New Physics Scales to be Lepton Colliders (CEPC)

Transcription

1 New Physics Scales to be Lepton Colliders (CEPC) Shao-Feng Ge (gesf02@gmail.com) Max-Planck-Institut für Kernphysik, Heidelberg, Germany Contribution to CEPC precdr & CDR Collaboration with Hong-Jian He & Rui-Qing Xiao arxiv:

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3 Higgs discovery is not just about H particle Force Mediators Gauge Forces Spin-1 Gauge Bosons Gravity Spin-2 Graviton (?) New Force Spin-0 Higgs Boson Deep understanding of Mass Generation Yukawa Forces Hierarchy & Mixing (Flavor Symmetries?) Discrete v.s. Continuous Full v.s. Residual [ , , ] Higgs Self-Interaction Forces h 3 & h 4 (concerns spontaneous EWSB and providing masses to all particles). True Self-Interactions Exactly the Same Quantum # Spin Charge Both Yukawa & Self-Interaction forces associated with spin-0 Higgs were Never Seen Before. Needs to be directly tested.

4 Current Status LEP/Tevatron/LHC have good tests only on gauge forces. Higgs Yukawa Force is Flavor-Dependent + Huge Hierarchy. LHC has limited sensitivity to Yukawa couplings of htt, hbb, hτ the order of 15% 30%. LHC cannot probe other Yukawa Couplings! Higgs Self-Interaction is also LHC Run-I κ W = κ Z = κ t = κ b = κ τ = < 1.87 κ µ CMS fb (8 TeV) fb (7 TeV) 68% CL 95% CL Parameter value 1/2 /2v) or (g λ f V CMS µ 68% CL 95% CL fb (8 TeV) fb (7 TeV) SM Higgs b τ (M, ε) fit W Z t 68% CL 95% CL Particle mass (GeV)

5 Standard Model is Incomplete! Mass Generation Yukawa force is Flavor-Dependent & Hierarchically Unnatural Higgs mass itself is Radiatively Unnatural Vacuum Stability Neutrino Oscillation Dark Matter Matter-Antimatter Asymmetry Vacuum Energy & Inflation Pole top mass Mt in GeV Instability ,2,3 Σ h Meta stability Stability

6 Beyond SM? NO particle beyond SM LHC yet! 1.9TeV di-boson? 750GeV di-photon? Full/Precise Picture of New Higher Energy? Even within SM, we are strongly motivated to quantitatively test Yukawa and Higgs Self-Interaction Forces! Precision Measurement + Discovery Machine: SLAC? + Sp ps [W/Z Masses] LEP + (Tevatron [t] + LHC [h]) Go beyond! CEPC (e + e, 250 GeV) SppC (pp, TeV)

7 Higgs 250 GeV LHC tells us: h(125) is SM-like Dream Case for Experiments! CEPC produces h(125) via e + e Zh, ν νh, e + e h Indirect Probe to New Physics. 5/ab with 2 detectors in 10y 10 6 Higgs Relative Error e + Z H e Z e + e W W - ν H ν e + e Z Z e + H e

8 Production & Background Processes Large Statistics 10 6 Higgs Relative Error Clean Background Easy for Simulation [Loop Calculation] Polarization

9 Mo, Li, Ruan & Lou, Chin.Phys.C 2015

10 e + e Zh Recoil Mass Distribution: m 2 rec ( s E ff ) 2 p 2 ff Cross Section: σ(zh) Γ(h ZZ) Higgs Mass: m h Higgs Width: Γ h Branching Ratios: Model-Independent Invisible Decay

11 Combination of Various Channels σ(zh) [0.51%] h bb [0.28%], cc [2.2%], gg [1.6%]

12 Combination of Various Channels h ZZ [4.3%] h WW [1.5%] h τ τ [1.2%] h γγ [9.0%] h µµ [17%] h invisible [0.14%] CEPC:

13 Extracting the Physics Potential Coupling: Cross Section: δσ(zh) g hii g sm hii σ(zh) 2δκ Z, Decay Width: Γ hii Γ sm hii Branching Ratio: Γ i = κ 2 i, κ i 1 + δκ i. Γ inv Γ sm tot Br i Br sm i 1 + Γ tot j with coefficients, δσ(ν νh) σ(ν νh) 2δκ W. = Br(inv) δκ inv. A ij δκ j, Br inv δκ inv. A ij = 2(δ ij Br sm j ), A i,inv = 1, A inv,i = 0, A inv,inv = 1.

14 Inputs: Event Rate Cross Section & BR SM Predictions: M h Γ h σ(zh) σ(ν νh) Br(h bb) 5.9 MeV 2.8% 0.51% 2.8% Decay Mode σ(zh) Br Br h bb 0.28% 0.57% h cc 2.2% 2.3% h gg 1.6% 1.7% h ττ 1.2% 1.3% h WW 1.5% 1.6% h ZZ 4.3% 4.3% h γγ 9.0% 9.0% h µµ 17% 17% h invisible 0.14% Br(b b) Br(c c) Br(gg) Br(τ τ) Br(WW ) Br(ZZ) Br(γγ) Br(µ µ) Br(inv) 58.1% 2.10% 7.40% 6.64% 22.5% 2.77% 0.243% 0.023% 0

15 Precision on Higgs Couplings CEPC precdr Table: Precisions on measuring Higgs couplings at CEPC (250GeV, 5ab 1 ), in comparison with LHC (14TeV, 300fb 1 ), HL-LHC (14TeV, 3ab 1 ) and ILC (250GeV, 250fb 1 )+(500GeV, 500fb 1 ). Precision (%) CEPC LHC HL-LHC ILC κ Z κ W κ γ κ g κ b κ c κ τ κ µ 8.59 Br inv Γ h LHC & ILC from

16 Precision on Higgs Couplings CEPC precdr

17 Precision on Higgs Couplings 1/2 /2v) or (g λ f V CMS µ 68% CL 95% CL fb (8 TeV) fb (7 TeV) SM Higgs b τ (M, ε) fit W Z t 68% CL 95% CL Particle mass (GeV) Particle Mass / VEV [246 GeV] CEPC c τ µ 95% CL b Particle Mass [GeV] 68% CL SM Higgs Z W

18 Precision on Higgs Couplings CEPC precdr

19 Higgs Self-Coupling Rescaling of the trilinear term h 3 L = 1 3! δκ h3λ sm hhh h3. Affect σ(zh) via Loop Correction Constrained by σ(zh) meansurement δσ(zh) σ(zh) 2 δκ Z δκ h

20 Higgs Self-Coupling Precision (%) HL-LHC (3ab -1 ) CEPC1 (1ab -1 ) CEPC3 (3ab -1 ) CEPC5 (5ab -1 ) CEPC10 (10ab -1 ) SPPC3 (3ab -1 ) SPPC30 (30ab -1 ) CEPC precdr HL-LHC CEPC1 CEPC3 CEPC5 CEPC10 SPPC3 SPPC30

21 CEPC Test of Higgs CP Violation LHC: h ZZ, τ τ CEPC: h τ τ L hττ y τ 2 h τ(cos + iγ 5 sin )τ. Complex enough to retain info about the τ spin. h τ + + τ ρ + ν τ + ρ ν τ π + π 0 ν τ + π π 0 ν τ. CP-even part (cos ) in p-wave & CP-odd (sin ) in s-wave. Precision CEPC Higgs Report

22 Effective Field Approach Unitarity see also New physics high energy scale & can only be probed Indirectly L = L SM + y ij Λ GeV (L i H)( H L j ) + c i Λ 2 O i. ij i SM Gauge Invariance is respected O H 1 2 ( µ H 2 ) 2, O T 1 2 (H Dµ H) 2, O WW g 2 H 2 W a µνw a,µν, O BB g 2 H 2 B µν B µν, O WB gg H σ a HW a µνb µν, O HB ig (D µ H) (D ν H)B µν, O HW ig(d µ H) σ a (D ν H)W a µν, O (3) L (ih σ a Dµ H)(Ψ L γ µ σ a Ψ L ), O (3) LL (Ψ Lγ µ σ a Ψ L )(Ψ L γ µ σ a Ψ L ), O L (ih Dµ H)(Ψ L γ µ Ψ L ), O g g 2 s H 2 G a µνg aµν, O R (ih Dµ H)(ψ R γ µ ψ R ).

23 Scheme-Independent Analysis EW Parameters: M (SM) Z = M (r) Z ( 1 + δm Z M Z which can be denoted as Observables: ) (, G (SM) F = G (r) F 1 + δg ) ( F, α (SM) = α (r) 1 + δα ). G F α f (SM) f (r) + δf f (r) ( 1 + δf f X X(f (SM) ) + δx = X(f (r) ) + X (f )δf + δx ) Analytical Fit: χ 2 ( δm Z, δg F, δα, c i Λ 2 ) = j [ ( O th j δmz, δg F, δα, c ) ] i Λ O exp 2 2 j, O j

24 Scheme-Independent Analysis Observables: EWPO + HO Observables Central Value Relative Error SM Prediction M Z GeV M W GeV G F GeV α σ[zh] 0.51% σ[ν νh] 2.86% σ[ν νh] 350GeV 0.75% Br[WW ] 1.6% 22.5% Br[ZZ] 4.3% 2.77% Br[bb] 0.57% 58.1% Br[cc] 2.3% 2.10% Br[gg] 1.7% 7.40% Br[ττ] 1.3% 6.64% Br[γγ] 9.0% 0.243% Br[µµ] 17% 0.023% Fitting Parameters: EW: M (SM) Z = M (r) Z ( ) 1 + δm Z M, G (SM) Z F dim-6 Higgs Operators: c i ( ) = G (r) F 1 + δg F G, α (SM) = α (r) ( 1 + δα ) F α.

25 Sensitivities from Existing EWPO & Future HO New Physics Scales to be Probed at CEPC via dim-6 Operators 95% EWPO+HO 5σ Λ/ c j (TeV) /4 2 0 c H c T c WW c BB c WB c HW c HB c (3) LL c (3) L c L c R c (3) Lq c Lq c Ru c Rd c g

26 Enhancement from M Z & M CEPC Observables Current Relative Error CEPC M Z M W Table: The M Z and M CEPC [Z.Liang, Z & W CEPC ]. Scheme-Independent Analysis Λ ci [TeV ] O H O T O WW O BB O WB O HW O HB O (3) LL O (3) L O L O R O (3) L,q O L,q O R,u O R,d O g HO+EWPO M Z M W M Z,W Table: Impacts of the projected M Z and M W measurements at CEPC on the reach of new physics scale Λ/ c j (in TeV) at 95% C.L. The Higgs observables (including σ(ν νh) at 350 GeV) and the existing electroweak precision observables are always included in each row. The differences among the four rows arise from whether taking into account the measurements of M Z and M W or not. The second (third) row contains the measurement of M Z (M W ) alone, while the first (last) row contains none (both) of them. We mark the entries of the most significant improvements from M Z /M W measurements in red color. SFG, Hong-Jian He, Rui-Qing Xiao,

27 Enhancement from Z-Pole CEPC N ν A FB (b) R b R µ R τ sin 2 θ w Table: The Z-pole measurements at CEPC [Z.Liang, Z & W CEPC ]. Z-Pole Observables are IMPORTANT for New Physics Scale Probe O H O T O WW O BB O WB O HW O HB O (3) LL O (3) L O L O R O (3) L,q O L,q O R,u O R,d O g Table: Impacts of the projected Z-pole measurements at the CEPC on the reach of new physics scale Λ/ c j (in TeV) at 95% C.L. For comparison, the first row of this table repeats the last row of Table??, as our starting point of this table. For the (n + 1)-th row, the first n observables are taken into account. In addition, the estimated M Z and M W measurements at the CEPC, the Higgs observables (HO), and the existing electroweak precision observables (EWPO) are always included for each row. The entries with major enhancements of the new physics scale limit are marked in red color. A factor of 2 enhancement from Z-Pole Observables

28 Sensitivity from EWPO+HO+Z-Pole New Physics Scales to be Probed at CEPC via dim-6 Operators 95% EWPO+HO+Z-Pole 5σ 30 Λ/ c j (TeV) c H c T c WW c BB c WB c HW c HB c (3) LL c (3) L c L c R c (3) Lq c Lq c Ru c Rd c g

29 Summary Higgs Discovery is not just about New Particle, but also New Force! Yukawa Force: Non-Trivial Mixing & Hierarchically Unnatural Higgs Self-Interaction Force: Radiatively Unnatural New Physics Neutrino Oscillation Dark Matter Matter-Antimatter Asymmetry Vacuum Energy & Inflation LHC Discovery Machine vs Poor sensitivity CEPC 10 6 Higgs Higgs Coupling O(1%) Level Higgs Self-Coupling 30% Precise measurement of CP 2.5 Probe new physics to 10 TeV (40 TeV for O g ) [35 Z-Pole]

30 Thank You!