166 research outputs found
Little Conformal Symmetry
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
We propose that weak scale leptogenesis via 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 is displaced a long distance from its origin by the thermal
population of fermions that become massive before electroweak symmetry
breaking. The fermion 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 and 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
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
Abstract: Gauge models with massive vector leptoquarks at the TeV scale provide a successful framework for addressing the -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
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
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 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
- …