Higgs ID at the LHC with V. Barger, H. E. Logan arxiv:0902.0170 - PowerPoint PPT Presentation

Higgs ID at the LHC with V. Barger, H. E. Logan arxiv:0902.0170 Gabe Shaughnessy Northwestern University Argonne National Laboratory Pheno 2009 May 11, 2009 1 May 11, 2009 Pheno 2009

The Higgs and the LHC • One of the first goals of the LHC is to discover the Higgs boson • Higgs coupling measurements are key to identifying a true Higgs boson (W/Z couplings) • Many models contain Higgs sector that includes more Higgs states than in SM • If we only see one Higgs state, can we expect to differentiate various Higgs sectors based on small deviations from SM couplings? 2 May 11, 2009 Pheno 2009

What we assume • Natural flavor conservation – Due to symmetry of model Glashow & Weinberg, PRD15, 1958 (1977); Paschos, PRD15, 1966 (1977) u, d, ℓ ± � – FCNCs can be mitigated by coupling of each fermion sector � to just one Higgs doublet • Flavor conservation motivates three general classes of models based on the number of Higgs doublets – One doublet, , couples to the three fermion sectors Φ f – Two doublets, , , couples to the three fermion sectors in 3 combination Φ f Φ f ′ – Three distinct doublets, , couple to each fermion sector separately Φ u , Φ d , Φ ℓ • Neglect loop induced couplings: ggh, γγ h, Z γ h – Many new physics states can propagate in loop. Interference can induce large shifts in effective couplings 3 May 11, 2009 Pheno 2009

Notation • Define the Higgs state as a sum of neutral, CP-even components of the doublets (and singlets, when present) � h = a i φ i i where are properly normalized: � a i ≡ � h | φ i � | a i | 2 ≡ 1 i • Define the Higgs VEV that gives masses to W/Z bosons in a similar way: � φ v = b i φ i i g W = g SM with so that � | b i | 2 ≡ 1 � h | φ v � W i • Barred couplings indicate rescaling with SM coupling – Observables from rate measurements: g W = g W /g SM = � h | φ v � ¯ W 4 May 11, 2009 Pheno 2009

Couplings • The W/Z coupling can be easily written as overlap of Higgs state with VEV that gives W/Z their mass g W = g W /g SM = � h | φ v � ¯ W � g W = � h | φ i � � φ i | φ v � = a i b i ( for singlets) ¯ b i = 0 i f R Φ † L = y f ¯ • Fermion couplings induced via Yukawa int. f F L + h.c. √ so that m f = y f b f v SM / 2 √ 2 � h | φ f � = m f → g f = y f / a f /b f v SM g f = g f /g SM = a f /b f → ¯ f • Decoupling limit: g W = ¯ ¯ g f = 1 5 May 11, 2009 Pheno 2009

Class 1: Fermion masses from 1 Doublet • Standard Model • SM + 1 gauge singlet • 2HDM-I (SM + 1 SU(2) doublet) • 2HDM-I + 1 gauge singlet • 2HDM-I + extra doublets 6 May 11, 2009 Pheno 2009

SM + 1 gauge singlet • Simplest extension of SM - all couplings universally reduced – Higgs state h = a f φ f + a s S � δ ≡ a s 1 − δ 2 – Normalization requires where is a decoupling a f = parameter • Couplings set only by decoupling SM+Singlet parameter: W b 10.0 t � # 1 − δ 2 g W = ¯ ¯ g f = 5.0 • No sensitivity to number of gauge 2.0 SM " x " x singlets 1.0 0.5 Expected LHC 0.2 sensitivities to , , and W b t τ for M h = 120 and 0.1 300 fb -1 x 2 detectors − 1.0 − 0.5 0.0 0.5 1.0 ! 7 May 11, 2009 Pheno 2009

2HDM-I (SM + 1 new Doublet) • Only SM doublet, , gives masses to fermions, both doublets, and φ f φ f φ 0 give masses to W/Z bosons – Higgs state: h = a f φ f + a 0 φ 0 • Two parameters: , tan β ≡ b f /b 0 δ ≡ cos( β − α ) = a f b 0 − a 0 b f 2HDM − I • W/Z Couplings: tan β = 5 W b � 10.0 t 1 − δ 2 g W = a f b f + a 0 b 0 = ¯ # 5.0 • Fermion couplings: � 1 − δ 2 + δ cot β 2.0 g f = ¯ SM " x " x 1.0 • Generic features: 0.5 g W � = ¯ g f ≡ ¯ ¯ g u = ¯ g d = ¯ g ℓ 0.2 0.1 − 1.0 − 0.5 0.0 0.5 1.0 ! 8 May 11, 2009 Pheno 2009

Class 2: Fermion masses from 2 Doublets • Classic 2HDM-II model (think SUSY Higgs sector) • Flipped 2HDM • Lepton-specific 2HDM • Free to add SU(2) doublet and singlet scalars for more extensions 9 May 11, 2009 Pheno 2009

2HDM-II • Masses for up fermions given by and down fermions by φ d φ u both contribute to W/Z masses – Higgs state: h = a u φ u + a d φ d • Two parameters: , tan β ≡ b u /b d δ ≡ cos( β − α ) = a u b d − a d b u � • W/Z Couplings: 1 − δ 2 g W = a u b u + a d b d = ¯ 2HDM − II tan β = 5 W • Fermion couplings: b 10.0 t # � 1 − δ 2 + δ cot β 5.0 g u = ¯ � 2.0 1 − δ 2 − δ tan β g d = ¯ ¯ g ℓ = SM " x " x 1.0 • Generic features: 0.5 g W � = ¯ g u � = ¯ ¯ g d = ¯ g ℓ • Pattern relation: 0.2 0.1 P ud = ¯ g W (¯ g u + ¯ g d ) − ¯ g u ¯ g d = 1 − 1.0 − 0.5 0.0 0.5 1.0 10 May 11, 2009 Pheno 2009 !

Lepton-specific 2HDM • Masses for quarks given by and leptons by φ q φ ℓ both contribute to W/Z masses – Higgs state: h = a q φ q + a ℓ φ ℓ • Two parameters: , δ ≡ cos( β − α ) = a q b ℓ − a ℓ b q tan β ≡ b q /b ℓ � • W/Z Couplings: 1 − δ 2 g W = a q b q + a ℓ b ℓ = ¯ Lepton − specific 2HDM tan β = 5 • Fermion couplings: W b 10.0 t # � 1 − δ 2 + δ cot β g q = ¯ 5.0 � 1 − δ 2 − δ tan β g ℓ = ¯ 2.0 SM " x " x 1.0 • Generic features: 0.5 g W � = ¯ g d � = ¯ ¯ g u = ¯ g ℓ • Pattern relation: 0.2 P u ℓ = ¯ g W (¯ g q + ¯ g ℓ ) − ¯ g q ¯ g ℓ = 1 0.1 − 1.0 − 0.5 0.0 0.5 1.0 11 May 11, 2009 Pheno 2009 !

How can we discriminate models? • Pattern relation helps discriminate models • Example: Lepton-specific 2HDM + additional singlets (with ) ξ ≤ 1 P u ℓ = ¯ g W (¯ g q + ¯ g ℓ ) − ¯ g q ¯ g ℓ = ξ – Fills 3-dim space of with g W , ¯ ¯ g q , ¯ 0 ≤ P u ℓ ≤ 1 g ℓ – Distinct relation from other models – Footprint of model inhabits different regions in g W , ¯ ¯ g u , ¯ g d , ¯ g ℓ • Invert relations to extract the Higgs components and VEV sharing of the model (step closer to understanding model): � ¯ � ξ − ¯ � 1 / 2 � 1 / 2 g 2 g W − ¯ g ℓ ℓ b q , = = g 2 g 2 g q − ¯ g ℓ ¯ ¯ q − ¯ ℓ � ¯ � 1 / 2 � 1 / 2 � g 2 ξ − ¯ g W − ¯ g q q b ℓ = = , g 2 g 2 g ℓ − ¯ g q ¯ ¯ ℓ − ¯ q � a q b q ¯ g q , a ℓ = b ℓ ¯ g ℓ , a s = 1 − ξ , = 12 May 11, 2009 Pheno 2009

Class 3: Fermion masses from 3 Doublets • Each doublet corresponds to each fermion sector (3HDM-D) – May add additional doublets and singlets that do not couple to fermions 3HDM − D W b 10.0 t # 5.0 2.0 SM " x " x 1.0 0.5 0.2 0.1 − 1.0 − 0.5 0.0 0.5 1.0 ! 13 May 11, 2009 Pheno 2009

Decision tree χ , ψ defined as pattern relation for specific model 14 May 11, 2009 Pheno 2009

Decoupling limit at the LHC SM Flipped 2HDM • Method, of course, fails up to 8 0.5 uncertainties in coupling 6 " 2 ! 2 # 0.0 measurements 4 2 1 # − 0.5 0 • Decoupling region defined by 0.0 0.2 0.4 0.6 0.8 1.0 5 10 15 20 tan $ ! uncertainties at the LHC/ILC for 2HDM − I Lepton − specific 2HDM 1.0 1.0 120 GeV Higgs mass: 0.5 0.5 g 2 g 2 g 2 g 2 t W b τ LHC 22% 43% 32% 27% ! ! 0.0 0.0 ILC 2.4% 4.4% 6.0% 6.6% − 0.5 − 0.5 5 10 15 20 5 10 15 20 χ 2 tan $ tan $ • Regions defined by : 2HDM − II 3HDM − D 1.0 1.0 0.8 0.5 ( Γ i − Γ SM ) 2 χ 2 = � i 0.6 � 2 � δ Γ SM ! & 0.0 i = W,b,t, τ i 0.4 0.2 − 0.5 0.0 5 10 15 20 0.0 0.2 0.4 0.6 0.8 1.0 15 May 11, 2009 Pheno 2009 cos 2 % tan $

Decoupling limit at the ILC SM Flipped 2HDM !") & !"# % !"' " # ! # # !"! $ ! !"' # ' # ! !"# ! ! !") !"! !"# !"$ !"% !"& '"! ( '! '( #! *+, $ ! !"#$ ! % &'()*+ ! ,('-./.-0!"#$ !"$ !"$ !") !") !"# !"# g 2 g 2 g 2 g 2 W b t τ !"' !"' LHC 22% 43% 32% 27% ! ! !"! !"! ILC 2.4% 4.4% 6.0% 6.6% ! !"' ! !"' ! !"# ! !"# ! !") ! !") ( '! '( #! ( '! '( #! *+, $ *+, $ !"#$ ! %% 1"#$ ! # !"$ '"! !") !"& !"# !"% !"' & ! !"! !"$ ! !"' !"# ! !"# ! !") !"! ( '! '( #! !"! !"# !"$ !"% !"& '"! *+, $ -./ # % 16 May 11, 2009 Pheno 2009