Search results for "Higgs"
showing 10 items of 1127 documents
First Order Electroweak Phase Transition from (Non)Conformal Extensions of the Standard Model
2015
We analyse and compare the finite-temperature electroweak phase transition properties of classically (non)conformal extensions of the Standard Model. In the classically conformal scenarios the breaking of the electroweak symmetry is generated radiatively. The models feature new scalars coupled conformally to the Higgs sector as well as new fermions. We uncover the parameter space leading to a first order phase transition with(out) the Veltman conditions. We also discuss dark (matter) aspects of some of the models and compare with existing literature when appropriate. We observe that to accommodate both, a first order electroweak phase transition, and a phenomenologically viable dark matter …
Subleading Regge limit from a soft anomalous dimension
2018
Wilson lines capture important features of scattering amplitudes, for example soft effects relevant for infrared divergences, and the Regge limit. Beyond the leading power approximation, corrections to the eikonal picture have to be taken into account. In this paper, we study such corrections in a model of massive scattering amplitudes in N = 4 super Yang-Mills, in the planar limit, where the mass is generated through a Higgs mechanism. Using known three-loop analytic expressions for the scattering amplitude, we find that the first power suppressed term has a very simple form, equal to a single power law. We propose that its exponent is governed by the anomalous dimension of a Wilson loop w…
Tracing symmetries and their breakdown through phases of heterotic (2,2) compactifications
2015
We are considering the class of heterotic $\mathcal{N}=(2,2)$ Landau-Ginzburg orbifolds with 9 fields corresponding to $A_1^9$ Gepner models. We classify all of its Abelian discrete quotients and obtain 152 inequivalent models closed under mirror symmetry with $\mathcal{N}=1,2$ and $4$ supersymmetry in 4D. We compute the full massless matter spectrum at the Fermat locus and find a universal relation satisfied by all models. In addition we give prescriptions of how to compute all quantum numbers of the 4D states including their discrete R-symmetries. Using mirror symmetry of rigid geometries we describe orbifold and smooth Calabi-Yau phases as deformations away from the Landau-Ginzburg Ferma…
Factorization at Subleading Power, Sudakov Resummation and Endpoint Divergences in Soft-Collinear Effective Theory
2020
Starting from the first renormalized factorization theorem for a process described at subleading power in soft-collinear effective theory, we discuss the resummation of Sudakov logarithms for such processes in renormalization-group improved perturbation theory. Endpoint divergences in convolution integrals, which arise generically beyond leading power, are regularized and removed by systematically rearranging the factorization formula. We study in detail the example of the $b$-quark induced $h\to\gamma\gamma$ decay of the Higgs boson, for which we resum large logarithms of the ratio $M_h/m_b$ at next-to-leading logarithmic order. We also briefly discuss the related $gg\to h$ amplitude.
On axionic dark matter in Type IIA string theory
2013
We investigate viable scenarios with various axions in the context of supersymmetric field theory and in globally consistent D-brane models. The Peccei-Quinn symmetry is associated with an anomalous U(1) symmetry, which acquires mass at the string scale but remains as a perturbative global symmetry at low energies. The origin of the scalar Higgs-axion potential from F-, D- and soft breaking terms is derived, and two Standard Model examples of global intersecting D6-brane models in Type II orientifolds are presented, which differ in the realisation of the Higgs sector and in the hidden sector, the latter of which is of particluar importance for the soft supersymmetry breaking terms.
Frame covariant nonminimal multifield inflation
2017
We introduce a frame-covariant formalism for inflation of scalar-curvature theories by adopting a differential geometric approach which treats the scalar fields as coordinates living on a field-space manifold. This ensures that our description of inflation is both conformally and reparameterization covariant. Our formulation gives rise to extensions of the usual Hubble and potential slow-roll parameters to generalized fully frame-covariant forms, which allow us to provide manifestly frame-invariant predictions for cosmological observables, such as the tensor-to-scalar ratio $r$, the spectral indices $n_{\cal R}$ and $n_T$, their runnings $\alpha_{\cal R}$ and $\alpha_T$, the non-Gaussianity…
On the Super Higgs Effect in Extended Supergravity
2002
We consider the reduction of supersymmetry in N-extended four dimensional supergravity via the super Higgs mechanism in theories without cosmological constant. We provide an analysis largely based on the properties of long and short multiplets of Poincare' supersymmetry. Examples of the super Higgs phenomenon are realized in spontaneously broken N=8 supergravity through the Scherk-Schwarz mechanism and in superstring compactification in presence of brane fluxes. In many models the massive vectors count the difference in number of the translation isometries of the scalar sigma-model geometries in the broken and unbroken phase.
Induced scalar potentials for hypermultiplets
1997
Charged BPS hypermultiplets can develop a non-trivial self-interaction in the Coulomb branch of an N=2 supersymmetric gauge theory, whereas neutral BPS hypermultiplets in the Higgs branch may also have a non-trivial self-interaction in the presence of Fayet-Iliopoulos terms. The exact hypermultiplet low-energy effective action (LEEA) takes the form of the non-linear sigma-model (NLSM) with a hyper-K"ahler metric. A non-trivial scalar potential is also quantum-mechanically generated at non-vanishing central charges, either perturbatively (Coulomb branch), or non-perturbatively (Higgs branch). We calculate the effective scalar potentials for (i) a single charged hypermultiplet in the Coulomb …
Duality and Spontaneously Broken Supergravity in Flat Backgrounds
2002
It is shown that the super Higgs mechanism that occurs in a wide class of models with vanishing cosmological constant (at the classical level) is obtained by the gauging of a flat group which must be an electric subgroup of the duality group. If the residual massive gravitinos which occur in the partial supersymmetry breaking are BPS saturated, then the flat group is non abelian. This is so for all the models obtained by a Scherk-Schwarz supersymmetry breaking mechanism. If gravitinos occur in long multiplets, then the flat groups may be abelian. This is the case of supersymmetry breaking by string compactifications on an orientifold T^6/Z_2 with non trivial brane fluxes.
N=2 Super-Higgs, N=1 Poincare' Vacua and Quaternionic Geometry
2002
In the context of N=2 supergravity we explain the occurrence of partial super-Higgs with vanishing vacuum energy and moduli stabilization in a model suggested by superstring compactifications on type IIB orientifolds with 3-form fluxes. The gauging of axion symmetries of the quaternionic manifold, together with the use of degenerate symplectic sections for special geometry, are the essential ingredients of the construction.