R' Kinnunen

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SUSY Higgs Searches at the LHC
Supersymmetry at the LHC Theoretical and
Experimental Perspectives British University in
Egypt, Cairo, 11-14 Mars, 2007

• R. Kinnunen

Helsinki Institute of Physics
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Latest EW data favour heavy SUSY
Mt 171.4 GeV MW 80.398 GeV
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Parameters and scenarios for studies in
CPconserving SUSY
Five Higgs bosons (CP-eigenstates) h, H, A, H,
mh lt mZ At tree level two parameters mA and
tanb vu/vd
SUSY parameters entering to the predictions (in
addition to mA and tanb) M2 SU(2), U(1)
gaugino mass terms unified at MGUT Msusy
sfermion mass terms unified at MEW Mg, m
gluino mass and Higgs mixing parameter Xt
mixing parameter in the stop sector, Xt At - ?
cot?, At unified squark trilinear
coupling at MEW
Scenarios mhmax M2 200 GeV/c2, Mgluino
800 GeV/c2, Msusy 1 TeV/c2 m
and X chosen to maximise mh No mixing X 0,
large values of M2, Mgluino , Msusy , small mh
Gluophobic scenario gg?h strongly
suppressed, large mixing, light stop Small ?eff
Brh(bb, ??) suppressed at large tan?, moderate mA
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Mass of the lighter scalar Higgs boson h
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Constraints from LEP searches
mtop174.3 GeV, 95 CL limits mhmax senario mh
gt 92.8 GeV, mA gt 93.4 GeV,insensitive to mtop
tan? exclusion
0.7 2.0, sensitive to mtop No mixing scenario
mh, mA gt 93.6 GeV (tan?gt0.7)
tan? exclusion 0.4 10.2
(mAgt3GeV) very sensitive to mtop scenario
fully excluded at mtop169.3 GeV
mt 169.3 174.3 179.3 183.0
High tanb area for search at LHC with pp-gtbbf
(fh, H, A) and f-gtmm, tt decays
Low tanb is not completely excluded search for
LHC with pp-gtA A-gtZh, gg, tt
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Production of the neutral MSSM Higgs bosons
Xt61/2MS (mhmax scenario), MS2TeV, mt178 GeV,
mb(mb)4.9 GeV NLO QCD corrections for all
channels, but ttF, bbF mRmF1/2(MF2mt) for ttF
and ¼(MF2mb) for bbF. NLO MRST set of PDF
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Discovery potential for the lighter scalar
MSSM Higgs boson
The LEP exclusion for tanb constrains h to be
mostly SM like -gt discovery potential from
the SM Higgs boson studies in mH lt 130 GeV
In the Gluophobic scenario gg-gt h -gt gg
suppressed, no discovery with inclusive h-gtgg for
mstop lt 300 GeV/c2
Isorate contours for mstop 200 GeV/c2, large
mixing
need 40-50 fb for a 5s-discovery in CMS
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Light Higgs Boson h in ATLAS 30 fb-1
observable channels VBF bbh h?mm tth
h?bb

• difference mainly due to
• different mh in same (tanb,MA) point
• ( up to 17 GeV difference)

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Small a scenario for h in ATLAS 30 fb-1
hole due to reduced branching ratio for H ? tt

• covered by enhanced BR to gauge bosons
• complementarity of search channels
• almost gurantees observation of h

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Light Higgs Boson h in ATLAS with 300 fb-1
(VBF only 30 fb-1)

• also h?gg, h?ZZ?4 leptons, tth?bb contribute
• large area covered by several channels
• ? sure discovery and parameter determination
  possible
• small area uncovered _at_ mh 90 to 100 GeV
• h?gg sensitive in gluophobic scenario due to Wh,
  tth production

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Heavy neutral MSSM Higgs bosons
Branching fractions and search channels
Large tanb (gt 10) H,A -gt tt -gt 2 leptons,
leptons jet, 2 jets H,A -gt mm H,A -gt
bb searches is associated bbH/A production
Small tanb H -gt Zh-gtllbb H,A -gt c20c20 -gt 4
leptons H,A -gt tt H-gtZZ/ZZ-gt4 leptons H -gt
hh-gtggbb
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Tevatron 2007 serches for MSSM Higgs -gt tt
MA-tanb exclusion region in MSSM no mix./mhmax
scenarios
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H/A -gt mm in gg -gt bbH/A production
Small branching fraction, BR(H -gt mm) 10-4 but
good mass resolution, 1.2
Backgrounds from Z,g-gtmm, tt
Background suppression with - b tagging
(Z,g-gtmm background) - central jet veto (tt
background)
Good mass resolution yields sensitivity to GH -gt
indirect measurement of tanb exploiting the GH
tan2q dependence
5s discovery region
without systematic uncertainties
s gt5, successfull background fit required
Dtanb 40 10 for tanb 30 50 at mA 160
GeV, including 15 theoretical uncertainty
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H/A -gt tt decay channels in gg-gtbbH/A production
Backgrounds Z,g-gt tt, Z,g-gtll, tt, Wt,
Wjets, bb, QCD multi-jet events

• Basic t identification
• isolation of a small signal cone (DR 0.3-0.4)
• one or three tracks in the signal cone
• high pT cut for the leading track (pT 35-40
  GeV)
• Addional identification methods
• - t mass measurement
• - track impact parameter measurement or
• vertex reconstruction for 3-prong t decays

• Further event selection
• - tagging an associated b jet to suppress Z/g
  and QCD backgrounds
• veto on extra central jets, to suppress tt
  background
• Higgs boson mass reconstruction
• with collinear neutrino approximation

Signed full recoconstructed flight path in mm

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H/A-gttt final states

• Leptonic (em) and semi-leptonic (mt jet and
  et jet) final states
• trigger through lepton(s)
• - Fully hadronic final state Double t trigger
  at the HLT with calorimeter
• and tracker isolation and pT cuts

Fully hadronic H/A -gt tt -gt 2 jets
e t jet
m t jet
backgrounds from Z,g ? ee-, bbZ,g ? ee- and
QCD multi-jet events
QCD multi-jet background dominates, challenging
search!
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5s discovery potential for the heavy neutral
MSSM Higgs bosons
CMS full simulation
SUSY corrections in the b/b sector and decays
to gauginos -gt variation of the discovery
region as a fuction of m

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ATLAS Heavy Neutral Higgs Bosons
large tanb covered by bbH/A, H/A?tt,mm s
(tanb)2

• running b-quark mass for Xsec.
• new tt?had had for MA gt450GeV

• reminder tanb exclusion depends on mtop
• coverage similar in 3 other scenarios

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Determination of tanb with the bbH/A channels
Cross section (and width) exhibits a large
sensitivity to tan(b) and thus can add a
significant observable to a global fit of the
SUSY parameters
Uncertainty for tanb measurement from direct
width measurement in the H/A-gtmm decay channel
in CMS
Uncertainty for tanb determination from
measurement of event rates in the H/A-gttt decay
channels in CMS
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Access to low tanb
A-gtZh, Z-gtll, h-gtbb
A/H-gtc20c20-gt4l ETmiss
Zjets
tt
Point in mSUGRA tanb 5, mo 50 GeV, m1/2
150 GeV, A0 0, sign(m)
Zbb
Signal
Sensitivity to m and M2
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Higgs boson searches in SUSY cascades with
gluino -gtqq, q-gtqc02 , c02 -gt hc01, h-gtbb


Main backgrounds from tt events and multi-jet
SUSY production Event selection 4 hard jets,
large ETmis, 2 b jets
Hemisphere separation method to reduce jet
association problem exploiting angles and
invariant masses
Reach in mSUGRA
Reach in MSSM in SUSY cascades mA gt 200 GeV for
A and H
Higgs boson mass reconstruction and background
extraction from fit
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Charged MSSM Higgs bosons

• Only few possiblities to discover the charged
  Higgs bosons
• - H -gt tn
• - H-gt tb difficult due to multijet backgrounds
• H -gt c0c medium tanb values in a part of
  parameter space
• - H -gt Wh, low tanb

The H-gttn decay channel can be used 1. for
mH lt mtop in tt events through t-gtbH
2. for mH gt mtop , in associated production
with top gb -gt tH and
gg(qq) -gt tbH
Advantage of the H-gttn decay channel Due to
helicity correlations harder leading pion from H
-gttn than from W-gttn can be exploited with the
cut pleading track / Et gt 0.8 for efficient
suppression of tt and W3jet backgrounds For t -gt
p p pn decay mode (10) a selection with
ppp(same sign pair) / Et lt 0.4 or ppp(same sign
pair) / Et gt 0.8 can be used
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Exclusion regions for charged Higgs bosons from
LEP and Tevatron
LEP direct search, 2001
Tevatron, CDF search, 2005
Tevatron, D0 2001
H-gttn in tt events
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Search for light charged Higgs bosons in gg -gt
tt -gt WHbb-gtlntnbb, l e or m
Leptonic trigger from the opposite side top,
t-gtlnb An excess of events is searched for over
the SM expectation
Backgrounds tt and W3 jet production
t helicity correlations in H -gttn and W -gttn
Discovery almost up to the kinematical limit mH
lt mtop - mb
Particle level study
Full simulation
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H -gt tn in the associated production with
fully hadronic final state

• Trigger with single t jet and missing ET
• Backgrounds tt, W3jets, QCD multi-jet
  production
• t identification exploiting polarization
• Isolation of the signal cone and a very hard
  leading track with
• pleading track / Et gt 0.8
• Further event selections
• Large missing ET
• Top mass reconstruction and
• tagging the b jet from t-gtbqq

Advantages of the fully hadronic channel missing
ET originates from transverse Higgs boson mass
mT(t jet,ETmis) can be reconstructed
An almost background-free signal can be reached
in the signal area defined by Df(t jet, ETmiss)
gt 60o or by mT(t jet, ETmiss) gt 100 GeV
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Discovery potential for charged Higgs bosons
No H Observability in the H -gttb decay at
low luminosity due to difficult jet
association and systematics
CMS full simulation
H -gttb decay
Study with full simulation with 3 or 4 tagged b
jets
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ATLAS reach for Charged Higgs Bosons
high mass mH-gt mtop
gb?H-t H-?tn t?bqq
low mass mH-lt mtop gg?tt tt?H-bW only low lumi
new W?qq H-?tn

• transition region around mtop
• needs revised experimental analysis
• running bottom quark mass used
• Xsec for gb?tH- from T. Plehns program

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Can MSSM be distinguished from SM in the area of
only light Higgs
discovery ?
discrepancy from the SM for light h
M. Duhrssen et al.,hep-ph/04063232
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SM or Extended Higgs Sector ?

• estimate of sensitivity from rate measurements in
  VBF channels (30fb-1)
• compare expected measurement of R in MSSM with
  prediction from SM

BR(H-gtWW) BR(H-gttt)
DRMSSM-RSM/sexp
R
potential for discrimination seems promising,
needs further study incl. sys. errors
only statistical errors, assume Mh exactly known
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Higgs searches in CP-violating MSSM scenarios
In CPV CP eigenstates h, A, H mix to mass
eigenstates H1, H2, H3 mH1 lt mH2 lt mH3 Tree
level parameters tan?, mH?
the MSSM parameters M2, Mgluino ,Msusy, m, X
two CPV phases arg(At,b) and arg(Mg)
Maximised CPV effect ? CPX scenario
arg(At)arg(Ab)arg(Mgluino)90o

• Phenomenology in the CPX scenario
• - H1, H2 and H3 may be produced in
• VBF, WH and ZH processes
• - decay to pair of W/Zs, pair of
• Higgs bosons, HZ bosons

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LEP exclusion for h1 in CPX
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ATLAS studies for CPX Scenario Light Higgs
Boson H1
300 fb-1

• border at low tanb due to
• availability of MC studies
• (VBF Mh gt110 GeV,
• ttH and gg Mh gt 70 GeV)
• border at low MH- due to
• decoupling of H1 from W,Z and t

main difference to CPC scenarios weaker
exclusion from LEP data CPC scenarios Mhlt MZ
excluded CPV no limit on MH1
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CPX Scenario Overall Discovery Potential
300 fb-1
H2/3 ? tt, 30fb-1
H2/3 ? mm 30fb-1
H2/3 ? mm 300fb-1

• FeynHiggs with Mt175 GeV
• OPAL exclusion for Mt174.3GeV
• small uncovered area at low MH-

MH1 lt 70 GeV MH2 105 to 120 GeV MH3 140 to
180 GeV
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Conclusions

• Latest full simulation results from CMS in CP
  conserving real MSSM
• for 30 fb-1, including systematics and pile-up
• Almost full plane covered with inclusive h-gtgg
  and qqh,h-gttt-gtljet (WBF)
• Realistic simulation and systematics has
  affected the expectations
• for the heavy MSSM Higgs bosons with A/H-gttt ,
  H-gttn and H-gt tb
• but discovery reach still large
• ATLAS has tested all 4 benchmark LHC scenarios
  for 30 and 300 fb-1
• and find entire parameter space covered for all
  scenarios
• - Full coverage obtained in the WBF channels with
  h-gttt and h-gtWW
• Preliminary resuts from ATLAS for CP-violating
  MSSM
• - probably a hole remains where no observation
  possible even for 300 fb-1
• In all scenarios a significant area remains where
  only the lightest Higgs
• boson observable
• - can be distinguished from the SM Higgs for mh
  lt 200-300 GeV