Generalized Numerical Radius And Unitary p-Dilation

In this paper, we,study an operator A on a Hilbert space H which satisfies one of the following inequalities For some ,\ with O ::; ,\ ::; 1 l(Ay, y)I ::; AIIYll2 + (1 - ,\)IIAYll2 (y EH) or AIIAYll2 + (1 - ,\)l(Ay, y)I ::; IIYll2 (y EH). These two inequalities can be regarded as special cases of generalized numerical ranges. If A has a p-dilation with p > 0, then it satisfies one of them. We show that the operator radii wp(A) of A are calculated using l(Ay,y)I and IIAYII- Several applications are given

The four-loop beta-function in Quantum Chromodynamics

We present the analytical calculation of the four-loop QCD beta-function within the minimal subtraction scheme.Comment: 9 pages, Latex, 1 figure, uses axodraw.st

Low-momentum Hyperon-Nucleon Interactions

We present a first exploratory study for hyperon-nucleon interactions using renormalization group techniques. The effective two-body low-momentum potential V_low-k is obtained by integrating out the high-momentum components from realistic Nijmegen YN potentials. A T-matrix equivalence approach is employed, so that the low-energy phase shifts are reproduced by V_low-k up to a momentum scale Lambda ~ 500 MeV. Although the various bare Nijmegen models differ somewhat from each other, the corresponding V_low-k interactions show convergence in some channels, suggesting a possible unique YN interaction at low momenta.Comment: 4 pages, 6 figure

Magnetic Monopoles As a New Solution to Strong CP Problem

A non-perturbative solution to strong CP problem is proposed. It is shown that the gauge orbit space with gauge potentials and gauge tranformations restricted on the space boundary in non-abelian gauge theories with a $\theta$ term has a magnetic monopole structure if there is a magnetic monopole in the ordinary space. The Dirac's quantization condition in the corresponding quantum theories ensures that the vacuum angle $\theta$ in the gauge theories must be quantized. The quantization rule is derived as $\theta=2\pi/n~(n\neq 0)$ with n being the topological charge of the magnetic monopole. Therefore, we conclude that the strong CP problem is automatically solved non-perturbatively with the existence of a magnetic monopole of charge $\pm 1$ with $\theta=\pm 2\pi$. This is also true when the total magnetic charge of monopoles are very large ($|n|\geq 10^92\pi$) if it is consistent with the abundance of magnetic monopoles. This implies that the fact that the strong CP violation can be only so small or vanishing may be a signal for the existence of magnetic monopoles.Comment: LBL-32491, June, 199