VBF Workshop: Collaborative Advances in Theory and Experiment

29 Oct 2024, 14:00 → 31 Oct 2024, 13:00 Europe/Zurich

13/2-005 (CERN)

Gaetano Barone (Brown University), Jiayi Chen (Simon Fraser University (CA)), Mathieu Pellen (Albert Ludwigs Universitaet Freiburg (DE)), Silvia Ferrario Ravasio (CERN)

This event aims at boosting activities within the VBF subgroup of the Higgs cross section working group. In particular, it should initiate new projects within the working group.

The program is made of both invited presentations and voluntary contributions. During the workshop, ample time for discussion is planned in order to boost theory/experiment cross talk.

If you wish to give a presentation, please submit an abstract.

Note that we expect in-person speakers and strongly encourage the in-person participation.

Previous edition (2022): Past, present, and future of VBF

 

BLK - LHC Higgs Working Group VBF OCT 2024 (5).pdf

Tuesday 29 October

1 Welcome

Speakers: Gaetano Barone (Brown University), Jiayi Chen (Simon Fraser University (CA)), Mathieu Pellen (Albert Ludwigs Universitaet Freiburg (DE)), Silvia Ferrario Ravasio (CERN)

welcome slides VBF workshop.pdf

State of the art

2 State of the art at fixed order and parton shower of VBF Higgs

Speaker: Barbara Jager

VBF-Barbara-theory-state-of-art.mp4

VBF-Higgs-2024.pdf

3 Experimental review of ATLAS and CMS

Speakers: Jan Steggemann (EPFL and ETH Zurich (CH)), Nicolas Berger (Centre National de la Recherche Scientifique (FR))

Experimental Overview.pdf

VBF-experimental-overview.mp4

15:35 Coffee break

4 Experimental bottleneck

Speaker: Alessandro Tricoli (Brookhaven National Laboratory (US))

Tricoli_VBFHiggs-VBS_LHC-Higgs-WG_Oct2024_final.pdf

VBF-bottleneck.mp4

Wednesday 30 October

Selected topics on VBF and related

5 Gluon-Fusion & Contamination in VBF

Speaker: Stephen Philip Jones (University of Durham (GB))

sjones_vbf.pdf

10:45 Coffee break

6 STXS and new STXS

Speaker: Robin Hayes (Nikhef National institute for subatomic physics (NL))

241019-STXSforVBFLHCHWG.pdf

12:30 Lunch break

Selected topics on VBF and related

7 Higgs boson production in weak-boson fusion and H → bb̄ decay at NNLO with realistic event selection criteria

The b-quark Yukawa coupling $y_b$ can be measured in $H\to b\bar{b}$ decay. While $H\to b\bar{b}$ is the main decay mode of the Higgs boson, measuring it experimentally is challenging because of the large number of b-quarks from other QCD processes. However, Higgs boson production in weak-boson fusion (WBF) can be distinguished from those QCD backgrounds by the presence of two nearly back-to-back forward jets. In order to isolate such a signal it is important to have a good theoretical model of this process in the kinematic region defined by event selection criteria.

We present fully-differential results for Higgs boson production in weak-boson fusion followed by $H\to b\bar{b}$ Higgs decay in the narrow-width approximation, at NNLO in QCD. The nested soft-collinear subtraction scheme is used to cancel infrared divergences between real and virtual corrections and obtain finite predictions.

We find that the perturbative corrections to this process reduce the fiducial cross-section by about 40% in comparison to the leading-order predictions. Such large corrections can be attributed to a number of distinct sources, the strongest of which is the tendency of the QCD radiation in the $H\to b\bar{b}$ decay to reduce the transverse momentum of b-jets to the point where they no longer pass the b-jet selection criteria.

Speaker: Ivan Novikov

slides.pdf

8 Electroweak Hjj production in the POWHEG-BOX

We present an implementation of the full electroweak Higgs plus two jets production process at hadron colliders. Our implementation, including vector-boson fusion and Higgsstrahlung contributions, is built in the framework of the resonance-aware version of the POWHEG BOX, which allows to match next-to-leading order QCD and EW corrections with shower Monte Carlo programs like PYTHIA8.
We provide phenomenological results for setups typical for VBF- and Higgsstrahlung analyses. For both cases we investigate the impact of NLO-QCD and EW corrections and their matching with parton showers.

Speaker: Simon Reinhardt (University of Tübingen)

ewHjj-prod-POWHEG-BOX.pdf

9 Precise prediction for Higgs plus two jets production

In this talk, I will present the NLO QCD prediction for loop-induced Higgs-plus-two-jets production (pp -> H + 2 jets) at the LHC in [2110.06953]. The top-quark mass effects in Born and real corrections are computed exactly, and the effects in the two-loop virtual corrections are taken into account through the so-called full-theory approximation. I will discuss the technical challenges for this calculation, and present inclusive and fiducial total cross sections as well as differential distributions.

Speaker: Hantian Zhang (Karlsruhe Institute of Technology)

Hjj_CERN2024_Zhang.pdf

10 Treatment of ggF contamination in VBF phase-spaces across CMS analyses

An in-depth discussion of the gluon gluon fusion contamination in the VBF phase-space for both simplified template cross section and fiducial measurements in CMS will be given. In particular, the talk will cover different mitigation techniques for several analyses and into the different mitigation treatments the different analyses use and will touch upon the experimental challenges this contamination poses.

Treatement_ggFContamination_VBFPhaseSpace.pdf

16:00 Coffee break

11 Higgs + photon and triboson production as probes of Higgs Yukawa couplings

The measurement of Yukawa couplings of the 125 GeV Higgs boson to light SM fermions (weakly constrained at present, particularly for first-generation fermions) is very challenging experimentally, yet key to unravel the details of the mass generation mechanism for the first two generations of matter and establish the role of the SM Higgs in such a mechanism. We discuss two recently proposed ways to constrain these Yukawa couplings at the LHC and future hadron colliders: Higgs production in association with a photon, and the production of three massive SM gauge bosons. We explore the sensitivity reach of both of them, and for the latter we briefly discuss the pros and cons of off-shell Higgs probes of SM Higgs couplings.

Speaker: Jose Miguel No (IFT-UAM/CSIC)

VBF_CERN_October_JMNo.pdf

12 Exploring the CP-sensitive SXTS staging in the HWW decay channel by the ATLAS experiment

The current STXS stage 1.2 binning is not sensitive to the charge-parity property of the Higgs boson. While there is an on-going effort to finalize the STXS stage 1.3 bins, the ATLAS experiment is making a first attempt at measuring CP-sensitive STXS-like bins in the H->WW decay channel. This is done by measuring cross-sections split by the signed azimuthal angle difference between the two leading jets. This STXS measurement considers both ggF and VBF production modes in order to explore the ggF and VBF CP-odd anomalous coupling simultaneously. The CP-odd effect is characterized by SMEFT operators in the Warsaw basis and the analysis aims to constrain the corresponding CP-odd Wilson coefficients, considering only the linear term from SM-BSM interference. The talk focuses on the motivation of the binning and gives an overview of the CPV test strategy.

Speaker: Metea Castilleja Marr (Simon Fraser University (CA))

MMarr_MBasso_VBFWS2024_HWW_STXS_CP_studies (1).pdf

19:30 Workshop Dinner

Dinner at Luigia Academy (https://www.luigiacademy.ch/) for those interested.

Thursday 31 October

Future of VBF

13 Open issues in general-purposed MC generators for VBF

Speakers: Daniel Reichelt, Daniel Reichelt

VBF2024_DReichelt.pdf

10:45 Coffee break

14 Experimental outlook

Speaker: Dr Giacomo Ortona (Universita e INFN Torino (IT))

VBFworkshop2024.pdf