Precision Phenomenology: Exploring the Higgs Sector and Beyond - PowerPoint PPT Presentation

18 December 2017 MPP Project Review 2017, Munich Precision Phenomenology: Exploring the Higgs Sector and Beyond Stephen Jones for the MPP Phenomenology Group

Group Goals What we do: • Take or develop well motivated mathematical models (Standard Model, SUSY Theories, Effective Field Theories,...) • Produce precise, concrete predictions for high energy colliders (LHC, ILC, FCC, ...) How we do it: • Establish a mathematical understanding of the theory • Develop and use state of the art computational tools and techniques Why we do it: • With our experimental colleagues, we want to test and refine our understanding of the fundamental forces • E.g: Probing the nature of Electro-weak symmetry breaking, constraining the solution space for new fundamental particles and interactions 2

MPP Phenomenology Group Director: Wolfgang Hollik Staff Members: Thomas Hahn, Gudrun Heinrich Postdoctoral Researchers: Stephen Jones, Matthias Kerner, Gionata Luisoni (short-term) Finishing this year: Joao Pires (Technical Institute of the University of Lisbon) Welcome: Long Chen PhD Students : Henning Bahl, Stephan Hessenberger, Stephan Jahn, Viktor Papara, Cyril Pietsch, Ludovic Scyboz (partial member) Welcome: Matteo Capozi 3

Project Highlights Part 1: Calculations Triple Higgs coupling effect on h 0 → bb and h 0 → τ + τ − in the 2HDM [A. Arhrib, R. Benbrik, J. El Falaki, W. Hollik] ZA production in vector-boson scattering at NLO QCD [F. Campanario, M. Kerner, D. Zeppenfeld] NNLO predictions for Z-boson pair production at the LHC [G. Heinrich, S. Jahn, SJ, M. Kerner, J. Pires] NNLO QCD predictions for single jet inclusive production at the LHC [J. Currie, E.W.N. Glover, J. Pires] Part 2: Precision studies NLO and off-shell effects in top quark mass determinations [G.Heinrich, A.Maier, R.Nisius, J.Schlenk, M.Schulze, L.Scyboz, J.Winter] NLO predictions for Higgs boson pair production matched to parton showers [G. Heinrich, SJ, M. Kerner, G. Luisoni, E. Vryonidou] Parton Shower and NLO-Matching uncertainties in Higgs Boson Pair Production [SJ, S.Kuttimalai] Reconciling EFT and hybrid calculations of the light MSSM Higgs-boson mass [H. Bahl, T. Hahn, S. Heinemeyer, W. Hollik, G. Weiglein] Part 3: Tools pySecDec: a toolbox for the numerical evaluation of multi-scale integrals [S. Borowka, G. Heinrich, S. Jahn, SJ, M. Kerner, J. Schlenk, T. Zirke] Loopedia: a Database for Loop Integrals [C. Bogner, S. Borowka, T. Hahn, G. Heinrich, SJ, M. Kerner, A. von Manteuffel, M. Michel, E. Panzer, V. Papara] 4

Part 1: Calculations 5

1) NLO QCD Vector Boson Scattering [ F. Campanario, M. Kerner, D. Zeppenfeld ] EW production (VBS) QCD production e − e − Z/ γ e − Z/ γ W W Z/ γ /W e − Z/ γ e + e + e + W W e + γ γ γ Z/ γ /W γ W W sensitivity to triple/quartic gauge couplings 
 → important test of EW symmetry breaking mechanism 10 − 2 2.5 NLO QCD EW LO EW LO EW NLO EW NLO 2.0 QCD NLO QCD NLO d σ / d m jj [fb / GeV] corrections: d σ / d ∆ y jj [fb] 1.5 10 − 3 significant 1.0 reduction of 0.5 10 − 4 scale 1.12 1.12 K-factor K-factor 1.04 1.04 uncertainty 0.96 0.96 0.88 0.88 0.80 0.80 500 1000 1500 2000 2500 3000 4.0 4.5 5.0 5.5 6.0 6.5 7.0 7.5 8.0 ∆ y jj m jj [GeV] 6

effects of modified gauge couplings investigated using EFT approach e.g. dimension-8 operator B µ ⌫ = ig 0 B µ ⌫ b O T, 8 = b B µ ⌫ b B ↵� b B ↵� b (with U Y (1) gauge field, ) 2 B µ ⌫ anomalous gauge couplings lead to unitarity violation for large s = m 2 Z γ Unitarity restored by: • higher-dimensional operators in UV-complete models • form factors in model-independent approach • commonly used form factor: f T 8 = 1200 TeV − 4 f T 8 = 600 TeV − 4 SM EW 10 − 2 dipole form factor no unitarization (dotted lines) d σ / d m Z γ [fb / GeV] 10 − 3 ◆ − 2 ✓ s F ( s ) = 1 + . Λ 2 F F • new, modified form factor 
 10 − 4 (dashed lines) nearly no 
 ◆ − 1 s 2 ✓ suppression 
 10 − 5 F c ( s ) = 1 − i 4 Λ c with modified FF F F leads to smaller suppression 
 10 − 6 without violating unitarity 0 500 1000 1500 2000 2500 3000 3500 4000 m Z γ [GeV] 7

2) NNLO Z-boson pair production [G. Heinrich, S. Jahn, SJ, M. Kerner, J. Pires] Computed NNLO QCD ZZ production using the "N-Jettiness" method NNLO calculations consists of several separately divergent pieces NNLO contributions perturbative order q Z 0 → qZZgg ¯ q tree-level VBFNLO [1] 0 → qZZQ ¯ Q ¯ q tree-level } q 00 ] 0 → qZZg ¯ q one-loop GOSAM [2] 0 → ggZZ one-loop QQVVAMP [3] 0 → q ¯ qZZ two-loop q 0 ¯ V Z [1] Baglio et al. 11, [2] Cullen 12,14 Fig: Gehrmann, von Manteuffel Tancredi 15 [3] Gehrmann, von Manteuffel Tancredi 15 T N-Jettiness: Z Z d Φ N |M V V | 2 + d Φ N +1 |M RV | 2 θ < X e Y ZZ n a · p k , e − Y ZZ n b · p k � T 0 = Q τ 0 = min σ NNLO = , 0 k Z Z Slice phase space into regions based d Φ N +2 |M RR | 2 θ < d Φ N +1 |M RV | 2 θ > + 0 + 0 based on , for small soft/collinear T 0 T 0 Z d Φ N +2 |M RR | 2 θ > + 0 emissions can be approximated using ≡ σ NNLO ( T 0 < T cut ) + σ NNLO ( T 0 > T cut ) . 0 0 SCET. Limit gives full result. T cut → 0 0 8

σ LO [pb] σ NLO [pb] σ NNLO [pb] 1.2 9 . 890 +4 . 9% 14 . 508 +3 . 0% 16 . 92 +3 . 2% Our Result − 6 . 1% − 2 . 4% − 2 . 6% pp ZZ + X s =13 TeV ( =m ) → µ Z 1.1 ATLAS [7] 17 . 3 ± 0 . 6(stat . ) ± 0 . 5(syst . ) ± 0 . 6(lumi . ) ( ∆ σ - gg)=0.833 ± 0.004 [pb] -gg) [pb] NNLO CMS [8] 17 . 2 ± 0 . 5(stat . ) ± 0 . 7(syst . ) ± 0 . 4(theo . ) ± 0 . 4(lumi . ) 1 NNLO √ NNLO corrections move theory σ 0.9 ∆ ( prediction towards ATLAS/CMS 0.8 measurements 0.7 3 2 1 2 − − − 10 10 10 10 1 10 cut [GeV] τ 0 pp ZZ + X s =13 TeV ( =m ) → µ Large part of the NNLO result Z LO comes from the opening up of the NLO 0.15 NLO+gg NNLO gluon channel [pb/GeV] 0.1 [pb] ZZ /m =0.5 µ 22 Z F /dm /m =1.0 µ σ Z F σ /m =2.0 µ d 20 Z F 0.05 18 NNLO NNLO w/o (gg → ZZ) 16 1.8 ratio to LO 14 1.6 1.4 NLO 1.2 12 1 ratio to NLO 200 250 300 350 m [GeV] 1.2 10 LO 1.1 8 1 0.9 0.2 0.5 2.0 4.0 8.0 200 250 300 350 1 m [GeV] /m µ ZZ Z R 9

Part 2: Precision studies 10

1) Top quark mass determinations [G. Heinrich, A. Maier, R. Nisius, J. Schlenk, M. Schulze, L. Scyboz, J. Winter] • Compare different theory descriptions of top quark pair production • Assess impact on top quark mass determinations NLO LOdec NLO production ⊗ LO decay t ¯ t o NWA : narrow width approximation NLO production ⊗ NLO decay NLO NLOdec t ¯ t : NWA NLO production ⊗ decay via parton showering t ¯ NLO PS : t pp → W + W − b ¯ ν µ ) b ¯ b at NLO b → ( e + ν e ) ( µ − ¯ NLO full : contains e.g. non-factorising non-resonant 11

Generate pseudo-data according to NLO full Use theory descriptions to calibrate template fit functions Determine off-set in top mass determination Offset with templates Offset − 1 . 52 ± 0 . 07 GeV with templates 0 . 83 ± 0 . 07 GeV based on NLO NLOdec based on LO W + W − b ¯ b NWA NLO corrections to decay more important than non-factorising/non-resonant contributions 12

2) NLO Higgs boson pair production + PS So far, measured Higgs couplings V t v m 1 ATLAS and CMS agree with the Standard Model Z V W LHC Run 1 κ or But: Higgs self coupling not yet well F 1 − 10 m v constrained F κ b SM Lagrangian: τ − 2 10 V ( Φ ) = 1 2 µ 2 Φ 2 + 1 ATLAS+CMS 4 λ Φ 4 L ⊃ − V ( Φ ) , SM Higgs boson 3 − 10 µ [M, ] fit ε EW sym. breaking 68% CL 95% CL 4 − 10 m 2 2 H 2 + m 2 2 v H 3 + m 2 H H 8 v 2 H 4 H 1 2 − 10 10 1 10 Particle mass [GeV] Higgs pair production probes triple-Higgs coupling 13

Computed NLO QCD (2-loop) corrections to HH production (2016) [ S. Borowka, N. Greiner, G. Heinrich, SJ, M. Kerner, J. Schlenk, U. Schubert, T. Zirke ] Interfaced to 2 public Monte-Carlo codes ( POWHEG , MG5_aMC@NLO ) • assess impact of NLO matching schemes/parton shower Large for p hh • full result made available for use by LHC experiments T [ G. Heinrich, SJ, M. Kerner, G. Luisoni, E. Vryonidou ] NLO NLO T [pb/GeV] T [pb/GeV] 10 − 3 T [pb/GeV] T [pb/GeV] 10 − 4 NLO+PY8 POWHEG hdamp =250 10 − 4 Q sh = Q new MG5_aMC@NLO POWHEG def 10 − 5 10 − 5 d σ / d p hh d σ / d p hh d σ / d p h d σ / d p h 10 − 6 Full SM Full SM 10 − 6 LHC 14 TeV LHC 14 TeV PDF4LHC15 NLO hdamp=250 10 − 7 PDF4LHC15 NLO µ = m hh / 2 10 − 7 µ = m hh / 2 2.0 2.0 3.0 3.0 ratio ratio ratio ratio 2.0 2.0 1.0 1.0 1.0 1.0 0 0 100 100 200 200 300 300 400 400 500 500 600 600 700 700 0 0 100 100 200 200 300 300 400 400 500 500 600 600 p h T [GeV] p hh T [GeV] 14