A radiative gluon or photon is a particle that carries the strong nuclear or electromagnetic force, respectively. These particles are responsible for mediating interactions between other particles, such as quarks and electrons.
Tree level refers to the simplest or most basic calculation of the interactions involving radiative gluons or photons. This calculation does not take into account any higher order corrections or more complex interactions.
Higher corrections refer to more complex calculations that take into account additional factors or interactions, such as loop diagrams or virtual particles, that were not included in the tree level calculation. These corrections can improve the accuracy of predictions and calculations.
Higher corrections are important because they can significantly impact the accuracy and precision of predictions for particle interactions. Including these corrections can improve our understanding of the underlying physics and help us make more accurate predictions and interpretations of experimental data.
Higher corrections are calculated using more advanced mathematical techniques, such as perturbation theory, which allows us to account for the interactions of virtual particles and other factors that were not included in the tree level calculation. These techniques involve solving complex equations and performing calculations to determine the effects of these higher order corrections.