Vector Boson Fusion Process

General information

• Convener mailing list ( lhc-higgs-vbf-convener@cernNOSPAMPLEASE.ch)
• Mailing list for discussions/meetings advertisement: lhc-higgs-vbf@cernNOSPAMPLEASE.ch
• Indico meetings ( https://indico.cern.ch/category/5847/)

Conveners

• Antonio Di Maria (Nanjing University), Stephane Cooperstein (UC San Diego), Mathieu Pellen (University of Freiburg), Simon Plätzer (University of Graz)

Meetings

• WG1 - VBF meeting TBA

Workshop

• To be planed.

Topics covered by the group

• Simplified Template Cross Sections uncertainties:
  • LHC analyses will provide results using categories defined by the Simplified Template Cross Sections method, mainly Stage 0 and Stage 1
  • Estimation of the systematic uncertainties in each bin is needed
• Higher-order corrections:
  • While NNLO QCD and NLO EWK exist at the fixed order, no prescriptions are available on how to apply them to events generated after parton shower and underlying event simulation.
  • Prescription on how to reweight existing simulations to NNLO QCD and NLO EWK without affecting the simulation precision could be subject of a publication
• Jet multiplicities merging and parton shower accuracy:
  • Comparisons between different merged samples and between different showering options
  • Possible new recommendations on the central value and on the uncertainties to be adopted in analyses
• CJV systematics:
  • Estimation based on ST gives an overestimation of the uncertainties which has then a high impact on the final result
  • Possible redefinition of the uncertainty and updated recommendations for more sophisticated analysis based on a multivariate discriminant
• Higgs spin in VBF
  • The Higgs spin can be constrained by looking at VBF jets as well
  • Do we have all the needed tools available to do it and to combine the results with other spin studies in ATLAS and CMS?
• High Higgs pT:
  • First measurements of the high-pT Higgs spectrum (above 0.5 TeV) are being published
  • Dedicated calculations to account for finite quark mass effects at higher orders in QCD and with additional jets are needed to be compared to data

Topic	Timescale	Manpower needed	Contacts	Last update	Comments	Status
Simplified Template Cross Sections uncertainties	Spring/Summer 2020	1-2 persons	yacine.haddad@cernNOSPAMPLEASE.ch	Updates on STXS bin definitions, uncertainties for VBF and VH bins Frank' slides Latest uncertainties estimation, 2020 Update, Tool		Complete: 90/100
Jet multiplicities merging and Parton shower accuracy	>Summer 2020	2 persons	alexander.karlberg@physicsNOSPAMPLEASE.ox.ac.uk simon.plaetzer@univie.ac.at	CJV and PS		Complete: 30/100
Higher-order corrections	>2021	1-2 persons				Complete: 0/100
Parton Shower Uncertainties	Summer 2020	1-2 persons	yacine.haddad@cern.ch antonio.de.maria@cern.ch alexander.karlberg@physics.ox.ac.uk simon.plaetzer@univie.ac.at	Paper		Complete: 50/100
Higgs Boson Plus Dijets	>2020	2 persons	jeppe.andersen@durhamNOSPAMPLEASE.ac.uk	Higgs Boson Plus Dijets		Complete: 30/100
High pT Higgs	Winter 2019	1 person	alexander.karlberg@physicsNOSPAMPLEASE.ox.ac.uk	Recommended predictions for the boosted-Higgs cross section Note	working on EW correction	Complete: 100/100
Higgs XS for a 27 TeV pp	Summer 2018	1 person		Results	Ready for YR	Complete: 100/100

Information on Simplified Template Cross Sections

• General description in YR4: https://arxiv.org/abs/1610.07922 (Chapter III.2)
• ggF latest updated on the systematic uncertainties: https://indico.cern.ch/event/618048/contributions/2519117/attachments/1428957/2193875/WG1_March16_2017.pdf
• Frank Trackman's proposal for VBF: https://indico.cern.ch/event/649948/contributions/2644014/attachments/1489051/2313802/2017-07-06_STXS_bins_unc.pdf
• A simple tool to propagate VBF uncertainties in STXS stage 1.2 bins. The details of the calculation and the method can be found https://indico.cern.ch/event/826136/contributions/3560473/attachments/1927391/3191007/STXS-uncertainties-VBF.pdf
  
• Electroweak Corrections for VBF STXS Stage 1.2 bins. These predictions are made using HAWK 3.0.

VBF cross-sections for 13.6 TeV

• Higgs mass [GeV]: cross section [fb] | Scale pos[%] / neg[%] | PDF+αs [%] | PDF [%] | αs [%]
• mH = 125.0 GeV: 4.078 fb | +0.5% / -0.3% | 2.1% | 2.1% | 0.5%
• mH = 125.09 GeV: 4.075 fb | +0.5% / -0.3% | 2.1% | 2.1% | 0.5%
• mH = 125.38 GeV: 4.067 fb | +0.5% / -0.3% | 2.1% | 2.1% | 0.5%

These numbers are obtained upon applying cubic spline interpolations based on the YR4 cross-sections.

VBF Calculation for YR4

• Link to VBF NLO histograms: https://twiki.cern.ch/twiki/bin/view/LHCPhysics/LHCHXSWGVBFYR4
• See Chapter I.5 in YR4

VBF cross-sections for YR4 (and beyond)

The VBF cross-sections as computed in the YR4 are reported here considering Higgs Boson mass of 125 GeV . The setup can be found in the YR4 itself. For the 13/14/27 TeV cross sections the EW, s-channel, and photon cross sections have been computed using LUXqed_plus_ PDF4LHC _nnlo_100 and hence the 13/14 TeV cross sections differ slightly from those reported in the YR4 where NNPDF23_nlo_as_0118_qed was used. The QCD cross-section was computed at NNLO with proVBFH and the EW/photon contributions have been computed at NLO with HAWK.

We note that the photon-induced contribution is more reliably predicted here than was the case in the YR4 due to the LUXqed method. In particular, the photon PDF should no longer be considered as a source of uncertainty as in eq. (I.5.7) in the YR4, as it is now constrained at the percent level. Quantitatively the photon-induced contributions are reduced by about 30% compared to in the YR4.

The s-channel contributions at 13 and 14 TeV have on the other hand increased compared to the YR4 results. This is due to the updated PDF used for this prediction, i.e. LUXqed_plus_PDF4LHC15_nnlo_100 instead of NNPDF23_nlo_as_0118_qed. We also note that the relative size of the s-channel decreases as the collider energy increases - from 47% at 7 TeV to 30% at 27 TeV.

Available Tools

• VV2H ( M. Spira):
• VBFNLO ( K. Arnold, M. Bahr, G. Bozzi, F. Campanario, C. Englert, T. Figy, N. Greiner, C. Hackstein, V. Hankele, B. Jager, G. Klamke, M. Kubocz, C. Oleari, S. Plätzer, S. Prestel, M. Worek, D. Zeppenfeld):
• * HJets ( F. Campanario, T.M. Figy, S. Plätzer and M. Sjödahl)
• HAWK ( A. Denner, S. Dittmaier, A. Mück):
• POWHEG BOX ( S. Alioli, K. Hamilton, P. Nason, C. Oleari, E. Re):
• PHANTOM ( A. Ballestrero, A. Belhouari, G. Bevilacqua, D. Buarque Franzosi, V. Kashkan and E. Maina):
• VBF@NNLO ( P. Bolzoni, F. Maltoni, S.-O. Moch and M. Zaro):
• proVBFH ( M. Cacciari, F. Dreyer, A. Karlberg, G. Salam, G. Zanderighi)
• VBF-qq2Hqq-uncertainties ( C. Bertella, Y. Haddad )

Historical Meetings

Minutes of the meeting are attached to the Indico agenda page.

• 21 February 2019
• 10 February 2010
• 24 March 2010
• 8 April 2010
• 17 June 2010
• 24 April 2012
• 9 May 2012

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AlexanderKarlberg - 2017-06-09