Higgs couplings Beyond the Standard Model

25 th Rencontres de Blois 2013 Higgs couplings Beyond the Standard Model based on arxiv:1210.8120 Guillaume Drieu La Rochelle drieu@ipnl.in2p3.fr IPN, Lyon, France May 29, 2013 G. Drieu La Rochelle Higgs couplings Beyond the Standard Model 1 / 17

25 th Rencontres de Blois 2013 Outline Motivation New Physics & Higgs phenomenology A complex business Looking at the Model Parameterising the Higgs couplings Looking at the Data Recasting SM searches Beyond simple methods Examples & Conclusion G. Drieu La Rochelle Higgs couplings Beyond the Standard Model 2 / 17

Motivation 25 th Rencontres de Blois 2013 Higgs phenomenology and New Physics Many BSM scenarios predict(ed) deviations in the Higgs sector But we do not see any! G. Drieu La Rochelle Higgs couplings Beyond the Standard Model 3 / 17

Motivation 25 th Rencontres de Blois 2013 Higgs phenomenology and New Physics Many BSM scenarios predict(ed) deviations in the Higgs sector But we do not see any! Higgs is now a constraint The question being : How much reduced is the parameter space? How to apply consistently the Higgs constraint? based on arxiv:1210.8120 G.Cacciapaglia, A.Deandrea, G.DLR, J-B. Flament G. Drieu La Rochelle Higgs couplings Beyond the Standard Model 3 / 17

Motivation 25 th Rencontres de Blois 2013 The Higgs constraint : Technical & Generic 90% : understanding experimental input Recasting experimental results Extract model independent quantities 10% : applying to a specific model Compute the compatibility of the model Setting limits for generic models is a vexed issue! G. Drieu La Rochelle Higgs couplings Beyond the Standard Model 4 / 17

Looking at the Model 25 th Rencontres de Blois 2013 A quick look on the model side How does one alter SM Higgs phenomenology? G. Drieu La Rochelle Higgs couplings Beyond the Standard Model 5 / 17

Looking at the Model 25 th Rencontres de Blois 2013 A quick look on the model side How does one alter SM Higgs phenomenology? by mixing with new scalars (H 1, H 2,... ) tree-level couplings g HZZ, g HWW, g H f f κ X = g HXX g SM HXX Custodial symmetry κ W = κ Z κ V (Hi ) singlets/doublets κ W, κ Z < 1 no such constraint for κf (2HDM, SUSY... ). G. Drieu La Rochelle Higgs couplings Beyond the Standard Model 5 / 17

Looking at the Model 25 th Rencontres de Blois 2013 A quick look on the model side How does one alter SM Higgs phenomenology? by mixing with new scalars (H 1, H 2,... ) tree-level couplings g HZZ, g HWW, g H f f κ X = g HXX g SM HXX Custodial symmetry κ W = κ Z κ V (Hi ) singlets/doublets κ W, κ Z < 1 no such constraint for κf (2HDM, SUSY... ). by loops of new states (t, t, τ... ) Alters tree-level couplings, but also loop-level ones gg H & H γγ One-loop operators : no obvious parameterisation. G. Drieu La Rochelle Higgs couplings Beyond the Standard Model 5 / 17

Looking at the Model 25 th Rencontres de Blois 2013 Loop-level couplings Two approaches : κ 2 g/γ = Γ h gg/γγ Γ SM h gg/γγ (Exp-like) LHC HXSWG arxiv:1209.0040 G. Drieu La Rochelle Higgs couplings Beyond the Standard Model 6 / 17

Looking at the Model 25 th Rencontres de Blois 2013 Loop-level couplings Two approaches : κ 2 g/γ = Γ h gg/γγ Γ SM h gg/γγ κ g/γ = ANP h gg/γγ A SM h gg/γγ (Exp-like) (Th-like) LHC HXSWG arxiv:1209.0040 The difference lies in correlations with κ W, κ f : (Exp) κ g/γ depends on κ W, κ f since they modify Γ h gg/γγ depends only on New Physics contribution κ (Th) g/γ In other words κ (Exp) g/γ = 0 is compatible with NP in loops, not κ(th) g/γ G. Drieu La Rochelle Higgs couplings Beyond the Standard Model 6 / 17

Looking at the Model 25 th Rencontres de Blois 2013 Parametrising Higgs couplings (II) Our choice : κ g/γ = ANP A h gg/γγ t, SM h gg/γγ tailored to top-partner models κ g = κ γ = f ( ) 1 M Higher-Order corrections (QCD) automatically included other particles : charge & spin impact the result G. Drieu La Rochelle Higgs couplings Beyond the Standard Model 7 / 17

Looking at the Model 25 th Rencontres de Blois 2013 Higher Order corrections Do we need to compute them? tree-level couplings : same K-factor as in SM (QCD/EW type) Indeed they are generated by mixing κ already include the K-factor loop-level couplings : K-factor is model specific QCD corrections depend on spin and colour NP corrections can be sizeable (e.g. SUSY-QCD) G. Drieu La Rochelle Higgs couplings Beyond the Standard Model 8 / 17

Looking at the Model 25 th Rencontres de Blois 2013 Higher Order corrections Do we need to compute them? tree-level couplings : same K-factor as in SM (QCD/EW type) Indeed they are generated by mixing κ already include the K-factor loop-level couplings : K-factor is model specific QCD corrections depend on spin and colour NP corrections can be sizeable (e.g. SUSY-QCD) In our scheme, if new particles are top-like then κ g/γ include QCD corrections G. Drieu La Rochelle Higgs couplings Beyond the Standard Model 8 / 17

Looking at the Data 25 th Rencontres de Blois 2013 miss Tt Tt Tt Tt Tt G. DrieuHiggs La Rochelle coupling experimental Higgs couplings notes Beyond the Standard Model 9 / 17 A quick look at the data Unconv. central low p Tt Unconv. central high p Unconv. rest low p Unconv. rest high p Tt Conv. central low p Conv. central high p Tt Conv. rest low p Conv. rest high p Conv. transition Loose high mass two jet Tight high mass two jet Low mass two jet E T significance One lepton 2012 data combined ATLAS Preliminary Data 2012, = 8 TeV 2 0 2 4 6 8 10 m H s 1 Ldt = 20.7 fb H γγ = 126.8 GeV Signal strength MET Electron Muon Di-jet loose Di-jet tight Untagged 3 Untagged 2 Untagged 1 Untagged 0 Di-jet Untagged 3 Untagged 2 Untagged 1 Untagged 0 8TeV 7TeV CMS preliminary -1 s = 7 TeV, L = 5.1 fb (MVA) -1 s = 8 TeV, L = 19.6 fb (MVA) Event Class Combined m H = 125.0 GeV σ/σ SM = 0.78+0.28-0.26-10 -5 0 5 10 Best Fit σ/σ SM 1 signal strength, CMS preliminary, L = 24.4 fb SF 1 jet 7 TeV SF 0 jet 7 TeV CMS m H Preliminary, = 125 GeV -1 s=7-8 TeV, L=24.3 fb, H ττ µµ DF 1 jet 7 TeV eµ DF 0 jet 7 TeV τ h τ h SF 1 jet 8 TeV SF 0 jet 8 TeV eτ h µτ h DF 1 jet 8 TeV VH ττ+l DF 0 jet 8 TeV 1 0 1 2 3 Best Fit σ/σ SM Combined 0 2 4 best fit for σ/σ SM

Looking at the Data 25 th Rencontres de Blois 2013 A quick look at the data Higgs coupling experimental notes Mass determination : M H ± 1σ CMS-PAS-HIG-13-005 ATLAS-CONF-2013-034 Impressive list of ˆµ ± 1σ µ = n S, ˆµ = ˆn ns SM S ns SM This is not telling much on the κx Large amount of (κ X, κ Y ) likelihood plots G. Drieu La Rochelle Higgs couplings Beyond the Standard Model 9 / 17

Looking at the Data 25 th Rencontres de Blois 2013 G. DrieuHiggs La Rochelle coupling experimental Higgs couplings notes Beyond the Standard Model 9 / 17 A quick look at the data κ F 3 2 1 0 1 ATLAS Preliminary 1 s = 7 TeV, Ldt = 4.6 4.8 fb 1 s = 8 TeV, Ldt = 13 20.7 fb SM Best fit 68% CL 95% CL 0.7 0.8 0.9 1 1.1 1.2 1.3 κ V κ u 2.0 CMS Preliminary 1 s = 7 TeV, L s = 8 TeV, L 19.6 fb λ du, κ u, κ V 1.8 1.6 1.4 1.2 1.0 0.8 0.6 0.4 0.2 1 5.1 fb 0.0 0.0 0.5 1.0 1.5 κ V κ g 2.2 ATLAS Preliminary SM 1 s = 7 TeV, Ldt = 4.6 4.8 fb Best fit 2 1 s = 8 TeV, Ldt = 13 20.7 fb 68% CL 1.8 95% CL 1.6 1.4 1.2 1 0.8 0.6 0.9 1 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 κ γ κ q 2.0 CMS Preliminary 1 s = 7 TeV, L s = 8 TeV, L 19.6 fb λ lq, κ q, κ V 1.8 1.6 1.4 1.2 1.0 0.8 0.6 0.4 0.2 1 5.1 fb 0.0 0.0 0.5 1.0 1.5 2.0 κ V

Looking at the Data 25 th Rencontres de Blois 2013 A quick look at the data Higgs coupling experimental notes Mass determination : M H ± 1σ CMS-PAS-HIG-13-005 ATLAS-CONF-2013-034 Impressive list of ˆµ ± 1σ µ = n S, ˆµ = ˆn ns SM S ns SM This is not telling much on the κx Large amount of (κ X, κ Y ) likelihood plots But 1D/2D plots only The other κ X are either fixed or profiled G. Drieu La Rochelle Higgs couplings Beyond the Standard Model 9 / 17

Looking at the Data 25 th Rencontres de Blois 2013 A quick look at the data Higgs coupling experimental notes Mass determination : M H ± 1σ CMS-PAS-HIG-13-005 ATLAS-CONF-2013-034 Impressive list of ˆµ ± 1σ µ = n S, ˆµ = ˆn ns SM S ns SM This is not telling much on the κx Large amount of (κ X, κ Y ) likelihood plots But 1D/2D plots only The other κ X are either fixed or profiled No way to assess directly the compatibility of a set (κ X ) G. Drieu La Rochelle Higgs couplings Beyond the Standard Model 9 / 17

Looking at the Data 25 th Rencontres de Blois 2013 Recasting SM searches (I) L(κ) sophisticated communication e.g. RooStats workspace Approximating L(κ) χ 2 ( (κ) 1 2ln L) ( ˆµi µ i ) 2 χ 2 (κ) = i σ i G. Drieu La Rochelle Higgs couplings Beyond the Standard Model 10 / 17

Looking at the Data 25 th Rencontres de Blois 2013 Recasting SM searches (I) L(κ) sophisticated communication e.g. RooStats workspace Approximating L(κ) χ 2 ( (κ) 1 2ln L) ( ˆµi µ i ) 2 χ 2 (κ) = i σ i Caution : this runs into 2 issues Getting all efficiencies Neglecting correlations G. Drieu La Rochelle Higgs couplings Beyond the Standard Model 10 / 17

Looking at the Data 25 th Rencontres de Blois 2013 Issue with χ 2 method The efficiencies ɛ p,i µ i = n S,i n n S,i SM S,i = (σ ggh ɛ ggh,i +...) BR H Xi X i ɛp,i are not always publicly available No correlations σ stat are uncorrelated, but not σ sys nor σ th! Example : ATLAS γγ : ˆµ = 1.65 ± 0.24(stat) +0.25 0.18 (syst) Some global uncertainties (e.g. luminosity, inclusive SM cross-sections) can be unfolded (see HiggsSignal arxiv:1305.1933) G. Drieu La Rochelle Higgs couplings Beyond the Standard Model 11 / 17

Looking at the Data 25 th Rencontres de Blois 2013 Issue with χ 2 method The efficiencies ɛ p,i µ i = n S,i n n S,i SM S,i = (σ ggh ɛ ggh,i +...) BR H Xi X i ɛp,i are not always publicly available No correlations σ stat are uncorrelated, but not σ sys nor σ th! Example : ATLAS γγ : ˆµ = 1.65 ± 0.24(stat) +0.25 0.18 (syst) Some global uncertainties (e.g. luminosity, inclusive SM cross-sections) can be unfolded (see HiggsSignal arxiv:1305.1933) Uncertainty on efficiencies can be large (up to 50% in some subchannels) G. Drieu La Rochelle Higgs couplings Beyond the Standard Model 11 / 17

Looking at the Data 25 th Rencontres de Blois 2013 Going Beyond simple χ 2 method Use χ 2 = f (µ ggh, µ tth, µ VBF, µ VH ) B/B SM µ VBF+VH 10 8 6 4 2 ATLAS Preliminary 1 s = 7 TeV: Ldt = 4.6 4.8 fb 1 s = 8 TeV: Ldt = 13 20.7 fb H γγ (*) H ZZ (*) H WW H ττ 4l lνlν Standard Model Best fit 68% CL 95% CL µ VBF,VH 1 1 CMS Preliminary s = 7 TeV, L 5.1 fb s = 8 TeV, L 19.6 fb 6 H ττ H WW H ZZ H bb 4 H γγ 2 0 2 m H = 125.5 GeV 4 2 1 0 1 2 3 4 5 6 7 8 µ B/B ggf+tth SM 0 1 0 1 2 µ 3 ggh,tth Define improved χ 2 χ 2 (κ) = ( ˆµ ggh/tth µ )T ggh/tth ˆµ VBF /VH µ V 1 ( ˆµ ggh/tth µ ggh/tth ) VBF /VH ˆµ VBF /VH µ VBF /VH G. Drieu La Rochelle Higgs couplings Beyond the Standard Model 12 / 17

Looking at the Data 25 th Rencontres de Blois 2013 Pros and Cons of the improved method (µ ggh, µ tth, µ VBF, µ VH ) ( ) µ ggh/tth, µ VBF /VH constrain the application range µvbf = µ VH if custodial symmetry holds µtth is often negligible (for the time being... ) Limited by gaussian approximation G. Drieu La Rochelle Higgs couplings Beyond the Standard Model 13 / 17

Looking at the Data 25 th Rencontres de Blois 2013 Pros and Cons of the improved method (µ ggh, µ tth, µ VBF, µ VH ) ( ) µ ggh/tth, µ VBF /VH constrain the application range µvbf = µ VH if custodial symmetry holds µtth is often negligible (for the time being... ) Limited by gaussian approximation What do we gain : All efficiencies automatically folded in. Part of the correlations included Deal s done! G. Drieu La Rochelle Higgs couplings Beyond the Standard Model 13 / 17

Looking at the Data 25 th Rencontres de Blois 2013 Last subtlety : the statistical test Given a likelihood L (or χ 2 ), one has to choose a statistical test most powerful : likelihood ratio, or χ 2 = χ 2 (κ) χ 2 (ˆκ) χ 2 χ 2 Example γγ However a χ 2 does a priori not follow a standard distribution χ 2 ( χ 2 with k d.o.f. ) in general. However an upper bound can be obtained with k d.o.f. We have checked on benchmarks that the to distributions were quite close G. Drieu La Rochelle Higgs couplings Beyond the Standard Model 14 / 17

Examples & Conclusion 25 th Rencontres de Blois 2013 Examples (I) First scenario : only κ g/γ 0 Some specific models have been plotted Decoupling : Lines meeting on the SM point Except for 4 th generation G. Drieu La Rochelle Higgs couplings Beyond the Standard Model 15 / 17

Examples & Conclusion 25 th Rencontres de Blois 2013 Examples (II) 2.0 κ V = 0.7 κ V = 0.89 κ V = 1.3 2.0 2.0 1.5 1.5 1.5 1.0 1.0 1.0 Κgg 0.5 Κgg 0.5 Κgg 0.5 0.0 0.0 0.0 0.5 0.5 0.5 1.0 1.0 1.0 2 1 0 1 2 2 1 0 1 2 2 1 0 1 2 Κ ΓΓ Κ ΓΓ Κ ΓΓ BR invisible = 0.1 BR invisible = 0.2 BR invisible = 0.3 2.0 2.0 2.0 1.5 1.5 1.5 1.0 1.0 1.0 Κgg 0.5 Κgg 0.5 Κgg 0.5 0.0 0.0 0.0 0.5 0.5 0.5 1.0 1.0 1.0 2 1 0 1 2 2 1 0 1 2 2 1 0 1 2 Κ ΓΓ Κ ΓΓ Κ ΓΓ G. Drieu La Rochelle Higgs couplings Beyond the Standard Model 16 / 17

Examples & Conclusion 25 th Rencontres de Blois 2013 Conclusion Summary Care must be taken when recasting Higgs limits to BSM models Higgs couplings are a very valuable piece of information Possibility to retain correlations in the improved χ 2 method Outlook Allow for the possibility of another scalar Stay tuned to the different possibilities of communicating experimental results G. Drieu La Rochelle Higgs couplings Beyond the Standard Model 17 / 17