Related papers: The Cutoff $\lambda \phi^4$ O(N) Model in the Larg…
We obtain the effective potential at finite temperature within the left-right symmetric model. We take the Higgs sector to consist of two doublets and calculate its finite temperature effective potential up to the order of…
In this paper, we investigate the $\phi^4$ model with cutoffs. By introducing a spatial cutoff and a momentum cutoff, the total Hamiltonian is a self-adjoint operator on a boson Fock space. Under regularity conditions of the momentum…
The 1/N expansion of the two-particle irreducible effective action offers a powerful approach to study quantum field dynamics far from equilibrium. We investigate the effective convergence of the 1/N expansion in the O(N) model by comparing…
The contribution to the $\rho$--parameter of the quark--Higgs sector of the supersymmetric standard model is computed non--perturbatively using the large--$\nf$ expansion for the case tan$\beta$=0. An explicit formula is found for the…
We use the semiclassical formalism based on singular solutions in complex time to compute scattering rates for multiparticle production at high energies. In a weakly coupled $\lambda \phi^4$ scalar field theory in four dimensions, we…
It is conventionally assumed that the negative mass squared term in the linear sigma model version of the pion Lagrangian is $M^2 \sim \Lambda_{\rm QCD}^2$ in powers of $N_c$. We consider the case where $M^2 \sim \Lambda^2_{\rm QCD}/N_c$ so…
The scaling properties of the free energy and some of universal amplitudes of a group of models belonging to the universality class of the quantum nonlinear sigma model and the O(n) quantum $\phi^4$ model in the limit $n\to \infty$ as well…
The thermodynamics of the O(N) nonlinear sigma model in 1+1 dimensions is studied. We calculate the finite temperature effective potential in leading order in the 1/N expansion and show that at this order the effective potential can be made…
We study the spectrum of the large $N$ quantum field theory of bosonic rank-$3$ tensors, whose quartic interactions are such that the perturbative expansion is dominated by the melonic diagrams. We use the Schwinger-Dyson equations to…
Nogga, Timmermans and van Kolck recently argued that Weinberg's power counting in the few-nucleon sector is inconsistent and requires modifications. Their argument is based on the observed cutoff dependence of the nucleon-nucleon scattering…
We consider modifications of the Higgs potential due to new physics at high energy scales. These upset delicate cancellations predicted by the Standard Model for processes involving Higgs bosons and longitudinal gauge bosons, and lead to a…
We compute the relevant parameters of the combined Higgs and \phi scalar effective potential in the Littlest Higgs (LH) model. These parameters are obtained as the sum of two kind of contributions. The first one is the one-loop radiative…
The definition of a double-scaling limit represents an important goal in the development of tensor models. We take the first steps towards this goal by extracting and analysing the next-to-leading order contributions, in the 1/N expansion,…
In the context of the minimal SO(5) linear {\sigma}-model, a complete renormalizable Lagrangian -including gauge bosons and fermions- is considered, with the symmetry softly broken to SO(4). The scalar sector describes both the electroweak…
In order to investigate the Higgs mechanism nonperturbatively, we compute the Gaussian effective potential (GEP) of the U(1) Higgs model ("scalar electrodynamics"). We show that the same simple result is obtained in three different…
We study the O(N) linear sigma model with spontaneous symmetry breaking at finite temperature in the framework of the two-particle point-irreducible (2PPI) effective action. We go beyond the Hartree approximation by including the two-loop…
A lattice simulation in the broken phase of four-dimensional (lambda Phi^4) theory in the Ising limit suggests that, in the continuum limit, the scalar condensate rescales by a factor different from the conventional wavefunction…
We consider a twin Higgs scenario where the $Z_2$ twin symmetry is broken spontaneously, not explicitly. This scenario provides an interesting interpretation of the Higgs metastability in the standard model; the $SU(4)$ breaking scale $f$…
We consider the Higgs sector in an extension of the MSSM with extra SM singlets, involving an extra $U(1)^\prime$ gauge symmetry, in which the domain-wall problem is avoided and the effective $\mu$ parameter is decoupled from the new gauge…
By analogy with the low energy QCD effective linear sigma model we construct a standard model effective potential based entirely on the requirement that the tree level and quantum level trace anomalies must be satisfied. We discuss a…