We investigate quantum entanglement in high-energy 2 → 2 scalar scattering, where the scalars are characterized by an internal flavor quantum number acting like a qubit. Working at the 1-loop order in perturbation theory, we build the final-state density matrix as a function of the scattering amplitudes connecting the initial to the outgoing state. In this construction, the unitarity of the S-matrix is guaranteed at the required order by the optical theorem. We consider the post-scattering entanglement between the momentum and flavor degrees of freedom of the final-state particles, as well as the entanglement of the two-qubit flavor subsystem. In each case we identify the couplings of the scalar potential that can generate, destroy, or transfer entanglement between different bipartite subspaces of the Hilbert space.

Poland

Kamila Kowalska

Enrico Sessolo

Entanglement in flavored scalar scattering

We perform a global analysis of a vectorlike extension of the Standard Model, which also features additional doublet and singlet scalars. The usual Yukawa interactions are forbidden in this setup by an extra U(1) global symmetry and the masses of the second and third family quarks and leptons are generated via the mixing with the vectorlike sector. We identify three best-fit benchmark scenarios which satisfy the constraints imposed by the stability of the scalar potential, the perturbativity of the coupling constants, the measurement of the muon anomalous magnetic moment and the nonobservation of the flavor violating tau decays. We show that dominant contributions to the muon (<math><mrow><mi>g</mi><mo>−</mo><mn>2</mn></mrow></math>) originate in this model from the charged Higgs/neutral lepton one-loop diagrams, thus correcting an inaccurate statement than can be found in the literature. We also perform a detailed LHC analysis of the benchmark scenarios. We investigate the experimental constraints stemming from direct searches for vectorlike quarks, vectorlike leptons, and exotic scalars. While we show that the model is not currently tested by any collider experiment, we point out that decays of a heavy Higgs boson into two tau leptons may offer a smoking gun signature for the model verification in upcoming runs at the LHC.

Chile

A. E. Cárcamo Hernández

Huchan Lee

Daniele Rizzo

Global analysis and LHC study of a vectorlike extension of the standard model with extra scalars

We revisit the dynamical generation of an arbitrarily small neutrino Yukawa coupling in the Standard Model with trans-Planckian asymptotic safety and apply the same mechanism to the gauged B − L model. We show that thanks to the presence of additional irrelevant couplings, the described neutrino-mass generation in the B − L model is potentially more in line with existing theoretical calculations in quantum gravity. Interestingly, the model can accommodate, in full naturalness and without extensions, the possibility of purely Dirac, pseudo-Dirac, and Majorana neutrinos with any see-saw scale. We investigate eventual distinctive signatures of these cases in the detection of gravitational waves from first-order phase transitions. We find that, while it is easy to produce a signal observable in new-generation space interferometers, its discriminating features are washed out by the strong dependence of the gravitational-wave spectrum on the relevant parameters of the scalar potential.

Abhishek Chikkaballi

Naturally small neutrino mass with asymptotic safety and gravitational-wave signatures

The framework of trans-Planckian asymptotic safety has been shown to generate phenomenological predictions in the Standard Model and in some of its simple new physics extensions. A heuristic approach is often adopted, which bypasses the functional renormalization group by relying on a parametric description of quantum gravity with universal coefficients that are eventually obtained from low-energy observations. Within this approach a few simplifying approximations are typically introduced, including the computation of matter renormalization group equations at 1 loop, an arbitrary definition of the position of the Planck scale at  $$10^{19}\,\textrm{GeV},$$  <math> <mrow> <msup> <mn>10</mn> <mn>19</mn> </msup> <mspace width="0.166667em"></mspace> <mtext>GeV</mtext> <mo>,</mo> </mrow> </math>   and an instantaneous decoupling of gravitational interactions below the Planck scale. In this work we systematically investigate, both analytically and numerically, the impact of dropping each of those approximations on the predictions for certain particle physics scenarios. In particular we study two extensions of the Standard Model, the gauged  $$B-L$$  <math> <mrow> <mi>B</mi> <mo>-</mo> <mi>L</mi> </mrow> </math>   model and the leptoquark  $$S_3$$  <math> <msub> <mi>S</mi> <mn>3</mn> </msub> </math>   model, for which we determine a set of irrelevant gauge and Yukawa couplings. In each model, we present numerical and analytical estimates of the uncertainties associated with the predictions from asymptotic safety.

Wojciech Kotlarski

How robust are particle physics predictions in asymptotic safety?

Motivated by the flavor anomalies in b → s transitions, we embed minimal models with a Z′ gauge boson, vector-like fermions, and a singlet scalar in the framework of trans-Planckian asymptotic safety. The presence of a fixed point in the renormalization group flow of the models’ parameters leads to predictions for the γ/Z′ kinetic mixing, the New Physics Yukawa couplings, and the quartic couplings of the scalar potential. We derive the constraint on the kinetic mixing from the most recent high-mass dilepton resonance searches at the LHC, showing that this bound is often inescapable in this framework, unless the U(1) charges conspire to forbid the radiative generation of kinetic mixing. In the latter case, the parameter space consistent with the flavor anomalies can still be probed in depth by direct LHC searches for heavy vector-like quarks and leptons. We derive the current exclusion bounds and projections for future high-luminosity runs.

Constraints on Z′ solutions to the flavor anomalies with trans-Planckian asymptotic safety

Within the Exceptional Supersymmetric Standard Model (E $$_6$$  <math> <msub> <mrow></mrow> <mn>6</mn> </msub> </math>  SSM), we investigate signatures at the Large Hadron Collider (LHC) for a long-lived charged inert higgsino, which is degenerate with the inert neutralino at tree level and a small mass splitting is generated at the loop level, resulting in a lifetime  $$\mathcal{O}(0.02)$$  <math> <mrow> <mi>O</mi> <mo>(</mo> <mn>0.02</mn> <mo>)</mo> </mrow> </math>   nanoseconds. We focus on the most sensitive search for long-lived charged inert higgsino decays to the lightest neutral inert higgsino dark matter and very soft charged leptons, which are eventually stopped in the detector resulting in a disappearing-track signal. Furthermore, we study the displaced vertex signature of the inert chargino in the case where it is produced via the  $$Z^{\prime }$$  <math> <msup> <mi>Z</mi> <mo>′</mo> </msup> </math>   portal. We illustrate how difficult it is to construct displaced vertices in this class of models, though some evidence could be gained at the High Luminosity LHC. Finally, we compare the spin independent and spin dependent cross sections of the lightest inert higgsino DM to those of current direct detection experiments, proving that it is possible to gain sensitivity to the active DM component of this scenario in the near future. The combination of these signatures with the one emerging from  $$Z'$$  <math> <msup> <mi>Z</mi> <mo>′</mo> </msup> </math>   production and decay via Drell–Yan, which can be characterised as belonging to the E $$_6$$  <math> <msub> <mrow></mrow> <mn>6</mn> </msub> </math>  SSM via both the cross section and Forward–Backward Asymmetry, could point uniquely to this non-minimal realisation of Supersymmetry.

Egypt

Shaaban Khalil

Sweden

United Kingdom

Stefano Moretti

Diana Rojas-Ciofalo

Harri Waltari

A combined approach to the analysis of space and ground experimental data within a simplified E $$_6$$  <math> <msub> <mrow></mrow> <mn>6</mn> </msub> </math>  SSM

In gauge-Yukawa systems embedded in the framework of trans-Planckian asymptotic safety we discuss the dynamical generation of arbitrarily small Yukawa couplings driven by the presence of a non-interactive infrared-attractive fixed point in the renormalization group flow. Additional ultraviolet-attractive fixed points guarantee that the theory remains well defined up to an infinitely high scale. We apply this mechanism to the Yukawa couplings of the Standard Model extended with right-handed neutrinos, finding that asymptotically safe solutions in agreement with the current experimental determination of the masses and mixing angles exist for Dirac neutrinos with normal mass ordering. We generalize the discussion by applying the same mechanism to a new-physics model with sterile-neutrino dark matter, where we generate naturally the feeble Yukawa interaction required to reproduce via freeze-in the correct relic abundance.

Soumita Pramanick

Naturally small Yukawa couplings from trans-Planckian asymptotic safety

In the context of the gauge coupling unification, we present a comprehensive analysis of the extensions of the Standard Model with vector-like fermions and scalars. We find 145 models that satisfy the unification condition, which are distinguishable by the number of new particles in the spectrum and by their transformation properties under the gauge symmetry group of the Standard Model. For all models we derive lower bounds on the exotic fermion and scalar masses, stemming from the measurement of the strong gauge coupling scale dependence, from the heavy stable charged particle searches, and from the electroweak precision tests. We also discuss the potential of testing the unification scenarios at the future 100 TeV collider and in the proton decay experiments. We show that many models can already be excluded based on the current data, while many others will be entirely probed in the coming years.

Ubaldo Olivas

India

Dinesh Kumar

Road map through the desert with scalars

We perform a phenomenological analysis of simplified models of light, feebly interacting particles (FIPs) that can provide a combined explanation of the anomalies in b → sl + l  −  transitions at LHCb and the anomalous magnetic moment of the muon. Different scenarios are categorised according to the explicit momentum dependence of the FIP coupling to the b−s and μ−μ vector currents and they are subject to several constraints from flavour and precision physics. We show that viable combined solutions to the muon g − 2 and flavour anomalies exist with the exchange of a vector FIP with mass larger than 4 GeV. Interestingly, the LHC has the potential to probe this region of the parameter space by increasing the precision of the Z → 4μ cross-section measurement. Conversely, we find that solutions based on the exchange of a lighter vector, in the m  V  &lt; 1 GeV range, are essentially excluded by a combination of B → K+ invisible and W-decay precision bounds.

Italy

Luc Darmé

Germany

Marco Fedele

Flavour anomalies and the muon g − 2 from feebly interacting particles

We use the framework of asymptotic safety above the Planck scale to constrain the parameter space of simple models of new physics that can accommodate the measured value of the anomalous magnetic moment of the muon and the relic density of dark matter. We couple parametrically to the trans-Planckian quantum physics a set of <math><mrow><mrow><msub><mrow><mi>SU</mi><mo>(</mo><mn>2</mn><mo>)</mo></mrow><mrow><mi>L</mi></mrow></msub><mo>×</mo></mrow><mi>U</mi><mo>(</mo><mn>1</mn><msub><mrow><mo>)</mo></mrow><mrow><mi>Y</mi></mrow></msub></mrow></math> invariant extensions of the Standard Model, each comprising an inert scalar field and one pair of colorless fermions that communicate to the muons through Yukawa-type interactions. The presence of an interactive UV fixed point in the system of gauge and Yukawa couplings imposes a set of boundary conditions at the Planck scale, which allow one to derive unique phenomenological predictions in each case and distinguish the different representations of the gauge group from one another. We apply to the models constraints from the <math><mi>h</mi><mo>→</mo><mi>μ</mi><mi>μ</mi></math> signal strength at ATLAS and CMS, direct LHC searches for electroweak production with leptons and missing energy in the final state, and the dark matter relic density. We find that they further restrict the available parameter space.