Higgs Pairs Workshop 2022

30 May 2022, 08:00 → 3 Jun 2022, 18:00 Europe/Zurich

This workshop aims at gathering both theorists and experimentalists to discuss recent results, analysis techniques and theoretical calculations of HH production.

We plan to cover LHC results, analysis techniques, prospects at future colliders, advances in theoretical calculations, BSM phenomenology, and EFT interpretations.

The main program will consist of several days dedicated to specific topics with invited talks, but we also allow for submitted talk contributions. We also plan to allow ample time for discussion.e

We will go ahead with an in-person meeting and look forward to welcoming everyone in Dubrovnik! The workshop is limited to 110 in-person participants, due to restrictions on the venue capacity. Once we reach this limit we will establish a first come first serve waiting list for further registrants. Note that Covid  measures in Croatia will be released after Easter; we are also considering local streaming options. In any case, in-person registration will close on 1st May. The in-person registration fee will be 220 Euros (payment details available here).

UPDATE: The registration period has been extended until May 15th. Registrations after this date will be possible upon request and will be considered on a case-by-case basis.

The workshop is supported by

  

 

 

HH2022_Bulletin.pdf

Higgs Pairs discussion sessions QR poster.pdf

Monday, 30 May

13:00 → 14:00 Registration

WIFI info:

network (SSID): higgs
password: unidu2022

14:00 → 14:05 Welcome from the Programme Committee

Higgs Pairs 2022 PC Welcome.pdf

14:05 → 14:15 Welcome from the Local Organisers

Speaker: Vuko Brigljevic (Rudjer Boskovic Institute (HR))

HiggsPairs-Welcome.pdf

14:15 → 17:00 Overview

Conveners: Javier Mazzitelli (Universidad de Buenos Aires (AR)), Petar Maksimovic (Johns Hopkins University (US))

14:15 HH Production in the SM: Theoretical Status

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

sjones_dubrovnik22v3.pdf

15:00 HH Production: ATLAS overview

Speaker: Rui Zhang (University of Wisconsin Madison (US))

DiHiggs2022ZhangRui.pdf

15:45 Tea break

16:15 HH Production: CMS overview

Speaker: Fabio Monti (Chinese Academy of Sciences (CN))

Fabio_Monti_H_pairs_workshop_2022_v3.pdf

17:00 → 18:00 Parallel Discussion: EW uncertainties

Conveners: Javier Mazzitelli (Universidad de Buenos Aires (AR)), Michael Spira (Paul Scherrer Institute (CH))

ATLAS+CMS comb. minutes

Discussion_Reinterpretation.pdf

Reinterpretation Live Notes

17:00 → 18:00 Parallel Discussion: Future combinations (ATLAS+CMS)

Conveners: Luca Cadamuro (Université Paris-Saclay (FR)), Valentina Cairo (CERN)

ATLAS+CMS comb. minutes

Discussion_Reinterpretation.pdf

Reinterpretation Live Notes

18:15 → 20:00 Welcome reception

Tuesday, 31 May

09:00 → 17:30 Non-resonant HH (ggF+VBF)

Conveners: Agni Bethani (University of Maryland (US)), Alessandra Betti (Sapienza Università e INFN, Roma I (IT)), Eleni Vryonidou (University of Manchester (GB)), Pier Paolo Giardino (IGFAE-Universidade de Santiago de Compostela)

09:00 ATLAS and CMS non-resonant HH->bbbb

Speakers: Daniel Guerrero (University of Florida (US)), Rafael Teixeira De Lima (SLAC National Accelerator Laboratory (US))

HH4bTalk_May31_2022.pdf

09:30 ATLAS and CMS non-resonant HH->bbtautau

Speakers: Francesco Brivio (Universita & INFN, Milano-Bicocca (IT)), Yanlin Liu (University of Michigan (US))

ATLAS and CMS Non-resonant HH→bb𝜏𝜏.pdf

10:00 ATLAS and CMS non-resonant HH->bbyy

Speakers: Louis D'Eramo (Northern Illinois University), Maxime Gouzevitch (Centre National de la Recherche Scientifique (FR))

HH_bbgg talk for Dubrovnik.pdf

10:30 Coffee break

11:00 HH at N3LO

Speaker: Huasheng Shao (Centre National de la Recherche Scientifique (FR))

Shao_HHN3LO.pdf

11:30 Top mass scheme uncertainty in HH cross-sections

Speakers: Michael Spira (Paul Scherrer Institute (CH)), Michael Spira (Unknown)

spira.pdf

12:30 Lunch

14:00 SMEFT vs HEFT -- pros and cons

Speaker: Raquel Gomez Ambrosio (Milano Bicocca)

Raquel_HiggsPairs.pdf

14:30 Technical summary of EFTs for HH

Speaker: Ludovic Scyboz

HiggsPairs-2022_Scyboz.pdf

15:00 Summary of the LHC EFT working group activities

Speaker: Nicolas Berger (Centre National de la Recherche Scientifique (FR))

HPairs2022_LHCEFTWG.pdf

15:30 Tea break

16:00 ATLAS and CMS non-resonant HH->leptons+X

Speakers: Alessandra Cappati (Centre National de la Recherche Scientifique (FR)), Julian Wollrath (University of California Irvine (US))

HHToleptonsPlusX_Cappati_Wollrath.pdf

16:30 HH combination and parameter scans

Speaker: Alexandra Carvalho Antunes De Oliveira (Vilnius University (LT))

nonres_HH_parameter_scans_croatia_2022.pdf

17:00 Combination of di-Higgs and single-Higgs measurements

Speaker: Stefano Manzoni (CERN)

presentazione_smanzoni_H_HH_WS2022.pdf

Wednesday, 1 June

08:45 → 17:00 Resonant HH/SH

Conveners: Duarte Azevedo (ITP/IAP - Karlsruher Institut für Technologie), Jana Schaarschmidt (University of Washington (US)), Jason Robert Veatch (California State University (US)), Rainer Mankel (Deutsches Elektronen-Synchrotron (DE)), Sebastian Baum (Stanford University)

08:45 Data driven QCD background estimates in HH/HS searches at CMS

Speaker: Matej Roguljic (Rudjer Boskovic Institute (HR))

220601_QCD_estimates_HiggsPairs.pdf

09:00 Overview of resonant HH/HS/SS production

Speakers: Rui Santos (University of Southampton and NExT Institute), Rui Santos, Rui Santos (ISEL and CFTC-UL), Rui Santos (ISEL), Rui Santos (University of Southampton and NExT Institute)

HH_Dubrovnik_Santos22.pdf

10:00 ATLAS and CMS resonant HH/SH->bbττ

Speakers: Ralf Schmieder (KIT - Karlsruhe Institute of Technology (DE)), Tatjana Lenz (University of Bonn (DE))

Higgs-Pairs-Workshop.pdf

10:40 Coffee break

11:10 ATLAS and CMS resonant HH/SH->4b

Speakers: Marco Valente (TRIUMF (CA)), Santeri Laurila (CERN)

HiggsPairsWorkshop_ResonantHH4b_20220601.pdf

11:50 CMS resonant HH/SH-> multilepton and bb+leptons

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

HHWorshopDubrovnik-TorbenLange.pdf

12:10 ATLAS resonant HH->bbγγ

Speaker: Ivan Sayago Galvan (Univ. of Valencia and CSIC (ES))

Higgs_Pairs_Resonant_bbyy.pdf

12:30 Group picture (in the IUC atrium)

12:45 Lunch

14:00 ATLAS and CMS jet and flavor tagging

Speaker: Loukas Gouskos (CERN)

lg-jets-higgspairs2022-v1.pdf

14:45 Interference effects

Speaker: Ian Lewis (The University of Kansas)

IL_HiggsPairs_2022.pdf

15:30 Tea break

16:00 Reinterpretation (theory) "Report from the LHC re-interpretation group"

Speaker: Nicholas Wardle (Imperial College (GB))

nwardle_Reinterpretations.pdf

16:30 Reinterpretation (experiment)

Speaker: Lukas Alexander Heinrich (CERN)

HiggsPairs2022.pdf

17:00 → 18:00 Parallel Discussion: Other HH production modes

Conveners: Giacomo Ortona (Universita e INFN Torino (IT)), Stephen Philip Jones (University of Durham (GB))

ATLAS+CMS comb. minutes

Discussion_Reinterpretation.pdf

Reinterpretation Live Notes

17:00 → 18:00 Parallel Discussion: Reinterpretations

Conveners: Lukas Alexander Heinrich (CERN), Nicholas Wardle (Imperial College (GB))

ATLAS+CMS comb. minutes

Discussion_Reinterpretation.pdf

Reinterpretation Live Notes

Thursday, 2 June

09:00 → 14:00 Future colliders

Conveners: Caterina Vernieri (SLAC National Accelerator Laboratory (US)), Tania Natalie Robens (Rudjer Boskovic Institute (HR))

09:00 Theory overview

Speakers: Zhen Liu (University of Minnesota (US)), Zhen Liu

HiggsPairs_TheoryOverview_ZhenLiu_HiggsPairs2022_split.pdf

09:30 HH prospects at the HL-LHC

Speaker: Nan Lu (California Institute of Technology (US))

HH_prospect_HL_LHC_v2.pdf

10:00 Snowmass activities overview

Speaker: Patrick Meade

higgspairsSnowmass.pdf

10:30 Coffee break

11:00 e+e- colliders

Speaker: Aidan Robson (University of Glasgow (GB))

HH_eeProspects1.pdf

11:30 mu+ mu- colliders

Speaker: Donatella Lucchesi (Universita e INFN, Padova (IT))

HH-muoncollider.pdf

12:00 FCC-hh

Speaker: Matthew James Sullivan (University of Liverpool (GB))

HHatFCChh-HiggsPairWorkshop2022.pdf

12:30 Lunch

14:00 → 16:00 Walking tour of old city

16:30 → 17:00 Future colliders

Conveners: Caterina Vernieri (SLAC National Accelerator Laboratory (US)), Tania Natalie Robens

16:30 Future colliders - discussion

ideas.pdf

17:00 → 18:00 Future colliders: Wildcard talks

Conveners: Caterina Vernieri (SLAC National Accelerator Laboratory (US)), Tania Natalie Robens (Rudjer Boskovic Institute (HR))

17:00 Di-Higgs projections for future high-energy e+e-colliders

Following the Higgs boson discovery in 2012 at the LHC, there has been an increased interest in the field of $e^+e^-$ collider physics suitable for performing precision measurements and testing the Standard Model (SM) in its limits. With the Higgs potential being characterised by the Higgs self-coupling, a model-independent measurement is crucial to either verify the SM mechaniscm for electroweak symmetry breaking sector or uncover new physics.
At future high-energy $e^+e^-$ colliders, the Higgs self-coupling can be directly accessed through the measurement of double Higgs boson production. The measurement is challenging due to the small production cross section and large multiplicity causing jets to overlap. Such challenges sets high standards on the analysis techniques and could sway which centre-of-mass energies to run at. Additionally, the possibility of new physics influences which channels might hold the better sensitivity.
In this contribution, we review the state-of-the-art of di-Higgs projections at future high-energy $e^+e^-$ colliders and give an outlook on how recent improvements in analysis techniques will impact the sensitivity, focusing on flavour-tagging, b-jet reconstruction, and kinematic fitting.

Speaker: Julie Munch Torndal (Deutsches Elektronen-Synchrotron (DE))

Higgs_Pairs_Workshop_2022.pdf

17:15 Triple Higgs couplings in the di-Higgs production in the 2HDM at future colliders

Two Higgs doublet models (2HDM) are one of the simplest and most popular extensions to the SM and predict very different scalar interactions compared to the SM. These new interactions include new triple couplings of the SM-like Higgs bosons with itself and with the new Higgs bosons present in the 2HDM. In consequence, these new triple Higgs interactions can enter at tree-level in the cross section production of two Higgs bosons. In this talk, we analyze the main production channels at future colliders in the 2HDM, and we study the possible effects coming from the triple Higgs couplings. The results of the cross sections are presented in benchmark planes where large triple Higgs couplings can be realized inside the region allowed by all the relevant theoretical and experimental constraints. We also discuss the relevance of studying the differential cross section on the invariant mass of the two final Higgs bosons to extract the effects of the triple Higgs couplings at future colliders.

Speaker: Francisco Arco (UAM - IFT)

Arco_HiggsPairs22.pdf

17:30 Triple Higgs production with extra scalars in proton-proton colliders

In this talk we will discuss the production of three Higgs bosons at the LHC, and at a proton-proton collider running at a centre-of-mass energy of 100 TeV. We will argue that the seemingly challenging 6-bottom jet final state is a very good candidate to investigate triple Higgs production within, and beyond, the SM at proton-proton colliders. In particular we will consider three different scenarios: one in which the triple and quartic Higgs boson self-couplings are not affected by
new physics phenomena besides the Standard Model (SM) and two possible SM extensions, by one or two new scalars. We will show that a 100 TeV machine can impose competitive constraints on the quartic coupling in the SM-like scenario. In the case of the scalar extensions of the SM, we will show that large significances can be obtained at the LHC and the 100 TeV collider, while obeying current theoretical and experimental constraints, including a first-order electroweak phase transition.

Speaker: Andreas Papaefstathiou (Kennesaw State University, GA, USA)

HiggsPairs_APapaefstathiou.pdf

17:45 GW waves and the triple Higgs boson coupling in the 2HDM

Many popular extensions of the SM require sizeable modifications to the trilinear Higgs boson coupling in order to accommodate a first-order electroweak (EW) phase transition. Cosmological first-order phase transitions can give rise to a primordial gravitational wave (GW) background which could be observable at future space-based GW detectors such as LISA. Focusing on the Yukawa type-II 2HDM and taking into account various theoretical and experimental constraints in combination with the condition of the presence of a first-order EW phase transition, we scrutinize the relevant parameter space regions and verify whether these regions could be probed in a complementary way at the HL-LHC via nonresonant Higgs boson pair production and at the LISA experiment via the possible observation of a GW signal. We find regions of the parameter space that give rise to GW signals that might be detectable at LISA, and these regions predict values of the triple Higgs boson couplings that are potentially observable at the HL-LHC or other future colliders. The measurements of Higgs boson pair production will therefore provide important constraints on the possiblity of observing GW signals at LISA.

Speaker: Maria Olalla Olea Romacho

Olea_Romacho.pdf

18:00 → 18:30 Tea break

18:30 → 19:30 Wildcard talks

Conveners: Milada Muhlleitner (KIT - Karlsruhe Institute of Technology (DE)), Ramona Groeber (Università di Padova and INFN, Sezione di Padova)

18:30 Non-resonant Higgs Production with a scalar Singlet at the LHC

We investigate the collider signature of the real singlet extension of the standard model. A definitive correlation exists between the strength of the phase transition and the trilinear coupling of the Higgs to two singlet-like scalars, and hence between the phase transition and non-resonant scalar pair production involving the singlet at colliders. We study the prospects for observing these processes at the high luminosity LHC, focusing particularly on the associated production of singlet and the SM Higgs.

Speaker: Haider Alhazmi

Haider_Higgs_Pairs_2022.pdf

18:45 New constraints on extended scalar sectors from the trilinear Higgs coupling

The trilinear Higgs coupling $\lambda_{hhh}$ is crucial for determining the structure of the Higgs potential and for probing possible effects of physics beyond the Standard Model (SM). Focusing on the Two-Higgs-Doublet Model as a concrete example, I will discuss the calculation of the leading two-loop corrections to $\lambda_{hhh}$, and show that this coupling can be significantly enhanced with respect to its SM prediction in certain regions of parameter space. Taking into account all relevant corrections up to the two-loop level, I will show that the current experimental bounds on $\lambda_{hhh}$ already rule out significant parts of the parameter space that would otherwise be unconstrained. Finally, I will present a benchmark scenario illustrating the interpretation of the current results and future measurement prospects on $\lambda_{hhh}$.

Speaker: Johannes Braathen (DESY)

Braathen_HiggsPairs22.pdf

19:00 Precise predictions for the trilinear Higgs coupling in arbitrary models

The investigation of the trilinear self-coupling of the discovered Higgs boson is one of the main goals of particle physics in the near future.
We provide predictions for this coupling, expressed in terms of the coupling modifier $\kappa_\lambda$, incorporating one-loop corrections within arbitrary renormalizable QFTs.
The presented framework allows to apply a wide class of pre- and user-defined renormalization conditions whereas the calculation of all required one-, two- and three-point functions is incorporated in an automated way.
In this talk I motivate precision predictions for $\kappa_\lambda$ in the context of di-Higgs production and the need for their automation.
The basic ingredients of a generic $\kappa_\lambda$ calculation at the one-loop order as well as the features of the resulting computer program are discussed.
I conclude with an outlook on possible applications.

Speaker: Martin Gabelmann (DESY)

gabelmann_higgspairs22.pdf

20:00 → 23:00 Conference dinner

At restaurant Orhan
https://goo.gl/maps/KTTML1svEVgaQtuPA

Restaurant Orhan

Friday, 3 June

09:00 → 10:30 Wildcard talks

Conveners: Milada Muhlleitner (KIT - Karlsruhe Institute of Technology (DE)), Ramona Groeber (Università di Padova and INFN, Sezione di Padova)

09:00 Predictions for $gg\to hh$ at full NLO QCD comparing non-linear and linear EFT frameworks and truncation effects

We present results for Higgs boson pair production in gluon fusion
including both, NLO (2-loop) QCD corrections with full top quark
mass dependence as well as anomalous couplings related to operators
describing effects of physics beyond the Standard Model. The latter
can be realized in non-linear (HEFT) or linear (SMEFT) Effective
Field Theory frameworks. We show results for both and discuss the
impact of different truncation options within the SMEFT description.

Speaker: Jannis Lang

JannisLang_HiggsPairs2022.pdf

09:15 Interplay between an SFOEWPT and Higgs pair production in a 2HDM-EFT

By extending the 2-Higgs Doublet Model (2HDM) by scalar dimension-6 effective field theory (EFT) operators we investigate to which extent the addition of these higher-dimensional operators can promote the electroweak phase transition to a strong first-order electroweak phase transition (SFOEWPT). We analyze the interplay between the choice of Wilson coefficients inducing an SFOEWPT and the generated size of the LHC Higgs pair production cross section in this 2HDM-EFT.

Speaker: Ms Lisa Biermann (Karlsruhe Institute of Technology)

LisaBiermann_HiggsPairs22.pdf

09:30 Falsification of SMEFT through Higgs measurements

From the embedding of the Standard Model Effective Field Theory (SMEFT) in the more general Higgs Effective Field Theory (HEFT), we expose correlations among the coefficients of the latter that, if found to be violated in future data, would lead to the experimental falsification of the SMEFT framework. These are derived from the necessary symmetric point of HEFT
and analiticity of the SMEFT Lagrangian
that allows the construction of the SMEFT expansion, as laid out by other groups, and properties at that point of the Higgs-flare function $\mathcal{F}(h)$ coupling Goldstone and Higgs bosons.

Speaker: Alexandre Salas-Bernárdez

Falsification of SMEFT.pdf

09:45 Higgs Pair Production in a Composite 2HDM

The Composite 2-Higgs-Doublet Model (C2HDM) is a composite Higgs Model where two Higgs doublets arise as pseudo Nambu-Goldstone bosons in order to retrieve the well known 2HDM but with couplings already predetermined by the composite nature of the model. Fermion masses are generated through partial compositeness entailing new heavy fermions. In this talk we present Higgs Pair production in this model via gluon fusion, including higher order QCD corrections. We investigate the impact of the higher-order corrections as well as the impact of the compositeness nature of the model with the new heavy fermions on the phenomenology of Higgs pair production.
The theoretical calculation is described in detail and specific benchmark scenarios are explored.

Speaker: Felix Egle (Institute for Theoretical Physics (ITP), Karlsruhe Institute of Technology (KIT))

HPPinComposite2HDM.pdf

10:00 Leading two-loop Yukawa corrections to gg -> HH

In this talk, I will present the first analytical calculations of leading two-loop Yukawa corrections to the Higgs pair production in the high energy limit. The electroweak corrections are expected to have a percent-level impact on the cross sections, and hence it is desirable to have the amplitudes ready for the future phenomenological studies. As a first step in this direction, we compute the leading two-loop Yukawa corrections of gg->HH process originating from exchanging an additional Higgs boson between virtual top-quark lines. In particular, I will discuss new theoretical advances which enable the analytical calculations.

Speaker: Hantian Zhang (Karlsruhe Institute of Technology)

zhang_EW2loop.pdf

10:30 → 11:00 Coffee break

11:00 → 12:30 Summary & Outlook

Conveners: Milada Muhlleitner (KIT - Karlsruhe Institute of Technology (DE)), Ramona Groeber (Università di Padova and INFN, Sezione di Padova)

11:00 Experimental Summary and Outlook

Speaker: Luca Cadamuro (Université Paris-Saclay (FR))

HH_experimental_summary.pdf

11:45 Theory Summary and Outlook

Speaker: Michael Spira (Paul Scherrer Institute (CH))

spira.pdf

12:30 → 14:00 Lunch