Hadron form factors and large-Ncphenomenology

Pere Masjuan,Enrique Ruiz Arriola,Wojciech Broniowski

doi:10.1051/epjconf/20147304021

Abstract

The half width rule provides a way to consider 1/Nc corrections to hadronic models containing resonances. Consequences of such ideas for hadron form factors and Regge trajectories are explored, with special emphasis on the possibility to describe the spectrum of light and heavy unflavored vector mesons in a universal way.

Highlights

The rigorous quantum-mechanical definition of a resonance with given quantum numbers corresponds to a pole in the second Riemann sheet in the partial-wave amplitude of the considered scattering channel
We discus the implications of such an idea for hadron form factors and linear Regge trajectories [3,4,5,6]
The following is assumed: hadronic form factors in the spacelike region are dominated by mesonic states with the relevant quantum numbers; the high-energy behavior is given by perturbative QCD [which determines the parameter A in (1)], and the number of mesons is taken to be minimal to satisfy these conditions; errors in the meson-dominated form factors are estimated by the halfwidth rule method (HWR) by treating masses as random variables distributed with the dispersion given by the width. 1/Nc corrections are linked with phenomenological predictions at Nc = 3 through the errors provided by the HWR

Summary

Introduction

The rigorous quantum-mechanical definition of a resonance with given quantum numbers corresponds to a pole in the second Riemann sheet in the (analytically continued) partial-wave amplitude of the considered scattering channel. Our observation is that since in the large-Nc limit /M = O(Nc−1) [2], the maximum level of discrepancy in quoting resonance mass parameters M should be compatible with its own width , i.e., in the interval M ± /2, the half-width rule In this presentation, we discus the implications of such an idea for hadron form factors and linear Regge trajectories [3,4,5,6].

Hadron form factors

Linear Regge trajectories

Ground State not included n

Universal radial Regge trajectory for unflavored vector mesons