GRV98 model of Differential Cross-section for neutrino scattering

Description

GRV98 model for the differential cross-section is obtained by the function sigbpy(iSV,iRC,iHC,Vfac,X,Y,E,POL,*p), where

E: Neutrino energy, POL=1 for neutrino, POL=-1.0 for anti-neutrino
iSV (Scaling variable)        : 0=old X-variable, 1=modified X-variable(X_omega)
iRC (Radiative correction)    : 0=turn off, 1=turn on
iHC (Heavy target correction) : 0=not corrected, 1=corrected
Vfac=0 for iso-scalar target, Vfac=0.0567 for non iso-scalar target

Radiative correction is obtained by calling barccmu(POL,E,X,Y). This is the charged current one-loop radiative correction from DIZET, assuming Z Mass= 91.1870, Top Mass=175.0000, Higgs Mass=150.0000, W mass=80.3812, sin2thW=.2230, with u,d,s,c masses= .0415, .0415, .1500, 1.5000.
Heavy target correction was introduced to correct the F2 calculation of Iron from the F2 calculation of Deutereum. Thus the correction is F2(iso-scalar-iron)/F2(deutron). The function itself is
```
anucl(x)=1.0963 - 0.36427*x - 0.27805*exp(-21.936*x)+2.7715*pow(x,14.417);
```
See B. Seligman parameterization.
A,B,C[1,2][vec][val,sea][u,d], fPDF were taken from the fit version 4 (v4).

The version 4 (v4) fit parameters are

A     = 0.541441+-0.011286
B     = 0.305889+-0.005147
C1vvu = 0.286222+-0.007659
C1vvd = 0.215013+-0.107655
C2vvu = 0.186127+-0.003959
C2vvd = 0.270253+-0.136246
C1vsu = 0.362798+-0.002928
C1vsd = 0.617987+-0.027510
fPDF  = 0.989831+-0.002608

For the axial parameters, we set

C1avu=C1vvu
C1avd=C1vvd
C2avu=C2vvu
C2avd=C2vvd
C1asu=C1vsu
C1asd=C1vsd
C2asu=0
C2asd=0

sigbpy calls sigmcq, which is the main calculation module. (Click here to see the code).
sigmcq further calls grv98_mod, which is modified GRV98 PDF modeli. Many thanks to Un-Ki for the original FORTRAN source.(Click here to see the code).

20040314-Inkyu.Park@bnl.gov