Renormalized Path Integral for the Two-Dimensional Delta-Function Interaction

A path-integral approach for delta-function potentials is presented. Particular attention is paid to the two-dimensional case, which illustrates the realization of a quantum anomaly for a scale invariant problem in quantum mechanics. Our treatment is based on an infinite summation of perturbation theory that captures the nonperturbative nature of the delta-function bound state. The well-known singular character of the two-dimensional delta-function potential is dealt with by considering the renormalized path integral resulting from a variety of schemes: dimensional, momentum-cutoff, and real-space regularization. Moreover, compatibility of the bound-state and scattering sectors is shown.Comment: 26 pages. The paper was significantly expanded and numerous equations were added for the sake of clarity; the main results and conclusions are unchange

Standard Model with Partial Gauge Invariance

We argue that an exact gauge invariance may disable some generic features of the Standard Model which could otherwise manifest themselves at high energies. One of them might be related to the spontaneous Lorentz invariance violation (SLIV) which could provide an alternative dynamical approach to QED and Yang-Mills theories with photon and non-Abelian gauge fields appearing as massless Nambu-Goldstone bosons. To see some key features of the new physics expected we propose partial rather than exact gauge invariance in an extended SM framework. This principle applied, in some minimal form, to the weak hypercharge gauge field B_{mu} and its interactions leads to SLIV with B field components appearing as the massless Nambu-Goldstone modes, and provides a number of distinctive Lorentz beaking effects. Being naturally suppressed at low energies they may become detectable in high energy physics and astrophysics. Some of the most interesting SLIV processes are considered in significant detail.Comment: 32 pages, extended version, to appear in Eur.Phys.J.

Achados ultrassonográficos nos testículos e epidídimos de carneiros deslanados jovens e clinicamente sadios

Objetivou-se descrever os achados ultrassonográficos nos testículos e epidídimos de carneiros jovens. Análises de desenvolvimento ponderal, mensurações das características biométricas testiculares e exames ultrassonográficos foram realizados dos 140 aos 280 dias de idade, a cada 28 dias. O parênquima testicular apresentou ecogenicidade homogênea (baixa a moderada) que aumentou com a idade. A ecogenicidade e a espessura do mediastino aumentaram com a idade, e a cauda do epidídimo apresentou aspecto hipoecoico em relação ao parênquima testicular. Foram observadas calcificações de grau leve nos testículos de cinco cordeiros. Conclui-se que o exame ultrassonográfico contribui para o monitoramento dos testículos e epidídimos de carneiros