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Klaus Desch, Report from the Higgs Working Group, ECFA/DESY Workshop Amsterdam, 4/4/03 1
Report from the Higgs Working Group
Convenors:M.BattagliaK.DeschA.DjouadiE.GrossB.Kniehl
ECFA/DESYLC workshopNIKHEF,Amsterdam4/4/03
Fully simulated+reconstructed HZ event (BRAHMS)
Klaus Desch, Report from the Higgs Working Group, ECFA/DESY Workshop Amsterdam, 4/4/03 2
Introduction
Framework:
Understanding the Nature of electro-weak symmetry breakingis one of the driving forces in the LC programmme
Existence of a light Higgs boson is favoured by experimental dataand most theoretical models
Exploration of the physics potential of the LC for Higgs physicshas three major motivations
1. Make the physics case
2. Give feedback to the design of the detector and the machine
3. Physics “R&D”: learn/don’t forget how to do the analyses
Klaus Desch, Report from the Higgs Working Group, ECFA/DESY Workshop Amsterdam, 4/4/03 3
Introduction
TDR conclusion: Higgs mechnanism can be established in all essential elements
extended study not essential??? No.
Goals:- close remaining (but essential) corners- keep up with new theoretical ideas- further study relation to LHC- further study option (A. deRoeck’s talk)- become more realistic in experimental simulation
Group was (and is) very active! 64 talks (35 exp/29 theo) in 4 workshops (sorry, I cannot mention all of them…)
Many (but certainly not all) goals achieved – good progress
Klaus Desch, Report from the Higgs Working Group, ECFA/DESY Workshop Amsterdam, 4/4/03 4
Introduction
Plan for this summary:
• Profile of a SM-like neutral Higgs Boson
• MSSM: additional Higgs Bosons and Sensitivity to Parameters
• Extended Models
• Relation to the LHC
• Thoughts about the Future
• Summary and Conclusion
Klaus Desch, Report from the Higgs Working Group, ECFA/DESY Workshop Amsterdam, 4/4/03 5
Profile of a SM-like Neutral Higgs Boson
Dominant production processes at LC:
Klaus Desch, Report from the Higgs Working Group, ECFA/DESY Workshop Amsterdam, 4/4/03 6
Profile of a SM-like Neutral Higgs Boson
Status of calculations for SM Higgs production and decay:In general in very good shape
Recent addition: full EW corrections to WW-fusion
Kniehl (LCWS02 review)
Denner et alBoudjema et alJegerlehner et al
complicated task, e.g. “Pentagons”:sizable correction (o(10%))
Klaus Desch, Report from the Higgs Working Group, ECFA/DESY Workshop Amsterdam, 4/4/03 7
Profile of a Higgs boson at the LC:
• Mass + Production Cross Sections
• Quantum Numbers
• Decay Branching Ratios
• Top Yukawa Coupling
• Double Higgsstrahlung (Self coupling)
Profile of a SM-like Neutral Higgs Boson
Klaus Desch, Report from the Higgs Working Group, ECFA/DESY Workshop Amsterdam, 4/4/03 8
Higgs Profile: Heavier SM Higgs
What, if Higgs mass (somewhat) larger, than EW precision data tell?
Study of
Most promising: final state
e e ZH ZWW and ZZZ e e ZH qqqq
only WW and ZZrelevant
measure width fromlineshape?
TDR: focus on mH=120,140,160 GeV
Klaus Desch, Report from the Higgs Working Group, ECFA/DESY Workshop Amsterdam, 4/4/03 9
H
H
Results:
m =400 MeV(0.17%)
ΔΓ =830 MeV(25%)
ΔBR(WW)/BR(WW)=5%
ΔBR(ZZ)/BR(ZZ)=11%
Δσ(HZ)=4%
Profile of a SM-like Neutral Higgs BosonMass + Production Cross Section
N. Meyer
Also results for 200, 280, 320 GeV available
Reconstructed Higgs Mass (GeV)
for 500 fb-1@500 GeVmH=240 GeV
Klaus Desch, Report from the Higgs Working Group, ECFA/DESY Workshop Amsterdam, 4/4/03 10
Higgs Profile: Quantum NumbersTDR: Spin from threshold scanTDR: CP from angular distributions of ZH
New Ideas:Spin from HZZCP from transverse polarisation correlations in H
Miller et al Was,WorekBowerImhof,KD
First estimate with detector simulation:
Observable: -acoplanarity:
> 8 separation between CP+ and CP-for 120 GeV Higgs (350GeV/1 ab-1)
Klaus Desch, Report from the Higgs Working Group, ECFA/DESY Workshop Amsterdam, 4/4/03 11
Higgs Profile: Decay Modes
TDR:
for 500 fb-1 , m=120 GeV
BattagliaRichard et alSchreiber et al
Results (rel. errors)
bb 2.4%
cc 8.3%
gg 5.5%
6.0%
23.0%
WW 5.4%
Klaus Desch, Report from the Higgs Working Group, ECFA/DESY Workshop Amsterdam, 4/4/03 12
Higgs Profile: Decay Modes
New analysis of hadronic BR’s has startedusing newest tools (ZVTOP, SIMDET4, kinematic fit)
study dependence on vtx layoutkinematic selection (Zhadronsand Zleptons only) not yet optimal
preliminary numbers seem to~confirm TDR numbers
T.Kuhl,KD
Klaus Desch, Report from the Higgs Working Group, ECFA/DESY Workshop Amsterdam, 4/4/03 13
Higgs Profile: Decay Modes
TDR study: obtain BR’s from measuring
( )( )
( ) / ( )
HZ X Z
BR H XHZ H BR Z
Alternative approach: measure fraction of events withinan unbiased sample of events
disadvantage: smaller event sampleadvantage : binomial errors smaller than gaussian errors (one measurement instead of two)
H X HZ H
J-C.Brient
Results (rel. errors)
bb 1.9%
cc 8.1%
gg 4.8%
7.1%
35.0%
WW 3.6%500 fb-1@350 GeVmH =120 GeV
Klaus Desch, Report from the Higgs Working Group, ECFA/DESY Workshop Amsterdam, 4/4/03 14
Higgs Profile: Rare Decay Modes
- rises with large number Higgs bosons at 800 GeV- test of ‘lepton universality in Higgs sector’- select events with two muons andmissing energy: clean signature- cut on recoil mass (remove ZZ)
ln s
H M.Battaglia
Result (rel. error)
BR(/BR() = 32 %ΔgH= 16 %for 1 ab-1@800 GeV
Klaus Desch, Report from the Higgs Working Group, ECFA/DESY Workshop Amsterdam, 4/4/03 15
Higgs Profile: Rare Decay ModesM.Battaglia
as rare decay ( 160 GeV)HH bb m
Fusion(800GeV) preferred over Higgsstrahlung(350GeV)
Results for 1ab-1@800 GeV
mH(GeV) S/sqrt(B) BR(bb)/BR(bb)
180 10.5 11.5%
200 7.5 16.5%
220 4.1 27.5%
Klaus Desch, Report from the Higgs Working Group, ECFA/DESY Workshop Amsterdam, 4/4/03 16
Higgs Profile: Rare Decay Modes
H ZSchreiber et al
Might add interesting informationIn case of anomalous coupling
Most promising channel: e e Z qq
Study for:
1500 ,1 s GeV ab
Results for 1ab-1@500 GeV
mH(GeV) S/sqrt(B) BR(Z)/BR(Z)
120 2.2 48%
140 4.4 27%
160 2.5 44%
Klaus Desch, Report from the Higgs Working Group, ECFA/DESY Workshop Amsterdam, 4/4/03 17
Higgs Profile: Rare Decay Modes
Summary of rare decays:
Klaus Desch, Report from the Higgs Working Group, ECFA/DESY Workshop Amsterdam, 4/4/03 18
Invisible Higgs DecaysMany SM extensions predict invisible Higgs Decays, e.g.:
• MSSM• Extra Dimensions• Model with new singlets (NMSSM,Majoron Models)• Stealthy Higgs
TDR: Estimate sensitivity from 1 = BR(vis) + BR(invis)
New study: explicit reconstruction in
Assumptions:
0 0
1 1H
e e ZH qq E
1350 , 500
120,140,160
H
s GeV L fb
m GeV
missing mass
Signal(120)
M.Schumacher
Klaus Desch, Report from the Higgs Working Group, ECFA/DESY Workshop Amsterdam, 4/4/03 19
Invisible Higgs Decays
Result:
M.Schumacher
Result for 500 fb-1@350 GeV (mH=120 GeV):ΔBR/BR(invis) = 10% for BR(invis) = 5%5σ observation down to BR = 2%
Klaus Desch, Report from the Higgs Working Group, ECFA/DESY Workshop Amsterdam, 4/4/03 20
Top Yukawa coupling
4 channels analysed:
- extension to higher masses- and inclusion of HWW- ANN based selection- event-wise IP-probability tag- results confirmed with SIMDET4+ZVTOP
A.Gay
Klaus Desch, Report from the Higgs Working Group, ECFA/DESY Workshop Amsterdam, 4/4/03 21
Top Yukawa coupling
Result: A.Gay
Precision on gttH
for 1ab-1@800 GeV
mH (GeV) gttH/gttH
120 7 %
140 17 %
170 13 %
200 15 %
for 5% syst. Backgrounduncertainty
Klaus Desch, Report from the Higgs Working Group, ECFA/DESY Workshop Amsterdam, 4/4/03 22
Higgs Self Coupling
TDR:
P.Gay et al
13 % leads to 23 % (“dilution effect”)(for 1 ab-1 @ 500 GeV)
Klaus Desch, Report from the Higgs Working Group, ECFA/DESY Workshop Amsterdam, 4/4/03 23
New Ideas for Higgs Self Coupling
Additional sensitivity from differential distributions to reduce the dilution:
Battaglia,Boos,Yao
/ 1.25SMHHH HHHg g
/ 0.5SMHHH HHHg g
Klaus Desch, Report from the Higgs Working Group, ECFA/DESY Workshop Amsterdam, 4/4/03 24
MSSM Higgs Sector
• Higgs sector of MSSM: 5 physical Higgses: h0, H0, A0, H±
• phenomenology determined at tree level by 2 parameters: tanβ and mA.• Higher order corrections from 3rd generation fermions/sfermions important
Crucial prediction: mh<135 GeV
Heavy Higgs Bosons: mA∞ decoupling limit, h is SM-like but H,A,H± might as well be within reach of LC: intense coupling regime
Goal: precise measurements of the observables (Higgs masses, couplings) to determine the fundamental SUSY parameters
Needs high precision predictions of observables. Theory has notyet reached this goal. E.g. current theo. uncertainty in mh≈3 GeV
Djouadi et al
Degrassi et al
Klaus Desch, Report from the Higgs Working Group, ECFA/DESY Workshop Amsterdam, 4/4/03 25
Additional MSSM Higgs Bosons
Analysis for e+e-HAbbbb at 500 GeV / 500 fb-1
-SIMDET4 -ZVTOP btagging -kinematic fit
Signals for sin()=1 and BR(H/Abb) = 85% :
Klimkovich
Klaus Desch, Report from the Higgs Working Group, ECFA/DESY Workshop Amsterdam, 4/4/03 26
Additional MSSM Higgs Bosons
Results for e+e-HAbbbb at 500 GeV / 500 fb-1 :
mA mH (m) (m) σ*BR2 Resol(m/m)
GeV GeV MeV MeV % GeV
100 150 170 170 1.7 5.1/6.7
100 200 300 2.1 4. /8.7
100 250 590 3.0 4. /11.5
140 150 300 410 2.3 4.0/7.9
observation up m(A)+m(H) ~ √s-30 GeV
Klimkovich
for sin()=1 and BR(H/Abb) = 85%
Klaus Desch, Report from the Higgs Working Group, ECFA/DESY Workshop Amsterdam, 4/4/03 27
Additional MSSM Higgs Bosons
Raspereza
Analysis for e+e-HAbb/bb at 500 GeV / 500 fb-1
-SIMDET4 -ZVTOP btagging -kinematic fit -Lepton-ID
Signals for sin()=1 and BR(H/Abb) = 85% / BR(H/A) = 15% :
Klaus Desch, Report from the Higgs Working Group, ECFA/DESY Workshop Amsterdam, 4/4/03 28
Additional MSSM Higgs Bosons
Results for e+e-HAbb/bb at 500 GeV / 500 fb-1 :
mA mH mA mH σ*BR2
HAbbσ*BR2
HAbb
GeV GeV MeV MeV % %
100 150 140 160 4.3 4.0
100 200 270 400 5.9 4.8
100 250 600 800 13.1 7.3
140 150 250 290 5.9 5.2
for sin()=1 and BR(H/Abb) = 85% / BR(H/A) = 15%
mass resolution ~ 4-8 GeV
Klaus Desch, Report from the Higgs Working Group, ECFA/DESY Workshop Amsterdam, 4/4/03 29
Charged Higgs
Battaglia,Ferrari,Kiiskinen,Maki
new: now with genuine tbtb background
At 800 GeV:5 discovery up to m=350 GeV
Klaus Desch, Report from the Higgs Working Group, ECFA/DESY Workshop Amsterdam, 4/4/03 30
Theory: new calculations to beat kinematic limit
Weiglein et al2. Heavy neutral Higgses
couple ~cos() in decoupling limitnormally no WW-fusion cross section
Loop effects can enhance the cross section (a bit…) (somewhat) higher mass reach than for pair production
fb
fb
fbfb
mH(GeV)
tan
Heavy SUSY Higgses: pair production dominant mass reach limited explore (supressed) single production modes
1. Charged Higgs: Kniehl et alMoretti et al
e e tbH
e e H
e e W H
e+e-HMSSM
sqrt(s)=800 GeV
Klaus Desch, Report from the Higgs Working Group, ECFA/DESY Workshop Amsterdam, 4/4/03 31
Constraining the MSSM Higgs sector
Ultimate goal: extract the underlying SUSY parameters from Higgs sector measurements from a global fit
We’re not there yet: difficult task since at higher orders, Higgs sectors depends on many parameters (stop mixing etc.)
Classical example: estimate from BR-measurement
Yes! But, BR’s also depend on
We should try to bring the bits and pieces together!
tan , , , ,..., ( ) t t btm m A m SUSY QCD
Am
Klaus Desch, Report from the Higgs Working Group, ECFA/DESY Workshop Amsterdam, 4/4/03 32
Constraining the MSSM Higgs sector: examples
A.Sopczak et altanfrom H/A
Sensitivity to tan at 500 GeV/2 ab-1 (mA=200GeV)
tanfrom charged cross section slope Verzegnassi, Trimarchi
Gross,Heinemeyer,Battaglia, Richard
mA from bb/WW
more ideas:
SUSY corrections (mb) from bb/ Guasch, Hollik, Penaranda
Klaus Desch, Report from the Higgs Working Group, ECFA/DESY Workshop Amsterdam, 4/4/03 33
Constraining the MSSM Higgs sector
Branching ratio deviation in constrained MSSM’s Ellis,Heinemeyer,Olive,Weiglein
(also results other constrained scenarios: NUHM, AMSB, GMSB)
mSugra
Klaus Desch, Report from the Higgs Working Group, ECFA/DESY Workshop Amsterdam, 4/4/03 34
CP violation in the MSSM Higgs sectorFrank,Heinemeyer,Hollik,WeigleinPilaftsis,Wagner,Carena,Ellis
MSSM Higgs sector is CP conserving at tree levelCP violation enters through sfermion loop if couplings are complexLeads to 3 neutral Higgs mass eigenstates which are not CP eigenstates:
Klaus Desch, Report from the Higgs Working Group, ECFA/DESY Workshop Amsterdam, 4/4/03 35
CP violation in the MSSM Higgs
T.KlimkovichMeasure masses and cross sections andscan parameter space assuming=10% and m=1GeV (conservative!)
Sensitivity to CPV parametersfrom a 3 parameter scan:
Klaus Desch, Report from the Higgs Working Group, ECFA/DESY Workshop Amsterdam, 4/4/03 36
Extended Models
• 2HDM
• NMSSM
• Effects of Extra Dimensions on Higgs sector
• Higher Higgs representations
Krawczyk, Osland; Gunion
Huitu
Miller, Nevzorov, Zerwas
Wells,Hewett,Rizzo,Dominici,Ghosh,Gabrielli,Huitu
Klaus Desch, Report from the Higgs Working Group, ECFA/DESY Workshop Amsterdam, 4/4/03 37
Extended Models: NMSSM
• NMSSM: additional Higgs singlet
• provides viable solution to -Problem of the MSSM
• Singlet introduces new U(1) Symmetry leading to massless
CP-odd Higgs (ruled out) symmetry must be broken
• Phenomenology depends on how strongly the symmetry is broken
(slightly broken symmetry = preferred from RG running)
• Physical states: 3 CP-even neutral
2 CP-odd neutral
2 charged
interesting phenomenology
Miller,Nevzorov,Zerwas
Klaus Desch, Report from the Higgs Working Group, ECFA/DESY Workshop Amsterdam, 4/4/03 38
Extended Models: NMSSM
Example parameters:
e.g. 2 light CP-even Higgses with sizable HZZ coupling
need for study of LC sensitivity to the scenario and its parameters
Miller,Nevzorov,Zerwas
Klaus Desch, Report from the Higgs Working Group, ECFA/DESY Workshop Amsterdam, 4/4/03 39
Extended Models: XD effects on Higgs sector Wells,Hewett,Rizzo,Dominici,Ghosh,Gabrielli,Huitu
• Models with 5D localized gravity (RS model) appear to exhibit a scalar state (connected to excitations of “force” which stabilizes the distance between SM- and Planck-Brane: The Radion
• Radion couples to trace of E-p-tensor (= very Higgs-like except for trace anomaly of QCD ‘tree level’ coupling to gluons
• Radion can mix with Higgs boson two Higgs-like scalars with production cross sections and branching ratios different from SM Higgs
• Rather few model parameters: - m(Higgs), m(Radion)- vev of Radion field- mixing parameter
Klaus Desch, Report from the Higgs Working Group, ECFA/DESY Workshop Amsterdam, 4/4/03 40
Extended Models: XD effects on Higgs sectorDominici,Battaglia,Gunion
LC ability of precise BR measurements allows to distingiushSM Higgs from mixed state (even if Radion itself is too heavy)
Red contours: deviation ofHbb BR > 2.5σ
Cyan Region: LHC H discoveryEnsured
Blue contours: LHC Radionobservation in ΦZZ
theoreticallynot allowed
theoreticallynot allowed
LC regions complementaryto LHC reach
Klaus Desch, Report from the Higgs Working Group, ECFA/DESY Workshop Amsterdam, 4/4/03 41
Relation to the LHC
• biggest asset of LC Higgs measurements: model independence!
• LHC studies (also) improved since TESLA TDR (e.g. VBF channels allow o(10%) measurement of various coupling ratios (WW/ZZ, /WW,…) or products (tt*bb)
• LHC+LC joint interpretation will be useful example (studied in LHC/LC group): tth)*BR(bb) @ LHC and BR(bb)@LC500 allows reasonable top Yukawa coupling measurement
• Light Higgs precision o(1%) measurements can guide LHC studies when simultaneous running is ensured example: sensitivity of h-BR’s on mA point to mass region of interest
Klaus Desch, Report from the Higgs Working Group, ECFA/DESY Workshop Amsterdam, 4/4/03 42
Thoughts About The Future
What are the goals for a Higgs working group in the next 2 years??
Experimental:
• Physics studies as crucial input to detector R&D
• Reexamine influence of machine parameters (Luminosity, Energy, Time structure, Backgrounds) on physics performance
• Become more realistic in simulation of our benchmark processes (recoil mass, BR’s, ZHH)
• Continue quantitative evaluation of the running options in , ee-e- modes (mass reach, light Higgs couplings, …)
Klaus Desch, Report from the Higgs Working Group, ECFA/DESY Workshop Amsterdam, 4/4/03 43
Thoughts About The Future
Facing Experimental Reality:
• full simulation (BRAHMS/MOKKA) is now really possible for physics studies
• development of appropriate analysis tools might take more time than the actual physics study (Kin.Fitting, Lepton-ID (esp. t) algorithms, ISR/BS photon ID, B-tagging, etc. etc.) – but it’s worth the effort!
• Study the dependency of physics observables as a function of detector/machine parameters (First examples are arriving, we clearly need more)
see e.g. V.Saveliev
see e.g. T.Kuhl
Klaus Desch, Report from the Higgs Working Group, ECFA/DESY Workshop Amsterdam, 4/4/03 44
Thoughts About The Future
Theory:
• match experimental and theoretical precision. Identify, where particular effort is needed
• Watch new theoretical ideas (models with modified H coupling now easy to explore general survey?)
General:
• International connections – exchange of ideas, codes, common projects etc can still improve!
• PhD theses on detector R&D are much nicer if accompanied by a physics applicability study (improve possibilities for publications of results?)
Klaus Desch, Report from the Higgs Working Group, ECFA/DESY Workshop Amsterdam, 4/4/03 45
International Connections: an example
Ronan
Compare and understand differences in three regional simulation programs
Klaus Desch, Report from the Higgs Working Group, ECFA/DESY Workshop Amsterdam, 4/4/03 46
Summary and Conclusions
• Higgs physics is a major pillar of the LC physics case • This case has been further strengthened: - higher masses carefully studied - rare Higgs decays - heavy SUSY Higgs Bosons - extraction of SUSY parameters from Higgs sector - sensitivity to extended models
• Studies with increased realism in the simulation have started They need be continued to give credible input to detector and machine design
• No reason to slow down – only an active community is able to plan and realize the experiment(s)!