Search results for "Regge theory"
showing 5 items of 5 documents
Standard and Z2-Regge theory in two dimensions
1998
Abstract We qualitatively compare two versions of quantum Regge calculus by means of Monte Carlo simulations. In Standard Regge Calculus the quadratic link lengths of the triangulation vary continuously, whereas in the Z2-Regge Model they are restricted to two possible values. The goal is to determine whether the computationally more easily accessible Z2 model retains the characteristics of standard Regge theory.
Structure of pion photoproduction amplitudes
2018
We derive and apply the finite energy sum rules to pion photoproduction. We evaluate the low energy part of the sum rules using several state-of-the-art models. We show how the differences in the low energy side of the sum rules might originate from different quantum number assignments of baryon resonances. We interpret the observed features in the low energy side of the sum rules with the expectation from Regge theory. Finally, we present a model, in terms of a Regge-pole expansion, that matches the sum rules and the high-energy observables.
New anomalous trajectory in Regge theory
1999
We show that a new Regge trajectory with \alpha_{f_1} (0) \approx 1 and slope \alpha_{f_1}'(0) \approx 0 explains the features of hadron-hadron scattering and photoproduction of the rho and phi mesons at large energy and momentum transfer. This trajectory with quantum numbers P = C = +1 and odd signature can be considered as a natural partner of the Pomeron which has even signature. The odd signature of the new exchange leads to contributions to the spin-dependent cross sections, which do not vanish at large energy. The links between the anomalous properties of this trajectory, the axial anomaly and the flavor singlet axial vector f_1 (1285) meson are discussed.
Z2-Regge versus standard Regge calculus in two dimensions
1999
We consider two versions of quantum Regge calculus: the standard Regge calculus where the quadratic link lengths of the simplicial manifold vary continuously and the ${Z}_{2}$ Regge model where they are restricted to two possible values. The goal is to determine whether the computationally more easily accessible ${Z}_{2}$ model still retains the universal characteristics of standard Regge theory in two dimensions. In order to compare observables such as the average curvature or Liouville field susceptibility, we use in both models the same functional integration measure, which is chosen to render the ${Z}_{2}$ Regge model particularly simple. Expectation values are computed numerically and …
Experimental Check of the Gerasimov-Drell-Hearn Sum Rule for H1
2004
For the first time we checked the fundamental Gerasimov-Drell-Hearn (GDH) sum rule for the proton experimentally in the photon energy range from 0.2-2.9 GeV with the tagged photon facilities at MAMI (Mainz) and ELSA (Bonn). New data of the doubly polarized total cross section difference are presented in the energy range from 1.6 to 2.9 GeV. The contribution to the GDH integral from 0.2-2.9 GeV yields [254+/-5(stat)+/-12(syst)] microb with negative contributions in the Regge regime at photon energies above 2.1 GeV. This trend supports the validity of the GDH sum rule.