Tuning to electron scattering data


July 22, 2005

Abstract:

In this short talk I will try to define the goals and some of the questions in our work tuning NEUGEN3/GENIE to electron scattering data in the resonance region.

At present we are evaluating three methods for tuning the models to electron data. For all expressions that follow most terms are a function of the kinematic variables at the point at which the cross section is being evaluated.

$${\frac{d\sigma}{d\theta dE'}} = {\frac{d\sigma}{d\theta dE'}}^{RES} + {\frac{d\sigma}{d\theta dE'}}^{DIS}$$ (1)

$${\frac{d\sigma}{d\theta dE'}}^{RES} = \sum_{i=1}^{17} {\frac{d\sigma}{d\theta dE'}}^{RS}_i \Theta (Wcut - W)$$ (2)

where the summation is over the 17 resonances in the Rein-Seghal model.

and in version 1:

$${\frac{d\sigma}{d\theta dE'}}^{DIS} = {\frac{d\sigma}{d\thet... ...\theta dE'}}^{DIS-OLD}_j \Theta (Wcut-W) \sum_{j=1}^{\inf} f_j$$ (3)

the index j refers to the multiplicity and the factor $f_j$ gives the fractional contribution of the DIS cross section at this kinematic point to the total DIS cross section. These terms themselves are calculated as $f_j = r_j P_j^{KNO}$, where $r_j$ is the tunable parameter (the RSQR elements in NEUGEN), and $P_j^{KNO}$ is the probability from the KNO model that the DIS cross section produces a multiplicity j final state. These are normalized to unity.

in version 2:

$${\frac{d\sigma}{d\theta dE'}}^{DIS} = {\frac{d\sigma}{d\thet... ...\frac{d\sigma}{d\theta dE'}}^{DIS-BY} \Theta (Wcut-W) * \alpha$$ (4)

where $\alpha$ is the ``RESDCF'' parameter in NEUGEN.

and in version 3:

$${\frac{d\sigma}{d\theta dE'}}^{DIS} = {\frac{d\sigma}{d\thet... ...}{d\theta dE'}}^{DIS-BY} \Theta (Wcut-W) \sum_{j=1}^{\inf} f_j$$ (5)

Best REsults so far?