Discovery Potential for MSSM Higgs Bosons with ATLAS

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

~


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


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


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!


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


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


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.)


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)


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?


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


Back-up slides


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.)


Charged Higgs Bosons

Documents

Discovery Potential for MSSM Higgs Bosons with ATLAS