Update on the MSSM Interpretation of

ATLAS Higgs SearchesMarkus Schumacher , Bonn University

On behalf of the ATLAS Collaboration

Physics at LHC, LHC-Praha 2003, July 2003

• Higgs Sector and 4 Benchmark Scenarios

• Observation potential for: h, A, H, H+-

• Conclusions

Markus Schumacher, University Bonn Physics at LHC, LHC-Praha 20032

The Higgs Sector of the MSSM

5 physical Higgs bosons: h, H, A, H+, H-

on Born level: 2 parameters tan, mA mass limit mh < MZ

large loop corrections mh < 133 GeV (+-3GeV) corrections depend on 5 SUSY parameters: Xt,M0,M2,Mgluino,

5 parameters fixed in 4 benchmark scenarios considered

scan performed over tan, mA

t b/ W/Z

h cossin -sincos sin()

H sinsin cos/cos cos()

A cot tan -----

high tanlarge BR(h,A,H bb,

smallsmall BR(hbb,

Couplings MSSM/SM

Markus Schumacher, University Bonn Physics at LHC, LHC-Praha 20033

The Four Benchmark Scenarios

(suggested by M.Carena et al. (hep/ph0202167), same as final LEP paper)

Influence mainly phenomenology of light Higgs boson h

1) MHMAX scenario (MSUSY=1 TeV ) maximal theoretically allowed region for mh

2) Nomixing scenario (now MSUSY= 2 TeV, 1TeV almost excluded by LEP )

small mh difficult for LHC

3) Gluophobic scenario (MSUSY=350GeV)

coupling to gluons suppressed (cancellation of top + stop loops)

small rate for gluon gluon H, Hand Z4 leptons

4) Small scenario (MSUSY = 800 GeV) coupling to b (and ) suppressed (cancellation of sbottom, gluino loops) for large tan and MA 100 to 500 GeV

Markus Schumacher, University Bonn Physics at LHC, LHC-Praha 20034

Mass of the light Higgs boson h

130GeV<Mh

120<Mh<130GeV

110<Mh<120GeV

100<Mh<110GeV

90<Mh<100GeV

Mh<90GeV

Markus Schumacher, University Bonn Physics at LHC, LHC-Praha 20035

Some Technicalities

All SM-like cross sections: leading order, no K-factors (K=1)

bottom and top pole masses used for tth, bbh and gbtH+,-

programs: HQQ,HIGLU, … (M.Spira) and xsec for gbtH+,-(T.Plehn)

Higgs masses, alpha_eff.: Feynhiggs 1.3 (S.Heinemeyer et al.)

Branching ratios: HDECAY 3.0 (M.Spira et el.)

(catch up with level of sophistication used at LEP)

decay in SUSY particles switched off for now

discovery = CLB(poisson) < 2.85x10-7 combination with likelihood ratio method (K. Cranmer, F.Cerutti)

Markus Schumacher, University Bonn Physics at LHC, LHC-Praha 20036

Light CP Even Higgs Boson h

New ! Vector Boson Fusion Channels : qqqqWWqqh

H,ZZ4l ( incl. analysis)

with hWW, (low luminosity only)

g

q

q

q

qh

ggttH

g

hbb,(WW)

Questions: observation after which int. luminosity?

which and how many channels ?

bbh(h)

See M. Vos‘ talk

ggHt

th h h

g

g

g

g

b

b

Markus Schumacher, University Bonn Physics at LHC, LHC-Praha 20037

Light Higgs boson h: 30 fb -1

bbh

VBF, h

VBF,h+WW

tthbb

WWhlbb

VBF,hWW

VBF channels

cover large part of

MSSM plane

combined

Excluded by LEP

Markus Schumacher, University Bonn Physics at LHC, LHC-Praha 20038

Light Higgs boson h: 10 fb -1

5 discovery

3observation

5 discovery

3observation

Almost no individual channel observable

need combination of all channels

Excluded by LEP

Markus Schumacher, University Bonn Physics at LHC, LHC-Praha 20039

Light Higgs boson h: 300 fb-1

All three

only B

A and B

A and C

For high lumi.: A: h B: tthbb C: hZZ4l contribute

Excluded by LEP

Markus Schumacher, University Bonn Physics at LHC, LHC-Praha 200310

h: Number of observable final states

1 channel

2 channels

3 channels

4 channels

5 channels

several channels

observable

allows parameter determination ?

300 fb-1

Excluded by LEP

Markus Schumacher, University Bonn Physics at LHC, LHC-Praha 200311

SM or MSSM ?

Direct search in the following channels:

• Heavy Neutral Higgs bosons: channels for light h + H/A , (lep.+had., had.+had., low lumi only) H/Att, Hhhbb, AZHZhhbbll, WHWWW3l3, HWWll

• Charged Higgs bosons: gbtH+- with H+-tb and one tbl ttbWbH+-blb H+- and t->bqq ttbW bH+-bqq b

(new channels since TDR, channel with extended mass range)

• Marginal differences between 4 benchmark scenarios only MHMAX scenario is shown and discussed

Direct observation of additional Higgs bosons

Discrimination via couplings of light boson h

Markus Schumacher, University Bonn Physics at LHC, LHC-Praha 200312

Heavy Neutral Bosons: H/A

VBF: H,WW

H/Att

H/Alept.had.

H/A

ttH with Hbb,WW H/A, HZZ4l, WHlbb, Hhhbb, AZHZhhbbll, WHWWW3l3, HWWll

30 fb-1H/Alept.had. +lept.lept. comb.

Excluded by LEP

Markus Schumacher, University Bonn Physics at LHC, LHC-Praha 200313

Charged Higgs Bosons

gbtH+-

H+tb,tblgbtH+- H+-

, tbqq

ttbWbH+-blb

ttbWbH+-

bqqb

Two mass regions:

i) MH < 170GeV (low lumi)

ii) MH > 180GeV

gbtH+-

top pairs

tH+- bt

tgg

bH

g t

Hb

10 fb-1

30 fb-1300 fb-1

Excluded by LEP

Markus Schumacher, University Bonn Physics at LHC, LHC-Praha 200314

How many can be seen: h,H,A,H+- ?

MHMAX scenario 300 fb-1

1 boson

2 bosons

3 bosons

All 4 bosons

h only

h,H,A,H+-

h,H,A

No holes !

Complete plane covered

h,H,A

(also in other 3 benchmark scenarios)

Excluded by LEP

Markus Schumacher, University Bonn Physics at LHC, LHC-Praha 200315

Only h seen: is it the SM or the MSSM ?

only h

> 1 Higgs boson

MHMAX scenario, 300fb-1

BR(h) BR(hWW)R =

From VBF (30 fb-1)

=(RMSSM-RSM)exp

> 2 >1

Only statistical error

2

First preliminary look

532

>1 Higgs bosonExcluded by LEP

Markus Schumacher, University Bonn Physics at LHC, LHC-Praha 200316

Conclusion

Updated interpretation of Higgs searches in 4 benchmark scenarios have been performed

Good coverage of MA-tan plane for all 4 scen., due to complementarity of search channels

New channels for h,H,A,H+- increase sensitivity

Multiple channels observable for light Higgs h hope for discrimination between SM and MSSM

Thanks for discussion and providing info and programs to

M. Spira (HDECAY,HIGLU,…), S. Heinemeyer (FeynHiggs)

T. Plehn (xsec for gbtH+-), K.Cranmer (statistics code)

especially Elzbieta R.W. +many others from the ATLAS Higgs group