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MSSM HiggsMSSM Higgs in in ATLASATLAS

Bill Murray, November 2001

ATLAS

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Talk OverviewTalk Overview

Introduction to MSSM HiggsWhat restrictions do we know?ATLAS benchmarksBeyond the benchmarkConclusions

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Basics of SUSY HiggsBasics of SUSY Higgs

5 Higgses: h, A, H, H+ and H-

Mass relations:

So MA and (or tan fix 5 masses (at tree level….)

222

2222

22222222

,

0

0 2cos42

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WAH

ZAHh

ZAZAZAhH

MMM

MMMM

MMMMMMM Tre

e

level

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Masses of SUSY Masses of SUSY HiggsesHiggses

Mh

MH+

MHLEP limit

MA

Lo

g t

an

Maximal

mixing

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Couplings of SUSY HiggsCouplings of SUSY Higgst b,, W,Z

h0 cos/sin -sin/cos sin( )

H0 sin/sin cos/cos cos( )

A0 -i5 cot -i5 tan 0

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2tan2tanZA

ZA

MM

MM is the h,H mixing

h decouples for large MA

Tree

level

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Couplings of the h to t and ZCouplings of the h to t and Z

h-Z coupling

h-top coupling

SM like for MA>150 Drops for MA<150

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Coupling of the h to the b/Coupling of the h to the b///

Enhanced for low MA and high tan .

i.e. when the top and Z couplings decrease

Gives h radiation off b quarks.

Can be used at Tevatron as well as

LHC...

h-bottom coupling

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Coupling of H to the b/Coupling of H to the b///and tand t

Enhanced at high tan for

mH>125GeVH-bottom coupling

H-top coupling

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Coupling of the A to the b/Coupling of the A to the b///

Enhanced for any large tan

Careful - the A width also increases….

A-bottom coupling

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Existing LimitsExisting Limits

LEP `benchmark’ scenarios– No mixing– Maximal mixing Least restrictive– large

Maximal Mixing has:

MSUSY=1TeV, M2=200GeV, =-200GeV, mgluino=800GeV, Xt=2MSUSY

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Maximal Maximal Mixing Mixing LimitLimit

Allowing MSSM scans (e.g. h00

decays) makes less than 1GeV

difference in limit

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Limits on mLimits on mAA, tan, tan - large - large Two parameters:

tan, MA

held to 1TeV

Regions of reduced Higgs to b coupling

Probably LEP will exclude this scenario

eventually

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MSSM regions surviving LEPMSSM regions surviving LEP

•A heavy: Decoupling region.

The h looks like the SM Higgs, mass below 130GeV

The A/H/H+ become quasi -degenerate in Mass

Mass scale NOT KNOWN

•A light, tan large.

The h may be hard to find

… but couples to down type (b,,)

The A/H/H+ become light and relatively easy to see

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What if there was a Higgs at What if there was a Higgs at 115?115?

•Essentially the whole unexcluded MSSM plane allows for a CP even Higgs at 115, depending upon loops….

No guidance here!

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Tevatron PotentialTevatron Potential•Can find h if we are in decoupling (heavy A) region, luminosity arrives, and mh<120

•For High tan , see:

Significant chance of 1 Higgs

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Signatures in ATLASSignatures in ATLAS•All SM channels relevant (h, tthttbb, HZZ)

•If A heavy, h behaves like SM Higgs (de-coupling)

•H may appear in SM channels

•Decays assuming super-partners too heavy :

A, , tt, H hh, H+tb, cs, t H+bcsb

•May also have:

h

,h

sparticles

Zoo of possible signatures, model dependent (h OK)

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Higgs from Weak Boson Fusion

Motivation: •Additional potential for Higgs boson discovery•Important for the measurement of Higgs boson parameters (couplings to bosons, fermions (taus), total width) •Detection of an invisible Higgs

proposed by D.Zeppenfeld et al. (several papers...)

= 4 pb (20% of total cross section for mH = 120 GeV) however: distinctive signature of - two high PT forward jets - little jet activity in the central region

Relevant to MSSM

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qqH qq WW qq l l - PYTHIA Signal and background simulations- El.weak backgrounds (t-channel vector boson exchange from matrix element calculation, D.Zeppenfeld et al.)- ISR & FSR included (PYTHIA)

• Basic cuts on isolated leptons: PT > 20 GeV | | < 2.5 • Basic cuts on tagging jets: PT > 20 GeV > 4.4 Dominant background at that level: tt production

Additional rejection: • Mjj (inv. Mass of tag jets)

• PT (tot) = PT(l1) + PT(l2) + Ptmiss + PT(j1) + PT(j2)

(less sensitive to pile-up than jet-veto over large rap.)• Jet Veto ( no jets with PT > 20 GeV in | | < 3.2 )

PT(tot)H

tt

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mH = 130 GeV mH = 160 GeV

• For the same cuts: significance is worse than in orig. publ. by Zeppenfeld et al. (ISR/FSR effects, jet calibration, efficiencies)

However: confirmed that WBF channel has

a large discovery potential

e decays e decays

Main background: remaining tt background (13.1 events) WW el. weak background ( 7.1 events)

MH 130 140 150 160 170 180 190

Signal 11 20 31 50 53 47 37

S/B 0.5 0.9 1.4 2.3 2.4 2.1 1.7

• Much to be done: proper estimate of forward jet tag efficiencies in a full simulation, combination with ee and ignature, optimization of cuts

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qqH qq qq l l - Similar basic cuts as in WW analysis- Tau mass reconstruction using collinear approximation - Optimized cuts for e, ee and channels

S = 17.3 events B = 11.4 events S/B > 1

mH = 115 GeV

30 fb-1

all channels (e best channel)

Combined significance (ee, , e):

10 fb-1

30 fb-1

2.2 2.6 2.6 2.4 2.3 1.3 0.6

110 115 120 125 130 140 150mH (GeV)

3.8 4.3 4.3 4.1 3.8 2.7 1.4 Preliminary, no systematics yet, l-had channel to be added

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• Two or more Higgs can be observed over most of the parameter space disentangle SM / MSSM

AssumingSUSY particlesare heavy

Not all channelsshown

LHC discovery potential

No holes at low L (30fb-1)

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How many Higgses?How many Higgses?

For low MA no little h visible

If we see h. or H, how do we know

which it is?

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5 contours

Discovery potential for 10 fb-1

Large part of plane can be explored in 2007

Hole

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Hole where h is hard to see

mh

bbhbb region expolits enhanced

coupling

Is cross section calculated properly?

(bb structure functions?)

Does experient allow for h width

Can we plug this gap??

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A and H bosons

Recall: mA > 200 GeV:A and H are ~ degenerate

• Small tan: Would have been fun… measurement of many couplings

(including Hhh, AZh)

Large tan : bbA and bbH enhanced

sMSSM/sSM~5000 tan=30, mA=300GeV

H/A seen through:

• - 300 times rate, missing neutrinos

• - Good mass measurement

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A/H h+ h :

CMS Pmiss analysis

30 fb-1

Provides best reach for large mA. Signature: two stiff opposite-sign isolated tracks (PT > 40 GeV) PT

miss or 1 b-tagged jet (bbA/H)

Main challenge: reject QCD jet background. (already at trigger-level) Feasible for mA > 300 GeV: (high PT hadrons, larger PT

miss, larger rejection from isolation) RQCD ~ 1010 QCD background << 10% (tt + Z/* )

b-tag requirement improves S/BMass resolution ~10%

mA = 500 GeVtan = 25

mA = 500 GeVtan = 25

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Going beyond the BenchmarkGoing beyond the Benchmark

•bs gives MH+>~350GeV: Benchmark simple!

•Susy particles light.

Huge parameter space

Reduce by assuming (normally) mSugra

Discussed in next 2 transparencies.

•nMSSMMuch more complex - I know no coherent study

•General 2 HDM

Much more complex - I know no coherent study

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ATLAS300 fb-1

Higgs decays via SUSY particles If SUSY exists : search for

H/A 020

2 01 0

1

5 contoursATLAS:SUGRA scan

m0 = 50 - 250 GeVm1/2 = 100 - 300 GeV tan = 1.5 - 50 A 0 = 0

Exclusions depend on MSSM parameters (slepton masses, )

No CP violation

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SUSY ON

forbidden

ATLAS

How robust is this potential ? • SUSY loops can enhance/suppress Higgs production (e.g. gg h) and decay (e.g. h • A/H/H sparticles can compete with SM decays

Preliminary study : mSUGRA impact of SUSY on Higgs decays to SM particles is small : -- gg h 10% smaller -- tth/Wh 30% smaller -- ttH tt bb not affected -- BR (A/H/H SM particles) reduced by at most 40%

However : impact of mixing on couplings not studied for all possible mixing scenarios more work needed

Larger effects outside mSugra

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Searching for invisible Higgs ?

Signal: qq qqVV qqH Hinvisible

Cut on:

•Trigger (needs of 4.9 for jets)

•Large jet-jet mass >1200GeV/c2

•Large PT miss >100GeV/c

•Isolation of PT miss

•Finally jj

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Invisible Higgs ?

Assume no systematics in background...

For MH (or MA), below 400GeV/c2

can see a SM Higgs going 50% to invisible

is fraction of SM Higgs rate

But IMHO systematics serious

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Conclusions•LHC has a large discovery potential for MSSM Higgs Bosons

•Some sign of MSSM Higgs sector should be observable•Two or more Higgs bosons accessible in many cases. •MA 200-500, tan> 15 gives all 5

•Vector Boson fusion channel significantly enhances the discovery potential •Tau tau channel in the low mass region • Enhanced WW channels • Can it be used to see invisible Higgs decays ?

•New promising channels also in the MSSM section (Charged Higgs, had. Tau decays)

•To be done:•Need improved calculations (K-factors for S and B) •MC work important (Follow Tevatron data MC LHC)•new topics (CP violation, ...)•Understand the measurements which can be made.