Higgs and Effective Field Theory - HEFT 2021

14 Apr 2021, 14:30 → 17 Apr 2021, 01:30 Asia/Shanghai

科大东区物质科研楼3楼报告厅 and Zoom online

Cen Zhang, Gauthier Durieux, Ilaria Brivio, Ken Mimasu, Shuang-Yong Zhou (USTC) , Tyler Corbett (N) , Yusheng Wu (University of Science and Technology of China) , meng xiao (Zhejiang University)

Talk videos are available at

https://www.youtube.com/channel/UC29q1a27SHLQxmOS1F49hzQ

Group photo: https://indico.ihep.ac.cn/event/13632/page/2

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HEFT is an annual workshop focusing on the use of effective field theories to search for physics beyond the Standard Model. A broad range of topics are encouraged, ranging from collider phenomenology and formal aspects to the latest experimental updates on dedicated searches. The meeting aims to foster discussions between theorists and phenomenologists from varied backgrounds as well as with experimental colleagues.

We would like to achieve a balance of senior and junior speakers, enhancing the visibility of younger scientists while keeping some overview talks.

The workshop this year will take a mixed format with both online and in-person participation (in-person for domestic participants) due to the on-going pandemic. The in-person participation will be hosted by University of Science and Technology of China (USTC) in Hefei, China. The workshop is jointly organized by Peng Huanwu Center for Fundamental theory (PCFT-USTC), Institute of High Energy Physics, Center for Particle Science and Technology at USTC, Center for High Energy Physics at Peking University, and Zhejiang University.

The workshop will begin in the afternoon of April 14th and end in the evening of April 16th (See Timetable on the left for the schedule). For in-person participants, please register by March 20.

 

Online attendance:

The Zoom conference room and its password will be announced in due time via email.

 

Registration times for in-person participants:

14:00 - 17:00, April 13rd （江南春酒店）

13:30 - 14:45, April 14th （Conference venue）

 

Organizers:

Ilaria Brivio, Tyler Corbett, Gauthier Durieux, Ken Mimasu,

Meng Xiao, Yusheng Wu, Cen Zhang, Shuang-yong Zhou (local organizers)

 

Local suponsors:

         

       

Wednesday, 14 April

4.14 Afternoon: Welcome

Convener: (高能所)

4.14 Afternoon

Convener: Ken Mimasu (King's College London)

1 ATLAS overview

Speaker: Lailin Xu (Brookhaven National Lab)

notes Xu_Lailin-4.14.mp4

Slides ATLAS_EFT_HEFT2021_202104_v4.pdf

2 Top, Higgs, Diboson and Electroweak Fit to the Standard Model Effective Field Theory

Speaker: Maeve Madigan

notes Madigan-4.14.mp4

Slides MaeveMadigan_HEFT.pdf

3 SMEFiT results

Speaker: Luca Mantani (UCLouvain)

notes MANTANI-4.14.mp4

Slides SMEFiT.pdf

16:05 Break

4.14 Afternoon

Convener: Ken Mimasu (King's College London)

4 SMEFT analysis of vector boson scattering and diboson data from the LHC Run II

We present a systematic interpretation of vector boson scattering (VBS) and diboson measurements from the LHC in the framework of the dimension-six Standard Model Effective Field Theory (SMEFT), based on our results available at https://arxiv.org/abs/2101.03180. We try to understand what is the interplay between VBS and diboson measurements in order to constrain 16 independent directions in the dimension-six EFT parameter space, finding that VBS provides complementary information on several operators relevant for the description of the electroweak sector. Finally we also quantify the ultimate EFT reach of VBS measurements via dedicated projections for the High Luminosity LHC. Our results motivate the integration of VBS processes with Higgs measurements in future global SMEFT interpretations of particle physics data.

Speaker: Giacomo Magni (NIKHEF)

notes MAGNI-4.14.mp4

Slides Magni_HEFT21_14_04_21.pdf

5 Parton distributions in the SMEFT from high-energy Drell-Yan tails

The high-energy tails of charged and neutral-current Drell-Yan (DY) processes provide important constraints on the light quark and antiquark parton distribution functions (PDFs) in the large-$x$ region. On the other hand, a hypothetical short-distance new physics would smoothly distort the high-energy tails as described by the Standard Model Effective Field Theory (SMEFT). In this work, we assess for the first time the interplay between PDF and EFT effects in high-mass DY at the LHC. We determine the extent to which EFT signals that would manifest themselves in the tails of the DY distributions could be reabsorbed into the large-$x$ (anti)quark PDFs, and present a strategy aimed at disentangling possible new physics effects from proton structure modifications. We quantify the impact that a consistent joint determination of the PDFs and Wilson Coefficients has in two motivated short-distance new physics scenarios: 1) electroweak oblique corrections ($\hat{W}$, $\hat{Y}$) and 2) four-fermion interactions possibly behind the LHCb anomalies in $R(K^{(*)})$. Finally, we present dedicated projections for the High-Luminosity LHC and evaluate its ultimate potential to constrain the EFT parameters, while taking into account potential modifications of the proton structure.

Speaker: Cameron Voisey (University of Cambridge)

notes VOISEY-4.14.mp4

Slides Cameron-Voisey-HEFT.pdf

6 A fully differential SMEFT analysis of the golden channel using the method of moments

Speaker: Elena Venturini

notes VENTURINI-4.14.mp4

Slides HEFT_Venturini.pdf

7 Parametrized classifiers for optimal EFT sensitivity

Speaker: Alfredo Glioti (EPFL)

notes GLIOTI-4.14.mp4

Slides Glioti_HEFT.pdf

4.14 Evening

Convener: Cen Zhang

8 Associated top quark production using EFT at CMS

Speaker: Brent Yates (O)

notes YATES-4.14.mp4

Slides heft2021-byates.pdf

9 Putting SMEFT Fits to Work

Speaker: Dr Samuel Homiller (Harvard University)

notes HOMILLER-4.14.mp4

Slides 210414_heft_smeft_homiller.pdf

10 $A_{FB}$ in the SMEFT: the LHC as a Z-physics laboratory

We study the forward-backward asymmetry $A_{FB}$ in $pp \rightarrow l^+l^-$ at the Z peak within the Standard Model Effective Field Theory (SMEFT). We find that this observable provides per mille level constraints on the vertex corrections of the Z boson to quarks, which close a flat direction in the electroweak precision SMEFT fit. Moreover, we show that current $A_{FB}$ data is precise enough so that its inclusion in the fit improves significantly LEP bounds even in simple New Physics setups. This demonstrates that the LHC can compete with and complement LEP when it comes to precision measurements of the Z boson properties.

Speaker: Mr Víctor Bresó (Universitat de Valencia)

notes BRESO-4.14.mp4

Slides slides_AFB.pdf

11 Reviving the interference: framework and proof-of-principle for the anomalous gluon self-interactions in the SMEFT

Interferences between Standard Model (SM) and new physics effective operators are not positive-definite and therefore they can change sign over the phase space. If the contributions of the regions where the interference is positive and negative nearly cancel each other, interference effects are hard to measure. In this talk, I will present a brand-new method, based on the matrix element, to quantify the efficiency of an observable to separate the interference positive and negative contributions and therefore to revive the interference effects in measurements. I will apply this method to the anomalous gluon operator in the Standard Model Effective Field Theory (SMEFT), for which the interference suppression is well-known. I will show that we can get, for the first time, constraints on its coefficient using the interference only, which are similar to those obtained by including the square of the new physics amplitude. This method is fully generic, so it can be intensively applied for any new physics searches or measurements that present an interference suppression, even beyond the SMEFT. (Based on arXiv:2012.06595[hep-ph])

Speaker: Mr Matteo Maltoni (UCLouvain)

notes MALTONI-4.14.mp4

Slides reviving_interference_no_builts.pdf

21:25 Break

4.14 Evening

Convener: Cen Zhang

12 Precision from Diboson Processes at FCC-hh

Thanks to its high luminosity and center of mass energy, the future FCC-hh collider will allow us to probe processes with clean but rare final states that are unaccessible at the LHC. The study of diboson production processes poses a promising way of indirectly constraining New Physics in the context of the Higgs Boson. Specifically, the diphoton leptonic decay channels of the Wh and Zh production processes are examples for the aforementioned clean but rare final states. I will discuss our study of these channels at the FCC-hh in the SMEFT framework and how doubly differential distributions can be used to gain even better sensitivity to certain higher dimensional EFT operators.

Speaker: Philipp Englert (DESY)

notes ENGLERT-4.14.mp4

Slides Presentation__Precision_from_Diboson_Processes_at_FCC_hh.pdf

13 All things EFT: SMEFT Practicalities

SMEFT has become the tool of choice for precision searches for new non-resonant physics effects at the LHC and there have been many beautiful theory talks in the All Things EFT series. In this talk, I will discuss some of the issues that arise when attempting to tease out new physics effects from SMEFT studies and I will have more questions than conclusions.  I begin with a discussion of LEP/SLD studies, and will then touch on di-boson studies at the LHC.  Finally, I conclude with a discussion of LHC EFT working group activities.

Speaker: Sally Dawson (BNL)

notes https://ihepbox.ihep.ac.cn/ihepbox/index.php/s/eb7Q12DvQyfm4Tp

Slides heft_2021_dawson.pdf

Thursday, 15 April

4.15 Morning

Convener: Yusheng Wu (University of Science and Technology of China)

14 Landscape of EFTs

Speaker: Jiang-Hao Yu (ITP, CAS)

notes Yu_Jianghao-4.15.mp4

Slides JHYu_HEFTtalk_present.pdf

15 Permutation Symmetry in Enumerating the SMEFT operators

Complete and independent bases of EFT operators are essential to study the new physics effect in a model-independent way. Not present in the lower dimensional operators, the problem of repeated fields and the flavor structures of the Wilson coefficients becomes an outstanding obstacle in enumerating the SMEFT operators of higher dimensions. We clarify the origin of the problem from both operator and amplitude points of view and provide a general algorithm to systematically obtain the independent operators or amplitude bases with definite permutation symmetries by applying the set of group algebra projectors. The resulting operator bases is easy for identifying the independent flavor components and guaranteed to be complete and independent serving as a foundation for various phenomenology studies.

Speaker: Haolin Li

notes Li_Haolin-4.15.mp4

Slides HEFT_v1.pdf

16 A preferred basis of effective operators

Operator basis in an effective field theory has always been one of the big concerns for field theorists and model builders. As we explore higher dimensional operators, it becomes common for degeneracy in a type of operators. We point out a preferred basis in the degenerate space, which contributes local amplitudes with definite total angular momentum as well as gauge quantum numbers. It has direct consequences in physics, such as selection rules in loop integrals and the indication of tree-level UV origins of the effective operators. Besides showing the proof and examples of such basis, we also introduce a code that automatically generates it for a generic effective field theory.

Speaker: Ming-lei Xiao

notes Xiao_Minglei-4.15.mp4

Slides j-basis.pdf

17 Developing the Hilbert series in EFT

Speaker: Tom Melia (K)

notes Melia-4.15.mp4

Slides heft_2021.pdf

10:45 Break

4.15 Morning

Convener: Yusheng Wu (University of Science and Technology of China)

18 Dimension-8 Operators in the SMEFT and LEFT

Speaker: Chris Murphy

notes Murphy-4.15.mp4

Slides HEFT2021_murphy.pdf

19 STrEAMlining EFT Matching

Speaker: Dr Xiaochuan Lu (University of Oregon)

notes Lu_Xiaochuan-4.15.mp4

Slides STrEAM_2021-04-14.pdf

20 An EFT Compendium for discoveries

Speaker: Joydeep Chakrabortty

notes Joydeep-4.15.mp4

Slides HEFT_JC.pdf

Thursday 15 afternoon

Convener: Gauthier Durieux (CERN)

Youtube playlist with the talks of this session https://www.youtube.com/playlist?list=PLX1x06rZtO1HfaExHrc2AJzozMstfC7Ry

21 Recent EFT interpretations in Higgs measurements at ATLAS

Speaker: Philipp Windischhofer (Oxford)

notes Philipp-4.15.mp4

Slides HEFT2021_ATLAS_Higgs_EFT.pdf

Youtube https://www.youtube.com/watch?v=AUY7LqLTo_c&list=PLX1x06rZtO1HfaExHrc2AJzozMstfC7Ry&index=1

22 Probing Higgs couplings to light quarks via Higgs pair production

One of the puzzles of the SM is the large hierarchy between the Yukawa couplings of different flavours. Yukawa couplings of the first and the second generation are constrained only very weakly so far. However, one can obtain large deviations in the Yukawa couplings in several New Physics (NP) models, such as e.g new vector-like quarks, or new Higgs bosons that couple naturally to individual fermion families. \\ In this talk, I will talk about the potential bounds on the NP Higgs Yukawa couplings modification, and new $hh \bar f f$ coupling for light quarks from double-Higgs at the LHC, starting from a model independent formalism, to studying specific models. We have looked at the Higgs's' final states $ b \bar b \gamma \gamma $, and the relevant experimental cuts to reduce backgrounds and estimated the potential exclusion bounds for light quark couplings with the Higgs. I will also talk about the potential for double Higgs production to probe non-linearity between Yukawa and $hh \bar f f$ couplings

Speaker: Lina Alasfar (H)

notes Lina-4.15.mp4

Slides HEFT_alasfar.pdf

Youtube https://www.youtube.com/watch?v=2oBcmiVKjV8&list=PLX1x06rZtO1HfaExHrc2AJzozMstfC7Ry&index=2

23 Light quark Yukawas in triboson final states

Speaker: Natascia Vignaroli (Pisa)

notes Natascia-4.15.mp4

Slides Vignaroli-heft.pdf

Youtube https://www.youtube.com/watch?v=aTtJRVv4Sdk&list=PLX1x06rZtO1HfaExHrc2AJzozMstfC7Ry&index=3

24 The present and future of four top operators

Speaker: Javi Serra (TUM Munich)

notes Javi-4.15.mp4

Slides JSerra_HEFT21.pdf

Youtube https://www.youtube.com/watch?v=xOZQ_at-fRs&list=PLX1x06rZtO1HfaExHrc2AJzozMstfC7Ry&index=4

16:40 Break

Thursday 15 afternoon

Convener: Gauthier Durieux (CERN)

Youtube playlist with the talks of this session https://www.youtube.com/playlist?list=PLX1x06rZtO1HfaExHrc2AJzozMstfC7Ry

25 The SMEFT at one-loop

Speaker: Eleni Vryonidou (Manchester)

notes Eleni-4.15.mp4

Slides HEFT2021_E_Vryonidou.pdf

Youtube https://www.youtube.com/watch?v=C1ck7is0p9A&list=PLX1x06rZtO1HfaExHrc2AJzozMstfC7Ry&index=5

26 EFT calculations from amplitude methods

Speaker: Alex Pomarol (IFAE Barcelona)

notes Alex-4.15.mp4

Slides HEFT21_AlexPomarol.pdf

Youtube https://www.youtube.com/watch?v=bKYXnjqoIeU&list=PLX1x06rZtO1HfaExHrc2AJzozMstfC7Ry&index=6

27 Constructing massive on-shell contact terms

Speaker: Camila Machado (DESY)

notes Camila-4.15.mp4

Slides HEFT21_CSMachado.pdf

Youtube https://www.youtube.com/watch?v=FZSELIZtQEM&list=PLX1x06rZtO1HfaExHrc2AJzozMstfC7Ry&index=7

4.15 night

Convener: Ilaria Brivio (U)

28 Exploring the ultraviolet from neutrino oscillations and Neff in the EFT framework

Since the discovery of the Higgs particle in 2012 at the LHC, the null observation from various experiments has gradually changed our strategy in searching for new physics from a model-dependent pattern into the EFT approach. In this talk, I will discuss our most recent work in this direction. The first part of my talk will mainly focus on constraining the ultraviolet physics within SMEFT by utilizing current neutrino-oscillation data [1]. And, in the second part of this talk, I will start from a different angle and discuss how to gain some knowledge on the ultraviolet from precision measurements of Neff [2]. Refs: [1] https://arxiv.org/abs/2101.10475 [2] https://arxiv.org/abs/2011.14292

Speaker: Yong Du (ITP)

notes YONG_DU_15.04.mp4

Slides HEFT-2021-YongDu.pdf

29 Neutrino masses in the Standard Model effective field theory

We compute the leading-logarithm correction to the neutrino mass matrix in the Standard Model effective field theory to dimension seven. In the limit of negligible Yukawa couplings, the neutrino mass matrix receives contributions from the Weinberg operator as well as from ten dimension-six and four dimension-seven independent interactions. We discuss the conditions under which the derived correction plays an important role.

Speaker: Dr Arsenii Titov (University of Valencia and IFIC)

notes Titov.mp4

Slides NuMassSMEFT_Titov.pdf

30 Running in the ALPs

In this talk I will present the complete anomalous dimension matrix at 1 loop of the Standard Model effective field theory extended with an axion-like particle (ALP) up to dimension 5. The ALP couplings are probed by different experiments across a huge range of energy scales and as such, a consistent analysis of the corresponding constraints requires the use of the renormalization group equations. The results are presented above and below the electroweak scale, assuming only that new physics does not violate CP. I will also discuss the different bases used in the literature and their relations with shift-symmetry.

Speaker: Mr Guilherme Guedes (University of Granada)

notes Guedes.mp4

Slides HEFT21.pdf

Friday, 16 April

4.15 night: continued

Convener: Ilaria Brivio (U)

31 Running in the ALPs (cont'd)

32 Effective Field Theory of Dark Matter Direct Detection With Collective Excitations

I will present a framework for computing dark matter direct detection rates via phonon and magnon excitations in crystal targets for general dark matter models. It consists of parameterizing dark matter interactions by a nonrelativistic EFT, and computing material responses to the EFT operators. Our work extends previous calculations that focused on simple models such as standard spin-independent interactions, and shows that new direct detection experiments that utilize collective excitations, such as SPICE, will have discovery potential over a broad range of dark matter theories.

Speaker: Zhengkang Zhang (C)

notes Zhang.mp4

Slides 2104_LDM_EFT_20mins.pdf

4.16 Morning

Convener: meng xiao (Zhejiang University)

33 Constructing massive on-shell operator basis

Speaker: Prof. Jing Shu (ITP)

notes Shu_Jing-4.16.mp4

Slides MassiveHEFT2021.pdf

34 Is SMEFT Enough?

Speaker: Prof. Nathaniel Craig (University of California, Santa Barbara)

notes Nathaniel-4.16.mp4

Slides Craig_HEFT_04:16:21.pdf

35 Causality, Unitarity and Symmetry in Effective Field Theory

Speaker: Timothy Trott

notes Timothy-4.16.mp4

Slides TalkTT.pdf

36 Positivity in Multi-Field EFTs

Speaker: 栩 黎 (高能所)

notes Li_Xu-4.16.mp4

Slides positivity_in_multifield_EFT_XuLi.pdf

10:50 Break

4.16 Morning

37 Higgs couplings measurements and unitarity bounds

Speaker: Markus Luty (U)

notes Markus-4.16.mp4

Slides 21_04_15_Higgs_Couplings_New_Physics.pdf

38 Geometric formulation of the SMEFT

Speaker: Andreas Helset (C)

notes Andreas-4.16.mp4

Slides HEFT2021_Helset.pdf

39 Custodial symmetry in SMEFT

Speaker: Tom Tong

notes Tom-4.16.mp4

Slides Custodial_SMEFT.pdf

4.16 afternoon

Convener: Shuang-Yong Zhou (University of Science and Technology of China)

40 S-matrix Bootstrap for Effective Field Theory

Speaker: Joao PENEDONES

notes Joao-4.16.mp4

Slides Penedones_HEFT_2021.pdf

41 Effective Field Theories and Positivity Bounds

Speaker: Andrew Tolley

notes Andrew-4.16.mp4

Slides HEFT_2021.pdf

42 Positivity bounds on Minimal Flavor Violation

Effective Field Theories are a very powerful mean to describe theories at energies well below a certain cutoff scale. However, not all points in the parameter space spanned by their coefficients allow for a UV completion that is both unitary and analytic, and various bounds have been derived in the literature. I will discuss to what extent are these bounds compatible with the Minimal Flavor Violation hypothesis in the Standard Model Effective Field Theory. The latter is the Effective Theory incorporating the effects of resonances whose mass is parametrically larger than the Electroweak Scale, where the Higgs phase transition happens. Since in this setting the coefficients of higher dimensional operators are expressed in terms of Yukawa matrices, I will show how this dependence reflects on the final parameter space the theory is allowed to span.

Speaker: Emanuele Gendy

notes Emanuele-4.16.mp4

Slides HEFT_slides.pdf

43 An unambiguous test of positivity at lepton colliders

The diphoton channel at lepton colliders, e+e−(μ+μ−)→γγ, has a remarkable feature that the leading new physics contribution comes only from dimension-eight operators. This contribution is subject to a set of positivity bounds, derived from fundamental principles of Quantum Field Theory, such as unitarity, locality and analyticity. These positivity bounds are thus applicable to the most direct observable -- the diphoton cross sections. This unique feature provides a clear, robust, and unambiguous test of these principles. We estimate the capability of various future lepton colliders in probing the dimension-eight operators and testing the positivity bounds in this channel. We show that positivity bounds can lift certain degeneracies among the effective operators and significantly change the perspectives of a global analysis. We also perform a combined analysis of the γγ/Zγ/ZZ processes in the high energy limit and point out the important interplay among them.

Speaker: Dr Jiayin Gu (JGU Mainz)

notes Gu_Jiayin-4.16.mp4

Slides sumpos8.pdf

Break

4.16 afternoon

44 Wilson is not anomalous: on gauge anomalies in SMEFT

Can higher-dimensional operators in an EFT generate gauge anomalies if the renormalizable part of the EFT is anomaly-free? When are certain Wilson Coefficients dictated by the global anomalies of the UV sector? These 2 questions, which cover both directions in the relationship between anomalies and Wilson Coefficients, can be answered with similar techniques. Here, I will discuss whether dimension-6 operators in SMEFT can induce gauge anomalies. We find a negative answer, contrarily to what was claimed by Cata et al in a recent paper (2011.09976) and therefore I'll discuss why the triangle-diagram computations performed in the aforementioned paper lead to apparent anomalies. I will explain how to compute these anomalies in EFTs with a toy model and show how to obtain the same conclusion using a bosonic EFT. The latter technique is the one I'll apply to SMEFT. Based on 2012.07740.

Speaker: Alejo ROSSIA

Diapositivas Rossia_AnomaliesSMEFT_HEFT21.pdf

notes Alejo-4.16.mp4

45 Higher order renormalisation in scalar effective field theory

There exist relations between operators in effective field theory (EFT) Lagrangians due to the freedom to perform field redefinitions and integration by parts. Recent progress in the characterisation of operators that are independent under such redundancies led to a particular basis that we call the "conformal basis". Since the conformal basis is mathematically singled out, it is interesting to study its properties by calculating basis-dependent objects such as the anomalous dimensions. These are essential quantities in EFT, because they relate Wilson coefficients between energy scales through the renormalisation group equations, which generally involves an intricate mixing structure. In a first application of the $R^*$-operator in EFT, we renormalise the single complex scalar field EFT up to 4 loops at mass dimension 6 and 2 loops at mass dimension 10. The $R^*$-operation is well suited to deal with Feynman graphs of high multiplicity and high degree of divergence by allowing for a procedure called infrared rearrangement. We will report on the observed structure in the anomalous dimension matrices at one-loop level and beyond.

Speaker: Jasper ROOSMALE NEPVEU

notes Jasper-4.16.mp4

Slides RoosmaleNepveu_HEFT2021.pdf

46 Diagrammatic one-loop renormalization within the EChL in the Rxi gauges and applications to scattering and decays

Effective field theories (EFTs) are an incredibly powerful tool in order to study and understand the true nature of the symmetry breaking sector dynamics of the Standard Model. The most general EFT, appropriate in the case that the new ultraviolet physics beyond the SM be strongly interacting, is the Electroweak Chiral Lagrangian (EChL) or Higgs Effective field theory (HEFT). We work here just with the bosonic sector and assume the fermion sector is as in the SM. In this talk, using diagrammatic methods, I will present a detailed computation of the generated divergencies at one-loop level corresponding to all 1PI relevant for Higgs decays and Vector Boson Scattering and the corresponding renormalization program within the EChL in the covariant Rxi gauges for the first time. I present the list of the needed counterterms to provide renormalized 1PI functions of 2, 3 and 4 legs and extract the corresponding renormalization of the EChL coefficients. As an illustration of the applicability of these results, I show both Higgs to photon+photon and photon+Z decays and the WZ scattering amplitude with longitudinal polarized bosons. Also, a comparison with the SM case is shown.

Speaker: Roberto MORALES

notes Reberto-4.16.mp4

Slides HEFT21_RAMorales.pdf

4.16 night

Convener: Tyler Corbett (NBI)

47 Flavor Symmetries in the Standard Model Effective Field Theory

Flavor symmetries play an essential role in the analysis of fermionic operators in the SMEFT by substantially reducing the number of independent parameters in the theory. Moreover, they provide an organizing principle for classifying the vast number of dimension-six operators involving fermions. Two particularly motivated cases are the $U(3)^5$ and the $U(2)^5$ flavor symmetry, which I will introduce with appropriate breaking patterns. I will present the operator classification according to these symmetries and analyze their utilization for the SMEFT. Furthermore, I will discuss the RG evolution of operators under the symmetries and their phenomenological implications for LHC searches.

Speaker: Mr Felix Wilsch (University of Zurich)

Slides HEFT_2021_flavor_symmetries.pdf zoom_0.mp4

48 Top and Beauty Synergy

Speaker: Prof. Gudrun Hiller (TU Dortmund)

Slides HEFT21-fits-ghiller-synergies.pdf zoom_1.mp4

49 Testing the Flavour Structure of the SMEFT

Speaker: Sebastian Bruggisser (Uni-Heidelberg)

Slides FlavourSMEFT_Bruggisser.pdf zoom_2.mp4

Saturday, 17 April

4.16 night: continued

Convener: Tyler Corbett (NBI)

50 Testing the Flavour Structure of the SMEFT (cont)

Speaker: Sebastian Bruggisser (Uni-Heidelberg)

51 SMEFT atlas of ΔF=2 Transitions

Speaker: J Kumar (TUM Munich)

Slides Kumar_HEFT2021.pdf zoom_3.mp4

52 Rare Kaon Decays in SMEFT: K->πνν,πll, ΔMk, and ε'/ε

Speaker: J Aebischer (UC San Diego)

Slides HEFT21_aebischer.pdf zoom_4.mp4

53 Charged Lepton Flavor Violation at the EIC

We present a comprehensive analysis of the potential sensitivity of the Electron-Ion Collider (EIC) to charged lepton flavor violation (CLFV) in the channel $ep\to \tau X$, within the model-independent framework of the Standard Model Effective Field Theory (SMEFT). We compute the relevant cross sections to leading order in QCD and electroweak corrections and perform simulations of signal and SM background events in various $\tau$ decay channels, suggesting simple cuts to enhance the associated estimated efficiencies. To assess the discovery potential of the EIC in $\tau$-$e$ transitions, we study the sensitivity of other probes of this physics across a broad range of energy scales, from $pp \to e \tau X$ at the Large Hadron Collider to decays of $B$ mesons and $\tau$ leptons, such as $\tau \to e \gamma$, $\tau \to e \ell^+ \ell^-$, and crucially the hadronic modes $\tau \to e Y$ with $Y \in \{ \pi, K, \pi \pi, K \pi, ...\}$. We find that electroweak dipole and four-fermion semi-leptonic operators involving light quarks are already strongly constrained by $\tau$ decays, while operators involving the $c$ and $b$ quarks present more promising discovery potential for the EIC. An analysis of three models of leptoquarks confirms the expectations based on the SMEFT results. We also identify future directions needed to maximize the reach of the EIC in CLFV searches: these include an optimization of the $\tau$ tagger in hadronic channels, an exploration of background suppression through tagging $b$ and $c$ jets in the final state, and a global fit by turning on all SMEFT couplings, which will likely reveal new discovery windows for the EIC.

Speaker: Dr Bin Yan (LANL)

notes Yan.mp4

Slides CLFV_BY.pdf