The 21st Workshop of the LHC Higgs Working Group

4 Dec 2024, 09:00 → 6 Dec 2024, 17:30 Europe/Zurich

The aim of the LHC Higgs Working Group (LHCHWG) is to collect and produce theoretical predictions relevant for Higgs physics in the Standard Model and beyond. Summaries of these activities have been made available in four CERN Reports: "Inclusive Observables" (CERN-2011-002), "Differential Distributions" (CERN-2012-002),  "Higgs Properties" (CERN-2013-004) and "Deciphering the nature of the Higgs Sector" (CERN-2017-002).

PHISHING ALERT!  PLEASE IGNORE ANY EMAILS ASKING FOR A DOCUSIGN AND CREDIT CARD DETAILS. This is a phishing attempt that has been reported to CERN.

 

The meeting will be in-person at CERN, however a Zoom connection will be available for those who cannot travel to CERN.

Zoom connection details will only be visible to registered participants.

A welcome drink, held jointly with the LHC EFT WG, will take place on the evening of Tuesday, 3rd December in Restaurant 1, at 18:00.

The meeting will start with a joint LHC EFT / LHC Higgs session on Wednesday morning.

Please register if you plan to attend the workshop (either in-person or online).

Related events/meetings during the week:

• 8th General Meeting of the LHC EFT Working Group 2-3 December: https://indico.cern.ch/event/1411765/ 

Wednesday 4 December

09:00 → 10:30 Opening and joint LHC EFT / LHC Higgs plenary

Convener: Ramona Groeber (University and INFN Padova)

[Wednesday AM-1] Opening and joint LHC EFT : LHC Higgs plenary.mp4

09:00 Workshop opening

Speaker: Julie Malcles (IRFU-CEA, Université Paris-Saclay)

21stWorkshopIntroduction.pdf

21stWorkshopIntroduction.pptx

09:15 LHCb meets the LHC Higgs WG (10'+5')

Speaker: Davide Zuliani (University and INFN Padova)

lhcb_higgsWG_zuliani.pdf

09:30 EFT/Higgs Experimental Summary (20'+10')

Speaker: Tae Hyoun Park (Max-Planck Institute for Physics)

slides.pdf

10:00 EFT Meets Cosmology (20'+10')

Speaker: Johan Löfgren (Uppsala)

eft-meets-cosmology.pdf

10:30 → 11:00 Coffee break

11:00 → 12:45 Joint LHC EFT / LHC Higgs plenary

Convener: Anke Biekoetter (JGU Mainz)

[Wednesday AM-2] Joint LHC EFT : LHC Higgs plenary.mp4

11:00 STXS Predictions (12'+3')

Speaker: Ken Mimasu (University of Southampton)

slides_EFTWG_24.pdf

11:15 EFT Interpretation of CMS VH(bb) (15'+5')

Speaker: Alessandro Calandri (ETH Zuerich)

Calandri_EFT_04122024.pdf

11:35 Running Effects in Higgs SMEFT (15'+5')

Speaker: Stefano Di Noi (KIT)

DiNoiLHCWGMeeting.pdf

11:55 SMEFiT (15'+5')

Speaker: Luca Mantani (IFIC Valencia)

Higgs_WG_Mantani.pdf

12:15 SMEFT/Higgs Experimental Outlook (20'+10')

Speaker: Giacomo Boldrini (LLR Palaisau - CNRS)

LHC_EFT_HIGGS_WG_04_12_2024.pdf

12:45 → 14:00 Lunch break

14:00 → 15:30 Plenary (WG1)

Conveners: Alessandro Calandri (ETH Zuerich), Alexander Karlberg (CERN)

[Wednesday PM-1] Plenary (WG1).mp4

14:00 Introduction

Speakers: Alessandro Calandri (ETH Zuerich), Alexander Karlberg (CERN), Bernhard Mistlberger (SLAC), Hannah Arnold (Stony Brook University)

WG1intro_LHCHWG_04122024.pdf

14:10 ggF status report (17'+5')

Speakers: Alessandra Cappati (Université Catholique de Louvain), Robin Hayes (Nikhef)

241204-ggFWG1Update-3.pdf

14:32 VBF status report (17+5') [remote]

Speaker: Jiayi Chen (Simon Fraser University)

VBF for general assembly 2024.pdf

14:54 VH status report (17'+5')

Speaker: Matthew Lim (University of Sussex)

HWGLim.pdf

15:30 → 16:00 Coffee break

16:00 → 17:30 Plenary (WG3)

Conveners: Rui Santos (ISEL and CFTC-UL), Tatjana Lenz (University of Bonn)

[Wednesday PM-2] Plenary (WG3).mp4

16:00 MSSM working group summary (15'+3')

Speaker: Emanuele Angelo Bagnaschi (INFN Frascati)

HXSWG-MSSM-2024-Bagnaschi-v3.pdf

16:18 bbH: subgroup report and NNLO+PS generators in the massless and massive schemes (15'+3')

We provide an update on the status of Higgs production in association with a bottom-quark pair, highlighting recent developments by the bbH subgroup. We discuss the differences between the two flavour schemes and their state-of-the-art predictions, including cross-section interpolations for 13.6 TeV. Additionally, we report on novel event generators developed in the massless and massive scheme at NNLO QCD accuracy matched to parton showers. We show that NNLO corrections in the 4FS solve the long-standing issue of discrepancies between 4FS and 5FS predictions. Future directions can involve developing consistent combinations of 4FS and 5FS NNLO+PS predictions and extending these calculations to lighter quark flavours.

Speaker: Christian Biello (Max-Planck Institute for Physics)

bbh-WG3-biello.pdf

16:36 NMSSM subgroup report (15'+3')

Speaker: Milada Margarete Muehlleitner (KIT)

NMSSMSubgroup.pdf

16:54 Exotic decays subgroup: Axion-like particle connections to the Higgs and top (15'+3')

Speaker: Anke Biekoetter (JGU Mainz)

HiggsWG_ALP_Biekoetter.pdf

17:12 Extended scalar sector subgroup report (15'+3')

Speaker: Khawla Jaffel (University of Science and Technology of China)

LHCHWG2024_kjaffel-4.pdf

Thursday 5 December

09:00 → 12:22 WG1 parallel session

Conveners: Alessandro Calandri (ETH Zuerich), Alexander Karlberg (CERN)

09:00 Higgs+charm ATLAS (10'+10')

Speaker: Elliot Reynolds (University of Kansas)

HcATLAS_LHCHiggsWGWorkshop_ElliotReynolds_05Dec24.pdf

09:20 Higgs+charm CMS (10'+10')

Speaker: Tiziano Bevilacqua (University of Zuerich)

HXSWG_Tiziano_Bevilacqua_241205.pdf

09:40 yt-induced Hbb as a background for HH searches (17'+5')

Speaker: Marco Zaro (Università degli Studi and INFN Milano)

bbh-hwg-dec2024.pdf

10:02 ttHbb highlights/summary of the WG1 - ttH/tH workshop (10'+10')

WG1 ttH/tH workshop: https://indico.cern.ch/event/1440845/

Speaker: Matthias Schroeder (University of Hamburg)

2024-12-05_LHCHWG_ttH.pdf

10:22 Updated ttHbb results ATLAS (10'+10')

Speaker: Alexander Froch (Université de Genève)

241205_ttH_LHC_HWG.pdf

10:42 VHcc ATLAS+CMS focusing on modelling uncertainties (20'+10')

Speaker: Zhuoran Feng (Nikhef)

Full Run 2 VH(cc) Results from ATLAS and CMS collaborations (2).pdf

11:12 VHbb ATLAS+CMS focusing on modelling uncertainties (20'+10')

Speaker: Christina Reissel (MIT)

LHC_HiggsWG_Reissel_v5.pdf

11:42 PDF uncertainties on predictions for Higgs production in gluon-gluon fusion (15'+5')

Lightning talk

Speaker: Maria Vittoria Garzelli (University of Hamburg)

semhi.pdf

09:00 → 12:00 WG2 parallel session

Conveners: Daniele Barducci (University and INFN Pisa), Pier Paolo Giardino (UAM and IFT Madrid)

09:00 Exotic decays of Higgs bosons to LLPs (ATLAS and CMS)

Speaker: Dominique Trischuk (Brandeis University)

Trischuk_ExoticHiggsDecaysToLLPs_LHCHiggsWG_Dec2024.pdf

09:25 A log story short: running contributions to radiative Higgs decays in SMEFT (20'+5')

Speaker: Guilherme Guedes (DESY)

LHC_Higgs_WG.pdf

09:50 Interference effects in gg→H→Zγ beyond Leading Order (20'+5') [remote]

Speaker: Federico Buccioni (Technical University of Munich)

buccioni_21stHWG.pdf

10:15 Short coffee break

10:35 CP-sensitive observables in STXS ttH cross sections (20'+5')

Speaker: Alberto Carnelli (IRFU Saclay - CNRS)

HWG_05_12_24_carnelli.pdf

11:00 Probing CPV with DPhijj in H→WW (ATLAS) (20'+5') [remote]

Speaker: Cameron Clarry (University of Toronto)

cclarry-cpv-hww.pdf

11:25 Off-shell coupling measurements (CMS) (20'+5')

Speaker: Andrei Gritsan (Johns Hopkins)

talk_LHCHWG_2024_offshell.pdf

09:00 → 12:22 WG3 parallel session

Conveners: Rui Santos (ISEL and CFTC-UL), Tatjana Lenz (University of Bonn)

video1719138411.mp4

09:00 Rare and Exotic Higgs decays in CMS (15'+3')

Speaker: Lakshmi Pramod (DESY)

HRareExo_LHCHWG2024.pdf

09:18 Rare and exotic Higgs decays in ATLAS (15'+3')

Speaker: Diallo Boye (Brookhaven National Laboratory)

LHCH_working_group_slides.pdf

09:36 LLPs from Exotic Higgs decays using faraway sub-detectors (15'+3')

Speaker: Nathan Grieser (University of Cincinnati)

Higgs_LLP.pdf

09:54 Higgs Mass Predictions in the CP-Violating High-Scale NMSSM (15'+3')

In a supersymmetric theory, large mass hierarchies can lead to large uncertainties in fixed-order calculations of the SM-like Higgs mass. A reliable prediction is then obtained by performing the calculation in an effective field theory (EFT) framework, involving the matching to the full supersymmetric theory at the high scale to include contributions from the heavy particles, and a subsequent renormalization-group running down to the low scale. In my talk, I report on the prediction of the SM-like Higgs mass within the CP-violating Next-to-Minimal Supersymmetric extension of the SM (NMSSM) in a scenario where all non-SM particles feature TeV-scale masses. The matching conditions are calculated at full one-loop order using two approaches. These are the matching of the quartic Higgs couplings as well as of the SM-like Higgs pole masses of the low- and high-scale theory. A comparison between the two methods allows for an estimate of the size of terms suppressed by the heavy mass scale that are neglected in a pure EFT calculation as given by the quartic-coupling matching. The calculation is implemented in a new version of the public program package NMSSMCALC.

Speaker: Christoph Borschensky (KIT)

NMSSM-Higgs-EFT_Borschensky.pdf

10:12 Recent developments in NMSSMCALC (15'+3') [remote]

Supersymmetry is among the most promising BSM frameworks solving many of the SM's theoretical and experimental shortcomings as well as providing a rich phenomenology across all sectors of the theory. The Next-to-Minimal-Supersymmetric-Standard-Model (NMSSM) is a natural successor of minimal supersymmetry providing a richer phenomenology in many regards such as e.g. more sources of CP-violating, scalar states lighter than the SM-like Higgs boson or additional dark matter candidates, to name a few. In order to scrutinize the NMSSM parameter space, precise predictions for a variety of observables within given scenarios are required. The program NMSSMCALC is addressing this demand by implementing precision calculations within the Higgs- and electroweak sector which are continuously improved and extended to match the experimental accuracy. Therefore, NMSSMCALC allows to confront a given benchmark-scenario with experimental observations and check its validity with high confidence.

In this talk we will present recent developments in NMSSMCALC that extend its portfolio by precision predictions for low-energy observables such as the W-boson mass, the muon anomalous magnetic moment or electric dipole moments. Furthermore, we report on improvements for precision predictions in the Higgs sector. Predictions for both, the Higgs boson masses and effective trilinear Higgs couplings have been recently improved at the two-loop level. We discuss the impact of loop-corrected couplings and masses on Higgs-to-Higgs decays, as computed by NMSSMCALC and demonstrate their potential to reduce the theoretical uncertainty of the Higgs boson pair production cross-section.

Speaker: Martin Gabelmann (DESY)

LHCHWG24_Martin_Gabelmann_NMSSMCALC.pdf

10:30 Short coffee break

10:50 MSSM Higgs boson production via gluon fusion (15'+3')

Speaker: Michael Spira (Paul Scherrer Institute)

spira_mssm.pdf

11:08 Updates on charged Higgs cross sections (15'+3')

Speaker: Emanuele Angelo Bagnaschi (INFN Frascati)

HXSHWG-charged-2024-BAGNASCHI-v3.pdf

11:26 Extended scalars and dark matter (15'+3')

Speaker: Rui Santos (ISEL and CFTC-UL)

ESDM_2024_Santos.pdf

11:44 Higgs to dark showers (15'+3')

Speaker: Emre Sitti (ETH Zuerich)

HiggsWG_Sitti.pdf

12:02 Recasting in resonant di-Higgs searches (15'+3')

Speaker: Daniele Barducci (University and INFN Pisa)

barducci_LHCWG_24.pdf

09:30 → 12:00 WG4 parallel session

Conveners: Arantxa Ruiz Martinez (IFIC Valencia), Milada Margarete Muehlleitner (KIT)

09:30 Introduction

Speakers: Arantxa Ruiz Martinez (IFIC Valencia), Fabio Monti (CERN), Ludovic Michel Scyboz (Monash University), Milada Margarete Mühlleitner (KIT), Stefano Manzoni (CERN)

HH_intro_051224.pdf

09:40 Triple Higgs searches in ATLAS

Speaker: William Balunas (University of Cambridge)

hhh-atlas.pdf

10:00 Overview of triple Higgs theory

Speaker: Tania Natalie Robens (Rudjer Boskovic Institute)

robens_hhh-n.pdf

10:30 Multi-Higgs Production and the Electroweak Phase Transition

Exploring the Higgs sector via multi-Higgs production searches is a main goal for run-3 and high-lumi LHC. Can these searches inform us about the electroweak phase transition and matter-antimatter asymmetry? We address this question in the context of the TRSM (Two-Real-Singlet Model), which has known benchmark points enhancing multi-Higgs production. We update the triple-Higgs production benchmark points to include refined perturbativity bounds and explore the type of electroweak phase transition that occurs in the early universe; whether continuous or the first-order discontinuous phase transition desired for matter-antimatter asymmetry. After presenting our work, I outline lessons on correlating the type of electroweak phase transition and the enhancement of di-Higgs or triple Higgs production, highlighting the importance of the theory's vacuum expectation value of today and the symmetries of the model.

Speaker: Osama Karkout (Nikhef)

EWSB_HHH_CERN.pdf

10:50 Effect of anomalous HHH and ZZHH couplings on the decay width of H→4l [remote]

Despite the discovery of the Higgs boson, the Higgs sector of the standard model is still not fully established. In particular, the self-couplings of the Higgs boson and its couplings with gauge bosons are still to be fully determined. We consider electroweak corrections to the processes H --> ve ve~ vm vm~ and H --> e+ e- mu+ mu-. The corrections depend on the HHH coupling. We investigate this dependence in the kappa-framework without violating gauge invariance. We find that the width depends on coupling significantly.

Speaker: Biswajit Das (The Institute of Mathematical Sciences, Chennai)

h_to_4l_LHC_HWG.pdf

11:10 Double Higgs production in vector boson fusion at NLO QCD with anomalous couplings

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 (KIT)

VBF_HH_HEFT_LHCHWG.pdf

11:30 Multi-Higgs production from VBS in HEFT (15'+5')

We computed some results for vector boson scattering  in HEFT for the production of 2, 3 and 4 Higgs bosons. This results are updated after the latest results from both CMS and ATLAS for single and double Higgs production.

Speaker: Javier Martínez Martín (Universidad Complutense de Madrid & IPARCOS)

21st_Higgs_WG.pdf

12:30 → 14:00 Lunch break

14:00 → 15:30 Plenary (WG1) + Future colliders

Conveners: Alessandro Calandri (ETH Zuerich), Alexander Karlberg (CERN)

[Thursday PM-1] Plenary (WG1) + Future colliders.mp4

14:00 ttH/tH status report (17'+5')

Speaker: Judith Katzy (DESY)

ttHtH_statusreport_LHCHWG2024_final.pdf

14:22 Off-shell status report (17'+5')

Speaker: Raoul Horst Roentsch (Università degli Studi and INFN Milano)

roentsch_HXSWG_20241205.pdf

14:44 BR status report (10'+5')

Speaker: Michael Spira (Paul Scherrer Institute)

spira_br.pdf

15:00 Higgs physics at future colliders (20'+10')

Speaker: Matthew Philip McCullough (CERN)

HiggsWorkingGroup.pdf

15:30 → 16:00 Coffee break

16:00 → 17:30 Plenary (WG2)

Convener: Daniele Barducci (University and INFN Pisa)

[Thursday PM-2] Plenary (WG2).mp4

16:00 Measurements of Higgs couplings to fermions and interpretations of Higgs XS measurements at ATLAS and CMS (17'+5')

Speaker: Jelena Jovicevic (Institute of Physics, University of Belgrade)

Jelena_LHCHWG2024.pdf

16:22 Measurements of Higgs couplings to bosons at ATLAS and CMS (17'+5') [remote]

Speaker: Jeffrey Davis (Johns Hopkins)

LHCHWG_Higgs_Couplings_to_Bosons_12_5_24.pdf

16:44 BSM & SMEFT Interpretation of Higgs measurements at LHC and HL-LHC (17'+5')

Speaker: Ken Mimasu (University of Southampton)

Mimasu_HWG_no_build.pdf

Mimasu_HWG.pdf

17:06 Non-linear CP violation (17'+5') [remote]

Speaker: Akanksha Bhardwaj (Oklahoma State University)

Akanksha_WG2_Higgs_CP.pdf

19:30 → 22:30 Workshop dinner

Fondue (or dairy-free option) at Cave Valaisanne. Please register and pay (55 CHF) before 30th November if you plan to attend.

Friday 6 December

09:00 → 11:35 Cross-topic plenary

Convener: Fabrizio Arturo Caola (University of Oxford)

[Friday AM-1] Cross-topic plenary.mp4

09:00 Updates from PDF global fits (20'+10')

Speaker: Joey Huston (Michigan State University)

huston_hxswg_meet_dec24_final.pdf

09:30 STXS Overview (15'+5') [remote]

Speaker: Matteo Bonanomi (University of Hamburg)

LHCHWG_STXS_Overview.pdf

09:50 Finite Width and Interference (15'+5')

Speaker: Georg Ralf Weiglein (DESY)

LHCHiggsWG_interfer_24.pdf

10:45 Coffee break

11:15 Accessing the Electroweak Phase Transition through Top Quark and Higgs Boson Production (15'+5')

If a first-order electroweak phase transition is realized by an extended scalar sector, this impacts observables at (future) colliders. In this talk I will discuss multiple SM extensions that allow for strong first-order electroweak phase transitions: Two-Higgs Doublet Model (2HDM), Next-to-Minimal Two-Higgs Doublet Model (N2HDM), and two dimension-six effective field theory extensions of the 2HDM. For these I will illustrate how the strength of the phase transition impacts cross sections of double Higgs production, triple Higgs boson production, or top pair production.

Speaker: Lisa Biermann (Paul Scherrer Institute)

LHCWG24_LBiermann.pdf

11:35 → 13:05 Plenary (WG4)

Conveners: Fabio Monti (CERN), Ludovic Michel Scyboz (Monash University), Stefano Manzoni (CERN)

[Friday AM-2] Plenary (WG4).mp4

11:35 Overview of HH searches at ATLAS

Speaker: Arantxa Ruiz Martinez (IFIC Valencia)

ARuiz_LHCHWG2024.pdf

11:50 Overview of HH searches at CMS

Speaker: Torben Lange (National Institute of Chemical Physics and Biophysics, Tallinn)

LHCHWG.pdf

12:05 VBF HH with Powheg

Speaker: Simon Reinhardt (University of Tuebingen)

VBFHH_with_POWHEG.pdf

12:25 NLO EW corrections on gg→HH cross section [remote]

Speaker: Huai-Min Yu (Peking University)

gg2HH_CERN.pdf

12:45 Resonant HH production: interference effects and higher-order corrections

Speaker: Kateryna Radchenko Serdula (DESY)

LHCHWG21_Radchenko.pdf

13:05 → 14:00 Lunch break

14:00 → 15:30 Lightning session for LHCHWG Report 5

Conveners: Katharine Leney (Southern Methodist University), Liza Brost (Brookhaven National Laboratory (US))

[Friday PM-1] Lightning session for LHCHWG Report 5.mp4

14:00 WG3: Rare and Exclusive Higgs boson decays (7'+3')

Speakers: David d'Enterria (CERN), Van Dung Le (Ho Chi Minh City University)

dde_rare_exclusive_Higgs_decays_dec24.pdf

14:10 WG3: Intelligent Scans in the NMSSM at Highest Precision (7'+3')

Speakers: Felix Egle (KIT), Felix Egle (DESY)

LHCWG21_FelixEgle.pdf

14:20 WG1: Parton shower aspects of Vector Boson Fusion Higgs production (7'+3') [remote]

Speaker: Jiayi Chen (Simon Fraser University)

lightning-talk-VBFshower.pdf

14:30 WG1: Resummed predictions for VH (7'+3') [remote]

Speaker: Kajal Samanta (IPPP Durham)

YR2024.pdf

14:40 WG1: NLO ggZH differential prediction (7'+'3') [remote]

Speaker: Marco Vitti (KIT)

HWG_24_Vitti.pdf

14:50 WG2: Recommendation for ATLAS + CMS full-likelihood publications (7'+3') [remote]

Speaker: Nicholas Wardle (Imperial College)

likelihoods.pdf

15:00 WG2: CPV STXS, CPV benchmark call in BSM models and dictionary note on different CPV parametrizations (7'+3') [remote]

Speaker: Henning Bahl (Heidelberg University)

LHCHWG24_Bahl.pdf

15:10 WG4: HH physics at 14 TeV (15'+5') [remote]

Speaker: Javier Mazzitelli (Paul Scherrer Institute)

mazzitelli_HH.pdf

15:30 → 16:00 Coffee break

16:00 → 17:30 Summary and closeout

Convener: Mauro Donega (ETH Zuerich)

[Friday PM-2] Summary and closeout.mp4

16:00 WG1 Higgs XS&BR: Outlook and Plans (10'+5') [remote]

Speaker: Hannah Arnold (Stony Brook University)

Arnold_LHCHWG_generalMeeting2024_closeout_v1.pdf

16:15 WG2 Higgs Properties: Outlook and Plans (10'+5')

Speaker: Pier Paolo Giardino (UAM and IFT Madrid)

SummaryWG2_2024.pdf

16:30 WG3 BSM Higgs: Outlook and Plans (10'+5')

Speaker: Tatjana Lenz (University of Bonn)

WG3-Dec6-2024.pdf

16:45 WG4 HH and multi-Higgs: Outlook and Plans (10'+5')

Speaker: Fabio Monti (CERN)

Summary WG4-4.pdf

17:00 Closing words from the Steering Committee (10'+5')

Speaker: Ennio Salvioni (University of Sussex)

21st_Workshop_Closing_SC_2.pdf