166 research outputs found

    Little Conformal Symmetry

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    We explore a new class of natural models which ensure the one-loop divergences in the Higgs mass are cancelled. The top-partners that cancel the top loop are new gauge bosons, and the symmetry relation that ensures the cancellation arises at an infrared fixed point. Such a cancellation mechanism can, a la Little Higgs models, push the scale of new physics that completely solves the hierarchy problem up to 5-10 TeV. When embedded in a supersymmetric model, the stop and gaugino masses provide the cutoffs for the loops, and the mechanism ensures a cancellation between the stop and gaugino mass dependence of the Higgs mass parameter.Comment: 15 pages, 3 figure

    Archimedean Lever Leptogenesis

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    We propose that weak scale leptogenesis via ∼10\sim 10 TeV scale right-handed neutrinos could be possible if their couplings had transitory larger values in the early Universe. The requisite lifted parameters can be attained if a light scalar ϕ\phi is displaced a long distance from its origin by the thermal population of fermions XX that become massive before electroweak symmetry breaking. The fermion XX can be a viable dark matter candidate; for suitable choice of parameters, the light scalar itself can be dark matter through a misalignment mechanism. We find that a two-component DM population made up of both XX and ϕ\phi is a typical outcome in our framework.Comment: 8 pages, 3 figures. We explain AL

    Radiative effects in the scalar sector of vector leptoquark models

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    Gauge models with massive vector leptoquarks at the TeV scale provide a successful framework for addressing the B-physics anomalies. Among them, the 4321 model has been considered as the low-energy limit of some complete theories of flavor. In this work, we study the renormalization group evolution of this model, laying particular emphasis on the scalar sector. We find that, despite the asymptotic freedom of the gauge couplings, Landau poles can arise at relatively low scales due to the fast running of quartic couplings. Moreover, we discuss the possibility of radiative electroweak symmetry breaking and characterize the fine-tuning associated with the hierarchy between the electroweak scale and the additional TeV-scale scalars. Finally, the idea of scalar fields unification is explored, motivated by ultraviolet embeddings of the 4321 model

    Radiative effects in the scalar sector of vector leptoquark models

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    Abstract: Gauge models with massive vector leptoquarks at the TeV scale provide a successful framework for addressing the BB-physics anomalies. Among them, the 4321 model has been considered as the low-energy limit of some complete theories of flavor. In this work, we study the renormalization group evolution of this model, laying particular emphasis on the scalar sector. We find that, despite the asymptotic freedom of the gauge couplings, Landau poles can arise at relatively low scales due to the fast running of quartic couplings. Moreover, we discuss the possibility of radiative electroweak symmetry breaking and characterize the fine-tuning associated with the hierarchy between the electroweak scale and the additional TeV-scale scalars. Finally, the idea of scalar fields unification is explored, motivated by ultraviolet embeddings of the 4321 model

    Hamiltonian Truncation Effective Theory

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    Hamiltonian truncation is a non-perturbative numerical method for calculating observables of a quantum field theory. The starting point for this method is to truncate the interacting Hamiltonian to a finite-dimensional space of states spanned by the eigenvectors of the free Hamiltonian H0 with eigenvalues below some energy cutoff Emax. In this work, we show how to treat Hamiltonian truncation systematically using effective field theory methodology. We define the finite-dimensional effective Hamiltonian by integrating out the states above Emax. The effective Hamiltonian can be computed by matching a transition amplitude to the full theory, and gives corrections order by order as an expansion in powers of 1/Emax. The effective Hamiltonian is non-local, with the non-locality controlled in an expansion in powers of H0/Emax. The effective Hamiltonian is also non-Hermitian, and we discuss whether this is a necessary feature or an artifact of our definition. We apply our formalism to 2D λφ4 theory, and compute the the leading 1/E 2 max corrections to the effective Hamiltonian. We show that these corrections non trivially satisfy the crucial property of separation of scales. Numerical diagonalization of the effective Hamiltonian gives residual errors of order 1/E 3 max, as expected by our power counting. We also present the power counting for 3D λφ4 theory and perform calculations that demonstrate the separation of scales in this theory

    On discrete Goldstone bosons

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    Exact discrete symmetries, if non-linearly realized, can reduce the ultraviolet sensitivity of a given theory. The scalars stemming from spontaneous symmetry breaking are massive without breaking the discrete symmetry, and those masses are protected from divergent quadratic corrections. This is in contrast to non-linearly realized continuous symmetries. The symmetry-protected masses and potentials of those discrete Goldstone bosons offer promising physics avenues, both theoretically and in view of the blooming experimental search for ALPs. In this text, we develop this theoretical setup for the specific case of a triplet of A5A_5 using invariant theory, showcasing the substantial improvements and compelling phenomenological consequences introduced by the invariance under a discrete symmetry.Comment: 6 pages, 2 figures. Contribution to the proceedings of the 8th Symposium on Prospects in the Physics of Discrete Symmetries (DISCRETE 2022
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