Electroweak Corrections to Higgs Production Alexander Mück RWTH Aachen University Workshop on electroweak corrections for LHC physics Durham, September 25, 2012 ⇐ ←→ ⇒ | | EW Corrections to Higgs Production – Alexander M¨ uck – p.1/ 24 EW Corrections to Higgs Production – p. 0/ 24
Outline Introduction (a few general remarks) Channels: Gluon fusion Vector-boson fusion (VBF) Higgsstrahlung (WH/ZH) (personal bias towards VBF and WH/ZH) Higgs decays Electroweak corrections: available calculations (tools) size ⇔ relevance ⇔ QCD uncertainties total cross sections ⇔ distributions Summary ⇐ ←→ ⇒ | | EW Corrections to Higgs Production – Alexander M¨ uck – p.2/ 24 EW Corrections to Higgs Production – p. 0/ 24
The new boson ATLAS-CONF-2012-127 CMS-HIG-12-020 m = 125 GeV CMS Preliminary ATLAS 2011 - 2012 H -1 m = 126.0 GeV s = 7 TeV, L = 5.1 fb H → -1 s = 8 TeV, L = 5.3 fb W,Z H bb ∫ -1 s = 7 TeV: Ldt = 4.7 fb → τ τ H → H bb (VH tag) ∫ -1 s = 7 TeV: Ldt = 4.6-4.7 fb (*) → → → ν ν H bb (ttH tag) H WW l l ∫ -1 → τ τ s = 7 TeV: Ldt = 4.7 fb H (0/1 jet) ∫ -1 s = 8 TeV: Ldt = 5.8 fb → τ τ → γ γ H (VBF tag) H ∫ -1 → τ τ s = 7 TeV: Ldt = 4.8 fb H (VH tag) ∫ -1 s = 8 TeV: Ldt = 5.9 fb (*) → γ γ → → H (untagged) H ZZ 4l ∫ -1 → γ γ s = 7 TeV: Ldt = 4.8 fb H (VBF tag) ∫ -1 s = 8 TeV: Ldt = 5.8 fb → H WW (0/1 jet) Combined → H WW (VBF tag) µ ± ∫ -1 = 1.4 0.3 s = 7 TeV: Ldt = 4.6 - 4.8 fb → ∫ H WW (VH tag) -1 s = 8 TeV: Ldt = 5.8 - 5.9 fb → H ZZ -1 0 1 -6 -4 -2 0 2 4 6 8 µ σ σ Signal strength ( ) Best fit / SM H Is it the SM Higgs boson? (spin, CP even/odd, anomalous couplings, etc. ) ⇐ ←→ ⇒ | | EW Corrections to Higgs Production – Alexander M¨ uck – p.3/ 24 EW Corrections to Higgs Production – p. 0/ 24
The new boson ATLAS-CONF-2012-127 CMS-HIG-12-020 m = 125 GeV CMS Preliminary ATLAS 2011 - 2012 H -1 m = 126.0 GeV s = 7 TeV, L = 5.1 fb H → -1 s = 8 TeV, L = 5.3 fb W,Z H bb ∫ -1 s = 7 TeV: Ldt = 4.7 fb → τ τ H → H bb (VH tag) ∫ -1 s = 7 TeV: Ldt = 4.6-4.7 fb (*) → → → ν ν H bb (ttH tag) H WW l l ∫ -1 → τ τ s = 7 TeV: Ldt = 4.7 fb H (0/1 jet) ∫ -1 s = 8 TeV: Ldt = 5.8 fb → τ τ → γ γ H (VBF tag) H ∫ -1 → τ τ s = 7 TeV: Ldt = 4.8 fb H (VH tag) ∫ -1 s = 8 TeV: Ldt = 5.9 fb (*) → γ γ → → H (untagged) H ZZ 4l ∫ -1 → γ γ s = 7 TeV: Ldt = 4.8 fb H (VBF tag) ∫ -1 s = 8 TeV: Ldt = 5.8 fb → H WW (0/1 jet) Combined → H WW (VBF tag) µ ± ∫ -1 = 1.4 0.3 s = 7 TeV: Ldt = 4.6 - 4.8 fb → ∫ H WW (VH tag) -1 s = 8 TeV: Ldt = 5.8 - 5.9 fb → H ZZ -1 0 1 -6 -4 -2 0 2 4 6 8 µ σ σ Signal strength ( ) Best fit / SM H Is it the SM Higgs boson? (spin, CP even/odd, anomalous couplings, etc. ) EW corrections calculated in the (MS)SM ( ⇒ assume the new boson is the SM Higgs and search for deviations) QCD corrections might be more universal ⇐ ←→ ⇒ | | EW Corrections to Higgs Production – Alexander M¨ uck – p.3/ 24 EW Corrections to Higgs Production – p. 0/ 24
EW corrections generic size: expect percent level corrections ⇐ ←→ ⇒ | | EW Corrections to Higgs Production – Alexander M¨ uck – p.4/ 24 EW Corrections to Higgs Production – p. 0/ 24
EW corrections generic size: expect percent level corrections 5-10% in Higgs production ⇐ ←→ ⇒ | | EW Corrections to Higgs Production – Alexander M¨ uck – p.4/ 24 EW Corrections to Higgs Production – p. 0/ 24
EW corrections generic size: expect percent level corrections 5-10% in Higgs production naive comparison with QCD: O ( α ) ∼ O ( α 2 s ) ⇒ needed for high precision observables (with small QCD uncertainties) ⇒ vector-boson fusion ⇐ ←→ ⇒ | | EW Corrections to Higgs Production – Alexander M¨ uck – p.4/ 24 EW Corrections to Higgs Production – p. 0/ 24
EW corrections generic size: expect percent level corrections 5-10% in Higgs production naive comparison with QCD: O ( α ) ∼ O ( α 2 s ) ⇒ needed for high precision observables (with small QCD uncertainties) ⇒ vector-boson fusion (logarithmically) enhanced EW corrections: at high energies: Sudakov logs ∝ α → α log 2 ( Q/M V ) ) in peaked distribution from photon radiation ⇐ ←→ ⇒ | | EW Corrections to Higgs Production – Alexander M¨ uck – p.4/ 24 EW Corrections to Higgs Production – p. 0/ 24
EW corrections generic size: expect percent level corrections 5-10% in Higgs production naive comparison with QCD: O ( α ) ∼ O ( α 2 s ) ⇒ needed for high precision observables (with small QCD uncertainties) ⇒ vector-boson fusion (logarithmically) enhanced EW corrections: at high energies: Sudakov logs ∝ α → α log 2 ( Q/M V ) ) in peaked distribution from photon radiation ⇒ boosted Higgs in WH/ZH ⇐ ←→ ⇒ | | EW Corrections to Higgs Production – Alexander M¨ uck – p.4/ 24 EW Corrections to Higgs Production – p. 0/ 24
EW corrections Generic features: relative EW correction rather independent of: collider energy (QCD) scale choices PDF choice EW effects neglected in PDFs O (1%) contribution from photons in initial state (estimated from MRST2004 PDF) ⇐ ←→ ⇒ | | EW Corrections to Higgs Production – Alexander M¨ uck – p.5/ 24 EW Corrections to Higgs Production – p. 0/ 24
QCD and EW corrections How to combine QCD and EW corrections? additive: σ best = σ LO (1 + δ QCD + δ EW ) ? factorized: σ best = σ QCD best (1 + δ EW ) ? difference is of higher order ⇐ ←→ ⇒ | | EW Corrections to Higgs Production – Alexander M¨ uck – p.6/ 24 EW Corrections to Higgs Production – p. 0/ 24
QCD and EW corrections How to combine QCD and EW corrections? additive: σ best = σ LO (1 + δ QCD + δ EW ) ? factorized: σ best = σ QCD best (1 + δ EW ) ? difference is of higher order Factorized approximation is commonly used assumptions: QCD corrections dominated by soft-collinear physics EW corrections in underlying hard process or FSR ⇐ ←→ ⇒ | | EW Corrections to Higgs Production – Alexander M¨ uck – p.6/ 24 EW Corrections to Higgs Production – p. 0/ 24
Higgs cross sections LHC Higgs cross section working group: https://twiki.cern.ch/twiki/bin/view/LHCPhysics/CrossSections Yellow reports: 1101.0593 and 1201.3084 2 10 H+X) [pb] 1 LHC HIGGS XS WG 2011 LHC HIGGS XS WG 2012 Higgs BR + Total Uncert b b WW s = 8 TeV pp → H (NNLO+NNLL QCD + NLO EW) 10 → τ τ gg -1 10 (pp ZZ pp → qqH (NNLO QCD + NLO EW) c c σ 1 pp pp → → WH (NNLO QCD + NLO EW) ZH (NNLO QCD +NLO EW) pp → ttH (NLO QCD) -2 10 -1 10 γ γ γ Z -2 10 -3 10 80 100 200 300 400 1000 100 120 140 160 180 200 M [GeV] M [GeV] H H joint effort to provide best predictions for cross sections and distributions EW corrections included where available ongoing effort: EW corrections in differential analysis ⇐ ←→ ⇒ | | EW Corrections to Higgs Production – Alexander M¨ uck – p.7/ 24 EW Corrections to Higgs Production – p. 0/ 24
Gluon-Fusion dominant production process at LHC h 0 t enormous efforts for the QCD prediction t t NNLO, resummation . . . uncertainty O (20%) ⇐ ←→ ⇒ | | EW Corrections to Higgs Production – Alexander M¨ uck – p.8/ 24 EW Corrections to Higgs Production – p. 0/ 24
Gluon-Fusion dominant production process at LHC h 0 t enormous efforts for the QCD prediction t t full NLO (2-loop) EW corrections g W, Z H g Actis, Passarino, Sturm, Uccirati [arXiv:0809.1301] ⇐ ←→ ⇒ | | EW Corrections to Higgs Production – Alexander M¨ uck – p.8/ 24 EW Corrections to Higgs Production – p. 0/ 24
Gluon-Fusion dominant production process at LHC h 0 t enormous efforts for the QCD prediction t t full NLO (2-loop) EW corrections 2.7 − 6 pp → H + X √ s = 14 TeV 2.6 MRST 2002 4 2.5 2.4 2 δ EW [%] δ EW [%] K factor 2.3 0 2.2 2.1 − 2 2 NNLO QCD − 4 1.9 NNLO QCD + NLO EW 1.8 100 150 200 250 300 350 400 450 500 100 150 200 250 300 350 400 450 500 M H [GeV] M H [GeV] M H [GeV] Actis, Passarino, Sturm, Uccirati [arXiv:0809.1301] non-trivial threshold behaviour inside loops (WW,ZZ, t ¯ t ) ⇒ complex-mass scheme at two loops ⇐ ←→ ⇒ | | EW Corrections to Higgs Production – Alexander M¨ uck – p.8/ 24 EW Corrections to Higgs Production – p. 0/ 24
Gluon-Fusion dominant production process at LHC h 0 t enormous efforts for the QCD prediction t t full NLO (2-loop) EW corrections mixed O ( αα s ) corrections (light fermion loops) Anastasiou, Boughezal, Petriello [arXiv:0811.3458] g W, Z H g ⇒ effective theory approach (corrections to Wilson coefficient in effective ggH coupling) ⇒ same philosophy like for QCD corrections ⇐ ←→ ⇒ | | EW Corrections to Higgs Production – Alexander M¨ uck – p.8/ 24 EW Corrections to Higgs Production – p. 0/ 24
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