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COMETA workshop on EFT in HH and VBS

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Paris

Paris

LPNHE, Paris, France
Ilaria Brivio (University & INFN Bologna), Joany Manjarres (Laboratoire des 2 Infinis - Toulouse, CNRS / Univ. Paul Sabatier (FR)), Luca Cadamuro (IJCLab - CNRS/IN2P3 - Université Paris-Saclay (FR)), Reina Coromoto Camacho Toro (LPNHE-Paris CNRS/IN2P3), Thomas Strebler (CPPM, Aix-Marseille Université, CNRS/IN2P3 (FR))
Description

The workshop aims to bring together theorists and experimentalists interested in effective field theory (EFT) interpretations of di-Higgs (HH) and vector boson scattering (VBS) analyses for the LHC Run 3. Discussions will focus on the synergy between VBS and HH measurements, and how their combination can tighten constraints on EFT operators. The workshop will span three days, with two days of joint plenary theory-experiment sessions followed by a day of parallel internal experiment-theory discussions.

This year's conference is organised jointly by LPNHE, CPPM-Marseille, IJClab and L2IT-Toulouse and hosted by LPNHE on the Paris Sorbonne Campus, France. 

The workshop is co-organized by the COMETA COST Action CA22130

 

Program committee members:

  • Nicolas Berger (LAPP, CNRS)

  • Ilaria Brivio (Unibo)

  • Luca Cadamuro (IJCLab, CNRS)
  • Reina Camacho Toro (LPNHE, CNRS)

  • Alessandra Cappati (UCLouvain)

  • Pietro Govoni (University of Milano-Bicocca)

  • Ramona Groeber (Padua, INFN)
  • Robert Les (Michigan)
  • Joany Manjarres (L2IT, Université de Toulouse-CNRS)

  • Matteo Presilla (KIT, Karlsruhe, Dept. Phys.)

  • Thomas Strebler (CPPM, CNRS)

 

Big thanks to Carla Carvalhais, Isabelle Cossin and Aurélie Boian for their local support as well.

COMETA workshop on EFT in HH and VBS
Zoom Meeting ID
67562206886
Host
Reina Coromoto Camacho Toro
Passcode
78213445
Useful links
Join via phone
Zoom URL
  • Monday 17 March
    • 1
      Workshop introduction
      Welcome_COMETAEFTWorkshop-2.pdf
    • EFT Review : theory and experimental landscape
      Conveners: Nicolas Morange (Université Paris-Saclay (FR)), Pietro Govoni (Universita & INFN, Milano-Bicocca (IT))
    • 16:00
      Coffee break
    • EFT Review : theory and experimental landscape
      • 5
        Discussion
    • Early career scientists presentations
      Convener: Alejo Nahuel Rossia (University of Padua and INFN Sezione di Padova)
      • 6
        A novel implementation of the Matrix Element Method at next-to-leading-order (NLO) for the measurement of the Higgs tri-linear coupling in di-Higgs production at the LHC (20+10)

        One of the LHC's priorities, following the discovery of the Higgs boson, is to observe the production of Higgs pairs and to measure the Higgs tri-linear coupling $\lambda_{3H}$.
        Due to the rarity of di-Higgs production, measuring $\lambda_{3H}$ has proven to be highly challenging. Exclusion limits have been observed using a variety of approaches, including cut-based methods and boosted decision trees (BDTs).
        To address this difficulty from a new perspective, our work explores the application of the Matrix Element Method (MEM), a technique that has demonstrated its effectiveness in multiple analyses in which measurements were performed in processes that were rare (at the time). One can mention the primordial role of the MEM in measuring the top-quark mass at Tevatron, or its role in the first evidence for single top production in the s-channel at the LHC for example.
        The MEM is a statistically optimal multivariate method that maximizes the utilization of both the experimental and theoretical information available to an analysis, making it inherently well-suited to rare process searches and Standard Model measurements at particle accelerators like the LHC.
        The MEM avoids the application of strict selection requirements to the data. It accounts for the entire dataset (with minimal preselection), which is very important when dealing with such rare processes.
        Most MEM studies have been limited to leading-order (LO) accuracy, with extensions to next-to-leading-order (NLO) explored only in specific cases due to the additional complexities introduced by virtual and real contributions. Building a MEM at LO is already a highly challenging task, and incorporating NLO formalism substantially amplifies this difficulty due to the increased computational demands and complex theoretical requirements.
        To contribute to the measurement of $\lambda_{3H}$ from LHC data in the $gg \to HH \to b\bar{b}\gamma\gamma$ channel, we developed a MEM framework by working on a new NLO implementation (which can be applied in many more analyses).
        This MEM framework utilizes state-of-the-art Matrix Elements at NLO from the POWHEG-BOX-V2 [1] and MG5_@NLO software packages, and can be extended to include Higgs boson pair production at full NLO QCD in SMEFT [2].
        The framework is implemented within a modified version of MoMEMta, a software designed for managing multi-variable phase-space integration, which has been extended to incorporate this new NLO implementation.
        To our knowledge, this work marks the first application of the MEM at NLO accuracy to the search for $HH$ and the measurement of $\lambda_{3H}$. This also represents the first application of the MEM using this new NLO formalism.
        We have demonstrated that this NLO framework is functional and effective.
        We also applied this framework to Monte Carlo (MC) simulated samples in a search for $\lambda_{3H}$, achieving promising results. This study aims to introduce this new approach to the community and position the MEM (at NLO) as a competitive alternative to other established methods to determine the Higgs self-coupling $\lambda_{3H}$.

        References:
        [1] G. Heinrich,  S.P. Jones , M. Kerner, G. Luisoni , L. Scyboz
        Probing the trilinear Higgs boson coupling in di-Higgs production at NLO QCD including parton shower effects , JHEP 06 (2019) 066 [https://inspirehep.net/literature/1725744]
        [2] G. Heinrich, J, Lang
        Renormalisation group effects in SMEFT for di-Higgs production ,[https://arxiv.org/pdf/2409.19578]

        Speaker: Matthias Jean Tartarin (Laboratoire des 2 Infinis - Toulouse, CNRS / Univ. Paul Sabatier (FR))
        COMETA 17th March TARTARIN [LIVE_POWERPOINT].pptx
        COMETA 17th March TARTARIN [PDF].pdf
      • 7
        HEFT Multi-Higgs Production in VBF (20+10)

        We have studied the production of 2, 3 and 4 Higgs bosons from the collision of Goldstone bosons using the equivalence theorem in HEFT. This work has been compared with results from both ATLAS and CMS. The measurements are being updated by the collaborations with the latest results.

        Speaker: Javier Martínez Martín (Universidad Complutense de Madrid & IPARCOS)
        HEFT_Multi_Higgs_Production_in_VBF.pdf
    • 18:30
      Welcome reception
  • Tuesday 18 March
    • 09:00
      Morning coffee
    • Modelling of EFT effects
      • 8
        Review of VBS EFT MC modelling in ATLAS and CMS
        Speakers: Costanza Carrivale (INFN - National Institute for Nuclear Physics), Costanza Carrivale (Universita e INFN, Perugia (IT)), Nicolas Morange (Université Paris-Saclay (FR))
        EFT modelling in ATLAS and CMS.pdf
      • 9
        Review of HH EFT MC modelling in ATLAS and CMS
        Speakers: Jona Motta (University of Zurich (CH)), Tom Ingebretsen Carlson (Stockholm University (SE))
        HH_MC_modeling_Ingebretsen_Motta.pdf
      • 10
        Pheno and theory overview : HH and VBS interplay, available tools
        Speaker: Gudrun Heinrich (KIT)
        COMETA_HH_VBS_Paris25.pdf
      • 11
        Discussion
    • 12
      Group picture
    • 12:05
      Lunch break
    • Publishing and exploiting the results
    • 15:30
      Coffee break
    • Early career scientists presentations
      • 15
        Electroweak WZ production measurement and an EFT interpretation with the ATLAS detector at 𝟏𝟑 𝑻𝒆𝑽 (20+10)

        Vector Boson Scattering in the WZ fully leptonic channel was studied in ATLAS with the full Run 2 data of 140 fb-1 and the results were published recently. The importance of the channel for the study of the Electroweak Symmetry Breaking and for indirect New Physics searches beyond the Standard Model will be presented. The results of the cross section measurements will be discussed and the procedure for an Effective Field Theory interpretation of the existence of quartic gauge couplings will be shown. Limits on anomalous couplings related to dimension-8 operators, which are relevant to the process, will be presented and discussed. Finally as it is known that the dimension 6 operators play an important role on VBS processes, a first study using the new UFO SmeftFR model, which incorporates both dimension 6 and dimension 8 operators, will be shown.

        Speaker: Dr Eirini Kasimi (Aristotle University of Thessaloniki (GR))
        COMETA_Paris_presentation_Kasimi.pdf
      • 16
        Double Higgs Production in Vector Boson Fusion at NLO QCD in HEFT

        We present a calculation of the NLO QCD corrections to Higgs boson pair production in vector boson fusion, combined with the leading operators parametrising anomalous interactions in non-linear Effective Field Theory (HEFT). Based on our Monte Carlo implementation using GoSam+Whizard, we investigate the effects of anomalous Higgs couplings on various observables.

        Speaker: Jens Braun (Karlsruhe Institute of Technology (KIT))
        Braun_VBF_HH_HEFT.pdf
      • 17
        Exploring multiple Higgs production at colliders with HEFT

        We have explored the effects of different HEFT coefficients to the multiple Higgs production via VBF at various colliders, studying their potential accessibility. We have also matched the bosonic HEFT to the 2HDM and the SMEFT in VBF processes.

        Speaker: Daniel Domenech Moya (Universidad Autónoma de Madrid (ES)))
        Multi-H-HEFT_COMETA2025.pdf
  • Wednesday 19 March
    • 09:30
      Morning coffee
    • ATLAS internal discussion
      ATLAS private discussion agenda
    • CMS internal discussion
      CMS parallel session agenda
    • Theory parallel discussion
      • 18
        The Art of Counting: where to cut-off SMEFT and HEFT in Higgs Pair Production [REMOTE]
        Speaker: Konstantin Schmid (University and INFN Padova)
        EFT_in_HH_VBS_Schmid.pdf
      • 19
        RGE effects in SMEFT predictions for HH production
        Speaker: Stefano Di Noi (KIT (ITP))
        DiNoi_EFT_HH_VBS_Paris.pdf
      • 20
        Probing Di-Higgs and Triple Higgs production in HEFT
        Speaker: Anisha . (Karlsruhe Institute of Technology)
        Anisha_cometa.pdf
      • 21
        VBS constraints on Higgs interactions in HEFT
        Speaker: Domenec Espriu Climent (University of Barcelona (ES))
        ESPRIU_PARIS _25.pdf
    • 12:30
      Lunch break
    • ATLAS internal discussion
      ATLAS private discussion agenda
    • CMS internal discussion
      CMS parallel session agenda
    • Theory parallel discussion
      • 22
        HHH and HH production as probes of the Higgs self-couplings
        Speaker: Panagiotis Stylianou
        COMETA_PanagiotisStylianou.pdf
      • 23
        SMEFT effects and CP violation in diboson production via gluon-fusion
        Speaker: Marion Thomas
        MarionThomas.pdf
      • 24
        Interplay between VBS and VBF-HH in constraining dimension-8 operators
        Speaker: Paolo Torrielli (Universita e INFN Torino (IT))
        Torrielli_VVHH.pdf
      • 25
        Double Higgs production via VBF NLO in SMEFT

        The process of double Higgs boson production via vector boson fusion (VBF), although strongly suppressed compared to the gluon fusion channel, remains an important area of study. Not only can it provide valuable insights into the EW sector and the mechanism of EWSB, but it is also highly sensitive to BSM physics. In this talk, we explore the impact of dimension-6 and dimension-8 SMEFT operators on VBF double Higgs production. We estimate and present the maximal effects, taking into account available constraints on SMEFT Wilson coefficients from fits to experimental data, perturbative unitarity constraints and the validity of the EFT expansion.

        Speaker: Michal Ryczkowski (Università di Padova and INFN, Sezione di Padova)
        RyczkowskiParis2025_VBFHH_Final.pdf
    • Final discussion
    • 17:30
      Coffee break
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