Can Kl This Talk Covers arXiv:1711.05300: Chacko, CK, Najjari, - PowerPoint PPT Presentation

Searching for new physics - Leaving no stone unturned (2019) Probing the Twin Higgs Mechanism at Collider Experiments f 1 / v = 3 f/ v = 3 2 � 2 � 0.9 H Discovery 1200 0.8 5 � � 5 5 � � 2 Higgs Coupling Sensitivity HL - LHC 10 � 1 10 � 1 1100 � HL � LHC � HL � LHC 5 � 2 � Z � �� Z � �� ✏ ✏ � HL � LHC � HL � LHC A � �� A � �� mis = 200 GeV 1000 E T � HL � LHC � HL � LHC Z � �� Z � �� 5 � � HL � LHC � HL � LHC 2 � A � �� A � �� 10 � 2 m H ( GeV ) 10 � 2 900 200 400 600 800 1000 200 400 600 800 1000 � [GeV] m A m B � [GeV] ATLAS DV f 1 / v = 5 f/ v = 5 800 2 � m 0 = 25 GeV 5 � 2 5 � � 5 � 2 � 700 10 � 1 10 � 1 5 � 2 � ✏ ✏ 2 � 5 � 600 Tuned � HL � LHC � HL � LHC � HL � LHC � HL � LHC CMS ≥ 5 σ Z � �� Z � �� Z � �� Z � �� � HL � LHC � HL � LHC � HL � LHC � HL � LHC 500 A � �� A � �� A � �� A � �� 10 � 2 10 � 2 300 350 400 450 500 550 600 200 400 600 800 1000 200 400 600 800 1000 � [GeV] m A m B � [GeV] m T ( GeV ) Can Kılıç

This Talk Covers arXiv:1711.05300: Chacko, CK, Najjari, Verhaaren arXiv: 1812.08173: CK, Najjari, Verhaaren arXiv: 1904.11990: Chacko, CK, Najjari, Verhaaren See also: arXiv: 1506.06141: Curtin, Verhaaren arXiv: 1811.05977: Bishara, Verhaaren arXiv: 1904.10468: Batell, Verhaaren

Probing Naturalness Naturalness of the electroweak breaking sector has been a major motivation for TeV scale physics. So far, null results only → “Little hierarchy problem” Neutral naturalness: Discovery at colliders is challenging. Next step: If we discover new degrees of freedom, how can we probe their connection to the naturalness puzzle? Adopt Twin Higgs Mechanism as a simple benchmark case.

MODEL DETAILS

Mirror TH vs Fraternal TH Chacko, Goh, Harnik Craig, Katz, Strassler, Sundrum hep-ph/0506256 1501.05310 Color x EW Color’ x EW’ Two scalar doublets 3 matter (hypercharge mixing) Twin matter generations SM sector Twin sector In MTH, twin matter content is identical to SM. In FTH, twin matter only contains 3rd generation.

Basics of the Model 0 1 @ H A H = A H B Symmetry structure: Z 2 (A ⟷ B) for the entire Lagrangian, scalar sector has SU(4) global symmetry, with SU(2) A x SU(2) B subgroup gauged. Symmetry breaking results in 1 heavy scalar (H), 1 physical light scalar (h), and massive W/Z/W’/Z’ The two physical scalars can mix → minimal portal

Soft Breaking Exact Z 2 symmetry is ruled out experimentally (h couplings SM-like). Introduce soft breaking: divergences still under control. ⌘ 2 V = − µ 2 ⇣ ⌘ ⇣ ⌘ 2 � SU(4) and Z 2 H † A H A + H † H † A H A + H † + λ B H B B H B ⇣ ⌘ 2 + m 2 ⇣ ⌘ ⇣ H † A H A − H † H † H † Z 2 only + δ + B H B A H A B H B Symmetric setup means few parameters, possible to overdetermine the system through measurements.

Scalar spectrum and couplings √ √ Start with: v EW ≡ 2 f sin ϑ , v B ≡ 2 f cos ϑ 0 1 0 1 0 1 @ h − @ cos θ sin θ @ h A = Mass eigenstates: A A h + − sin θ cos θ σ Consistency condition m + ≥ cot ϑ = v B = m T on scalar potential m − v EW m t g h − SM = g SM cos( ϑ − θ ) , Couplings to SM states: g h + SM = g SM sin( ϑ − θ ) .

H h MIRROR TWIN HIGGS DISCOVERY OF A SCALAR OR VECTOR(S)

Discovery of Heavy Higgs HL-LHC 1000 0.6 0.7 0.8 0.9 0.95 σ ( pp → h ) Γ ( h → SM ) SM 900 Probe into scalar sector. 800 0.99 m h , v fix 2 out of 4 700 m + ( GeV ) parameters in the potential. 600 h couplings to SM fermions 500 suppressed by cos( 𝜄 ), can be determined by precision 400 Higgs measurements. 300 300 400 500 600 700 800 900 1000 m T ( GeV )

Parameters vs. Observables 1 0.50 B - sector tt BR 0.10 WW ZZ 0.05 hh m T = 500 GeV m T = 800 GeV 0.01 400 500 600 700 800 900 1000 m + ( GeV ) If Z 2 symmetry is softly broken, the same mixing angle also appears in h couplings to twin states. Once H mass measured, potential is fully determined, rate is predicted. In the SU(4) limit, H → V SM V SM (and hh) is not suppressed, good discovery channel.

H Discovery Prospects at the LHC 0.9 0.8 σ ( pp → H ) Γ ( H → ZZ → 4l ) 0.99 L = 3000 fb - 1 1400 s = 100 TeV 1200 Higgs Coupling Sensitivity M + ( GeV ) 1000 s = 33 TeV ATLAS ≥ 2 σ 800 s = 14 TeV 600 CMS ≥ 2 σ CMS ≥ 5 σ 400 600 800 1000 1200 1400 m T ( GeV ) Large part of LHC discovery region for H in tension with existing Higgs coupling constraints.

Future Lepton Colliders ILC (1 TeV) and CLIC (1.5 TeV) as benchmarks Higgs couplings can be probed to 1% W-fusion dominates production H → hh → 4b decay mode has best S/B e + e + e + ν e e + H W + Z Z H H W − Z ν e e − e − e − Z e −

H → hh → 4b Search Demand 3 b-tagged jets with p T >20 GeV, | 𝜃 |<2.5 Reconstruct two pairs with 75 GeV< m jj < 135 GeV 1000 0.8 1000 0.9 0.8 0.9 σ ( ee → H v e v e ) Γ ( H → hh → bbbb ) → bbbb ) σ ( ee → H v e v e ) Γ ( H → hh → bbbb ) σ → Γ → L = 1500 fb - 1 s = 1.5 TeV L = 3000 fb - 1 s = 1 TeV 900 900 ≥ 2 σ 800 Higgs Coupling Sensitivity 99 ≥ 5 σ 800 0.99 0.99 M + ( GeV ) M + ( GeV ) ≥ 2 σ Higgs Coupling Sensitivity ≥ σ 700 700 ≥ 5 σ 600 ≥ σ 600 500 500 1000 300 400 500 600 700 800 900 1000 300 400 500 600 700 800 900 1000 m T ( GeV ) m T ( GeV )

Checking the Prediction Assume that dominant uncertainty arises from Higgs coupling measurements. 900 900 0.2 σ ( ee → H v e v e ) Γ ( H → hh → bbbb ) L = 3000 fb - 1 0.3 s = 1 TeV σ ( ee → H v e v e ) Γ ( H → hh → bbbb ) L = 1500 fb - 1 s = 1.5 TeV 800 800 m + ( GeV ) m + ( GeV ) 0.5 700 700 0.4 0.5 0.3 0.4 0.2 600 600 0.1 500 500 500 600 700 800 900 500 600 700 800 900 m T ( GeV ) m T ( GeV )

Hypercharge Portal The following term is dimension 4 and consistent with the Z 2 symmetry: ✏ 2 B 0 µ ν B µ ν However, a massless twin photon ruled out (mixing at 1 loop). Case 1) Explicit mass term (Proca) m 2 B 0 µ B 0 µ , 2 B 0 Model parameters relevant for vectors : f, 𝜁 , m B’ . Two observable masses and rates.

2x2HDM Case 2) Two (twin) Higgs doublets. Additional physical scalars in our sector can be made heavy. Freedom to choose degree of alignment in the twin sector. 0 † 0 2 | 2 | H 1 H , 0 † 0 † 0 0 ( H 1 H 1 )( H 2 H 2 ) Maximal alignment in gives massless dark photon. Choose maximal misalignment as benchmark. Model parameters relevant for vectors: f 1 , f 2 , 𝜁 . Two observable masses and rates as before.

Spectrum and Limits - Proca mass 1000 ✏ = 0 . 1 m Z m A � ✏ =0 . 1 ✏ =0 . 1 10 5 f/ v =3 f/ v =3 10 4 m Z � 800 f/ v =5 f/ v =5 � ( pp ! Z � ) [fb] � ( pp ! A � ) [fb] m V [GeV] 10 4 f/ v 600 10 3 3 10 3 5 400 10 2 10 2 13 TeV 13 TeV 100 TeV 100 TeV 200 10 1 300 400 500 600 700 800 900 1000 200 250 300 350 m Z � [GeV] m A � [GeV] 200 400 600 800 1000 m B � [GeV] Define A’ (Z’) to be the lighter (heavier) mass eigenstate. In the limit of large m B’ , Z’ = B’. A’ decouples from SM.

Spectrum and Limits - 2x2HDM 1200 ✏ = 0 . 1 m Z ✏ =0 . 1 m A � ✏ =0 . 1 f 1 / v =3 10 3 10 6 1000 f 1 / v =5 m Z � � ( pp ! Z � ) [fb] � ( pp ! A � ) [fb] f 1 / v m V [GeV] 10 2 10 5 800 3 5 10 1 10 4 600 10 0 10 3 400 f 1 / v =3 13 TeV 13 TeV 10 � 1 f 1 / v =5 100 TeV 100 TeV 10 2 200 400 600 800 1000 150 200 250 300 350 m Z � [GeV] m A � [GeV] 200 400 600 800 1000 � [GeV] m A For a particular ratio of vev’s, the Z’ becomes W’ 3 , which is orthogonal to the B’ and decouples from the SM. Unlike the Proca mass case, the A’ remains coupled at large values of m B’ . Bounds are stronger than the other case.

Constraints Resonant production, Z coupling deviations LEP: Z coupling to electrons decreases, invisible decay channels added. ∆Γ Inv = − 2 . 2 ± 1 . 6 MeV . For invisible width, first effect dominates, no significant bound. Z partial width to electrons gives bound. Z → e + e − � � = 83 . 91 ± 0 . 12 MeV Γ Bound from S and T parameters. Direct searches for dilepton resonances basically dominate over the constraints listed above.