Light Front Cloudy Bag Model

Gerald A. Miller

The light front version of the cloudy bag model is now under construction. The model consists of a relativistic system of three bound quarks interacting with a pion cloud. Light front dynamics is used so that the boosts can be treated as kinematic. The quark aspects of the model are given at

This model can not account for the neutron electromagnetic form factors using only quarks. The light front cloudy bag model is defined by including the effects of a pion cloud along with the quarks. As in the original cloudy bag model, the pion effects are a perturbative correction. References to the original cloudy bag model are given at
The present work can be thought of as a relativistic version of the the original cloudy bag model. The photon can interact with the bare nucleon, or a pion in flight, or a nucleon while there is a pion in flight. I have not yet written up this work, but I want to make the numerical results available now. Before listing the figures, let me explain the parameters of the model. The original Schlumpf model has three parameters, a quark mass, a paramter to determine the average momentum of a quark and another parameter to determine the high momentum tail of the nucleon wave function. These were chosen to reproduce the nucleon magnetic moments, the proton charge radius, the proton GM at high momentum transfer, and other observables. Including the effects of the pion cloud allows us to choose different parameters than Schlumpf and still reproduce the same quantities. There is also one more parameter needed to describe the pion-nucleon form factor. The figures shown represent a best fit, obtained using reaonable values of the four parameters, to the four nucleon electromagnetic form factors. The different curves shown in the figures represent the results for different parameter sets. These figures are the basis for a 2002 paper LFCBM The resulting model wave functions reveal interesting features regarding the shape of the nucleon. It can be shaped like a peanut, sausage, bagel or pretzel. See shapes for more details.