with prediction from SM
=|RMSSM-RSM|exp
M. Schumacher, Discovery Potential for Higgs Bosons of the MSSM, ATLAS Physics Workshop, June 05, Roma 19
The CP violating CPX scenario
maximise effect CPX scenario (Carena et al., Phys.Lett B495 155(2000))
arg(At)=arg(Ab)=arg(Mgluino)=90 degree
scan of Born level parameters: tan and MH+-
CP eigenstates h, A, H mix to mass eigenstates H1, H2, H3
CP conserving at Born level, but CP violation via complex At, Ab Mgl
M. Schumacher, Discovery Potential for Higgs Bosons of the MSSM, ATLAS Physics Workshop, June 05, Roma 20
Phenomenology in the CPX scenarioH1,H2, H3 couple to W,Z
H3
H2
H1
H2,H3 H1H1, ZH1,WW, ZZ decays
sum rule:
i gi (ZZHi)
= gSM
LHWG-Note 2004-01
no absolute limit on mass of H1 from LEP
strong dependence of excluded region
on value for mtop
on calculation used FeynHiggs vs CPH
2
2
M. Schumacher, Discovery Potential for Higgs Bosons of the MSSM, ATLAS Physics Workshop, June 05, Roma 21
CPX Scenario: Light Higgs Boson H1
border at low tan due to availability of MC studies (VBF: Mh >110 GeV, ttH and :Mh> 70 GeV)
border at low MH+- due to
decoupling of H1 from
W,Z and t
300 fb-1
main difference to CPC scenarios: weaker exclusion from LEP data
CPC scenarios: Mh< MZ excluded CPV: no limit on MH1
M. Schumacher, Discovery Potential for Higgs Bosons of the MSSM, ATLAS Physics Workshop, June 05, Roma 22
Overall Discovery potential in CPX Scenario
size of „hole“ depends on
assumed Mt due to LEP exclusion
program for calculation used
FH versus CPSUPER
MH1: < 70 GeVMH2: 105 to 120 GeVMH3: 140 to 180 GeV
small masses below 70 GeVnot yet studied in ATLAS
Small uncoverd region !300 fb-1
promising channel:
tt bH+bW- H+H1 W+ H1bb, sáme final state as ttH, Hbb
1st look at Les Houches05, ongoing Diploma thesis
M. Schumacher, Discovery Potential for Higgs Bosons of the MSSM, ATLAS Physics Workshop, June 05, Roma 23
Conclusions
Thanks to: P. Bechtle, T. Hahn, S. Heinemeyer, J.S. Lee, A. Pilaftsis, T. Plehn, D.avid Rainwater, M. Spira, G. Weiglein and ATLAS Higgs WG
CP-conserving MSSM:
probably „hole“ as Mh below 70 GeV no studied yet in ATLAS
check sensitivity ttWb H+- b,H+WH1Wbb
continue comparison of calculations and mtop dependence
whole parameter space covered by at least one Higgs boson
evaluation of discovery potenital with sys. err. in progress
only h observable at intermediate tan
ongoing studies for SUSY decay modes and
discrimination between SM and beyond via parameter meas.
CP-violating MSSM:
M. Schumacher, Discovery Potential for Higgs Bosons of the MSSM, ATLAS Physics Workshop, June 05, Roma 24
MC Studies with Discovery Potential
channel lumi mass range publication
VBF, HWW low M>110 GeV SN-ATLAS-2003-024
ttH, Hbb * low+high M>70GeV ATL-PHYS-2003-003
bbH/A low+high 70<M<135GeV
M> 120 GeV
ATL-PHYS-2002-021
ATL-PHYS-2000-005
bbH/Alep.had
had. had.
low
low
M >120 GeV
M > 450 GeV
ATL-PHYS-2000-001 ATL-PHYS-2003-009
ATL-PHYS-2003-003
WWll low+high 140<M <120GeV ATL_PHYS-2000-015
H low+high M > 70 GeV TDR
ZZ4l low+high M > 100 GeV TDR
AZhllbb, Hhhbb
low+high 60 <ML<130 100<MH<360
TDR TDR
H/Att low+high M > 350 GeV TDR
gbtH+-, H,tb low+high M >180 GeV SN-ATLAS-2002-017
ttbW bH+-, H+- low M < 170 GeV ATL-PHYS-2003-58/TDR
*ttH, Hbb at high. lumi see MSSM note