We obtain SMEFT bounds using an approach that utilises the complete multi-dimensional differential information of a process. This approach is based on the fact that at a given EFT order, the full angular distribution in the most important electroweak processes can be expressed as a sum of a fixed number of basis functions. The coefficients of these basis functions — the so-called angular moments — and their energy dependance, thus form an ideal set of experimental observables that encapsulates the complete multi-dimensional differential information of the process. This approach is generic and the observables constructed allow to avoid blind directions in the SMEFT parameter space. While this method is applicable to many of the important electroweak processes, as a first example we study the pp → V(ℓℓ)h(bb) process (V ≡ Z/W±, ℓℓ ≡ ℓ+ℓ−/ℓ±ν), including QCD NLO effects, differentially. We show that using the full differential data in this way plays a crucial role in simultaneously and maximally constraining the different vertex structures of the Higgs coupling to gauge bosons. In particular, our method yields bounds on the $$ {hV}_{\mu \nu}{V}^{\mu \nu},{hV}_{\mu \nu}{\tilde{V}}^{\mu \nu} $$ hV μν V μν , hV μν V ˜ μν and $$ hVff\left( ff\equiv f\overline{f}/f\overline{f}^{\prime}\right) $$ hVff ff ≡ f f ¯ / f f ¯ ′ couplings, stronger than projected bounds reported in any other process. This matrix-element-based method can provide a transparent alternative to complement machine learning techniques that also aim to disentangle correlations in the SMEFT parameter space.

These notes provide a comprehensive review of the semiclassical approach for calculating multiparticle production rates for initial states with few particles at very high energies. In this work we concentrate on a scalar field theory with a mass gap. Specifically, we look at a weakly-coupled theory in the high-energy limit, where the number of particles in the final state scales with energy, n ∼ E → ∞, and the coupling λ → 0 with nλ held fixed. In this regime, the semiclasical approach allows us to calculate multiparticle rates non-perturbatively.

We propose differential observables for pp → Z( + − )h(bb) that can be used to completely determine the tensor structure of the hZZ * /hZf f couplings relevant to this process in the dimension-6 SMEFT. In particular, we propose a strategy to probe the anomalous hZµν Z µν and hZµνZ µν vertices at the percent level. We show that this can achieved by resurrecting the interference term between the transverse Zh amplitude, which receives contributions from the above couplings, and the dominant SM longitudinal amplitude. These contributions are hard to isolate without a knowledge of the analytical amplitude, as they vanish unless the process is studied differentially in three different angular variables at the level of the Z-decay products. By also including the differential distributions with respect to energy variables, we obtain projected bounds for the two other tensor structures of the Higgs coupling to Z-bosons.

Higgsplosion is the mechanism that leads to exponentially growing decay rates of highly energetic particles into states with very high numbers of relatively soft Higgs bosons. In this paper we study quantum effects in the presence of Higgsplosion. First, we provide a non-perturbative definition of Higgsplosion as a resolved short-distance singularity of quantum propagators at distances shorter than the inverse Higgsplosion energy scale, E * . We then consider quantum effects arising from loops in perturbation theory with these propagators on internal lines. When the loop momenta exceed the Higgsplosion scale E * , the theory dynamics deviates from what is expected in the standard QFT settings without Higgsplosion. The UV divergences are automatically regulated by the Higgsplosion scale, leading to the change of slopes for the running couplings at the RG scales µ > E * . Thus, the theory becomes asymptotically safe. Further, we find that the finite parts are also modified and receive power-suppressed corrections in 1/E 2 * . We use these results to compute a set of precision observables for the Higgsploding Standard Model. These and other precision observables could provide experimental evidence and tests for the existence of Higgsplosion in particle physics. arXiv:1709.08655v3 [hep-ph]

We present a unified relaxion solution to the five major outstanding issues in particle physics: the hierarchy problem, dark matter, matter-antimatter asymmetry, neutrino masses and the strong CP problem. The only additional field content in our construction with respect to standard relaxion models is an up-type vector-like fermion pair and three right-handed neutrinos charged under the relaxion shift symmetry. The observed dark matter abundance is generated automatically by oscillations of the relaxion field that begin once it is misaligned from its original stopping point after reheating. The matter-antimatter asymmetry arises from spontaneous baryogenesis induced by the CPT violation due to the rolling of the relaxion after reheating. The CPT violation is communicated to the baryons and leptons via an operator, ∂µφJ µ , where J µ consists of right-handed neutrino currents arising naturally from a simple neutrino mass model. Finally, the strong CP problem is solved via the Nelson-Barr mechanism, i.e. by imposing CP as a symmetry of the Lagrangian that is broken only spontaneously by the relaxion. The CP breaking is such that although an O(1) strong CKM phase is generated, the induced strong CP phase is much smaller, i.e., within experimental bounds.