Lectures on the SM beyond LO and VBS/VBF

Transcription

1 Lectures on the SM beyond LO and VBS/VBF Mathieu PELLEN Cavendish Laboratory, University of Cambridge University of Pavia - Lectures 3 rd and 4 th of April 9

2 References: Textbook Böhm/Denner/Joos: Gauge Theories of the Strong and Electroweak Interaction Collins: Renormalization Itzykson/Zuber: Quantum Field Theory Peskin/Schroeder: An Introduction to Quantum Field Theory Weinberg: The Quantum Theory of Fields, Vol. : Foundations ; The Quantum Theory of Fields, Vol. : Modern Applications Maggiore: A Modern Introduction to Quantum Field Theory Aitchison/Hey: Gauge Theories in Particle Physics Vol. and Schwartz: Quantum Field Theory and the Standard Model Mathieu PELLEN Lectures on the SM beyond LO and VBS/VBF / 5

3 References: Others EWSB: Lecture of Riccardo Torre: See references inside Exercises (corrected) in my lecture: Review on VBS/VBF: Michael Rauch many more on the Internet or libraries... Mathieu PELLEN Lectures on the SM beyond LO and VBS/VBF 3 / 5

4 Part II: The Standard Model beyond leading order Mathieu PELLEN Lectures on the SM beyond LO and VBS/VBF 4 / 5

5 Higgs coupling Mathieu PELLEN Lectures on the SM beyond LO and VBS/VBF 5 / 5

6 General rule for QCD corrections There is no rule... Mathieu PELLEN Lectures on the SM beyond LO and VBS/VBF 6 / 5

7 QCD effects () Example: NLO QCD corrections to pp t t (W ν µ µ ) (W ν e e + ) b b dσ/dmt [fb/gev] K pp νee + µ νµb s = 8 TeV FwW [%] LON NLO Mt [GeV] Mt [GeV] [Denner et al.; 7.58] Same effect for QED corrections (kinematic effect) Mathieu PELLEN Lectures on the SM beyond LO and VBS/VBF 7 / 5

8 QCD effects () Example: NNLO QCD corrections to pp Zj [Gehrmann-De Ridder et al.; 57.85] Sudakov shoulder due to non-local cancelation of IR divergences [Catani, Webber; hep-ph/97333] Mathieu PELLEN Lectures on the SM beyond LO and VBS/VBF 8 / 5

9 General rule for EW corrections Leading effects EW = QED + Weak QED effects: photon radiation kinematic effects in particular close to resonances Weak effects: Sudakov logarithms in high-energy limit NB: QED and Weak corrections cannot always be separated Possible when no W-boson exchange at tree level [Collins; Renormalization] Chapter.9 Example: pp Z Z 4l [Biedermann et al.; ] Mathieu PELLEN Lectures on the SM beyond LO and VBS/VBF 9 / 5

10 QED effects () ] Example: NLO EW corrections to pp t t (W ν µ µ ) (W ν e e + ) b b 3 LO NLO EW [ fb GeV dσ dmt δ [%] NLO EW photon Mt [GeV] [Denner, MP; ] M t = ( p νµ + p µ + p b ) In the real radiation, γ is carrying some energy if not reconstructed with final states, shift events below the peak Mathieu PELLEN Lectures on the SM beyond LO and VBS/VBF / 5

11 QED effects () ] Example: NLO QCD to pp Z Z 4l [Biedermann et al.; ] Very different QED correction due to rich resonance structure M 4l = M Z 9 GeV single-resonant Z boson M 4l = M Z + p T,min GeV kinematic cut M 4l = M Z 8 GeV double-resonant Z bosons Weak corrections small in this energy range [ dσ fb δ[%] dm4l GeV [µe]/( [4µ]) δ[%] δ weak qq [4µ] δ EW δ weak qq [4µ] qq [µe] δ EW qq [µe] LO [4µ] NLO EW [4µ] LO [µe] NLO EW [µe] s = 3 TeV δγγ[4µ] δqγ[4µ] δγγ [µe] δqγ [µe] LO: [µe]/( [4µ]) NLO: [µe]/( [4µ]) M4l [GeV] 6 8 Mathieu PELLEN Lectures on the SM beyond LO and VBS/VBF / 5

12 Weak corrections ] Example: NLO QCD to pp Z Z 4l [ dσ fb dm4l GeV 3 LO [4µ] NLO EW [4µ] LO [µe] NLO EW [µe] s = 3 TeV [Biedermann et al.; ] Weak corrections become negatively large in the high energy limit log ( M V /s), log ( M V /s) High-energy limit: high invariant mass, high transverse momentum, etc. when the typical energy (s) of the partonic-process is large NB: Small difference between EW and weak at high energy δ[%] [µe]/( [4µ]) δ[%] δ weak qq [4µ] δ EW δ weak qq [4µ] qq [µe] δ EW qq [µe] δγγ [4µ] δqγ[4µ] δγγ [µe] δqγ[µe] LO: [µe]/( [4µ]) NLO: [µe]/( [4µ]) M4l [GeV] Mathieu PELLEN Lectures on the SM beyond LO and VBS/VBF / 5

13 Principle of (N)LO calculation σ = F dpsp ME What is needed to compute a cross section at the LHC? Phase space Matrix element PDF factor At LO and for low multiplicity processes: Phase-space and Matrix element can be computed analytically PDF factor has to be obtained numerically Mathieu PELLEN Lectures on the SM beyond LO and VBS/VBF 3 / 5

14 Principle of (N)LO calculation Beyond 3, analytic computations become difficult (even with computer algebra) Numerical computations are more appropriate Use of Monte Carlo integration Allow for large number of integration variables (high-multiplicity processes) Arbitrary differential distributions Simpler (provided you have matrix elements and phase-space generators) Mathieu PELLEN Lectures on the SM beyond LO and VBS/VBF 4 / 5

15 Principle of NLO calculation LO cross section: σ LO = dφ n M,n NLO corrections: δσ NLO = = dφ n+ M,n+ + real + virtual dφ n Re [ M ],nm,n Problem: these two terms are separately divergent Analytically not a problem With a regulator, these can be computed separately Adding them, the regulator dependence disappears Numerically impossible to integrate (without regulator) a divergent quantity (the two terms have different integration variables) Mathieu PELLEN Lectures on the SM beyond LO and VBS/VBF 5 / 5

16 Principle of NLO calculation Two solutions: Slicing method Use of a cut-off to integrate divergent part analytically Computationally intensive as The cut-off should be small enough (to only cut the divergent part) The final result should be independent of this cut-off Subtraction method: Catani-Seymour (CS) dipole Frixione-Kunszt-Signer (FKS) Local cancellation of divergences Very efficient numerically More details in [Frederix s lecture] and [Denner s lecture] Mathieu PELLEN Lectures on the SM beyond LO and VBS/VBF 6 / 5

17 Brief state-of-the-art of higher-order computations NLO QCD / EW Automatised and available for all 4/5 processes MadGraph5 amc@nlo or Sherpa For 6/7: specific tools required NNLO QCD Almost all processes known but not all available publicly One 3: VBF in approximate way [Cacciari et al.; 53.66], [Cruz-Martinez et al.; 8.445] N 3 LO QCD gg H in infinite top mass limit [Anastasiou et al.; ] VBF in approximate way [Dreyer and Karlberg; 8.796] Mathieu PELLEN Lectures on the SM beyond LO and VBS/VBF 7 / 5

18 Part III: Vector-boson fusion and vector-boson scattering Mathieu PELLEN Lectures on the SM beyond LO and VBS/VBF 8 / 5

19 Slide from Christopher Schwan Mathieu PELLEN Lectures on the SM beyond LO and VBS/VBF 9 / 5

20 LO contributions at: O ( α 6) and O ( α s α 4) (EW contribution/signal and QCD contribution/background) Example of W + W + : σ (fb) per bin (m, y ): α 6 jj jj σ (fb) per bin (m, y jj ): jj α 4 α s jj y jj y m jj (GeV) m jj (GeV) [Ballestrero, MP et al.; ] The contributions have different kinematic Need for exclusive cuts to enhance the EW contribution typical cuts are m jj and y jj. Mathieu PELLEN Lectures on the SM beyond LO and VBS/VBF / 5

21 LO cross sections in fiducial volume for W + W + : [Biedermann, Denner, MP; 78.68] for W + Z: Order O ( α 6) O ( α s α 4) σ LO [fb].478().79(5) Order O ( α 6) O ( α s α 4) σ LO [fb].546(6).99() [Andersen, MP et al.; LH proceedings] The relative size of the EW contribution is process dependent (87% for W + W + vs. % for W + Z) Background can be overwhelming (8% e.g. for W + Z) Mathieu PELLEN Lectures on the SM beyond LO and VBS/VBF / 5

22 Example of WZ: LO EW LO INT LO QCD Sum 3 LO EW LO INT LO QCD Sum dσ d Rj j [fb] 3 [ dσ fb ] dmj j GeV δ [%] 5 8 LO EW LO INT LO QCD Rj j δ [%] 6 LO EW LO INT LO QCD Mj j [GeV] [Andersen, MP et al.; LH proceedings] Phase-space regions where EW contribution is dominating: very low statistics Challenge for experimental collaborations Mathieu PELLEN Lectures on the SM beyond LO and VBS/VBF / 5

23 Quality of the VBS approximation (LO) j (fb/gev) dσ / dm j j Inclusive study at LO: dσ / dm j j (fb/gev) α 6 α α 5 s α α 4 s α 6 + α α 5 + α α 4 s s (fb) dσ / d y j Inclusive study at LO: dσ / d y (fb) j j α 6 α α 5 s α α 4 s α 6 + α α 5 + α α 4 s s (GeV) m j j y j j [Ballestrero, MP et al.; ] Using the full computation: Presence of a peak at the W-boson mass (s-channel contribution) Mathieu PELLEN Lectures on the SM beyond LO and VBS/VBF 3 / 5

24 Quality of the VBS approximation (LO) jj y α 6 : ] σ [ t + u σ [full] in the (m, y ) plane jj jj m jj (GeV) jj y α 6 : ] σ [ s + t + u σ [full] in the (m, y ) plane jj jj m jj (GeV) [Ballestrero, MP et al.; ] For low m jj and low y jj, significant s-channel contributions tri-boson contributions with resonant W-boson Good approximation in fiducial region for W + W + confirmed for W ± Z [Andersen, MP et al.; ] Mathieu PELLEN Lectures on the SM beyond LO and VBS/VBF 4 / 5

25 Quality of the VBS approximation (LO) dσ/d m j j [fb/gev] LO -3 BONSAY MG5_aMC -4 MoCaNLO+Recola PHANTOM POWHEG dσ/d Δy j j [fb].5 LO BONSAY MG5_aMC MoCaNLO+Recola PHANTOM POWHEG VBFNLO WHIZARD Ratio /MoCaNLO+Recola VBFNLO WHIZARD Ratio /MoCaNLO+Recola m j j [GeV] Δy j j [Ballestrero, MP et al.; ] In single-differential distributions in fiducial region at LO: hardly any differences especially compared to QCD-scale band Mathieu PELLEN Lectures on the SM beyond LO and VBS/VBF 5 / 5

26 VBF at NNLO QCD - [Cacciari et al.; 56.66] dσ/dp t, j [pb/gev] dσ/dp t,j [pb/gev] - LO NLO NNLO POWHEG - LO NLO NNLO POWHEG -3 VBF CUTS LHC 3 TeV VBF CUTS LHC 3 TeV -3-4 NNPDF3_nnlo_as_8 µ (p t,h )/ < µ R = µ F < µ (p t,h ) -4 NNPDF3_nnlo_as_8 µ (p t,h )/ < µ R = µ F < µ (p t, H ) With updated NLO VBF H+3-jet virtual corrections With updated NLO VBF H+3-jet virtual corrections p t,j [GeV] p t,j [GeV] Mathieu PELLEN Lectures on the SM beyond LO and VBS/VBF 6 / 5

27 VBF at NNLO QCD - [Cacciari et al.; 56.66] dσ/dp t,h [pb/gev] - LO NLO NNLO POWHEG VBF CUTS LHC 3 TeV -3 NNPDF3_nnlo_as_8 µ (p t,h )/ < µ R = µ F < µ (p t,h )..9 With updated NLO VBF H+3-jet virtual corrections p t,h [GeV] Mathieu PELLEN Lectures on the SM beyond LO and VBS/VBF 7 / 5

28 Jet dependence VBF - [Rauch and Zeppenfeld; ] σ [fb] σ/σ NLO LO 8 NLO NNLO R Mathieu PELLEN Lectures on the SM beyond LO and VBS/VBF 8 / 5

29 Jet dependence VBF - [Rauch and Zeppenfeld; ] R=.4 R=. R=.6 dσ/dp T,j [fb/gev] NNLO NLO NNLO NLO NLO (R=.4) NNLO NLO NLO (R=.4) σ/σ NLO..5 anti-kt. C/A kt p T,j [GeV] Mathieu PELLEN Lectures on the SM beyond LO and VBS/VBF 9 / 5

30 WZ analysis - [CMS; 9.46] Mathieu PELLEN Lectures on the SM beyond LO and VBS/VBF 3 / 5

31 NLO corrections - W + W + Calculation of both NLO QCD and EW corrections to pp µ + ν µ e + ν e jj NLO fiducial cross sections: (normalised to σ LO ) Order O ( α 7) O ( α s α 6) O ( α s α 5) O ( α 3 s α 4) Sum δσ NLO [fb].69(3).568(5).3(3).63(4).84(7) δσ NLO /σ LO [%] [Biedermann, Denner, MP; 78.68] Large EW corrections at O ( α 7) Negative corrections at O ( α s α 6) : Photon PDF contribution at NLO (not included in NLO definitions): +.5% with LUXqed [Manohar et al.; ] Mathieu PELLEN Lectures on the SM beyond LO and VBS/VBF 3 / 5

32 NLO corrections - W + W + / Separated contributions ] ] 3 LO EW LO QCD LO INT NLO 3 LO EW LO QCD LO INT NLO [ dσ fb dmj j GeV 4 [ dσ fb dpt,j GeV δ [%] δ [%] α 7 αsα 6 NLO α s α 5 α 3 s α 4 photon α Mj j [GeV] δ [%] δ [%] 4 3 α 7 αsα 6 NLO αs α 5 αs 3 α 4 photon α pt,j [GeV] [Biedermann, Denner, MP; 78.68] Clear hierarchy of LO contributions Different behaviour of the NLO corrections (normalised to the full LO) Mathieu PELLEN Lectures on the SM beyond LO and VBS/VBF 3 / 5

33 NLO corrections - W + W + / Combined predictions ] [ fb GeV dσ dm e + µ + δ [%] 3 4 LO NLO M e + µ + [GeV] dσ d y [fb] e + µ δ [%] y e + µ [Biedermann, Denner, MP; 78.68] Large negative corrections for the full process Corrections dominated by EW correction to EW process Bands do not overlap LO NLO Mathieu PELLEN Lectures on the SM beyond LO and VBS/VBF 33 / 5

34 NLO corrections Common feature of all VBS signatures EW corrections O ( α 7) large with respect to LO O ( α 6) Correction of O ( α s α 6) are expected to be of comparable size Small but not negligible photon contribution The size of O ( α 3 s α 4) depends strongly on the size of the QCD-induced process at LO Mathieu PELLEN Lectures on the SM beyond LO and VBS/VBF 34 / 5

35 NLO EW corrections - W ± W ± LO: O ( α 6) NLO: O ( α 7) σ LO [fb] σew NLO [fb] δ EW [%].5348().895(6) 6. LO NLO EW ] [ dσ fb dpt,j GeV δ [%] NLO EW pt,j [GeV] Huge NLO electroweak correction (!) [Biedermann, Denner, MP; 6.95] Mathieu PELLEN Lectures on the SM beyond LO and VBS/VBF 35 / 5

36 NLO EW corrections - WZ Cross section: LO O ( α 6) [fb] NLO EW O ( α 7) [fb] Corrections [%] [Denner, Dittmaier, Maierhöfer, MP, Schwan] Preliminary Differential distribution: dσ/d R µ µ +[fb] LO NLO QCD NLO EW NLO QCD+EW.. 5 δ[%] R µ µ + [Denner, Dittmaier, Maierhöfer, MP, Schwan] Preliminary Also large corrections! Mathieu PELLEN Lectures on the SM beyond LO and VBS/VBF 36 / 5

37 Quality of the VBS approximation (LO) jj y α 6 : ] σ [ t + u σ [full] in the (m, y ) plane jj jj m jj (GeV) jj y α 6 : ] σ [ s + t + u σ [full] in the (m, y ) plane jj jj m jj (GeV) [Ballestrero, MP et al.; ] For low m jj and low y jj, significant s-channel contributions tri-boson contributions with resonant W-boson Good approximation in fiducial region for W + W + confirmed for W ± Z [Andersen, MP et al.; ] Mathieu PELLEN Lectures on the SM beyond LO and VBS/VBF 37 / 5

38 Quality of the VBS approximation (NLO) y j j α α 6 s : σ[ t + u ] σ[full] in the (m, y ) plane j j j j m j j (GeV) [Ballestrero, MP et al.; ] y j j α α 6 s : σ[ s + t + u ] σ[full] in the (m, y ) plane j j j j m j j (GeV) The approximations are in general worse at NLO Approximation can fail by up to % even in fiducial region OK now for current experimental precision but might be important in the future Similar behaviour expected for other signatures: but harder to predict full computation not available for other signatures (yet) Mathieu PELLEN Lectures on the SM beyond LO and VBS/VBF 38 / 5

39 Quality of the VBS approximation (NLO) dσ/d m j j [fb/gev] NLO -3 BONSAY -4 MG5_aMC MoCaNLO+Recola POWHEG dσ/d Δy j j [fb].5 NLO BONSAY MG5_aMC MoCaNLO+Recola POWHEG VBFNLO Ratio /MoCaNLO+Recola VBFNLO Ratio /MoCaNLO+Recola m j j [GeV] Δy j j [Ballestrero, MP et al.; ] Differences lie outside the band relevant for precision measurements Mathieu PELLEN Lectures on the SM beyond LO and VBS/VBF 39 / 5

40 Beyond fixed order () Dijet invariant mass (LO+PS) Dijet invariant mass (NLO+PS) d σ pp e + νµ + νjj /d m j j [fb/gev] 3 4 NLO (fixed order) MG5 amc+h7-default MG5 amc+py8 PHANTOM+H7-Default PHANTOM+Py8 VBFNLO 3+H7-Dipole WHIZARD+Py8 d σ pp e + νµ + νjj /d m j j [fb/gev] 3 4 NLO (fixed order) MG5 amc+h7-default MG5 amc+py8 Powheg+Py8 Powheg-no shower VBFNLO 3+H7-Default VBFNLO 3+H7-Dipole Ratio m j j [GeV] Ratio m j j [GeV] [Ballestrero, MP et al.; ] Reasonable agreement at both LO (left) and NLO (right) for observables defined at LO NB: input parameters (masses, widths, PDF, scales) all set to common values Mathieu PELLEN Lectures on the SM beyond LO and VBS/VBF 4 / 5

41 Beyond fixed order () d σ pp e + νµ + νjj /d z j3 [fb] Normalised average rapidity of the third jet (LO+PS). NLO (fixed order) MG5 amc+h7-default MG5 amc+py8.8 PHANTOM+H7-Default PHANTOM+Py8 VBFNLO 3+H7-Dipole.6 WHIZARD+Py8.4. d σ pp e + νµ + νjj /d z j3 [fb] Normalised average rapidity of the third jet (NLO+PS). NLO (fixed order) MG5 amc+h7-default MG5 amc+py8.8 MG5 amc+py8, Q sh / Powheg+Py8 Powheg-no shower.6 VBFNLO 3+H7-Default VBFNLO 3+H7-Dipole.4. Ratio Ratio z j3 [Ballestrero, MP et al.; ] Very large differences for observables related to the third jet (only defined at NLO) Different treatment of recoil in Pythia Triggered similar study in ATLAS with Sherpa [ATL-PHYS-PUB-9-4] z j3 Mathieu PELLEN Lectures on the SM beyond LO and VBS/VBF 4 / 5

42 Beyond fixed order (3) Also observed by CMS in VBF-Z production [CMS; 7.984] (i.e. pp jjz) Gap veto efficiency. Dilepton BDT > fb (3 TeV) CMS.5.4 Data DY (MG5_aMC NLO + Pythia8) DY + EWK Zjj (MG5_aMC LO + Pythia8) DY + EWK Zjj (MG5_aMC LO + Herwig) Third jet p (GeV) T Processes with larger cross sections but similar topologies can help to improve on the predictions for VBS Mathieu PELLEN Lectures on the SM beyond LO and VBS/VBF 4 / 5

43 State-of-the-art VBF Full NLO QCD [Figy, Oleari, Zeppenfeld; hep-ph/9646] NLO EW [Ciccolini, Denner, Dittmaier; 77.38, ] NLO QCD matched to parton shower in VBS approximation [Nason, Oleari; 9.599] Available in VBFNLO, Powheg, MG5 or Sherpa NNLO QCD in VBS approximation [Cacciari et al.; 53.66], [Cruz-Martinez et al.; 8.445] N 3 LO QCD in VBS approximation and for total cross section only [Dreyer, Karlberg; 66.84] (using stucture function) Mathieu PELLEN Lectures on the SM beyond LO and VBS/VBF 43 / 5

44 State-of-the-art VBS W ± W ± NLO QCD to EW-induced process in VBS approximation [Jäger, Oleari, Zeppenfeld; 97.58], [Denner, Hošeková, Kallweit; 9.389] NLO QCD to QCD-induced process [Melia et al.; 7.533, 4.37], [Campanario et al.; ] Matching to parton shower [Jäger, Zanderighi; 8.864], [Melia et al.;.4846] Available in VBFNLO or Powheg-Box Full NLO QCD and EW to EW- and QCD-induced process [Biedermann, Denner, MP; 6.95, 78.68] W ± Z NLO QCD to EW-induced process in VBS approximation [Bozzi et al.; hep-ph/75] Matching to parton shower [Jäger, Karlberg, Scheller; 8.58] NLO QCD to QCD-induced process [Campanario et al.; 35.63] Available in VBFNLO and Powheg-Box Mathieu PELLEN Lectures on the SM beyond LO and VBS/VBF 44 / 5

45 State-of-the-art VBS W + W ZZ NLO QCD to EW-induced process in VBS approximation [Jäger, Oleari, Zeppenfeld; hep-ph/6377] NLO QCD to QCD-induced process [Melia et al.; 4.37], [Greiner et al.;.64] Matching to parton shower [Jäger, Zanderighi; 3.695], [Rauch, Plätzer; ] Available in VBFNLO or Powheg-Box NLO QCD to EW-induced process in VBS approximation and matching to parton shower [Jäger, Karlberg, Zanderighi; 3.35] NLO QCD to QCD-induced process [Campanario et al.; ] Available in VBFNLO or Powheg-Box Mathieu PELLEN Lectures on the SM beyond LO and VBS/VBF 45 / 5

46 State-of-the-art VBS All processes known at NLO QCD accuracy matched to PS in VBS approximation for both QCD-/EW-induced process all available in VBFNLO (apart from QCD-induced W + W ) all available in Powheg-Box possible to generate in MG5 amc@nlo or Sherpa NLO EW corrections only known for W + W + (WZ preliminary) Full NLO computation only known for W + W + No NNLO computation known apart in VBF [Cacciari et al.; 53.66], [Cruz-Martinez et al.; 8.445] Mathieu PELLEN Lectures on the SM beyond LO and VBS/VBF 46 / 5

47 Higgs witdh determniation - [Campbell, Ellis, Williams; ] Mathieu PELLEN Lectures on the SM beyond LO and VBS/VBF 47 / 5

48 σ [pb] Production Cross Section, July 8 n jet(s) n jet(s) =n jet(s) CMS Preliminary - 7 TeV CMS measurement (L 5. fb ) - 8 TeV CMS measurement (L 9.6 fb ) - 3 TeV CMS measurement (L 35.9 fb ) Theory prediction CMS 95%CL limits at 7, 8 and 3 TeV 3 4 W Z Wγ Zγ WW WZ ZZ EW EW γγ EW EW qqw qqz WW qqwγssww EW: W lν, Z ll, l=e,µ All results at: EW qqzγ EW EW WVγ qqwz qqzz Zγγ Wγγ tt t tw t t-ch s-ch ttγ tzq ttz tγ ttw tttt ggh VBF VH WH ZH tth th HH qqh Th. σ H in exp. σ Limited experimental precision for VBS (for now) Mathieu PELLEN Lectures on the SM beyond LO and VBS/VBF 48 / 5

49 Experimental status (): Measured Several VBS signatures according to the final state (VV ): VV = W ± W ± (leptonic) Golden channel Low background Evidence by ATLAS and CMS at Run-I [45.64, 6.48, 4.635] Measurement by ATLAS and CMS at run-ii [CMS-PAS-SMP-7-4; 79.58], [ATLAS-CONF-8-3] VV = WZ (leptonic) Good rate but large background Observation by ATLAS and CMS at Run-II [ATLAS-CONF-8-33, 8.974], [CMS-PAS-SMP-8-, 9.46 ] VV = ZZ (leptonic) Low cross section but good reconstruction Evidence by CMS at Run-II for ZZ [78.8] Mathieu PELLEN Lectures on the SM beyond LO and VBS/VBF 49 / 5

50 Experimental status (): Not (yet) measured Several VBS signatures according to the final state (VV ): VV = W + W (leptonic) VBF (pp jjh) + H W + W in a larger phase space Very large background from t t VV (semi-leptonic: 4 jets in the final state) Large cross section but very large background Used for BSM exlcusion only (for now) [ATLAS; 69.5, 7.735] VV (fully-leptonic: 6 jets in the final state) Very large cross section but gigantic background Mathieu PELLEN Lectures on the SM beyond LO and VBS/VBF 5 / 5

51 Slide from Jakob Salfeld-Nebgen ( " Mathieu PELLEN Lectures on the SM beyond LO and VBS/VBF 5 / 5