[en] A lattice simulation in the broken phase of (λPHI⁴)₄ theory in the Ising limit suggests that, in the continuum limit, the scalar condensate rescales by a factor different from the conventional wavefunction renormalization. Possible effects on the present bounds of the Higgs mass are discussed

[en] Radiative corrections are known to play a fundamental role in the understanding of quantum electrodynamics (QED) since high-precision measurements were performed in the low-energy sector of the theory (Lamb shift, g-2,...). At the same time, the analysis of electron-positron interaction in storage rings has provided precious information about O(α/sup 3/) effects, such as, for example, in the case of the forward-backward asymmetry in the process e/sup +/e/sup -/ → μ/sup +/μ/sup -/. In this paper, the author presents an analysis of the higher order effects of the intermediate vector boson (IVB) parameters, i.e., their masses and leptonic decay rates. Also the experimental precision for a meaningful test of the theory at the one-loop level is discussed

[en] The 'triviality' of PHI₄⁴ has been traditionally interpreted within perturbation theory where the prediction for the Higgs boson mass depends on the magnitude of the ultraviolet cutoff π. This approach crucially assumes that the vacuum field and its quantum fluctuations rescale in the same way. The results of the present lattice simulation, confirming previous numerical indications, show that this assumption is not true. As a consequence, large values of the Higgs mass m_H can coexist with the limit π → ∞. As an example, by extrapolating to the Standard Model our results obtained in the Ising limit of the one-component theory, one can obtain a value as large as mH = 760 ± 21 GeV, independently of π

[en] In the Standard Model the Fermi constant is associated with the vacuum expectation value of the Higgs field, 'the condensate', usually believed to be a cutoff-independent quantity. General arguments related to the 'triviality' of PHI⁴ theory in 4 space-time dimensions suggest, however, a dramatic renormalization effect in the continuum limit that is clearly visible on the relatively large lattices available today. The result can be crucial for the Higgs phenomenology and in any context where spontaneous symmetry breaking is induced through scalar fields

[en] The idea of a 'condensed' vacuum state is generally accepted in modern elementary particle physics. After comparison with existing measurements, we argue that there is a need for a new generation of precise 'ether-drift' experiments with present-day technology

[en] Radiative corrections to Bhabha scattering are calculated in the simplest example of non-Abelian gauge theories. A detailed analysis of the higher-order effects is presented and the total differential cross section including weak corrections is evaluated at different angles in an energy range up to 70 GeV per beam. The effects of weak interactions appear to be negligible up to the production of the neutral vector boson. (Auth.)

[en] We simulate a four dimensional self-interacting scalar field theory on the lattice at finite temperature. By varying temperature, the system undergoes a phase transition from broken phase to symmetric phase. Our data show that the zero-momentum field renormalization increases by approaching critical temperature. On the other hand, finite-momentum wave-function renormalization remains remarkably constant

[en] The broken-symmetry vacuum of present particle physics is modeled as a Bose condensate of elementary quanta whose trivial empty vacuum state is not the true ground state of the theory. The symmetric phase will eventually be reestablished above a critical temperature that, in the Standard Model of electroweak interactions, is so high that, even at ordinary temperature, one can safely approximate the vacuum as a zero-temperature, superfluid medium where bodies can flow without any apparent friction consistently with the experimental results. In this sense, the basic quantum phenomenon of superfluidity, resolving the apparent contradiction existing in the notion of a non-empty vacuum state, seems to provide a key ingredient to reconcile the presently accepted view with the original foundations of Einstein's special relativity in 1905. Nevertheless, according to general theoretical arguments, this form of quantum ether characterizes the physically realized form of relativity and could play the role of preferred reference frame in a modern Lorentzian approach. By adopting a phenomenological two-fluid model of the vacuum, I explore the experimental implications of this scenario in connection with a new generation of dedicated ether-drift experiments.

[en] A general equivalence between functional techniques and canonical quantization for a simple self-interacting scalar theory is proposed. Vacuum instability for the symmetric ((phi) = 0) and nonsymmetric cases is analysed in detail

[en] A non-Gaussian ansatz for the ground-state wave function of the one-dimensional anharmonic oscillator, which takes, ab initio, into account the anharmonic effects for large x, is proposed. By minimizing the variational parameters, one obtains excellent egreement with the exact eigenvalue for 0.1 < λ < 1000. The approach is successfully applied to the first excited state