Precision Constraints on Higgs and Z couplings Joachim Brod ERC Workshop “Effective Field Theories for Collider Physics, Flavor Phenomena and Electroweak Symmetry Breaking” Schloss Waldthausen, November 12, 2014 With Ulrich Haisch, Jure Zupan – JHEP 1311 (2013) 180 [arXiv:1310.1385] With Admir Grelio, Emmanuel Stamou, Patipan Uttayarat – arXiv:1408.0792 With Martin Schmaltz – work in progress Joachim Brod (University of Mainz) Precision Constraints on Higgs and Z couplings 1 / 38
“Effective Field Theories for Collider Physics, Flavor Phenomena and Electroweak Symmetry Breaking” We usually think of flavor-conserving Higgs and Z couplings in terms of collider observables Can we get bounds on flavor-conserving couplings from precision (flavor) observables? Here I will discuss two examples: CP-violating Yukawa couplings (EDMs) Anomalous t ¯ tZ couplings (rare decays) Joachim Brod (University of Mainz) Precision Constraints on Higgs and Z couplings 2 / 38
Outline Anomalous Higgs couplings ttH bbH eeH Anomalous ttZ couplings Conclusion Joachim Brod (University of Mainz) Precision Constraints on Higgs and Z couplings 3 / 38
SM EFT No BSM particles at LHC ⇒ use EFT with only SM fields [See, e.g., Buchm¨ uller et al. 1986, Grzadkowski et al. 2010] L eff = L SM + L dim.6 + . . . For instance, m t = y t v EWSB y f ( ¯ √ Q L t R H ) + h.c. − → 2 √ √ 2) 3 2) 2 H † H δ m t ∝ ( v / δ y t ∝ 3( v / EWSB Λ 2 ( ¯ Q L t R H ) + h.c. − → , Λ 2 Λ 2 If both terms are present, mass and Yukawa terms are independent 2 κ f ¯ Y = − y f L ′ f L f R h + h.c. with complex κ f √ Joachim Brod (University of Mainz) Precision Constraints on Higgs and Z couplings 4 / 38
What do we know about Higgs couplings to fermions? -1 -1 19.7 fb (8 TeV) + 5.1 fb (7 TeV) CMS m = 125 GeV Combined H µ = 1.00 ± 0.13 Preliminary H → bb tagged µ = 0.93 ± 0.49 H tagged → τ τ = 0.91 0.27 µ ± H → γ γ tagged µ = 1.13 ± 0.24 H WW tagged → = 0.83 0.21 µ ± H → ZZ tagged µ = 1.00 ± 0.29 0 0.5 1 1.5 2 Best fit σ / σ SM [ATLAS-CONF-2013-034] [CMS-PAS-HIG-14-009] Joachim Brod (University of Mainz) Precision Constraints on Higgs and Z couplings 5 / 38
From h → γγ . . . In the SM, Yukawa coupling to fermion f is L Y = − y f ¯ √ γ f f h 2 We will look at modification h � � Y = − y f t κ f ¯ κ f ¯ L ′ √ f f + i ˜ f γ 5 f h 2 γ New contributions will modify Higgs production cross section and decay rates Joachim Brod (University of Mainz) Precision Constraints on Higgs and Z couplings 6 / 38
. . . to electric dipole moments Attaching a light fermion line leads to EDM Indirect constraint on CP -violating Higgs γ coupling f SM “background” enters at three- and h four-loop level t Complementary to collider measurements f γ Constraints depend on additional f assumptions Joachim Brod (University of Mainz) Precision Constraints on Higgs and Z couplings 7 / 38
Anomalous ttH couplings Joachim Brod (University of Mainz) Precision Constraints on Higgs and Z couplings 8 / 38
Constraints from gg → h gg → h generated at one loop Have effective potential α s α s h h µν G µν, a − ˜ µν � G µν, a v G a v G a V eff = − c g c g 12 π 8 π g c g , ˜ c g given in terms of loop functions h b, t κ g ≡ c g / c g , SM , ˜ κ g ≡ 3˜ c g / 2 c g , SM g σ ( gg → h ) = | κ g | 2 + | ˜ κ g | 2 = κ 2 κ 2 t + 2 . 6 ˜ t + 0 . 11 κ t ( κ t − 1) σ ( gg → h ) SM Joachim Brod (University of Mainz) Precision Constraints on Higgs and Z couplings 9 / 38
Constraints from h → γγ h → γγ generated at one loop Have effective potential α 3 α h h v F µν F µν − ˜ v F µν � F µν V eff = − c γ c γ π 2 π γ γ c γ , ˜ c γ given in terms of loop functions h h κ γ ≡ c γ / c γ, SM , ˜ κ γ ≡ 3˜ c γ / 2 c γ, SM W b, t γ γ Γ( h → γγ ) = | κ γ | 2 + | ˜ κ γ | 2 = (1 . 28 − 0 . 28 κ t ) 2 + (0 . 43 ˜ κ t ) 2 Γ( h → γγ ) SM Joachim Brod (University of Mainz) Precision Constraints on Higgs and Z couplings 10 / 38
LHC input CMS Preliminary -1 -1 2.0 s = 7 TeV, L ≤ 5.1 fb s = 8 TeV, L ≤ 19.6 fb g κ , κ κ g γ 1.8 1.6 1.4 Naive weighted average of ATLAS, CMS 1.2 1.0 0.8 κ g , WA = 0 . 91 ± 0 . 08 , κ γ, WA = 1 . 10 ± 0 . 11 0.6 0.4 g /γ, WA = | κ g /γ | 2 + | ˜ We set κ 2 κ g /γ | 2 0.2 0.0 0.0 0.5 1.0 1.5 2.0 κ γ [CMS-PAS-HIG-13-005] Joachim Brod (University of Mainz) Precision Constraints on Higgs and Z couplings 11 / 38
Electron EDM γ t γ h e EDM induced via “Barr-Zee” diagrams [Weinberg 1989, Barr & Zee 1990] | d e / e | < 8 . 7 × 10 − 29 cm (90% CL) [ACME 2013] with ThO molecules Constraint on ˜ κ t vanishes if Higgs does not couple to electron Joachim Brod (University of Mainz) Precision Constraints on Higgs and Z couplings 12 / 38
Neutron EDM γ g g h t t γ g t h h g g q q Three operators; will mix, need to perform RGE analysis � � � d n κ t + 5 . 1 · 10 − 2 κ t ˜ e = (1 . 0 ± 0 . 5) − 5 . 3 κ q ˜ κ t � + (22 ± 10) 1 . 8 · 10 − 2 κ t ˜ · 10 − 25 cm . κ t w ∝ κ t ˜ κ t subdominant, but involves only top Yukawa | d n / e | < 2 . 9 × 10 − 26 cm (90% CL) [Baker et al., 2006] Joachim Brod (University of Mainz) Precision Constraints on Higgs and Z couplings 13 / 38
Combined constraints on top coupling Assume SM couplings to electron and light quarks Future projection for 3000fb − 1 @ high-luminosity LHC [J. Olsen, talk at Snowmass Energy Frontier workshop] Factor 90 (300) improvement on electron (neutron) EDM [Fundamental Physics at the Energy Frontier, arXiv:1205.2671] Joachim Brod (University of Mainz) Precision Constraints on Higgs and Z couplings 14 / 38
Combined constraints on top couplings Set couplings to electron and light quarks to zero Contribution of Weinberg operator will lead to strong constraints in the future scenario Joachim Brod (University of Mainz) Precision Constraints on Higgs and Z couplings 15 / 38
Anomalous bbH couplings Joachim Brod (University of Mainz) Precision Constraints on Higgs and Z couplings 16 / 38
Collider constraints Modifications of gg → h , h → γγ due to κ b � = 1, ˜ κ b � = 0 are subleading ⇒ Main effect: modifications of branching ratios / total decay rate � � Br( h → b ¯ κ 2 κ 2 b + ˜ b ) SM Br( h → b ¯ b b ) = � � Br( h → b ¯ κ 2 κ 2 1 + b + ˜ b − 1 b ) SM Br( h → X ) SM Br( h → X ) = � � Br( h → b ¯ κ 2 κ 2 1 + b + ˜ b − 1 b ) SM Use naive averages of ATLAS / CMS signal strengths ˆ µ X for X = b ¯ b , τ + τ − , γγ , WW , ZZ µ X = Br( h → X ) / Br( h → X ) SM up to subleading corrections of production ˆ cross section Joachim Brod (University of Mainz) Precision Constraints on Higgs and Z couplings 17 / 38
RGE analysis of the b -quark contribution to EDMs g EDMs suppressed by small bottom Yukawa ≈ 3 scale uncertainty in CEDM Wilson coefficient b Two-step matching at M h and m b : g h q Mixing into Integrate out Higgs Matching onto O q qq ¯ O q q σ µν T a q ¯ bi σ µν γ 5 T a b 4 = ¯ mb 1 = ¯ bi γ 5 b O q 6 = − i q σ µν T a γ 5 qG a gs ¯ 2 µν Joachim Brod (University of Mainz) Precision Constraints on Higgs and Z couplings 18 / 38
RGE analysis of the b -quark contribution to EDMs γ b γ h q � α s � 3 γ (0) 14 γ (0) 48 γ (0) (4 π ) 2 Q q log 2 m 2 log 3 m 2 C q 5 ( µ b ) = − 4 αα s h + O ( α 4 b h + 87 b s ) , M 2 4 π 48 M 2 � α s � 2 γ (0) 14 γ (0) log 2 m 2 C q h + O ( α 3 6 ( µ b ) = s ) , 48 b M 2 4 π 8 � α s � 2 γ (1) log m 2 h + O ( α 3 C 7 ( µ b ) = 5 , 11 s ) . b M 2 4 π 2 Joachim Brod (University of Mainz) Precision Constraints on Higgs and Z couplings 19 / 38
Combined constraints on bottom couplings Assume SM couplings to electron and light quarks Future projection for 3000fb − 1 @ high-luminosity LHC Factor 90 (300) improvement on electron (neutron) EDM Joachim Brod (University of Mainz) Precision Constraints on Higgs and Z couplings 20 / 38
Combined constraints on bottom couplings Set couplings to electron and light quarks to zero Contribution of Weinberg operator will lead to competitive constraints in the future scenario Joachim Brod (University of Mainz) Precision Constraints on Higgs and Z couplings 21 / 38
What do we know about the electron Yukawa? Joachim Brod (University of Mainz) Precision Constraints on Higgs and Z couplings 22 / 38
Indirect bounds: electron EDM A different look at Barr & Zee: γ γ γ ⇒ t t W γ γ γ h h h e e e | d e / e | < 8 . 7 × 10 − 29 cm (90% CL) [ACME 2013] leads to | ˜ κ e | < 0 . 0013 (for κ t = 1) Joachim Brod (University of Mainz) Precision Constraints on Higgs and Z couplings 23 / 38
Indirect bounds: electron g − 2 Usually, measurement of a e ≡ ( g − 2) e / 2 used to extract α Using independent α masurement, can make a prediction for a e [Giudice et al., arXiv:1208.6583] With α = 1 / 137 . 035999037(91) [Bouchendira et al., arXiv:1012.3627] a e = 11596521807 . 3(2 . 8) × 10 − 13 [Gabrielse et al. 2011] . . . I find | κ e | � 3000 Bound expected to improve by a factor of 10 Joachim Brod (University of Mainz) Precision Constraints on Higgs and Z couplings 24 / 38
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