Investigation of the Disovery Potential for Higgs Bosons of the MSSM with ATLAS Markus Schumacher

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


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


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


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


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


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?


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.


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


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


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


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


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)


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.


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+- ?


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+- ?+-


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


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


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


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


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


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


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:


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

Documents

Investigation of the Disovery Potential for Higgs Bosons of the MSSM with ATLAS Markus Schumacher