discovery potential for mssm higgs bosons with atlas johannes haller (cern) on behalf of the atlas...
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Discovery Potential for MSSM Higgs Bosons
with ATLAS
Johannes Haller (CERN)
on behalf of the ATLAS collaboration
International Europhysics Conference on High Energy Physics,July 21st-27th 2005, Lisbon, Portugal
Johannes Haller MSSM Higgs Bosons with ATLAS 2
• large loop corrections to masses and couplings
• mainly dependent on t/ t sector • parameters:
Mtop and Xt, MSUSY, M2, , Mgluino
• mass prediction Mh < 133 GeV
(for Mt = 175GeV)
• large loop corrections to masses and couplings
• mainly dependent on t/ t sector • parameters:
Mtop and Xt, MSUSY, M2, , Mgluino
• mass prediction Mh < 133 GeV
(for Mt = 175GeV)
MSSM Higgs Sector
MSSM: 2 Higgs doublets 5 physical bosons: h, H, A, H+, H-
phenomenology at Born level described by tan, m A
mass prediction: Mh < MZ
couplings: gMSSM = ξ · gSM
no coupling of A to W/Z
large tan large BR(h,H,A,bb)
MSSM: 2 Higgs doublets 5 physical bosons: h, H, A, H+, H-
phenomenology at Born level described by tan, m A
mass prediction: Mh < MZ
couplings: gMSSM = ξ · gSM
no coupling of A to W/Z
large tan large BR(h,H,A,bb)
ξ t b/ W/Zh cos/sin -sin/cos sin(-)H sin/sin cos/cos cos(-)A cot tan -----
: mixing angle between CP even Higgs bosons (calculable from tanand MA)
for exclusion bounds and discovery potential: fix the 5 parameters inbenchmark scenarios and scan (tan, MA)- plane
for exclusion bounds and discovery potential: fix the 5 parameters inbenchmark scenarios and scan (tan, MA)- plane
~
Johannes Haller MSSM Higgs Bosons with ATLAS 3
current exclusion in (tan,MA)-plane:
LEP excludes low tan and low MA region
note: no exclusion from LEP for Mt larger
~183 GeV
current exclusion in (tan,MA)-plane:
LEP excludes low tan and low MA region
note: no exclusion from LEP for Mt larger
~183 GeV
main questions for LHC/ ATLAS:
Can at least 1 Higgs be discovered in the allowed parameter space?
How many Higgs bosons can be observed ?
Can the SM be discriminated from models with extended Higgs sectors (like MSSM) ?
main questions for LHC/ ATLAS:
Can at least 1 Higgs be discovered in the allowed parameter space?
How many Higgs bosons can be observed ?
Can the SM be discriminated from models with extended Higgs sectors (like MSSM) ?
The (tan, MA)-Plane
Johannes Haller MSSM Higgs Bosons with ATLAS 4
Benchmark Scenarios
1) MHMAX scenario maximal Mh < 133 GeV
2) Nomixing scenario small Mh < 116 GeV
3) Gluophobic scenario Mh < 119 GeV • coupling of h to gluons suppressed • designed to affect discovery via
gg h, h and hZZ 4l4) Small scenario Mh < 123
GeV• coupling of h to b () suppressed
(for large tan and MA 150500GeV)• designed to affect discovery via
VBF, hand tth, hbb
1) MHMAX scenario maximal Mh < 133 GeV
2) Nomixing scenario small Mh < 116 GeV
3) Gluophobic scenario Mh < 119 GeV • coupling of h to gluons suppressed • designed to affect discovery via
gg h, h and hZZ 4l4) Small scenario Mh < 123
GeV• coupling of h to b () suppressed
(for large tan and MA 150500GeV)• designed to affect discovery via
VBF, hand tth, hbb
• 4 CP conserving scenarios considered
• to examplify the discovery potential
• mainly influence on phenomenology of h
masses, coupling and BRs calculated with FeynHiggs (Heinemeyer et
al.)
Name MSUSY (GeV)
(GeV)
M2 (GeV)
Xt (GeV)
Mgluino (GeV)
mh-max 1000 200 200 2000 800
no mixing 2000 200 200 0 800gluophobic 350 300 300 -750 500
small 800 2000 500 -1100 500
suggested by Carena et al.,EPJ C26, 601(2003)
eff. hg - coupling
hbb - coupling
already at LEP
Newly designed for hadron colliders
Johannes Haller MSSM Higgs Bosons with ATLAS 5
Technical Issues
• combination of latest results from (MSSM corrected) studies for SM Higgs boson (see talk of P.Conde) and dedicated MSSM Higgs analysis (heavy higgs states)
• key performance numbers obtained from full simulation: (e.g. trigger efficiencies, b-tagging, -
identification, mass resolutions ...)
• signal efficiencies and background expectations from fast simulations
• combination of latest results from (MSSM corrected) studies for SM Higgs boson (see talk of P.Conde) and dedicated MSSM Higgs analysis (heavy higgs states)
• key performance numbers obtained from full simulation: (e.g. trigger efficiencies, b-tagging, -
identification, mass resolutions ...)
• signal efficiencies and background expectations from fast simulations
developments/ improvements:1) new and updated search channels:
• new: VBF with Higgs decay to , WW, .• new: ttbW+bHbqq+b• updated: ttH, Hbb (better simulation of bgr.)• updated/ new: bbHHnow also had. decay
2) improved theoretical calculations:• FeynHiggs: full one-loop corrections and dominant two-
loop corrections included (increase of Mh by several GeV) considered to give most accurate calculations at present
developments/ improvements:1) new and updated search channels:
• new: VBF with Higgs decay to , WW, .• new: ttbW+bHbqq+b• updated: ttH, Hbb (better simulation of bgr.)• updated/ new: bbHHnow also had. decay
2) improved theoretical calculations:• FeynHiggs: full one-loop corrections and dominant two-
loop corrections included (increase of Mh by several GeV) considered to give most accurate calculations at present
• two expected data sets: 30 fb-1 and 300 fb-1
• discovery = 5 excess using Poisson statistics
• no systematics included
• two expected data sets: 30 fb-1 and 300 fb-1
• discovery = 5 excess using Poisson statistics
• no systematics included
LO SM prod. cross section (M. Spira) corrected with FeynHiggs
conservative!
Johannes Haller MSSM Higgs Bosons with ATLAS 6
most important channels: VBF
differences mainly due to Mh
almost entire (tan, MA)-plane covered
most important channels: VBF
differences mainly due to Mh
almost entire (tan, MA)-plane covered
Light Higgs Boson (30 fb-1)
h observable in entire parameter space and for all benchmark scenarios? h observable in entire parameter space and for all benchmark scenarios?
ATLAS (prel.)
ATLAS (prel.) ATLAS (prel.)
See talk of P. Conde for SM Higgs searches with ATLAS
Johannes Haller MSSM Higgs Bosons with ATLAS 7
hole due to reduced BR for H hole due to reduced BR for H
Light Higgs in Small Scenario (30 fb-1)
Complementarity of search channels almost guaranteesthe discovery of h
Complementarity of search channels almost guaranteesthe discovery of h
ATLAS (prel.)
ATLAS (prel.)
covered by enhanced BR to gauge bosons
Johannes Haller MSSM Higgs Bosons with ATLAS 8
Light Higgs Boson (300 fb-1)
VBF: only 30 fb-1
• also h, hZZ4 leptons, tthbb contribute • large area covered by several channels stable discovery and parameter determination possible
• small area uncovered (Mh = 90 to 100 GeV)
• also h, hZZ4 leptons, tthbb contribute • large area covered by several channels stable discovery and parameter determination possible
• small area uncovered (Mh = 90 to 100 GeV)
ATLAS (prel.)
ATLAS (prel.)
Johannes Haller MSSM Higgs Bosons with ATLAS 9
rec. mass for had.had.
Neutral Heavy Higgs Bosons (H/A)
prod ~ (tan)2; important at large tan new analysis: had. had. BR(H/A) ~ 10 % , rest is bb
prod ~ (tan)2; important at large tan new analysis: had. had. BR(H/A) ~ 10 % , rest is bb
example: bbH/A, H/A
bb H/A bb covers large tanregion
other scenarios similar intermediate tan region
not covered
bb H/A bb covers large tanregion
other scenarios similar intermediate tan region
not covered
New: take running b-quark mass for prod
30fb-1
discovery reach for H/A:
ATLAS (prel.)
ATLAS (prel.)
only very few events remain after cuts (acceptance ~10-3)
LVL1 trigger performance crucial detailed study: >90% LVL1 efficiency for
MA>450GeV via “jet+ET,miss” and “+ ET,miss” triggers with a rate of ~1.4 kHz (within rate limit)
only very few events remain after cuts (acceptance ~10-3)
LVL1 trigger performance crucial detailed study: >90% LVL1 efficiency for
MA>450GeV via “jet+ET,miss” and “+ ET,miss” triggers with a rate of ~1.4 kHz (within rate limit)
Johannes Haller MSSM Higgs Bosons with ATLAS 10
VBF channels, H/A only 30fb-1
300 fb-1
Overall Discovery Potential (300 fb-1)
ATLAS (prel.)
at least one Higgs boson is observable for all parameter points (in all four benchmark scenarios)
in some parts: >1 Higgs bosons observable
distinguish between SM and extended Higgs sector
but: significant area where only h is observable.
basic conclusions independent of mtop
at least one Higgs boson is observable for all parameter points (in all four benchmark scenarios)
in some parts: >1 Higgs bosons observable
distinguish between SM and extended Higgs sector
but: significant area where only h is observable.
basic conclusions independent of mtop
ongoing: including SUSY decay modes to increase areas for heavy
Higgs bosons , e.g. H
3l + ET,miss can SM be discriminated from extended Higgs sector by
parameter determination e.g. via rate measurements?
ongoing: including SUSY decay modes to increase areas for heavy
Higgs bosons , e.g. H
3l + ET,miss can SM be discriminated from extended Higgs sector by
parameter determination e.g. via rate measurements?
Johannes Haller MSSM Higgs Bosons with ATLAS 11
Summary
• A consistent investigation of the ATLAS discovery potential in the MSSM Higgs sector with new MC studies and new theoretical calculations has been performed.
• In all 4 CP conserving MSSM benchmark scenarios at least one Higgs boson can be discovered.
• In some areas of the parameter space more than one Higgs bosons can be discovered.
direct discrimination between SM and extended Higgs sector
• A consistent investigation of the ATLAS discovery potential in the MSSM Higgs sector with new MC studies and new theoretical calculations has been performed.
• In all 4 CP conserving MSSM benchmark scenarios at least one Higgs boson can be discovered.
• In some areas of the parameter space more than one Higgs bosons can be discovered.
direct discrimination between SM and extended Higgs sector
Johannes Haller MSSM Higgs Bosons with ATLAS 13
SM or extended Higgs Sector ?
BR(h WW) BR(h )
estimate of sensitivity from rate measurements in VBF channels (30 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 R =
ATLAS (prel.)
ATLAS (prel.)