8th General Meeting of the LHC EFT Working Group

2 Dec 2024, 13:00 → 4 Dec 2024, 12:30 Europe/Zurich

4/3-006 - TH Conference Room (CERN)

General meeting of the LHC EFT Working Group 

The meeting will start in the afternoon of Dec 2nd and end on Dec 4th at noon. 
To subscribe to the WG mailing list, please click here.

Joint-session with the LHC Higgs WG

There will be a joint session with LHC Higgs WG on Wednesday morning, please access the LHC Higgs WG Meeting Indico (and associated Zoom room) for this.

 

CERN access

During registration you will be asked if you need a CERN access card - if you select yes, you may be immediately asked to fill in some additional details (or alternatively sent an e-mail in the following days asking for the same information). We will then grant access which will generate an Access Card which you should print out and bring with you to show to the staff at the front gate.

If you are unable to print your pass, you can use the provided access code on a small machine at the front gate to print your pass on the day.

CERN accommodation

A number of rooms at the CERN hostel have been pre-booked for the meeting. For information on how to access the room booking, please see the Accommodation section. 

If the pre-booked rooms are full, non-CERN users can alternatively book any remaining accommodation at the CERN hostel by filling the form here (provided there is additional availability):

CERN Hostel Booking - External

As part of the form you will be asked to name a guarantor for your stay, please put down either of:

• Jacob Julian Kempster (jacob.julian.kempster@NOSPAMcern.ch)
• Michelangelo Mangano (michelangelo.mangano@NOSPAMcern.ch)

 

(Removing 'NOSPAM' from the e-mail!)

If you have no current affliation to CERN, your CERN status will likely be "External CONF" for the hostel booking form.

Hotels in the local area

If you prefer to stay off-site in a hotel, the Housing Service has identified some hotels and apartment hotels in close vicinity to CERN. More details on these can be found at the link here.

Monday 2 December

13:00 → 14:30 General

Convener: Robert Schoefbeck (Austrian Academy of Sciences (AT))

13:00 Highlights from ATLAS

Speaker: Eleonora Rossi (University of Oxford (GB))

0212_ER_LHC_EFT_ATLAS.pdf

13:30 Highlights from CMS

Speaker: Fabian Stager (University of Zurich (CH))

eftwg_cms_highlights.pdf

14:00 Highlights from LHCb

Speaker: Zahra Ghorbanimoghaddam (University of Bristol)

EFT_Report2024_v2.pdf

14:30 → 14:50 Coffee

14:50 → 15:50 General

Convener: Ken Mimasu

14:50 RG effect in SMEFT (fits)

Speakers: Eleni Vryonidou (The University of Manchester (GB)), Luca Mantani (IFIC, Valencia)

EFTWG_Dec.pdf

15:20 NLO SMEFT predictions (for Zh and beyond)

Speaker: Konstantin Asteriadis

asteriadis_8th_eft_wg_meeting_2_12_24.pdf

15:50 → 16:35 Area 1

Convener: David Sutherland

15:50 Quantifying EFT Truncation Uncertainties at the LHC

Speakers: Markus Luty (University of California Davis), Markus Luty

24_12_05 LCH_EFTWG.pdf

16:10 Discussion on truncation

16:35 → 16:55 Coffee

16:55 → 18:10 Area 1

Convener: David Sutherland

16:55 SMEFT predictions for semileptonic processes

The $SU(2)_L\times U(1)_Y$ invariance of the Standard Model Effective Field Theory (SMEFT) predicts multiple restrictions in the space of Wilson coefficients of $U(1)_{em}$ invariant effective lagrangians such as the Low-energy Effective Field Theory (LEFT), used for low-energy flavor-physics observables, or the Higgs Effective Field Theory (HEFT) in unitary gauge, appropriate for weak-scale observables. In this work, we derive and enumerate all such predictions for semileptonic operators up to dimension 6. We find that these predictions can be expressed as 2223 linear relations among the HEFT/LEFT Wilson coefficients, that are completely independent of the choice of the SMEFT flavor basis. These relations interconnect a wide array of experimental searches, including high-$p_T$ dilepton searches, top decays, $Z$-pole observables, charged lepton flavor violating observables, non-standard neutrino interaction searches and semileptonic decays of $B$, $K$ and $D~$ mesons. We illustrate how these relations can be utilized to impose stringent indirect constraints on several Wilson coefficients that are currently weakly constrained or entirely unconstrained by direct experiments. Moreover, these relations imply that any evidence of new physics in a specific search channel would generally be accompanied by correlated anomalies in other channels.

Speaker: Siddhartha Karmakar (Tata Institute of Fundamental Research)

Siddhartha_SMEFT.pdf

17:15 Towards the HEFT-hedron: the complete set of positivity constraints on HEFT operators at NLO

We present the complete set of positivity bounds on the Higgs Effective Field Theory (HEFT) at next-to-leading order. We identify the 15 operators that can be constrained by positivity, as they contribute to $s^2$-growth in the amplitude for longitudinal gauge-Higgs scattering, that is to the $VV \to VV$, $hh$, $Vh$, and $hh \to VV$, $Vh$ processes, where $V = W^\pm, Z$, $h$ is the observed Higgs boson, and $s$ is the center-of-mass energy squared. We find two categories of constraints: (i) specific linear combinations of CP-even Wilson coefficients must be positive, and (ii) the magnitudes of some Wilson coefficients--including all CP-odd ones--must be smaller than products of other CP-even Wilson coefficients. Our results can thus provide indirect upper bounds on Wilson coefficients of the second category. Additionally, we obtain double-sided bounds on these Wilson coefficients by imposing unitarity and $st$-crossing symmetry. We present our final constraints on the 15 dimensional HEFT space as well as on the space of anomalous couplings and show how known positivity bounds on the 3 dimensional space of dimension 8 SMEFT can be recovered from them. For the $VV \to hh$ and $VV \to VV$ channels, we find that a significant portion of the parameter space is excluded by these requirements. In particular for quartic gauge couplings we find that less than $8\%$ of the experimentally allowed parameter space is consistent with our positivity bounds. Furthermore, positivity constraints of the second category above imply upper bounds on Wilson coefficients contributing to the $VV \to Vh$ process from collider bounds on $VV \to VV, hh$ searches.

Speaker: Debsubhra Chakraborty

LHC_EFT_WG_GM_021224.pdf

17:35 Evanescent operators at the one-loop level

I will discuss general basis transformations in Effective Field theories at the tree- and one-loop level. To this end, the notion of Evanescent operators and their formulation in terms of one-loop Fierz transformations will be introduced. To illustrate the usefulness of this approach several examples will be discussed, including scheme factorization. Comments on Evanescence free renormalization schemes will conclude the talk.

Speaker: Jason Aebischer (CERN)

EFTWG_Aebischer.pdf

17:55 On the SMEFT basis for Anomalous Quartic Gauge Couplings

Speakers: Nicholas Llewellyn Rodd (School of Physics-University of Melbourne-Unknown), Nicholas Llewellyn Rodd (CERN), Nicholas Rodd

aQGC-Basis.pdf

Tuesday 3 December

09:00 → 10:40 Area 5

Conveners: Javier Fuentes-Martin (Universidad de Granada), Peter Stangl (CERN)

09:00 EFT Analysis of Composite Higgs Models

Speaker: Benjamin Stefanek (IFIC Valencia)

stefanek_EFTWG8_2024.pdf

09:25 Two-Higgs Doublet Model Matched to Nonlinear Effective Theory

Speaker: Florian Pandler (LMU Munich)

cernefttalk_pandler.pdf

09:50 Matching the MSSM to the SMEFT

Speaker: Felix Wilsch (RWTH Aachen University)

MSSM-matching_LHC-EFT-WG.pdf

10:15 From the EFT to the UV: the complete SMEFT one-loop dictionary

Effective field theories (EFTs) offer a rationale to classify new physics models based on the size of their contribution to the effective Lagrangian, and therefore to experimental observables. However, given the amount of UV theories, it is in practice difficult to identify the set of UV theories which can generate a particular low-energy pattern. While current matching softwares have made the top-down approach (once you have chosen a model) much more systematic, starting instead from a Wilson Coefficient and identifying the specific theories from which it can arise is still challenging. Dictionaries, which allow us to systematically go from EFT to the UV are the solution for this. In this talk I will present the first one-loop UV/IR dictionary of the complete SMEFT for extensions encompassing an arbitrary number of scalars and fermions. This dictionary is encoded in a Mathematica package called SOLD (SMEFT One Loop Dictionary), which includes further functionalities to facilitate the usage of the results. I will go over the relevance of dictionaries for phenomenological efforts and explore a particular scenario of how SOLD can help identify the UV source of an existing experimental tension.

Speaker: Guilherme Guedes (DESY)

LHC_EFT_WorkingGroup.pdf

10:40 → 11:10 Coffee

11:10 → 11:40 Area 3

Convener: Anke Biekoetter (JGU Mainz)

11:10 SMEFT meets Quantum Gravity

Speaker: Astrid Eichhorn

LHC_EFT_WG_Eichhorn.pdf

11:40 → 12:15 Area 2

Conveners: Ken Mimasu, Robert Schoefbeck (Austrian Academy of Sciences (AT))

11:40 Electroweak corrections from Sudakov logarithms in the SMEFT

Electroweak (EW) corrections, significantly influenced by Sudakov logarithms, become the predominant higher-order effect at the TeV scale and beyond. In this study, we compute EW corrections in the high-energy limit for selected dimension-six SMEFT operators. Our findings reveal that while four-fermion operators exhibit universally similar corrections as those seen in the Standard Model (SM), distinct structural variations emerge for other operators. We investigate the phenomenological implications of these findings through illustrative processes involving four-fermion operators and assess the impact of Sudakov EW corrections on the tails of differential distributions, both at the LHC and future lepton colliders. Given the complex effects of EW corrections within SMEFT, we caution against the use of simplistic K-factor approaches, which do not adequately capture the nuanced physics involved.

Speaker: Hesham El Faham (The University of Manchester)

EWSL_SMEFT_Faham.pdf

12:00 SMEFT NLO correction to Higgs decay in an events generator

In recent years, particle physicists have actively constrained potential new physics contributions by leveraging the Large Hadron Collider (LHC) data and the SMEFT framework. Measurement of the properties of Higgs boson is central to this program. However, the robust analysis hinges on the inclusion of higher order (NLO) Electroweak (EW) and QCD corrections arising from dimension-6 SMEFT operators for a more accurate picture. While significant progress has been made in calculating NLO QCD corrections within SMEFT, and some EW corrections exist, there is a crucial gap: a lack of event generators incorporating these corrections for optimal data analysis. This talk addresses this gap by proposing the implementation of these corrections into an event generator like SHERPA. This is an important step for a more realistic framework for analysing LHC data.

Speaker: Mr shakeel ur rahaman

SMEFT_NLO_SHERPA.pdf

12:15 → 13:45 Lunch

13:45 → 14:25 Area 2

Conveners: Ken Mimasu, Robert Schoefbeck (Austrian Academy of Sciences (AT))

13:45 Wilk's theorem follow-up discussion

Speaker: Stephen Burns Menary (University of Manchester (GB))

SMenary_LHCEFT_241202_short.pdf

14:05 Staying on Top of SMEFT-Likelihood Analyses

Speakers: Nikita Schmal, Nikita Schmal (Heidelberg University)

LHCEFT_2024_Schmal.pdf

14:25 → 14:45 Area 4

Conveners: Ken Mimasu, Robert Schoefbeck (Austrian Academy of Sciences (AT))

14:25 Round-table discussion on Likelihoods for EFT

Speakers: Ken Mimasu, Nikita Schmal (Heidelberg University), Nikita Schmal, Robert Schoefbeck (Austrian Academy of Sciences (AT))

14:45 → 15:45 Area 3

Conveners: Anke Biekoetter (JGU Mainz), Carmen Diez Pardos (Universitaet Siegen (DE))

14:45 EFT dimension-6 and dimension-8 study with VBS events at CMS

A first measurement is presented of the cross-section for the scattering of same-sign W boson pairs via the detection of a τ lepton. The data from proton-proton collisions at the center-of-mass energy of 13 TeV were collected by the CMS detector at the LHC, corresponding to an integrated luminosity of 138 fb−1. Events containing two jets with large pseudorapidity and large invariant mass, one τ lepton,
one light lepton (e or μ), and significant missing transverse momentum were selected. In addition, a search is presented for the indirect effects of processes beyond the standard model via the effective field theory framework, in terms of dimension-6 and dimension-8 operators.

Speaker: Costanza Carrivale (Universita e INFN, Perugia (IT))

LHC EFT WG.pdf

15:02 New physics effects at colliders via HEFT

Due to the lack of direct evidence in the search for new physics (NP), the Effective Field Theory (EFT) framework offers an indirect and model-independent approach to parameterize NP effects. In this talk, I will focus on the non-linear EFT framework, also known as Higgs Effective Field Theory (HEFT), and include next-to-leading order (NLO) bosonic operators to study Higgs-related processes at current and future colliders. First, using the Higgs propagator corrections, I will revisit the measurement of off-shell Higgs boson contribution in massive gauge boson pair production. Then, by including radiative corrections within HEFT, I will discuss the sensitivity of single-Higgs data to quartic Higgs-gauge interactions. Finally, I will highlight the impact of one-loop HEFT modifications to the Higgs-self couplings and their effects on multi-Higgs production.

Speaker: Anisha . (Karlsruhe Institute of Technology)

Anisha_EFTWG.pdf

15:20 Interplay between LHC and EIC for SMEFT (remote)

Speakers: Radja Boughezal, Radja Boughezal (Argonne National Laboratory)

Boughezal-CERNEFT.pdf

15:45 → 16:15 Coffee

16:15 → 17:55 Area 6

Convener: Christoph Michael Langenbruch (Heidelberg University (DE))

16:15 Power to the RGE!

Speaker: Uli Haisch

EFTWG24.pdf

16:40 Long-distance QCD contributions in rare b→sll decays

Speaker: Arianna Tinari

eftwg_tinari.pdf

17:05 Probing third-generation New Physics with K→πνν and B→K(∗)νν

Speaker: Lukas Allwicher

eftwg_allwicher.pdf

17:30 EFT in semileptonic decays at LHCb

Speaker: Abhijit Mathad (CERN)

Abhijit_EFT.pdf

18:00 → 19:00 Drinks with LHC Higgs WG in R1 - Glassbox

Wednesday 4 December

09:00 → 10:30 Joint session w/ LHC Higgs WG - Please see Higgs WG indico entry for details and Zoom connection

https://indico.cern.ch/event/1276727/

https://indico.cern.ch/event/1389221/

10:30 → 11:00 Coffee

11:00 → 12:30 Joint session w/ LHC Higgs WG - Please see Higgs WG indico entry for details and Zoom connection

https://indico.cern.ch/event/1276727/

https://indico.cern.ch/event/1389221/