Coupled channel method for the π-4He elastic and inelastic scattering
Equations of the coupled channel method written in the momentum space are solved in the K-matrix approach. In this way we are able to consider simultaneously the elastic and inelastic pion-nuclear reactions. Calculated total elastic and total inelastic cross sections are given for several outgoing channels of the reaction4He(π−,π−)4He*. The single-charge-exchange reaction on4He is discussed.
We describe preliminary results from an effort to quantify the uncertainties in parton distribution functions and the resulting uncertainties in predicted physical quantities. The production cross section of the $W$ boson is given as a first example. Constraints due to the full data sets of the CTEQ global analysis are used in this study. Two complementary approaches, based on the Hessian and the Lagrange multiplier method respectively, are outlined. We discuss issues on obtaining meaningful uncertainty estimates that include the effect of correlated experimental systematic uncertainties and illustrate them with detailed calculations using one set of precision DIS data.