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Precision Higgs Physics: Theory Status
Robert Harlander
Bergische Universitat Wuppertal
UK HEP Forum
Cosener’s House, 7-8 May 2009
Robert Harlander — Precision Higgs physics – p. 1
Vacuum
t
x
Robert Harlander — Precision Higgs physics – p. 2
Vacuum
e+
e−
t
x
Robert Harlander — Precision Higgs physics – p. 2
Vacuum
e+
e−
t
x
Robert Harlander — Precision Higgs physics – p. 2
Vacuum fluctuations
e+
e−
t
x
Robert Harlander — Precision Higgs physics – p. 3
Vacuum fluctuations
e+
e−
t
x
Robert Harlander — Precision Higgs physics – p. 3
Vacuum fluctuations
e+
e−
t
xγ
Robert Harlander — Precision Higgs physics – p. 3
Vacuum fluctuations
e+
e−
t
xW γ
Robert Harlander — Precision Higgs physics – p. 3
Vacuum fluctuations
t
xW γ
e+
e−t
t
Robert Harlander — Precision Higgs physics – p. 3
ρ parameter
t
x
t
Robert Harlander — Precision Higgs physics – p. 4
ρ parameter
t
x
tZ Z
Robert Harlander — Precision Higgs physics – p. 4
ρ parameter
t
x
tZ Z
tW W
b
vs.
sin2 θW = 1 −M2
W
M2Z
=g′2
g2 + g′2
(
1 −c2W
s2W
∆ρ
)
Robert Harlander — Precision Higgs physics – p. 4
ρ parameter
t
x
tZ Z
tW W
b
vs.
sin2 θW = 1 −M2
W
M2Z
=g′2
g2 + g′2
(
1 −c2W
s2W
∆ρ
)
Robert Harlander — Precision Higgs physics – p. 4
ρ parameter
t
x
tZ Z
tW W
b
vs.
sin2 θW = 1 −M2
W
M2Z
=g′2
g2 + g′2
(
1 −c2W
s2W
∆ρ
)
∆ρ ∼ m2t
Robert Harlander — Precision Higgs physics – p. 4
ρ parameter
t
x
W W
vs.
Z Z
sin2 θW = 1 −M2
W
M2Z
=g′2
g2 + g′2
(
1 −c2W
s2W
∆ρ
)
∆ρ ∼ m2t
∆ρ ∼ lnM2H
Robert Harlander — Precision Higgs physics – p. 5
Higgs production
t
x
t
Robert Harlander — Precision Higgs physics – p. 6
Higgs production
t
x
Higgs
Proton
Proton
Gluon
Robert Harlander — Precision Higgs physics – p. 6
Example: Higgs mass
t
x
t
Robert Harlander — Precision Higgs physics – p. 7
Example: Higgs mass
t
x
t
expected: ∆M exph ∼ O(0.1%)
⇒ Mh will be precision quantity
Robert Harlander — Precision Higgs physics – p. 7
Example: Higgs mass
t
x
expected: ∆M exph ∼ O(0.1%)
⇒ Mh will be precision quantity
note: in SUSY
Mh = Mh(MA, tanβ, . . .)
Robert Harlander — Precision Higgs physics – p. 7
Example: Higgs mass
Mh = Mh(MA, tanβ, . . .)
1-loop:
[Ellis, Ridolfi, Zwirner ’91], [Okada, Yamaguchi, Yanagida ’91], [Haber, Hempfling 91], [Chankowski,
Pokorski, Rosiek ’92], [Brignole ’92], [Dabelstein ’95], [Pierce, Bagger, Matchev, Zhang ’97]
2-loop logarithmic:
[Carena, Espinosa, Quiros, Wagner ’95], [Espinosa, Navarro ’01], [Haber, Hempfling, Hoang ’97]
2-loop:
[Hempfling, Hoang ’94], [Heinemeyer, Hollik, Weiglein ’98], [Zhang ’99], [Espinosa, Zhang ’00],
[Brignole, Degrassi, Slavich, Zwirner ’02]
3-loop logarithmic:
[Martin ’03]
3-loop:
[R.H., Kant, Mihaila, Steinhauser ’08] O(1GeV)-effect!
Robert Harlander — Precision Higgs physics – p. 8
Higgs couplings
tt
t
H
t
_t
H H
q
q
Vq
V
q
q
q H
V_
V
⊗
b
b
HW
W
γ
γ
HV
V
H
Robert Harlander — Precision Higgs physics – p. 9
Higgs couplings
tt
t
H
t
_t
H H
q
q
Vq
V
q
q
q H
V_
V
⊗
b
b
HW
W
γ
γ
HV
V
H
⇒ΓgΓγ
Γ,
ΓgΓV
Γ,
ΓV ΓV
Γ,
ΓV Γτ
Γ, etc.
⇒ΓV
Γ(Γg + ΓV + Γτ + . . .) = ΓV
⇒ Γγ , Γg , etc.[Zeppenfeld et al.], [Duhrssen et al.],
[Lafaye et al.]
Robert Harlander — Precision Higgs physics – p. 9
pp → H at 14 GeV
tt
t
H
t
_t
H H
q
q
Vq
V
q
q
q H
V_
V
⊗
b
b
HW
W
γ
γ
HV
V
H
σ(pp → H + X) [pb]√s = 14 TeV
NLO / NNLO
MRST
gg → H (NNLO)
qq → Hqqqq
_' → HW
qq_ → HZ
gg/qq_ → tt
_H (NLO)
MH [GeV]
10-4
10-3
10-2
10-1
1
10
10 2
100 200 300 400 500 600 700 800 900 1000
⊗
bb WW
ZZττ
gg
γγ
tt
Mhsm(GeV)
BR
SM Higgs
10-6
10-5
10-4
10-3
10-2
10-1
1
90 100 200 300 400
Robert Harlander — Precision Higgs physics – p. 10
Discovery Potential
1
10
10 2
100 120 140 160 180 200
mH (GeV)
Sig
nal s
igni
fica
nce
H → γ γ ttH (H → bb) H → ZZ(*) → 4 l H → WW(*) → lνlν qqH → qq WW(*)
qqH → qq ττ
Total significance
∫ L dt = 30 fb-1
(no K-factors)
ATLAS tt
t
H
Robert Harlander — Precision Higgs physics – p. 11
Discovery Potential
1
10
10 2
100 120 140 160 180 200
mH (GeV)
Sig
nal s
igni
fica
nce
H → γ γ ttH (H → bb) H → ZZ(*) → 4 l H → WW(*) → lνlν qqH → qq WW(*)
qqH → qq ττ
Total significance
∫ L dt = 30 fb-1
(no K-factors)
ATLAS tt
t
H
t
_t
H
Robert Harlander — Precision Higgs physics – p. 11
Discovery Potential
1
10
10 2
100 120 140 160 180 200
mH (GeV)
Sig
nal s
igni
fica
nce
H → γ γ ttH (H → bb) H → ZZ(*) → 4 l H → WW(*) → lνlν qqH → qq WW(*)
qqH → qq ττ
Total significance
∫ L dt = 30 fb-1
(no K-factors)
ATLAS tt
t
H
t
_t
H
H
q
q
Vq
V
q
Robert Harlander — Precision Higgs physics – p. 11
Disovery Potential
2006
use NLO for inclusive analysis
tt
t
H
H
q
q
Vq
V
q
Robert Harlander — Precision Higgs physics – p. 12
Gluon Fusion
tt
t
H
dominant production mode
sensitive to heavy particle spectrum
Robert Harlander — Precision Higgs physics – p. 13
Gluon Fusion
tt
t
H
dominant production mode
sensitive to heavy particle spectrum
but
H → bb decay mode not usable for discovery
LO is 1-loop → radiative corrections difficult
depends on Yukawa coupling
Robert Harlander — Precision Higgs physics – p. 13
Gluon Fusion
tt
t
H
dominant production mode
sensitive to heavy particle spectrum
but
H → bb decay mode not usable for discovery
LO is 1-loop → radiative corrections difficult — really?
depends on Yukawa coupling
Robert Harlander — Precision Higgs physics – p. 14
Gluon fusioneffective theory for mt ≫ MH :
t
t
t Hmt≫MH
→ C(mt, αs) × H
Robert Harlander — Precision Higgs physics – p. 15
Gluon fusioneffective theory for mt ≫ MH :
t
t
t Hmt≫MH
→ C(mt, αs) × H
10-1
1
10
100 200 300 400 500 600 700 800 900 1000MH [GeV]
NLO, LHC
σ(pp→H+X)[pb]
HIGLU
tH
t
Robert Harlander — Precision Higgs physics – p. 15
Gluon fusioneffective theory for mt ≫ MH :
t
t
t Hmt≫MH
→ C(mt, αs) × H
10-1
1
10
100 200 300 400 500 600 700 800 900 1000MH [GeV]
NLO, LHC
σ(pp→H+X)[pb]
HIGLU
tH
t
H[Kramer, Laenen, Spira ’96]
Robert Harlander — Precision Higgs physics – p. 15
Gluon fusioneffective theory for mt ≫ MH :
t
t
t Hmt≫MH
→ C(mt, αs) × H
10-1
1
10
100 200 300 400 500 600 700 800 900 1000MH [GeV]
NLO, LHC
σ(pp→H+X)[pb]
HIGLU
tH
t
H
Holds also at NNLO?
see, e.g., [Marzani et al. ’08]
Robert Harlander — Precision Higgs physics – p. 15
Gluon fusion at NNLO
1
10
100 120 140 160 180 200 220 240 260 280 300
σ(pp→H+X) [pb]
MH [GeV]
LONLONNLO
√ s = 14 TeV
[R.H., Kilgore ’02][Anastasiou, Melnikov ’02][Ravindran, Smith, Neerven ’03]
[Spira, Djouadi, Graudenz,
Zerwas ’91/’93]
[Dawson ’91]
Robert Harlander — Precision Higgs physics – p. 16
Gluon fusion at NNLO
1
10
100 120 140 160 180 200 220 240 260 280 300
σ(pp→H+X) [pb]
MH [GeV]
LONLONNLO
√ s = 14 TeV
[R.H., Kilgore ’02][Anastasiou, Melnikov ’02][Ravindran, Smith, Neerven ’03]
[Spira, Djouadi, Graudenz,
Zerwas ’91/’93]
[Dawson ’91]
Why so large?
Robert Harlander — Precision Higgs physics – p. 16
Gluon fusion – beyond NNLO
soft resummation s → M2H [Catani, Grazzini, de Florian, Nason ’03]
Robert Harlander — Precision Higgs physics – p. 17
Gluon fusion – beyond NNLO
N3LO soft
0
20
40
60
80
1µr /
MH
0.2 0.5 2 3
σ(pp → H+X) [pb]
MH = 120 GeV
LO
NLO
N2LO
N3LOSV
√
µr / MH
0.2 0.5 2 3
σ(pp → H+X) [pb]
MH = 240 GeV
N2LO
N3LOSV LO
NLO
0
5
10
15
20
1
[Moch, Vogt ’05][Laenen, Magnea ’05][Ravindran ’05][Kidonakis ’05][Idilbi, Ju, Yuan ’06]
Robert Harlander — Precision Higgs physics – p. 18
Latest developments
Resumming (CAπαs)n from ln(−q2) = ln q2 − iπ
fixed order
mH (GeV)
σ(p
b)
200180160140120100
80
70
60
50
40
30
20
10
0
resummed
mH (GeV)
σ(p
b)
200180160140120100
80
70
60
50
40
30
20
10
0
Robert Harlander — Precision Higgs physics – p. 19
Latest developments
Resumming (CAπαs)n from ln(−q2) = ln q2 − iπ
fixed order
mH (GeV)
σ(p
b)
200180160140120100
80
70
60
50
40
30
20
10
0
resummed
mH (GeV)
σ(p
b)
200180160140120100
80
70
60
50
40
30
20
10
0
Message: π2 is large
Robert Harlander — Precision Higgs physics – p. 19
Latest developments
Resumming (CAπαs)n from ln(−q2) = ln q2 − iπ
fixed order
mH (GeV)
σ(p
b)
200180160140120100
80
70
60
50
40
30
20
10
0
resummed
mH (GeV)
σ(p
b)
200180160140120100
80
70
60
50
40
30
20
10
0
Message: π2 is large but some π2’s are larger than others. . .
Robert Harlander — Precision Higgs physics – p. 19
Gluon fusion
QCD corrections
under good control, but
final word on origin of large corrections (probably) not spoken
better understanding more important than full N3LO
Robert Harlander — Precision Higgs physics – p. 20
Gluon fusion
QCD corrections
under good control, but
final word on origin of large corrections (probably) not spoken
better understanding more important than full N3LO
Electro-weak corrections
can be large at LHC due to “Sudakov” ln2(s/M2W )
in fact:
Higgs-Strahlung [Ciccolini, Dittmaier, Kramer ’03]
Robert Harlander — Precision Higgs physics – p. 20
Higgs Strahlungq
q H
V_
V
0.9
0.95
1
1.05
1.1
1.15
1.2
1.25
1.3
1.35
80 100 120 140 160 180 200MH[GeV]
KW
H(L
HC
)
LO
NLO
NNLO [Brein, Djouadi, R.H. ’03][Han, Willenbrock ’90]
Robert Harlander — Precision Higgs physics – p. 21
Higgs Strahlungq
q H
V_
V
0.9
0.95
1
1.05
1.1
1.15
1.2
1.25
1.3
1.35
80 100 120 140 160 180 200MH[GeV]
KW
H(L
HC
)
QCD+EW
LO
NLO
NNLO [Brein, Djouadi, R.H. ’03][Han, Willenbrock ’90]
[Ciccolini, Dittmaier, Kramer ’03]
Robert Harlander — Precision Higgs physics – p. 21
Gluon fusion
QCD corrections
under good control, but
final word on origin of large corrections (probably) not spoken
better understanding more important than full N3LO
Electro-weak corrections
can be large at LHC due to “Sudakov” ln2(s/M2W )
in fact:
Higgs-Strahlung [Ciccolini, Dittmaier, Kramer ’03]
Robert Harlander — Precision Higgs physics – p. 22
Gluon fusion
QCD corrections
under good control, but
final word on origin of large corrections (probably) not spoken
better understanding more important than full N3LO
Electro-weak corrections
can be large at LHC due to “Sudakov” ln2(s/M2W )
in fact:
Higgs-Strahlung [Ciccolini, Dittmaier, Kramer ’03]
WBF [Ciccolini, Denner, Dittmaier ’08] → later
Robert Harlander — Precision Higgs physics – p. 22
Gluon fusion
QCD corrections
under good control, but
final word on origin of large corrections (probably) not spoken
better understanding more important than full N3LO
Electro-weak corrections
can be large at LHC due to “Sudakov” ln2(s/M2W )
in fact:
Higgs-Strahlung [Ciccolini, Dittmaier, Kramer ’03]
WBF [Ciccolini, Denner, Dittmaier ’08] → later
gluon fusion
Robert Harlander — Precision Higgs physics – p. 22
Gluon fusionelectro-weak corrections:
[GeV]HM150 200 250 300 350 400
[%
]E
Wδ
-4
-2
0
2
4
6
8
10 WW ZZ tt
EW, light ferm.δ
EW, light ferm., Fig.2 of first paper of Ref.[27]δ
EW, total, CMδ[Actis, Passarino, Sturm,
Uccirati ’08]
partial:
[Aglietti, Bonciani, Degrassi,Vicini ’04]
[Degrassi, Maltoni ’04]
[Djouadi, Gambino ’94]
Robert Harlander — Precision Higgs physics – p. 23
Gluon fusionelectro-weak corrections:
[GeV]HM150 200 250 300 350 400
[%
]E
Wδ
-4
-2
0
2
4
6
8
10 WW ZZ tt
EW, light ferm.δ
EW, light ferm., Fig.2 of first paper of Ref.[27]δ
EW, total, CMδ[Actis, Passarino, Sturm,
Uccirati ’08]
partial:
[Aglietti, Bonciani, Degrassi,Vicini ’04]
[Degrassi, Maltoni ’04]
[Djouadi, Gambino ’94]
mixed EW/QCD? (remember LEP?)
→ do they factorize? [Anastasiou, Boughezal, Petriello ’08]
Robert Harlander — Precision Higgs physics – p. 23
Putting things together. . .
Compared to
O(10%) increase
Robert Harlander — Precision Higgs physics – p. 24
Putting things together. . .
1
10
100 110 120 130 140 150 160 170 180 190 200
1
10
mH(GeV/c2)
95%
CL
Lim
it/S
M
Tevatron Run II Preliminary, L=0.9-4.2 fb-1
ExpectedObserved±1σ Expected±2σ Expected
LEP Exclusion TevatronExclusion
SMMarch 5, 2009
but note: change MRST2006→ MSTW2008 leads to O(10%) decrease!
[de Florian, Grazzini ’09], [Anastasiou, Boughezal, Petriello ’08]
Robert Harlander — Precision Higgs physics – p. 25
PDF uncertainty?
MSTW 2008 [cf. talk by J. Stirling]
Robert Harlander — Precision Higgs physics – p. 26
Distributions
[Bozzi, Catani, de Florian, Grazzini ’05]
Robert Harlander — Precision Higgs physics – p. 27
Distributions
0 20 40 60 80 1000
0.2
0.4
0.6
0.8
1
1.2
(GeV)Tp0 20 40 60 80 100
(p
b/G
ev)
T/d
pσ
d
0
0.2
0.4
0.6
0.8
1
1.2
(GeV)Tp0 20 40 60 80 100
(p
b/G
ev)
T/d
pσ
d
0
0.2
0.4
0.6
0.8
1
1.2 = 39.4 pbσ = 125 GeV, H H + X at LHC, m→gg
Grazzini et al, MRST2002
ResBos, MRST2001, step
ResBos, MRST2001, smooth
Kulesza et al, CTEQ5M
Berger et al, CTEQ5M
MC@NLO, MRST2001
from [hep-ph/0403052]
Robert Harlander — Precision Higgs physics – p. 28
Higher orders with Cuts
Consider Z → 2 jets: inclusive
LO:
NLO: +
∫
cone
A
ǫ+ B −
A
ǫ+ Ccut = B + Ccut
Robert Harlander — Precision Higgs physics – p. 29
Higher orders with Cuts
Consider Z → 2 jets: exclusive
LO:
NLO: +
∫
cone
A
ǫ+ B −
A
ǫ+ Ccut = B + Ccut
Robert Harlander — Precision Higgs physics – p. 29
Exclusive at NNLO
+
∫
cone
+
∫
cone
+
∫ ∫
cones
+ · · ·
[Anastasiou, Melnikov, Petriello], [Gehrmann, G.-de Ridder, Glover],
[Grazzini, Frixione], [Kilgore], [Kosower], [Somogyi, Trocsanyi, Del Duca], [Weinzierl]
Robert Harlander — Precision Higgs physics – p. 30
Exclusive at NNLO
e+e− → 2 jets
[Anastasiou, Melnikov, Petriello ’04]
using sector decomposition [Binoth, Heinrich]
e+e− → 3 jets
[Gehrmann-De Ridder, Gehrmann, Glover, Heinrich ’08]
[Weinzierl ’08]
using antenna subtraction [Gehrmann-De Ridder, Gehrmann, Glover]
qq → V
[Melnikov, Petriello ’06]
gg → H
FEHIP: [Anastasiou, Melnikov, Petriello ’04]
HNNLO: [Catani, Grazzini ’07] subtraction method
Robert Harlander — Precision Higgs physics – p. 31
NNLO with cuts
tt
t
H ⊗W
W
γ
γ
H
Robert Harlander — Precision Higgs physics – p. 32
NNLO with cuts
tt
t
H ⊗W
W
γ
γ
H
mh σcutNNLO/σinc
NNLO K(2)cut/K
(2)inc
110 0.590 0.981
115 0.597 0.968
120 0.603 0.953
125 0.627 0.970
130 0.656 1.00
135 0.652 0.98
[Anastasiou, Melnikov, Petriello ’05]
see also [Grazzini ’07]
Robert Harlander — Precision Higgs physics – p. 32
NNLO with cuts
tt
t
H ⊗
ν
ν
W
W
l
H
_l
+
Robert Harlander — Precision Higgs physics – p. 33
NNLO with cuts
tt
t
H ⊗
ν
ν
W
W
l
H
_l
+
σ[fb] LO NLO NNLO
µ = Mh/2 21.002± 0.021 22.47± 0.11 18.45± 0.54
µ = Mh 17.413± 0.017 21.07± 0.11 18.75± 0.37
µ = 2Mh 14.529± 0.014 19.50± 0.10 19.01± 0.27
[Anastasiou, Dissertori, Stockli ’07]
see also [Grazzini ’08]
Robert Harlander — Precision Higgs physics – p. 33
NNLO with cuts
tt
t
H ⊗
ν
ν
W
W
l
H
_l
+
σ[fb] LO NLO NNLO
µ = Mh/2 21.002± 0.021 22.47± 0.11 18.45± 0.54
µ = Mh 17.413± 0.017 21.07± 0.11 18.75± 0.37
µ = 2Mh 14.529± 0.014 19.50± 0.10 19.01± 0.27
[Anastasiou, Dissertori, Stockli ’07]
see also [Grazzini ’08]Questions:
can one understand the size of the radiative corrections (with cuts)?
are the cuts sensitive to heavy top limit?
effect of “π2-resummation” ?
Robert Harlander — Precision Higgs physics – p. 33
Including soft radiation
match NLO calculation with parton shower
without double counting
Robert Harlander — Precision Higgs physics – p. 34
Including soft radiation
match NLO calculation with parton shower
without double counting
two successful approaches so far:
MC@NLO [Frixione, Nason, Webber ’03]
POWHEG [Frixione, Nason, Oleari ’07]
Robert Harlander — Precision Higgs physics – p. 34
Including soft radiation
match NLO calculation with parton shower
without double counting
two successful approaches so far:
MC@NLO [Frixione, Nason, Webber ’03]
POWHEG [Frixione, Nason, Oleari ’07]
[Alioli, Nason, Oleari, Re ’08]
[Hamilton, Richardson, Tully ’09]
Robert Harlander — Precision Higgs physics – p. 34
Including soft radiation
approximate solutions:
Robert Harlander — Precision Higgs physics – p. 35
Including soft radiation
approximate solutions:
ME ⊕ PS
CKKW [Catani, Kuhn, Krauss, Webber] → SHERPA [Gleisberg et al.]
AlpGen [Mangano]
Robert Harlander — Precision Higgs physics – p. 35
Including soft radiation
approximate solutions:
ME ⊕ PS
CKKW [Catani, Kuhn, Krauss, Webber] → SHERPA [Gleisberg et al.]
AlpGen [Mangano]
differential re-weighting of LO MC
e.g. reweight Pythia by FEHIP
[Davatz et al. ’04,’06]
Robert Harlander — Precision Higgs physics – p. 35
Gluon Fusion
tt
t
H
dominant production mode
sensitive to heavy particle spectrum
but
H → bb decay mode not usable for discovery
LO is 1-loop → radiative corrections difficult
depends on Yukawa coupling
Robert Harlander — Precision Higgs physics – p. 36
Gluon Fusion
tt
t
H
dominant production mode
sensitive to heavy particle spectrum
but
H → bb decay mode not usable for discovery
LO is 1-loop → radiative corrections difficult
depends on Yukawa coupling
Robert Harlander — Precision Higgs physics – p. 36
Effects of SUSY[Djouadi 98], [Carena et al. 99]
tt
t
H +~t
~
t~ Ht
may interfere destructively!
Robert Harlander — Precision Higgs physics – p. 37
Effects of SUSY[Djouadi 98], [Carena et al. 99]
tt
t
H +~t
~
t~ Ht
may interfere destructively!
mt1= 200 GeV
mg = 1 TeV
tan β = 10 ,
α = 0 ,
θt =π
4
0
20
40
60
80
100
300 400 500 600 700 800 900
σ(pp→h+X) [pb]
m [GeV]t2~
SUSY, LO
SM, LO
LHC
Robert Harlander — Precision Higgs physics – p. 37
Effects of SUSY[Djouadi 98], [Carena et al. 99]
tt
t
H +~t
~
t~ Ht
may interfere destructively!
mt1= 200 GeV
mg = 1 TeV
tan β = 10 ,
α = 0 ,
θt =π
4
0
20
40
60
80
100
300 400 500 600 700 800 900
σ(pp→h+X) [pb]
m [GeV]t2~
SUSY, NNLO’SUSY, NLOSUSY, LO
SM, LO
LHC
[R.H., Steinhauser ’04],
[Anastasiou et al. ’06/’08]
[Muhlleitner, Rzehak,Spira ’07/’08]
[Aglietti, Bonciani,Degrassi, Vicini ’06]
[Degrassi, Slavich ’08]
Robert Harlander — Precision Higgs physics – p. 37
H/A + bb
H
b
_b
Robert Harlander — Precision Higgs physics – p. 38
Numerical relevance
bb–→hsm
gg→hsm
gg+bb–→hsm
Mhsm (GeV)
σ (p
b)
(a) LHC, √s = 14.0 TeV, SM
10-2
10-1
1
10
10 2
10 3
10 4
90 100 200 300 400
from [Belyaev et al., ’05]
Robert Harlander — Precision Higgs physics – p. 39
Numerical relevance
bb–→A
gg→A
gg+bb–→A
MA (GeV)
σ (p
b)
(b) LHC, √s = 14.0 TeV, MSSM, tan β=10
10-2
10-1
1
10
10 2
10 3
10 4
90 100 200 300 400
from [Belyaev et al., ’05]
Robert Harlander — Precision Higgs physics – p. 39
4-FNS vs. 5-FNS
σLO [fb]
√S = 14 TeV
bb_
→ H
gg → bb_
H
MH = 120 GeV
µY = MH
µR = µF = µ
µ/MH
10 2
10 3
10-1
1 10
_
H
b
b
b_
b
H
Robert Harlander — Precision Higgs physics – p. 40
4-FNS vs. 5-FNS
σLO [fb]
√S = 14 TeV
bb_
→ H
gg → bb_
H
MH = 120 GeV
µY = MH
µR = µF = µ
µ/MH
10 2
10 3
10-1
1 10
_
H
b
b
b_
b
H
Robert Harlander — Precision Higgs physics – p. 40
4-FNS vs. 5-FNS
σLO [fb]
√S = 14 TeV
bb_
→ H
gg → bb_
H
MH = 120 GeV
µY = MH
µR = µF = µ
µ/MH
10 2
10 3
10-1
1 10
_
H
b
b
b_
b
H
Robert Harlander — Precision Higgs physics – p. 40
5-FNS at NNLO
00.10.20.30.40.50.60.70.80.9
1
10-1
1 10
σ/pb
µF/MH
0.25
LHCMH=120 GeV
NNLO
Robert Harlander — Precision Higgs physics – p. 41
pp → H + bb
σ(pp → bb_
h + X) [fb]
√s = 14 TeV
µ = (2mb + Mh)/4
Mh [GeV]
bb_
→ h (NNLO)
gg → bb_
h (NLO)10
10 2
10 3
100 150 200 250 300 350 400
b_
b
H
_
H
b
b
meanwhile also electro-weak corrections available[Dittmaier, Kramer, Muck, Schluter ’06]
Robert Harlander — Precision Higgs physics – p. 42
Weak Boson Fusion
H
q
q
Vq
V
q
σ(pp → H + X) [pb]√s = 14 TeV
NLO / NNLO
MRST
gg → H (NNLO)
qq → Hqqqq
_' → HW
qq_ → HZ
gg/qq_ → tt
_H (NLO)
MH [GeV]
10-4
10-3
10-2
10-1
1
10
10 2
100 200 300 400 500 600 700 800 900 1000
Robert Harlander — Precision Higgs physics – p. 43
Discovery Potential
1
10
10 2
100 120 140 160 180 200
mH (GeV)
Sig
nal s
igni
fica
nce
H → γ γ ttH (H → bb) H → ZZ(*) → 4 l H → WW(*) → lνlν qqH → qq WW(*)
qqH → qq ττ
Total significance
∫ L dt = 30 fb-1
(no K-factors)
ATLAS tt
t
H
H
q
q
Vq
V
q
Robert Harlander — Precision Higgs physics – p. 44
WBF Signature
H
q
q
Vq
V
q→ 0
Robert Harlander — Precision Higgs physics – p. 45
WBF Signature
H
q
q
Vq
V
q→ 0
pp
J1J2
µ+
e-
ϕ
θ1θ2
Robert Harlander — Precision Higgs physics – p. 45
WBF Signature
V
q
H
q_
V→ 0
pp
J1J2
µ+
e-
ϕ
θ1θ2
Robert Harlander — Precision Higgs physics – p. 45
WBF Signature
VV
q
q
q
qH
→ 0
pp
J1J2
µ+
e-
ϕ
θ1θ2
NLO QCD: [Figy, Oleari, Zeppenfeld ’03] + EW: [Ciccolini, Denner, Dittmaier ’08]
Robert Harlander — Precision Higgs physics – p. 45
WBF: QCD+EW corrections
EW, cutsEW, no cuts
QCD, cutsQCD, no cuts
pp → Hjj + X
MH [GeV]
δ [%]
700600500400300200100
10
5
0
−5
−10
[Ciccolini, Denner, Dittmaier ’08]
Robert Harlander — Precision Higgs physics – p. 46
WBF: other corrections
mixed QCD/EW [Bredenstein, Hagiwara, Jager ’08]
gluon fusion/WBF interference [Andersen, Binoth, Heinrich, Smillie ’07]
gluon induced WBF [R.H., Vollinga, Weber ’08]
Robert Harlander — Precision Higgs physics – p. 47
Weak Boson Fusion
H
q
q
Vq
V
q
vs.
gg → H+2 jets: [Del Duca, Kilgore, Oleari, Schmidt, Zeppenfeld ’01]
NLO for mt → ∞: [Campbell, Ellis, Zanderighi ’06]
gg → H + n jets: [Andersen, Del Duca, White ’08]
appropriate cuts allow distinction
Robert Harlander — Precision Higgs physics – p. 48
Measure CP
0
0.001
0.002
0.003
0.004
0.005
0.006
0.007
0.008
0.009
-160 -120 -80 -40 0 40 80 120 160
1/σ
dσ /
d ∆φ
jj
∆φjj
CP-even, CP-odd
CP-even
CP-odd
SM
Robert Harlander — Precision Higgs physics – p. 49
General theory progress
1-loop multileg
“classical” approach
[Passarino, Veltman ’79], [Davydychev ’91],[Giele, Glover ’04], [Ellis, Giele, Zanderighi ’05], [Denner, Dittmaier ’05],[v. Hameren, Vollinga, Weinzierl ’05], [Binoth et al. ’08]
Robert Harlander — Precision Higgs physics – p. 50
General theory progress
1-loop multileg
“classical” approach
[Passarino, Veltman ’79], [Davydychev ’91],[Giele, Glover ’04], [Ellis, Giele, Zanderighi ’05], [Denner, Dittmaier ’05],[v. Hameren, Vollinga, Weinzierl ’05], [Binoth et al. ’08]
generalized unitarity
[Bern, Dixon, Dunbar, Kosower ’94],[Britto, Cachazo, Feng ’05], [Berger, Bern, Dixon, Forde, Kosower ’06],[Ossola, Papadopoulos, Pittau ’08], [Giele, Kunszt, Melnikov ’08],[Giele, Zanderighi ’08], [Ellis, Giele, Kunszt, Melnikov, Zanderighi ’08]
Robert Harlander — Precision Higgs physics – p. 50
Background processes: Les Houches ’05 wishlist
Reaction background for existing calculations
pp→ V V j ttH, new physics WWj: Dittmaier, Kallweit, Uwer ’07WWj: Campbell, R.K.Ellis, Zanderighi ’07WWj: Binoth, Guillet, Karg, Kauer, Sanguinetti
(in progress)
pp→ ttbb ttH this talk
pp→ ttjj ttH –
pp→ V V bb VBF→ H→ V V , tt, NP –
pp→ V V jj VBF→ H→ V V VBF: Jäger, Oleari, Zeppenfeld ’06 + Bozzi ’07
pp→ V jjj new physics amplitudes: Berger et al. ’08, R.K.Ellis et al. ’08
pp→ V V V SUSY trilepton signal ZZZ: Lazopoulos, Melnikov, Petriello ’07
WWZ: Hankele, Zeppenfeld ’07
V V V : Binoth, Ossola, Papadopoulos, Pittau ’08
NLO for 2→ 3 processes established
very few calculations for 2→ 4, no complete calculation for pp process
e+e+→ 4f (EW) Denner et al. ’05 , e
+e+→ HHνν (EW) Boudjema et al. ’05
γγ → ttbb (QCD) Lei et al. ’07, uu→ ssbb (QCD) Binoth et al. ’08
Workshop on Higgs Boson Phenomenology, Zurich, January 7–9, 2009 Ansgar Denner (PSI) pp → ttbb + X – p.2
Robert Harlander — Precision Higgs physics – p. 51
Open questions
perturbative calculations become more and more precise – beware of the
non-perturbative factors:
take pdf variations serious
underlying event models? → VBF central jet veto!
to what extent do we need (N)NLO MC’s?
can we put CKKW, MLM on a more solid ground?
Robert Harlander — Precision Higgs physics – p. 52
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