Shadow poles in a coupled-channel problem calculated with Berggren basis

In coupled-channel models the poles of the scattering S-matrix are located on different Riemann sheets. Physical observables are affected mainly by poles closest to the physical region but sometimes shadow poles have considerable effect, too. The purpose of this paper is to show that in coupled-channel problem all poles of the S-matrix can be calculated with properly constructed complex-energy basis. The Berggren basis is used for expanding the coupled-channel solutions. The location of the poles of the S-matrix were calculated and compared with an exactly solvable coupled-channel problem: the one with the Cox potential. We show that with appropriately chosen Berggren basis poles of the S-matrix including the shadow ones can be determined.Comment: 11 pages, 4 figures, 59 reference

Effects of Backpack Load and Trekking Poles on Energy Expenditure During Field Track Walking

This study evaluates the effects of the use of backpack load and trekking poles on feld track walking energy expenditure. Twenty male volunteer pole walkers (age: 22.70 ± 2.89 years; body mass: 77.90 ± 11.19 kg; height: 1.77 ± 0.06 m; percentage of body fat: 14.6 ± 6.0 %) walked at a self-selected pace on a pedestrian feld track over a period of more than six months. Each subject was examined at random based on four walking conditions: non-poles and non-load, with poles and non-load, nonpoles and with load, with poles and with load. Heart rate, oxygen uptake and energy expenditure were continuously recorded by a portable telemetric system. Non-load walking speed was lower during walking with poles when compared with no poles (p ≤ 0.05). Oxygen uptake, energy expenditure and heart rate varied signifcantly across different conditions. Our results suggest that the use of trekking poles does not influence energy expenditure when walking without an additional load, but it can have an effect during backpack load walking. Moreover, our results indicate that the use of trekking poles may not be helpful to lower the exertion perceived by the subjects when walking with an additional load.info:eu-repo/semantics/publishedVersio

Poles apart

Economics

Resummation of classical and semiclassical periodic orbit formulas

The convergence properties of cycle expanded periodic orbit expressions for the spectra of classical and semiclassical time evolution operators have been studied for the open three disk billiard. We present evidence that both the classical and the semiclassical Selberg zeta function have poles. Applying a Pad\'{e} approximation on the expansions of the full Euler products, as well as on the individual dynamical zeta functions in the products, we calculate the leading poles and the zeros of the improved expansions with the first few poles removed. The removal of poles tends to change the simple linear exponential convergence of the Selberg zeta functions to an $\exp\{-n^{3/2}\}$ decay in the classical case and to an $\exp\{-n^2\}$ decay in the semiclassical case. The leading poles of the $j$th dynamical zeta function are found to equal the leading zeros of the $j+1$th one: However, in contrast to the zeros, which are all simple, the poles seem without exception to be {\em double}\/. The poles are therefore in general {\em not}\/ completely cancelled by zeros, which has earlier been suggested. The only complete cancellations occur in the classical Selberg zeta function between the poles (double) of the first and the zeros (squared) of the second dynamical zeta function. Furthermore, we find strong indications that poles are responsible for the presence of spurious zeros in periodic orbit quantized spectra and that these spectra can be greatly improved by removing the leading poles, e.g.\ by using the Pad\'{e} technique.Comment: CYCLER Paper 93mar00

Parameterization dependence of T matrix poles and eigenphases from a fit to piN elastic scattering data

We compare fits to piN elastic scattering data, based on a Chew-Mandelstam K-matrix formalism. Resonances, characterized by T-matrix poles, are compared in fits generated with and without explicit Chew-Mandelstam K-matrix poles. Diagonalization of the S matrix yields the eigenphase representation. While the eigenphases can vary significantly for the different parameterizations, the locations of most T-matrix poles are relatively stable.Comment: 6 pages, 3 figures, 1 tabl