We consider fermionic and scalar dark matter (DM) candidates that couple predominantly to third-generation Standard Model fermions, describing their interactions within an effective field theory framework. We show that current direct-detection constraints on these interactions are more than an order of magnitude weaker than those for flavor-universal couplings: effective scales in the few-TeV range remain allowed by existing data, leaving open the possibility of a connection between this type of new physics and a solution to the electroweak hierarchy problem. Imposing the observed relic abundance from thermal freeze-out within the same effective theory, a well-defined region for a fermionic DM candidate with mass in the 1–2 TeV range emerges. Notably, this region will be fully probed by upcoming direct-detection experiments. Finally, we show that additional parameter space for both fermion and scalar cases can be recovered by going beyond the effective theory, through the introduction of a suitable vector mediator enabling resonant DM annihilation.

Switzerland

Georgios Demetriou

Gino Isidori

Gioacchino Piazza

Emanuelle Pinsard

The third-generation-philic WIMP: an EFT analysis

We illustrate the potential of a future high-intensity $$e^+ e^-$$ collider running at the $\textit{Z}$ pole in probing extensions of the Standard Model via precise measurements of flavor-changing processes. We illustrate this potential both within effective field theories and simplified models inspired by current $\textit{B}$-physics data, focusing on selected flavor-physics measurement projections at FCC-ee, and by the theoretically well-motivated scenario of TeV-scale new physics predominantly coupled to third-generation fields. In particular, we demonstrate the key role played by the interplay among different flavor-physics measurements, and between flavor and electroweak measurements, in cornering the New Physics parameter space. Updated constraints on new physics, in the limit that no deviations from the Standard Model are observed, are also presented.

Germany

Lukas Allwicher

Marko Pesut

Flavored circular collider: cornering New Physics at FCC-ee via flavor-changing processes

<p>We analyze <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msup><mrow><mi>B</mi></mrow><mrow><mn>0</mn></mrow></msup><mo stretchy="false">→</mo><msup><mrow><mi>K</mi></mrow><mrow><mn>0</mn></mrow></msup><mover accent="true"><mrow><mo>ℓ</mo></mrow><mrow><mo stretchy="true">¯</mo></mrow></mover><mo>ℓ</mo></mrow></math> long-distance contributions induced by the rescattering of a pair of charmed and charmed-strange mesons. We present an explicit estimate of these contributions using an effective description in terms of hadronic degrees of freedom, supplemented by data on the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>B</mi><mn>0</mn></msup><mo stretchy="false">→</mo><msup><mi>D</mi><mo>*</mo></msup><msub><mi>D</mi><mi>s</mi></msub><mo stretchy="false">(</mo><msubsup><mi>D</mi><mi>s</mi><mo>*</mo></msubsup><mi>D</mi><mo stretchy="false">)</mo></math> transition in order to reproduce the corresponding discontinuity in the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>B</mi><mn>0</mn></msup><mo stretchy="false">→</mo><msup><mi>K</mi><mn>0</mn></msup><mover accent="true"><mo>ℓ</mo><mo stretchy="true">¯</mo></mover><mo>ℓ</mo></math> amplitude. The <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>D</mi><mo>*</mo></msup><msub><mi>D</mi><mi>s</mi></msub><mo stretchy="false">(</mo><msubsup><mi>D</mi><mi>s</mi><mo>*</mo></msubsup><mi>D</mi><mo stretchy="false">)</mo><mi>K</mi></math> vertex is estimated using heavy-hadron chiral perturbation theory, obtaining an accurate description of the whole rescattering process in the low-recoil (or high-<math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>q</mi><mn>2</mn></msup></math>) limit. We also present an extrapolation to the whole kinematical region introducing hadronic form factors. The explicit estimate of the leading <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>D</mi><mo>*</mo></msup><msub><mi>D</mi><mi>s</mi></msub><mo stretchy="false">(</mo><msubsup><mi>D</mi><mi>s</mi><mo>*</mo></msubsup><mi>D</mi><mo stretchy="false">)</mo></math> intermediate state leads to a long-distance amplitude which does not exceed a few percent relative to the short-distance one. The consequences of this result for the extraction of the short-distance coefficient <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>C</mi><mn>9</mn></msub></math> are discussed.</p>

Zachary Polonsky

Arianna Tinari

Explicit estimate of charm rescattering in <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msup><mrow><mi>B</mi></mrow><mrow><mn>0</mn></mrow></msup><mo stretchy="false">→</mo><msup><mrow><mi>K</mi></mrow><mrow><mn>0</mn></mrow></msup><mover accent="true"><mrow><mo>ℓ</mo></mrow><mrow><mo stretchy="true">¯</mo></mrow></mover><mo>ℓ</mo></mrow></math>

We present a flavour non-universal extension of the Standard Model combined with the idea of Higgs compositeness. At the TeV scale, the gauge groups SU(2) and U(1) − are assumed to act in a non-universal manner on light- and third-generation fermions, while the Higgs emerges as a pseudo Nambu-Goldstone boson of the spontaneous global symmetry breaking Sp(4) → SU(2) × $$ \textrm{SU}{(2)}_R^{\left[3\right]} $$ , attributed to new strong dynamics. The flavour deconstruction means the couplings of the light families to the composite sector (and therefore the pNGB Higgs) are suppressed by powers of a heavy mass scale (from which the Higgs is nevertheless shielded by compositeness), explaining the flavour puzzle. We present a detailed analysis of the radiatively generated Higgs potential, showing how this intrinsically-flavoured framework has the ingredients to justify the unavoidable tuning in the Higgs potential necessary to separate electroweak and composite scales. This happens for large enough values of the $$ \textrm{SU}{(2)}_R^{\left[3\right]} $$ gauge coupling and light enough flavoured gauge bosons resulting from the deconstruction, whose phenomenology is also investigated. The model is compatible with current experimental bounds and predicts new states at the TeV scale, which are within the reach of near future experimental searches.

Sebastiano Covone

Joe Davighi

Flavour deconstructing the composite Higgs

Flavor deconstruction refers to non-universal gauge extensions where the original gauge symmetry is deconstructed into separate copies, one for each family. A hierarchical chain of symmetry breaking provides an attractive low-scale solution to the flavor puzzle, consistent with flavor-changing neutral currents and finite naturalness. Although successful in explaining the origin of flavor hierarchies in the quark and charged lepton sectors, existing models have struggled with the large and seemingly anarchic mixing observed in neutrino oscillations. This letter identifies conditions under which neutrino anarchy may arise from flavor deconstruction in generic models with right-handed neutrinos. When deconstruction is applied to carefully chosen subgroups of the extended gauge symmetry, hierarchies in the seesaw formula cancel out.

Admir Greljo

Neutrino anarchy from flavor deconstruction

The recent <italic>B</italic>-meson anomalies are coherently explained at the TeV scale by <italic>4321 gauge models</italic> with hierarchical couplings reminiscent of the Standard Model Yukawas. We show that such models arise as the low-energy limit of a complete theory of flavor, based on a warped fifth dimension where each Standard Model family is quasi-localized on a different brane. The Higgs is identified as a pseudo-Nambu-Goldstone boson emerging from the same dynamics responsible for 4321 symmetry breaking. This novel construction unifies quarks and leptons in a flavor non-universal manner, provides a natural description of flavor hierarchies, and addresses the electroweak hierarchy problem.

Spain

Javier Fuentes-Martín

Javier M. Lizana

Nudžeim Selimović

Ben A. Stefanek

Flavor hierarchies, flavor anomalies, and Higgs mass from a warped extra dimension

We analyze data on  $$B\rightarrow K\mu ^+\mu ^-$$  <math> <mrow> <mi>B</mi> <mo>→</mo> <mi>K</mi> <msup> <mi>μ</mi> <mo>+</mo> </msup> <msup> <mi>μ</mi> <mo>-</mo> </msup> </mrow> </math>   and  $$B\rightarrow K^*\mu ^+\mu ^-$$  <math> <mrow> <mi>B</mi> <mo>→</mo> <msup> <mi>K</mi> <mo>∗</mo> </msup> <msup> <mi>μ</mi> <mo>+</mo> </msup> <msup> <mi>μ</mi> <mo>-</mo> </msup> </mrow> </math>   decays in the whole dilepton invariant mass spectrum with the aim of disentangling short- vs. long-distance contributions. The sizable long-distance amplitudes from  $$c \overline{c}$$  <math> <mrow> <mi>c</mi> <mover> <mi>c</mi> <mo>¯</mo> </mover> </mrow> </math>   narrow resonances are taken into account by employing a dispersive approach. For each available  $$q^2=m^2_{\mu \mu }$$  <math> <mrow> <msup> <mi>q</mi> <mn>2</mn> </msup> <mo>=</mo> <msubsup> <mi>m</mi> <mrow> <mi>μ</mi> <mi>μ</mi> </mrow> <mn>2</mn> </msubsup> </mrow> </math>   bin and each helicity amplitude an independent determination of the Wilson coefficient  $$C_9$$  <math> <msub> <mi>C</mi> <mn>9</mn> </msub> </math>  , describing  $$b\rightarrow s\ell ^+\ell ^-$$  <math> <mrow> <mi>b</mi> <mo>→</mo> <mi>s</mi> <msup> <mi>ℓ</mi> <mo>+</mo> </msup> <msup> <mi>ℓ</mi> <mo>-</mo> </msup> </mrow> </math>   transitions at short distances, is obtained. The consistency of the  $$C_9$$  <math> <msub> <mi>C</mi> <mn>9</mn> </msub> </math>   values thus obtained provides an a posteriori check of the absence of additional, sizable, long-distance contributions. The systematic difference of these values from the Standard Model expectation supports the hypothesis of a non-standard  $$b\rightarrow s \mu ^+\mu ^-$$  <math> <mrow> <mi>b</mi> <mo>→</mo> <mi>s</mi> <msup> <mi>μ</mi> <mo>+</mo> </msup> <msup> <mi>μ</mi> <mo>-</mo> </msup> </mrow> </math>   amplitude of short-distance origin.

CERN

Marzia Bordone

Sandro Mächler

Short- vs. long-distance physics in  $$B\rightarrow K^{(*)} \ell ^+\ell ^-$$  <math> <mrow> <mi>B</mi> <mo>→</mo> <mmultiscripts> <mi>K</mi> <mrow></mrow> <mrow> <mo>(</mo> <mrow></mrow> <mo>∗</mo> <mo>)</mo> </mrow> </mmultiscripts> <msup> <mi>ℓ</mi> <mo>+</mo> </msup> <msup> <mi>ℓ</mi> <mo>-</mo> </msup> </mrow> </math>  : a data-driven analysis

We construct two concrete examples of flavour non-universal gauge theories which, after the inclusion of all d ≤ 4 gauge invariant operators, allow to describe the observed pattern of flavour in the charged fermion sector without any small Yukawa coupling (y ≳ 0.1). Guided by the criterium of minimality, we assume that flavour non universality is confined to the Abelian sector of the gauge group: the universal hypercharge emerges after a sequence of symmetry-breaking steps characterised by two high mass scales, Λ[23] &lt; Λ[12], where the second and the first fermion generations get their mass respectively. At least in one of the two models the smaller of these scales can be in the 10 TeV range, consistently with current bounds from flavour observables. Both models are extended to include as well neutrino masses and mixings.

Italy

Riccardo Barbieri

Minimal flavour deconstruction

We present a comprehensive analysis of electroweak, flavor, and collider bounds on the complete set of dimension-six SMEFT operators in the U(2)5-symmetric limit. This operator basis provides a consistent framework to describe a wide class of new physics models and, in particular, the motivated class of models where the new degrees of freedom couple mostly to the third generation. By analyzing observables from all three sectors, and consistently including renormalization group evolution, we provide bounds on the effective scale of all 124 U(2)5-invariant operators. The relation between flavor-conserving and flavor-violating observables is analyzed taking into account the leading U(2)5 breaking in the Yukawa sector, which is responsible for heavy-light quark mixing. We show that under simple, motivated, and non-tuned hypotheses for the parametric size of the Wilson coefficients at the high scale, all present bounds are consistent with an effective scale as low as 1.5 TeV. We also show that a future circular e + e  −  collider program such as FCC-ee would push most of these bounds by an order of magnitude. This would rule out or provide clear evidence for a wide class of compelling new physics models that are fully compatible with present data.

Claudia Cornella

United Kingdom

Ben Stefanek

New physics in the third generation. A comprehensive SMEFT analysis and future prospects

We present an updated Standard Model (SM) estimate of the inclusive <math><mi>b</mi><mo>→</mo><mi>s</mi><mover><mo>ℓ</mo><mo>¯</mo></mover><mo>ℓ</mo></math> rate at a high dilepton invariant mass (<math><msup><mi>q</mi><mn>2</mn></msup><mo>≥</mo><mn>15</mn><mtext> </mtext><mtext> </mtext><msup><mi>GeV</mi><mn>2</mn></msup></math>). We show that this estimate is in good agreement with the result obtained summing the SM predictions for the leading one-body modes (<math><mi>K</mi></math> and <math><msup><mi>K</mi><mo>*</mo></msup></math>) and the subleading nonresonant <math><mi>K</mi><mi>π</mi></math> channel (for which we also present an updated estimate). On the contrary, the semi-inclusive sum based on data exhibits a deficit compared to the inclusive SM prediction in the muon modes. The statistical significance of this deficit does not exceed <math><mn>2</mn><mi>σ</mi></math> but is free from uncertainties on hadronic form factors and fully compatible with the deficit observed at low-<math><msup><mi>q</mi><mn>2</mn></msup></math> on the exclusive modes. The implications of these results in conjunction with other SM tests on <math><mi>b</mi><mo>→</mo><mi>s</mi><mover><mi>μ</mi><mo>¯</mo></mover><mi>μ</mi></math> modes are briefly discussed.

Semi-inclusive <math><mrow><mi>b</mi><mo>→</mo><mi>s</mi><mover><mrow><mo>ℓ</mo></mrow><mrow><mo>¯</mo></mrow></mover><mo>ℓ</mo></mrow></math> transitions at high <math><msup><mi>q</mi><mn>2</mn></msup></math>