Motivated by recently observed anomalies in the flavour sector, we analyse the potential of measurements of top quarks at the Large Hadron Collider (LHC) to provide complementary constraints on interactions that shape low-energy precision investigations in the sector. The measurement of top quark properties, such as the top width and the abundant top pair production channels, are already reaching the percent level at this relatively early stage of the LHC phenomenology program. A focused analysis of four-fermion interactions, employing effective field theory without flavour structure assumptions and incorporating renormalization group evolution effects, bridges meson scale phenomena with key top quark measurements. We demonstrate that the LHC is increasingly competitive with, and complementary to, flavour physics constraints. Our results, which include a first comprehensive analysis of non-leptonic decays in this context, suggest that the LHC’s top physics program could serve as a valuable, complementary tool in the search for physics beyond the Standard Model within the flavour sector.

United Kingdom

Oliver Atkinson

Christoph Englert

Matthew Kirk

Germany

France

Gilberto Tetlalmatzi-Xolocotzi

Collider-flavour complementarity from the bottom to the top

We here report on the progress of the HHH Workshop, that took place in Dubrovnik in July 2023. After the discovery of a particle that complies with the properties of the Higgs boson of the Standard Model, all Standard Model (SM) parameters are in principle determined. However, in order to verify or falsify the model, the full form of the potential has to be determined. This includes the measurement of the triple and quartic scalar couplings.

Morocco

Hamza Abouabid

Abdesslam Arhrib

United States

Hannah Arnold

Duarte Azevedo

Croatia

Vuko Brigljevic

Maggie Chen

Daniel Diaz

Javier Duarte

Netherlands

Tristan Pree

Jaouad Falaki

Dinko Ferencek

Portugal

Pedro. Ferreira

Benjamin Fuks

India

Japan

Sanmay Ganguly

Osama Karkout

Marina Kolosova

Jacobo Konigsberg

Greg Landsberg

Canada

China

Bingxuan Liu

CERN

Switzerland

Brian Moser

Margarete Mühlleitner

Andreas Papaefstathiou

Sweden

Roman Pasechnik

Tania Robens

Rui Santos

Brian Sheldon

Gregory Soyez

Marko Stamenkovic

Panagiotis Stylianou

Tatjana Susa

Georg Weiglein

Giulia Zanderighi

Rui Zhang

HHH whitepaper

The production of three Higgs bosons at hadron colliders can be enhanced by a double-resonant effect in the ℤ2-symmetric two-real-singlet extension of the Standard Model, making it potentially observable in future LHC runs. The production rate is maximized for large scalar couplings, which prompts us to carefully reconsider the perturbativity constraints on the theory. This leads us to construct a new set of 140 benchmark points that have a triple Higgs boson production cross-section at least 100 times larger than the SM value.

Marieke Postma

Jorinde Vis

Triple Higgs boson production and electroweak phase transition in the two-real-singlet model

We study the penguin-mediated   <math> <msub> <mover> <mi>B</mi> <mo>¯</mo> </mover> <mrow> <mi>d</mi> <mfenced> <mi>s</mi> </mfenced> </mrow> </msub> <mo>→</mo> <msup> <mover> <mi>K</mi> <mo>¯</mo> </mover> <mrow> <mo>∗</mo> <mn>0</mn> </mrow> </msup> <mfenced> <msup> <mi>K</mi> <mrow> <mo>∗</mo> <mn>0</mn> </mrow> </msup> </mfenced> <mi>ϕ</mi> </math>  $$ {\overline{B}}_{d(s)}\to {\overline{K}}^{\ast 0}\left({K}^{\ast 0}\right)\phi $$  transitions, proposing a new optimised observable L  K*ϕ  from the ratio of longitudinal branching ratios of these decays, with limited hadronic uncertainties and enhanced sensitivity to New Physics. This observable exhibits a deviation at the 1.48 σ level between its experimental value and its SM determination within QCD factorisation. This result can be accommodated together with the significant deviations found for the   <math> <msup> <mi>K</mi> <mfenced> <mo>∗</mo> </mfenced> </msup> <msup> <mover> <mi>K</mi> <mo>¯</mo> </mover> <mfenced> <mo>∗</mo> </mfenced> </msup> </math>  $$ {K}^{\left(\ast \right)}{\overline{K}}^{\left(\ast \right)} $$  modes in our earlier works if New Physics affects either the QCD penguin operator Q 4 or the chromomagnetic dipole operator Q 8g  for both b → d and b → s transitions. The allowed range for the Wilson coefficients C 4s,8gs  is narrower compared to C 4d,8gd  since the b → s transition channel   <math> <msub> <mover> <mi>B</mi> <mo>¯</mo> </mover> <mi>d</mi> </msub> <mo>→</mo> <msup> <mover> <mi>K</mi> <mo>¯</mo> </mover> <mrow> <mo>∗</mo> <mn>0</mn> </mrow> </msup> <mi>ϕ</mi> </math>  $$ {\overline{B}}_d\to {\overline{K}}^{\ast 0}\phi $$  is in better agreement with the SM. However, if we add the measured branching ratio for the   <math> <msub> <mover> <mi>B</mi> <mo>¯</mo> </mover> <mi>d</mi> </msub> <mo>→</mo> <msup> <mover> <mi>K</mi> <mo>¯</mo> </mover> <mn>0</mn> </msup> <mi>ϕ</mi> </math>  $$ {\overline{B}}_d\to {\overline{K}}^0\phi $$  to our analysis, the simultaneous explanation of all the experimental data for the   <math> <msup> <mi>K</mi> <mfenced> <mo>∗</mo> </mfenced> </msup> <msup> <mover> <mi>K</mi> <mo>¯</mo> </mover> <mfenced> <mo>∗</mo> </mfenced> </msup> </math>  $$ {K}^{\left(\ast \right)}{\overline{K}}^{\left(\ast \right)} $$  and the   <math> <msup> <mi>K</mi> <mo>∗</mo> </msup> <mfenced> <msup> <mover> <mi>K</mi> <mo>¯</mo> </mover> <mfenced> <mo>∗</mo> </mfenced> </msup> </mfenced> <mi>ϕ</mi> </math>  $$ {K}^{\ast}\left({\overline{K}}^{\left(\ast \right)}\right)\phi $$  channels in terms of New Physics in the Wilson coefficients C 4d,s  or C 8gd,s  only, is not possible. This set of observables can be explained more easily if we assume New Physics in both f = d, s sectors, either in (C 4f  , C 6f  ) or (C 6f  , C 8gf  ). The addition of the branching ratios of the charged modes B − → K (∗)− ϕ to the above mix of observables results in a reduction of the parameter space for the (C 4f  , C 6f  ) scenario, while discarding the (C 6f  , C 8gf  ) scenario completely. This can be traced to the discrepancy of more than 1 σ between the experimental measurements of the branching ratios of the   <math> <msub> <mover> <mi>B</mi> <mo>¯</mo> </mover> <mi>d</mi> </msub> <mfenced> <msup> <mi>B</mi> <mo>−</mo> </msup> </mfenced> <mo>→</mo> <msup> <mover> <mi>K</mi> <mo>¯</mo> </mover> <mn>0</mn> </msup> <mfenced> <msup> <mi>K</mi> <mo>−</mo> </msup> </mfenced> <mi>ϕ</mi> </math>  $$ {\overline{B}}_d\left({B}^{-}\right)\to {\overline{K}}^0\left({K}^{-}\right)\phi $$  transitions. This should provide a strong incentive for the LHCb/Belle II experiments to measure the branching ratios of   <math> <msub> <mover> <mi>B</mi> <mo>¯</mo> </mover> <mi>d</mi> </msub> <mo>→</mo> <msup> <mover> <mi>K</mi> <mo>¯</mo> </mover> <mrow> <mfenced> <mo>∗</mo> </mfenced> <mn>0</mn> </mrow> </msup> <mi>ϕ</mi> </math>  $$ {\overline{B}}_d\to {\overline{K}}^{\left(\ast \right)0}\phi $$ ,   <math> <msub> <mover> <mi>B</mi> <mo>¯</mo> </mover> <mi>s</mi> </msub> <mo>→</mo> <msup> <mi>K</mi> <mrow> <mo>∗</mo> <mn>0</mn> </mrow> </msup> <mi>ϕ</mi> </math>  $$ {\overline{B}}_s\to {K}^{\ast 0}\phi $$  and particularly B − → K − ϕ to confirm or dismiss the conclusions hinted at by present data.

Spain

Aritra Biswas

Sébastien Descotes-Genon

Joaquim Matias

Optimised observables and new physics prospects in the penguin-mediated decays B  d(s) → K (∗)0 ϕ

We investigate multi-Higgs boson production at proton colliders, in a framework involving anomalous interactions, focusing on triple Higgs boson production. We consider modifications to the Higgs boson self-couplings, to the Yukawa interactions, as well as new contact interactions of Higgs bosons with either quarks or gluons. To this end, we have developed a MadGraph5_aMC@NLO loop model, publicly available at [1], designed to incorporate the relevant operators in the production of multiple Higgs bosons (and beyond). We have performed cross section fits at various energies over the anomalous interactions, and have derived constraints on the most relevant anomalous coefficients, through detailed phenomenological analyses at proton-proton collision energies of 13.6 TeV and 100 TeV, employing the 6 b-jet final state.

Multi-Higgs boson production with anomalous interactions at current and future proton colliders

We build a set of new observables using closely related non-leptonic penguin-mediated B  d  and B  s  decays:   <math> <msub> <mover> <mi>B</mi> <mo>¯</mo> </mover> <mrow> <mi>d</mi> <mo>,</mo> <mi>s</mi> </mrow> </msub> <mo>→</mo> <msup> <mi>K</mi> <mrow> <mo>∗</mo> <mn>0</mn> </mrow> </msup> <msup> <mover> <mi>K</mi> <mo>¯</mo> </mover> <mrow> <mo>∗</mo> <mn>0</mn> </mrow> </msup> <mo>,</mo> <msub> <mover> <mi>B</mi> <mo>¯</mo> </mover> <mrow> <mi>d</mi> <mo>,</mo> <mi>s</mi> </mrow> </msub> <mo>→</mo> <msup> <mi>K</mi> <mn>0</mn> </msup> <msup> <mover> <mi>K</mi> <mo>¯</mo> </mover> <mn>0</mn> </msup> <mo>,</mo> <msub> <mover> <mi>B</mi> <mo>¯</mo> </mover> <mrow> <mi>d</mi> <mo>,</mo> <mi>s</mi> </mrow> </msub> <mo>→</mo> <msup> <mi>K</mi> <mn>0</mn> </msup> <msup> <mover> <mi>K</mi> <mo>¯</mo> </mover> <mrow> <mo>∗</mo> <mn>0</mn> </mrow> </msup> </math>  $$ {\overline{B}}_{d,s}\to {K}^{\ast 0}{\overline{K}}^{\ast 0},{\overline{B}}_{d,s}\to {K}^0{\overline{K}}^0,{\overline{B}}_{d,s}\to {K}^0{\overline{K}}^{\ast 0} $$  and   <math> <msub> <mover> <mi>B</mi> <mo>¯</mo> </mover> <mrow> <mi>d</mi> <mo>,</mo> <mi>s</mi> </mrow> </msub> <mo>→</mo> <msup> <mover> <mi>K</mi> <mo>¯</mo> </mover> <mn>0</mn> </msup> <msup> <mi>K</mi> <mrow> <mo>∗</mo> <mn>0</mn> </mrow> </msup> </math>  $$ {\overline{B}}_{d,s}\to {\overline{K}}^0{K}^{\ast 0} $$  together with their CP conjugate partners. These optimised observables are designed to reduce hadronic uncertainties, mainly coming from form factors and power-suppressed contributions, and thus maximize their sensitivity to New Physics (NP). The deviations observed with respect to the Standard Model (SM) in the ratios of branching ratios of   <math> <msub> <mover> <mi>B</mi> <mo>¯</mo> </mover> <mrow> <mi>d</mi> <mo>,</mo> <mi>s</mi> </mrow> </msub> <mo>→</mo> <msup> <mi>K</mi> <mrow> <mo>∗</mo> <mn>0</mn> </mrow> </msup> <msup> <mover> <mi>K</mi> <mo>¯</mo> </mover> <mrow> <mo>∗</mo> <mn>0</mn> </mrow> </msup> <mfenced> <mrow> <mn>2.6</mn> <mi>σ</mi> </mrow> </mfenced> </math>  $$ {\overline{B}}_{d,s}\to {K}^{\ast 0}{\overline{K}}^{\ast 0}\left(2.6\sigma \right) $$  and   <math> <msub> <mover> <mi>B</mi> <mo>¯</mo> </mover> <mrow> <mi>d</mi> <mo>,</mo> <mi>s</mi> </mrow> </msub> <mo>→</mo> <msup> <mi>K</mi> <mn>0</mn> </msup> <msup> <mover> <mi>K</mi> <mo>¯</mo> </mover> <mn>0</mn> </msup> <mfenced> <mrow> <mn>2.4</mn> <mi>σ</mi> </mrow> </mfenced> </math>  $$ {\overline{B}}_{d,s}\to {K}^0{\overline{K}}^0\left(2.4\sigma \right) $$  can be explained by simple NP scenarios involving the Wilson coefficients   <math> <mi>C</mi> </math>  $$ \mathcal{C} $$  4 and   <math> <mi>C</mi> </math>  $$ \mathcal{C} $$  6 associated with QCD penguin operators and the coefficient   <math> <mi>C</mi> </math>  $$ \mathcal{C} $$  8g  of the chromomagnetic operator. The optimised observables for   <math> <msub> <mover> <mi>B</mi> <mo>¯</mo> </mover> <mrow> <mi>d</mi> <mo>,</mo> <mi>s</mi> </mrow> </msub> <mo>→</mo> <msup> <mi>K</mi> <mn>0</mn> </msup> <msup> <mover> <mi>K</mi> <mo>¯</mo> </mover> <mrow> <mo>∗</mo> <mn>0</mn> </mrow> </msup> </math>  $$ {\overline{B}}_{d,s}\to {K}^0{\overline{K}}^{\ast 0} $$  and   <math> <msub> <mover> <mi>B</mi> <mo>¯</mo> </mover> <mrow> <mi>d</mi> <mo>,</mo> <mi>s</mi> </mrow> </msub> <mo>→</mo> <msup> <mover> <mi>K</mi> <mo>¯</mo> </mover> <mn>0</mn> </msup> <msup> <mi>K</mi> <mrow> <mo>∗</mo> <mn>0</mn> </mrow> </msup> </math>  $$ {\overline{B}}_{d,s}\to {\overline{K}}^0{K}^{\ast 0} $$  show distinctive patterns of deviations with respect to their SM predictions under these NP scenarios. The pattern of deviations of individual branching ratios, though affected by significant hadronic uncertainties, suggests that NP is needed both in b → d and b → s transitions. We provide the regions for the Wilson coefficients consistent with both optimised observables and individual branching ratios. The NP scenarios considered to explain the deviations of   <math> <msub> <mover> <mi>B</mi> <mo>¯</mo> </mover> <mrow> <mi>d</mi> <mo>,</mo> <mi>s</mi> </mrow> </msub> <mo>→</mo> <msup> <mi>K</mi> <mrow> <mo>∗</mo> <mn>0</mn> </mrow> </msup> <msup> <mover> <mi>K</mi> <mo>¯</mo> </mover> <mrow> <mo>∗</mo> <mn>0</mn> </mrow> </msup> </math>  $$ {\overline{B}}_{d,s}\to {K}^{\ast 0}{\overline{K}}^{\ast 0} $$  and   <math> <msub> <mover> <mi>B</mi> <mo>¯</mo> </mover> <mrow> <mi>d</mi> <mo>,</mo> <mi>s</mi> </mrow> </msub> <mo>→</mo> <msup> <mi>K</mi> <mn>0</mn> </msup> <msup> <mover> <mi>K</mi> <mo>¯</mo> </mover> <mn>0</mn> </msup> </math>  $$ {\overline{B}}_{d,s}\to {K}^0{\overline{K}}^0 $$  can yield deviations up to an order of magnitude among the observables that we introduced for   <math> <msub> <mover> <mi>B</mi> <mo>¯</mo> </mover> <mrow> <mi>d</mi> <mo>,</mo> <mi>s</mi> </mrow> </msub> <mo>→</mo> <msup> <mi>K</mi> <mn>0</mn> </msup> <msup> <mover> <mi>K</mi> <mo>¯</mo> </mover> <mrow> <mo>∗</mo> <mn>0</mn> </mrow> </msup> </math>  $$ {\overline{B}}_{d,s}\to {K}^0{\overline{K}}^{\ast 0} $$  and   <math> <msub> <mover> <mi>B</mi> <mo>¯</mo> </mover> <mrow> <mi>d</mi> <mo>,</mo> <mi>s</mi> </mrow> </msub> <mo>→</mo> <msup> <mover> <mi>K</mi> <mo>¯</mo> </mover> <mn>0</mn> </msup> <msup> <mi>K</mi> <mrow> <mo>∗</mo> <mn>0</mn> </mrow> </msup> </math>  $$ {\overline{B}}_{d,s}\to {\overline{K}}^0{K}^{\ast 0} $$ . Probing these new observables experimentally by improving the measurements of individual branching ratios of penguin-mediated decays would confirm the consistency of the deviations already observed and provide a highly valuable hint of NP in the non-leptonic sector.

A new puzzle in non-leptonic B decays

As a result of the helicity suppression effect, within the Standard Model the rare decay channel <math><mrow><msub><mrow><mi>B</mi></mrow><mrow><mi>s</mi></mrow></msub><mo>→</mo><msup><mrow><mi>e</mi></mrow><mrow><mo>+</mo></mrow></msup><msup><mrow><mi>e</mi></mrow><mrow><mo>−</mo></mrow></msup></mrow></math> has a decay probability that is five orders of magnitude below current experimental limits. Thus, any observation of this channel within the current or forthcoming experiments will give unambiguous evidence of physics beyond the Standard Model. In this work, we present for the first time a new physics scenario in which the branching fraction <math><mover><mi>B</mi><mo>¯</mo></mover><mi>r</mi><mo>(</mo><msub><mi>B</mi><mi>s</mi></msub><mo>→</mo><msup><mi>e</mi><mo>+</mo></msup><msup><mi>e</mi><mo>−</mo></msup><mo>)</mo></math> is enhanced up to values which saturate the current experimental bounds. More concretely, we study the general two-Higgs-doublet model with a pseudoscalar coupling to electrons unsuppressed by the electron mass. Furthermore, we demonstrate how this scenario can arise from a UV-complete theory of quark-lepton unification that can live at a low scale. This latter step allows us to establish correlations between <math><msub><mi>B</mi><mi>s</mi></msub><mo>→</mo><msup><mi>e</mi><mo>+</mo></msup><msup><mi>e</mi><mo>−</mo></msup></math> and the lepton-flavor-violating decays <math><msup><mi>τ</mi><mo>−</mo></msup><mo>→</mo><msup><mi>μ</mi><mo>−</mo></msup><msup><mi>e</mi><mo>+</mo></msup><msup><mi>e</mi><mo>−</mo></msup></math> and <math><mi>τ</mi><mo>→</mo><mi>μ</mi><mi>γ</mi></math>.

Matthew Black

Italy

Alexis D. Plascencia

Enhancing <math><msub><mi>B</mi><mi>s</mi></msub><mo>→</mo><msup><mi>e</mi><mo>+</mo></msup><msup><mi>e</mi><mo>−</mo></msup></math> to an observable level in the two-Higgs-doublet model

We estimate the potential size of the weak annihilation amplitudes in QCD factorization as allowed by experimental data. To achieve this goal, we establish a connection between the amplitudes in the QCD factorization and the so-called topological and SU(3)-invariant descriptions. Our approach is based purely on the analysis of the tensor structure of the decay amplitudes. By focusing on the processes  $$B\rightarrow P P$$  <math> <mrow> <mi>B</mi> <mo>→</mo> <mi>P</mi> <mi>P</mi> </mrow> </math>   and considering data from CP asymmetries and branching fractions, we perform a global fit to the SU(3)-irreducible quantities assuming minimal theoretical bias. Subsequently we translate the outcome to the QCD factorization decomposition, and find that the most constrained weak annihilation amplitudes are below 0.04. However, in view of the large uncertainties in several of the experimental input parameters, values up to  $$\sim 0.3$$  <math> <mrow> <mo>∼</mo> <mn>0.3</mn> </mrow> </math>   are allowed in certain cases.

Tobias Huber

Estimating QCD-factorization amplitudes through SU(3) symmetry in  $$B\rightarrow P P$$  <math> <mrow> <mi>B</mi> <mo>→</mo> <mi>P</mi> <mi>P</mi> </mrow> </math>   decays

Decays of B mesons with leptons in the final state offer an interesting laboratory to search for possible effects of physics from beyond the Standard Model. In view of puzzling patterns in experimental data, the violation of lepton flavour universality is an interesting option. We present a strategy, utilising ratios of leptonic and semileptonic B decays, where the elements  $$|V_{ub}|$$  <math> <mrow> <mrow> <mo>|</mo> </mrow> <msub> <mi>V</mi> <mrow> <mi>ub</mi> </mrow> </msub> <mrow> <mo>|</mo> </mrow> </mrow> </math>   and  $$|V_{cb}|$$  <math> <mrow> <mrow> <mo>|</mo> </mrow> <msub> <mi>V</mi> <mrow> <mi>cb</mi> </mrow> </msub> <mrow> <mo>|</mo> </mrow> </mrow> </math>   of the Cabibbo–Kobayashi–Maskawa (CKM) matrix cancel, to constrain the short-distance coefficients of (pseudo)-scalar, vector and tensor operator contributions. The individual branching ratios allow us then to extract also the CKM matrix elements, even in the presence of new-physics contributions. Bounds on unmeasured leptonic and semileptonic decays offer important additional constraints. In our comprehensive analysis, we give also predictions for decays which have not yet been measured in a variety of scenarios.

Robert Fleischer

Ruben Jaarsma

Mapping out the space for new physics with leptonic and semileptonic  $$B_{(c)}$$  <math> <msub> <mi>B</mi> <mrow> <mo>(</mo> <mi>c</mi> <mo>)</mo> </mrow> </msub> </math>   decays

We investigate the production of three Higgs bosons in the Two Real Singlet extension of the Standard Model, where the scalar sector is augmented by two additional real scalar fields which are singlets under the Standard Model gauge group. The model contains three neutral CP-even scalars, allowing for resonant production and asymmetric decay chains. We focus on the signature pp → h 3 → h 1 h 2 → h 1 h 1 h 1, where we identify h 3 as the heaviest scalar state, h 2 as the second heaviest and the lightest, h 1, as the Standard Model-like Higgs boson discovered by the Large Hadron Collider experiments. The dominant final state occurs when all three Higgs bosons decay to bottom-anti-bottom quark pairs, h 1 →   <math> <mi>b</mi> <mover> <mi>b</mi> <mo>¯</mo> </mover> </math>  $$ b\overline{b} $$ , leading to 6 b-jets. Taking into account all current theoretical and experimental constraints, we determine the discovery prospects for this channel in future runs of the Large Hadron Collider, as well as in the high-luminosity phase.

Triple Higgs boson production at the Large Hadron Collider with Two Real Singlet scalars