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A bstract The “Cabibbo Angle Anomaly” (CAA) originates from the disagreement between the CKM elements V ud and V us extracted from superallowed beta and kaon decays, respectively, once compared via CKM unitarity. It points towards new physics with a significance of up to 4 σ , depending on the theoretical input used, and can be explained through modified W couplings to leptons. In this context, vector-like leptons (VLLs) are prime candidates for a corresponding UV completion since they can affect Wℓν couplings at tree-level, such that this modification can have the dominant phenomenological impact. In order to consistently assess agreement data, a global fit is necessary which we perform for gauge-invariant dimension-6 operators and all patterns obtained for the six possible representations (under the SM gauge group) of VLLs. We find that even in the lepton flavour universal case, including the measurements of the CKM elements V us and V ud into the electroweak fit has a relevant impact, shifting the best fit point significantly. Concerning the VLLs we discuss the bounds from charged lepton flavour violating processes and observe that a single representation cannot describe experimental data significantly better than the SM hypothesis. However, allowing for several representations of VLLs at the same time, we find that the simple scenario in which N couples to electrons via the Higgs and Σ 1 couples to muons not only explains the CAA but also improves the rest of the electroweak fit in such a way that its best fit point is preferred by more than 4 σ with respect to the begin.

A bstract New neutral heavy gauge bosons ( Z′ ) are predicted within many extensions of the Standard Model. While in case they couple to quarks the LHC bounds are very stringent, leptophilic Z′ bosons (even with sizable couplings) can be much lighter and therefore lead to interesting quantum effects in precision observables (like ( g − 2) μ ) and generate flavour violating decays of charged leptons. In particular, ℓ → ℓ ′ v v ¯ decays, anomalous magnetic moments of charged leptons, ℓ → ℓ ′ γ and ℓ → 3 ℓ′ decays place stringent limits on leptophilic Z′ bosons. Furthermore, in case of mixing Z′ with the SM Z , Z pole observables are affected. In light of these many observables we perform a global fit to leptophilic Z′ models with the main goal of finding the bounds for the Z′ couplings to leptons. To this end we consider a number of scenarios for these couplings. While in generic scenarios correlations are weak, this changes once additional constraints on the couplings are imposed. In particular, if one considers an L μ − L τ symmetry broken only by left-handed rotations, or considers the case of τ − μ couplings only. In the latter setup, on can explain the ( g − 2) μ anomaly and the hint for lepton flavour universality violation in τ → μv v ¯ / τ → ev v ¯ without violating bounds from electroweak precision observables.

A bstract We use the current CMS and ATLAS data for the leptonic pp → WW , WZ channels to show that diboson production is, for a broad class of flavour models, already competitive with LEP-1 measurements for setting bounds on the dimension six operators parametrising the anomalous couplings between the quarks and the electroweak gauge bosons, at least under the assumption that any new particle is heavier than a few TeV. We also make an estimate of the HL-LHC reach with 3 ab −1 . We comment on possible BSM interpretations of the bounds, and show the interplay with other searches for a simplified model with vector triplets. We further study the effect of modified Z -quark-quark couplings on the anomalous triple gauge coupling bounds. We find that their impact is already significant and that it could modify the constraints on δg 1 z and δκ γ by as much as a factor two at the end of HL-LHC ( λ z is only marginally affected), requiring a global fit to extract robust bounds. We stress the role of flavour assumptions and study explicitly flavour universal and minimal flavour violation scenarios, illustrating the differences with results obtained for universal theories.

A bstract We use global fits to analyze the most recent Higgs data from ATLAS, CMS and Tevatron and compare the Standard Model (SM) prediction with natural extensions of the SM. In particular we study wide classes of composite Higgs models based on different coset structures (leading at low energy to different Higgs sectors including extra singlets and Higgs doublets) and different coupling structures of the elementary fermions to the strong sector. We point out in what situations the composite models could improve (or worsen) the fit to the data and compare with similar trends in the MSSM.

A bstract The increase in luminosity and center of mass energy at the FCC-hh will open up new clean channels where BSM contributions are enhanced at high energy. In this paper we study one such channel, Wh → ℓνγγ . We estimate the sensitivity to the O φq 3 , O φ W , and O φ W ˜ SMEFT operators. We find that this channel will be competitive with fully leptonic WZ production in setting bounds on O φq 3 . We also find that the double differential distribution in the p T h and the leptonic azimuthal angle can be exploited to enhance the sensitivity to O φ W ˜ . However, the bounds on O φ W and O φ W ˜ we obtain in our analysis, though complementary and more direct, are not competitive with those coming from other measurements such as EDMs and inclusive Higgs measurements.

A bstract The future 100 TeV FCC-hh hadron collider will give access to rare but clean final states which are out of reach of the HL-LHC. One such process is the Zh production channel in the v v ¯ / ℓ + ℓ − γγ final states. We study the sensitivity of this channel to the O φq 1 , O φq 3 , O φu , and O φd SMEFT operators, which parametrize deviations of the W and Z couplings to quarks, or, equivalently, anomalous trilinear gauge couplings (aTGC). While our analysis shows that good sensitivity is only achievable for O φq 3 , we demonstrate that binning in the Zh rapidity has the potential to improve the reach on O φq 1 . Our estimated bounds are one order of magnitude better than projections at HL-LHC and is better than global fits at future lepton colliders. The sensitivity to O φq 3 is competitive with other channels that could probe the same operator at FCC-hh. Therefore, combining the different diboson channels sizeably improves the bound on O φq 3 , reaching a precision of | δg 1 z | ≲ × 10 − 4 on the deviations in the ZWW interactions.

A bstract We study the magnetic response of holographic superconductors exhibiting an insulating ‘normal’ phase. These materials can be realized as a CFT compactified on a circle, which is dual to the AdS Soliton geometry. We study the response under i) magnetic fields and ii) a Wilson line on the circle. Magnetic fields lead to formation of vortices and allows one to infer that the superconductor is of type II. The response to a Wilson line is in the form of Aharonov-Bohm-like effects. These are suppressed in the holographic conductor/superconductor transition but, instead, they are unsuppressed for the insulator case. Holography, thus, predicts that generically insulators display stronger Aharonov-Bohm effects than conductors. In the fluid-mechanical limit the AdS Soliton is interpreted as a supersolid. Our results imply that supersolids display unsuppressed Aharonov-Bohm (or ‘Sagnac’) effects — stronger than in superfluids.

Holographic superconductors have been studied so far in the absence of dynamical electromagnetic fields, namely in the limit in which they coincide with holographic superfluids. It is possible, however, to introduce dynamical gauge fields if a Neumann-type boundary condition is imposed on the AdS-boundary. In 3 + 1 dimensions, the dual theory is a 2 + 1 dimensional CFT whose spectrum contains a massless gauge field, signaling the emergence of a gauge symmetry. We study the impact of a dynamical gauge field in vortex configurations where it is known to significantly affect the energetics and phase transitions. We calculate the critical magnetic fields H c1 and H c2 , obtaining that holographic superconductors are of Type II ( H c1 < H c2 ). We extend the study to 4 + 1 dimensions where the gauge field does not appear as an emergent phenomenon, but can be introduced, by a proper renormalization, as an external dynamical field. We also compare our predictions with those arising from a Ginzburg-Landau theory and identify the generic properties of Abrikosov vortices in holographic models.

A bstract In supersymmetric models, a correlation exists between the structure of the Higgs sector quartic potential and the coupling of the lightest CP-even Higgs to fermions and gauge bosons. We exploit this connection to relate the observed value of the Higgs mass m h  ≈ 125 GeV to the magnitude of its couplings. We analyze different scenarios ranging from the MSSM with heavy stops to more natural models with additional non-decoupling D-term/F-term contributions. A comparison with the most recent LHC data, allows to extract bounds on the heavy Higgs boson masses, competitive with bounds from direct searches.

We propose a new way of explaining the observed Higgs mass, within the cosmological relaxation framework. The key feature distinguishing it from other scanning scenarios is that the scanning field has a non-canonical kinetic term, whose role is to terminate the scan around the desired Higgs mass value. We propose a concrete realisation of this idea with two new singlet fields, one that scans the Higgs mass, and another that limits the time window in which the scan is possible. Within the provided time period, the scanning field does not significantly evolve after the Higgs field gets close to the Standard Model value, due to particle production friction.