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Introduction
- Run I showed the Higgs boson is broadly SM-like
- How can we constrain the CP-properties of the Higgs?
CONSTRAINING HIGGS CP - PROPERTIES IN GLUON FUSION Matthew Dolan - - PowerPoint PPT Presentation
CONSTRAINING HIGGS CP - PROPERTIES IN GLUON FUSION Matthew Dolan - - PowerPoint PPT Presentation
CONSTRAINING HIGGS CP - PROPERTIES IN GLUON FUSION Matthew Dolan SLAC and University of Melbourne 1406.3322 with P . Harris, M. Jankowiak and M. Spannowsky Introduction Run I showed the Higgs boson is broadly SM-like How can we
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SLIDE 3
Introduction
- Higgs an even eigenstate of CP in the SM
- Many BSM theories include CP-odd scalars (pseudoscalars)
- Or have CP-violation in the Higgs sector
- Physical Higgs then not an eigenstate of CP
Don’t ask ‘is the Higgs CP-even or odd’ but ‘how much’?
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- Traditional analyses rely on angular correlations between
decay products in
Φ µ− µ+ jα jβ θ` θh X Z Z p p ˆ ez ˆ ez θ Φ1
p p e− e+ µ+ µ−
θµ
θe ∆φ
φe
()
Q
(
Q
θ1 θ2 j1 j2 V1 V2 d θ
∆φ
From Englert et al, 1212.0840
X ! ZZ ! 4` Higgs-like state X
Or in correlations between tagging jets and decay products in weak boson fusion (WBF)
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Pseudoscalars do not have renormalisable couplings to massive vector bosons
2 4 6 0.2 0.4 0.6 Γ d∆φ 1 dΓ
- D5
+ D5 + SM
2
+
2 4 6 0.2 0.4 0.6 σ d∆φ 1 dσ
- D5
+ D5 + SM
2
+
2 4 6 0.2 0.4 0.6 σ d∆φjj 1 dσ
- D5
+ D5 + SM
2
+
e hV µVµ
Leading order scalar couplings are d=3 Leading order pseudoscalar couplings are d=5 e hV µν e
Vµν ecays and
From Englert et al, 1212.0840
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Results from ATLAS-CONF-2015-008 Sets constraints on
LV
0 =
( cαSM f 1
2gH Z Z ZµZ µ + gHWWW+ µW−µg
−1
4 1 Λ
f cαH Z Z Zµν Z µν + sα AZ Z Zµν ˜ Z µνg −1
2 1 Λ
f cαHWWW+
µνW−µν + sα AWWW+ µν ˜
W−µνg) X0.
mixing angles and higher dimension
- perators suppressed by scale
sα = sinα, cα = cos α
Λ
Tree-level SM is κSM = 1, cα = 1, Λ → ∞
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Naive expectation: 1 Λ ∼ α 2πv How large should CP-violating effects be? κSM ∼ 1, κAV V ∼ 1
Coupling ratio Best fit value 95% CL Exclusion Regions Combined Expected Observed Expected Observed ˜ HVV/SM 0.0 −0.48 (−∞, −0.55] S[4.80, ∞) (−∞, −0.73] S[0.63, ∞) ( ˜ AVV/SM) · tan ↵ 0.0 −0.68 (−∞, −2.33] S[2.30, ∞) (−∞, −2.18] S[0.83, ∞)
(˜ κAV V /κSM) tan α ∼ 10−3 tan α ˜ κAV V = 1 4 v ΛκAV V ∼ α 8π ∼ 10−3
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Information in Higgs production too BR(h → ZZ∗) and WBF negligible for a pure CP-odd state Gluon fusion increases by a factor ~9/4 Signal strength info rules out pure pseudoscalar at 4σ
Djouadi, Moreau 1303.6591 Freitas, Schwaller 1211.1980
0.5 1 1.5 0.5 1 1.5
- 0.0
0.5 1.0 1.5 0.0 0.5 1.0 1.5 2.0 2.5 3.0 Α xu
α < 0.76 (95% C.L.)
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What Other Couplings Can Be Probed?
- Scalar and pseudoscalar couplings to fermions and massless
vector bosons arise at the same order
g hGµνGµν d hGµν e Gµν, r
Tree-level couplings to fermions 1-loop couplings to gluons/photons
h ¯ ff
h ¯ fγ5f
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- Will focus on CP-sensitive variables in Higgs production
- Production via gluon fusion arises at same order in both cases
H (a)
H (b) H (c)
What Other Couplings Can Be Probed?
For decay see Felix and Marco’s talks
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What Other Couplings Can Be Probed?
- Will focus on CP-sensitive variables in Higgs production
- WBF amenable to angular analysis
- Gauge-Higgs invariant mass in associated production
For decays see Felix and Marco’s talks
()
Q
(
Q
θ1 θ2 j1 j2 V1 V2 d θ
∆φ
VX
M 500 1000 1500 2000 2500 Arbitrary Units 2000 4000 6000 8000 10000 12000
LHC8
+
- +
2
Ellis, Sanz, You 1208.6002
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- Higgs plus two jet production is known to be sensitive to the
Higgs CP properties through angular correlations in the jets
- In particular differences between azimuthal angles
Klamke, Zeppenfeld ’07
What Other Couplings Can Be Probed?
∆φjj
jj
Φ ∆
- 150
- 100
- 50
50 100 150
jj
Φ ∆ /d σ d σ 1/ 10 15 20 25 30 35 40 45
- 3
10 ×
CP-even CP-odd CP-mixed jj H → pp = 160 GeV
H
m
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Lh ¯
ff = cos ↵ yf ¯
f fh + sin ↵ e yf ¯ fi5 fh .
Lhgg = cos ↵ ↵S 12⇡v hGa
µνGa,µν + sin ↵ ↵S
4⇡v hGa
µν e
Ga,µν LhV V ⊃ cos α 2m2
W
v hWµW µ + cos α 2m2
Z
v hZµZµ
We will consider a mixed CP-state with couplings Mixing parametrised by angle is pure CP-even is pure CP-odd
α
α = 0
α = π/2
This generates couplings to gluons
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Event Generation
We generate signal using VBFNLO 2.6.3 at 8 and 14 TeV Gluon fusion generated at NLO WBF generated at LO Background using Sherpa 2.0.0 Generate Zjj (QCD + EW), W+jets and t¯ t QCD multijets assumed to be flat across phase-space
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Cross-Sections
α 8 TeV GF cross-section (fb) 8 TeV WBF cross-section (fb) 14 TeV GF cross-section (fb) 14 TeV WBF cross-section (fb) 0.00 250 467 1141 1481 0.30 278 426 1268 1351 0.60 352 318 1606 1009 0.90 447 181 2038 572 1.20 529 61 2411 194
In the CP-odd limit the WBF cross-section vanishes at tree-level The CP-odd GF cross-section is larger than the CP-even case by 9/4 We focus on h → ττ
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τhτh µτh eτh eµ lepton selection pτ
T > 45 GeV
pµ
T > 20 GeV
pτ
T > 30 GeV
pe
T > 25 GeV
pτ
T > 30 GeV
plead
T
> 20 GeV ptrail
T
> 10 GeV kinematic selection pH
T > 100 GeV
mµ
T < 30 GeV
me
T < 30 GeV b-tag veto with pb T > 20 GeV
loose jet selection mjj > 500 GeV |∆ηjj| >3.5 mjj > 500 GeV |∆ηjj| >3.5 mjj > 500 GeV |∆ηjj| >3.5 mjj > 500 GeV |∆ηjj| >3.5 tight jet selection mjj > 700 GeV |∆ηjj| > 4.5 pH
T > 100 GeV
mjj > 700 GeV |∆ηjj| >4.5 pH
T > 100 GeV
mjj > 700 GeV |∆ηjj| >4.5 pH
T > 100 GeV
Event Selection
We consider four different final states: di-hadronic, semi-leptonic and leptonic (e+mu) Cuts designed to mimic ATLAS/CMS di-tau analyses
CMS: 1401.5041 ATLAS-CONF-2013-108 updated to 1501.04943
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(GeV)
jj
m 500 1000 1500 2000 2500 3000 GeV)
- 1
(100
jj
/dm σ d
- 1
σ
- 2
10
- 1
10 1
Bkgs Higgs(WBF) = 0.0) α ggH+2j ( = 0.6) α ggH+2j ( = 1.2) α ggH+2j (
(rad)
jj
φ ∆
- 3
- 2
- 1
1 2 3 rad)
- 1
(0.1
jj
φ ∆ /d σ d
- 1
σ 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1
Bkgs Higgs(WBF) = 0.0) α ggH+2j ( = 0.6) α ggH+2j ( = 1.2) α ggH+2j ( jj
η 4 4.5 5 5.5 6 6.5 7 7.5 8 8.5 9 9.510 |
jj
η /d| σ d
- 1
σ 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5
Bkgs Higgs(WBF) = 0.0) α ggH+2j ( = 0.6) α ggH+2j ( = 1.2) α ggH+2j (
|/2)
jj
φ ∆ sin(| 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 |/2)
jj
φ ∆ /dsin(| σ d
- 1
σ
- 1
10 1
Bkgs Higgs(WBF) = 0.0) α ggH+2j ( = 0.6) α ggH+2j ( = 1.2) α ggH+2j (
Kinematic Distributions ∆φjj = φy>0 − φy<0 Most sensitive variable is
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is pretty optimal ∆φjj = φy>0 − φy<0 Trained a BDT to discriminate between two gluon fusion samples with and α = 0 α = 1.2
Background Efficiency 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 Signal Efficiency 0.2 0.4 0.6 0.8 1
(bdt)
1.5
α |))
jj
φ ∆ (sin(|
1.5
α (bdt)
0.6
α |))
jj
φ ∆ (sin(|
0.6
α
Background Efficiency 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 Signal Efficiency 0.2 0.4 0.6 0.8 1
(bdt)
1.5
α |))
jj
φ ∆ (sin(|
1.5
α (bdt)
0.6
α |))
jj
φ ∆ (sin(|
0.6
α
14 TeV 8 TeV
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Also trained a BDT to discriminate between GF+WBF signal and sum of backgrounds A category-based analysis using only does about as well as the BDT trained on full set of variables mττ, ∆φjj, mjj, ∆ηjj
leading Jet (GeV)
T
p 50 100 150 200 250 300 350 400 GeV)
- 1
(20
T
/dp σ d
- 1
σ 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2
Bkgs Higgs(VBF) = 0.0) α ggH+2j ( = 0.6) α ggH+2j ( = 1.2) α ggH+2j (
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α 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 Significance 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5
) α /2|) loose(
jj
φ ∆ and sin(|
τ τ
m ) α /2|) tight(
jj
φ ∆ and sin(|
τ τ
m ) α /2|) tight(
jj
φ ∆ mva and sin(| /2|) loose
jj
φ ∆ and sin(|
τ τ
m /2|) tight
jj
φ ∆ and sin(|
τ τ
m /2|) tight
jj
φ ∆ mva vs sin(| loose
τ τ
m tight
τ τ
m
8 TeV
- 1
20 fb
α 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 Significance 2 4 6 8 10 12 14
) α /2|) loose(
jj
φ ∆ and sin(|
τ τ
m ) α /2|) tight(
jj
φ ∆ and sin(|
τ τ
m ) α /2|) tight(
jj
φ ∆ mva and sin(| /2|) loose
jj
φ ∆ and sin(|
τ τ
m /2|) tight
jj
φ ∆ and sin(|
τ τ
m /2|) tight
jj
φ ∆ mva vs sin(| loose
τ τ
m tight
τ τ
m
14 TeV
- 1
50 fb
Constraints Dashed: Significance of total signal over SM background Solid: Exclusion significance relative to case with 50/fb at 14 TeV α = 0 α ≤ 0.7
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α 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 )
- 1
Exclusion (fb σ 2 1 10
2
10
3
10
Loose φ ∆ and
τ τ
m Tight φ ∆ and
τ τ
m Tight φ ∆ MVA and
Constraints Expected exclusion limit as a function of integrated luminosity at 14 TeV
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Comments We set limits assuming mixed interactions between the Higgs and matter fields: probed CP nature of Could also interpret in terms of SM + higher dimensional operators Orthogonal to limits derived from WBF/4l angular correlations Info from hadronic event shapes?: 1203.5788 h¯ tt
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Conclusions
- Higgs CP properties important part of Run II program:
probe as many couplings as possible!
- Lots of information available from Higgs production
- Gluon fusion a promising avenue for constraining Higgs CP
properties
- Limits on mixing angles: with 20/fb, with
500 /fb
- Further improvements possible with decay information
α ≤ 0.9 α ≤ 0.3
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