3,735 research outputs found
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
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 in the gauge theories must be
quantized. The quantization rule is derived as 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 with . This
is also true when the total magnetic charge of monopoles are very large
() 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
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