TABLE OF CONTENTS
- 1. /ParamEP
- 1.1. ParamEP/useParam
- 1.2. ParamEP/initInput
- 1.3. ParamEP/paramEP
- 1.4. ParamEP/CalcParamEP
- 1.5. ParamEP/CalcParamEP_Brasse
- 1.6. ParamEP/Flux_Bosted
- 1.7. ParamEP/CalcParamEP_Bosted
- 1.8. ParamEP/CalcParamEP_ALLM
- 1.9. ParamEP/CalcParamEP_ALLM97
- 1.10. ParamEP/CalcParamEP_R1990
/ParamEP [ Modules ]
NAME
module ParamEP
PURPOSE
This module defines routines which return parametrizations of the electron proton cross section.
INPUTS
The Namelist "paramEP" in the Jobcard.
NOTES
At the moment we include the parametrizations:
- F. W. Brasse et al., ``Parametrization Of The Q**2 Dependence Of Virtual Gamma P Total Cross-Sections In The Resonance Region,'' Nucl. Phys. B {\bf 110}, 413 (1976).
- M. E. Christy and P. E. Bosted, ``Empirical Fit to Precision Inclusive Electron-Proton Cross Sections in the Resonance Region,'' Phys.Rev. C81 (2010) 055213
In addition, we also include here the the ALLM parametrization for high W values (W>1.75 GeV):
- H. Abramowicz, E. M. Levin, A. Levy and U. Maor, ``A Parametrization of sigma-T (gamma* p) above the resonance region Q**2 >= 0,'' Phys. Lett. B {\bf 269} (1991) 465.
Here the authors claim, that this provides a smooth continuation of the parametrization by Brasse et al.. The newest version is also implemented:
- H. Abramowicz and A. Levy, ``The ALLM parameterization of sigma(tot)(gamma* p): An update,'' arXiv:hep-ph/9712415.
We also provide the parametrizations for R=sigma_L/sigma_T by:
- L.W.Whitlow et al., ``A Precise extraction of R = sigma-L / sigma-T from a global analysis of the SLAC deep inelastic e p and e d scattering cross-sections,'' Phys.Lett.B250:193-198,1990.
- V.Tvaskis et al., ``Longitudinal-transverse separations of structure functions at low Q**2 for hydrogen and deuterium,'' Phys.Rev.Lett.98:142301,2007. PhD thesis, http://www1.jlab.org/Ul/Publications/documents/thesis_V_Tvaskis.pdf
ParamEP/useParam [ Global module-variables ]
[ Top ] [ ParamEP ] [ Global module-variables ]
SOURCE
integer, save :: useParam = 2
PURPOSE
select, which parametrization to use:
- 1: Brasse
- 2: Bosted
ParamEP/initInput [ Subroutines ]
[ Top ] [ ParamEP ] [ Subroutines ]
NAME
subroutine initInput
PURPOSE
Reads in job card, checks the settings of the input parameters and also reads the data arrays
ParamEP/paramEP [ Namelists ]
[ Top ] [ ParamEP ] [ Namelists ]
NAME
NAMELIST /paramEP/
PURPOSE
Namelist for module ParamEP includes:
ParamEP/CalcParamEP [ Subroutines ]
[ Top ] [ ParamEP ] [ Subroutines ]
NAME
subroutine CalcParamEP(W,Q2,eps, XS, XSerr)
PURPOSE
Calculate the XS (and its error) according the selected Parametrization
INPUTS
- real :: W -- incoming photon (W)
- real :: Q2 -- incoming photon (Q^2)
- real :: eps -- incoming photon (epsilon)
OUTPUT
- real :: XS -- cross section
- real,OPTIONAL :: XSerr -- error
ParamEP/CalcParamEP_Brasse [ Subroutines ]
[ Top ] [ ParamEP ] [ Subroutines ]
NAME
subroutine CalcParamEP_Brasse(W,Q2,eps, XS, XSerr)
PURPOSE
Calculate the XS (and its error) according the Brasse Parametrization:
- F.~W.~Brasse et al., ``Parametrization Of The Q**2 Dependence Of Virtual Gamma P Total Cross-Sections In The Resonance Region,'' Nucl. Phys. B {\bf 110}, 413 (1976)
INPUTS
- real :: W -- incoming photon (W)
- real :: Q2 -- incoming photon (Q^2)
- real :: eps -- incoming photon (epsilon)
OUTPUT
- real :: XS -- cross section
- real,OPTIONAL :: XSerr -- error
NOTES
The range of validity is:
The returned cross section is
\sigma^* = \sigma_T+\epsilon\sigma_L
= \frac{1}{\Gamma} \frac{d\sigma}{dE' d\Omega}
Unfortunately, the authors do not giv a definition of Gamma.
An interpolation between different W bins would smoothen the results.
ParamEP/Flux_Bosted [ Functions ]
[ Top ] [ ParamEP ] [ Functions ]
NAME
real function Flux_Bosted(W,Q2,eps)
PURPOSE
return the value of equation (4) in Phys.Rev. C81 (2010) 055213
Multiplying this return value with the value given by CalcParamEP_Bosted() yields
\frac{d\sigma}{dE' d\Omega}
INPUTS
- real :: W -- incoming photon (W)
- real :: Q2 -- incoming photon (Q^2)
- real :: eps -- incoming photon (epsilon)
OUTPUT
- function value -- flux in 1/GeV
ParamEP/CalcParamEP_Bosted [ Subroutines ]
[ Top ] [ ParamEP ] [ Subroutines ]
NAME
subroutine CalcParamEP_Bosted(W,Q2,eps, XS)
PURPOSE
Calculate the XS according the Bosted Parametrization:
- M. E. Christy and P. E. Bosted, ``Empirical Fit to Precision Inclusive Electron-Proton Cross Sections in the Resonance Region,'' Phys.Rev. C81 (2010) 055213
INPUTS
- real :: W -- incoming photon (W)
- real :: Q2 -- incoming photon (Q^2)
- real :: eps -- incoming photon (epsilon)
OUTPUT
- real :: XS -- cross section
NOTES
This is a wrapper function around code provided by P.Bosted.
The returned cross section is
\sigma^* = \sigma_T+\epsilon\sigma_L
= \frac{1}{\Gamma} \frac{d\sigma}{dE' d\Omega}
with
\Gamma = \frac{\alpha E' (W^2-M^2)}{(2\pi)^2 Q^2 M E (1-\epsilon)}
The returned values are given in mub.
The range of validity is:
ParamEP/CalcParamEP_ALLM [ Subroutines ]
[ Top ] [ ParamEP ] [ Subroutines ]
NAME
subroutine CalcParamEP_ALLM(W,Q2, XS)
PURPOSE
Calculate the XS according the ALLM Parametrization:
- H. Abramowicz, E. M. Levin, A. Levy and U. Maor, ``A Parametrization of sigma-T (gamma* p) above the resonance region Q**2 >= 0,'' Phys. Lett. B {\bf 269} (1991) 465.
INPUTS
OUTPUT
- real :: XS -- cross section (in mub)
NOTES
The range of validity is:
This routine returns sigma_tot == sigma_L+sigma_T
ParamEP/CalcParamEP_ALLM97 [ Subroutines ]
[ Top ] [ ParamEP ] [ Subroutines ]
NAME
subroutine CalcParamEP_ALLM97(W,Q2, XS)
PURPOSE
Calculate the XS according the ALLM97 Parametrization:
- H. Abramowicz and A. Levy, ``The ALLM parameterization of sigma(tot)(gamma* p): An update,'' arXiv:hep-ph/9712415.
INPUTS
OUTPUT
- real :: XS -- cross section (in mub)
NOTES
The range of validity is:
This routine returns sigma_tot == sigma_L+sigma_T
ParamEP/CalcParamEP_R1990 [ Subroutines ]
[ Top ] [ ParamEP ] [ Subroutines ]
NAME
subroutine CalcParamEP_R1990(W,Q2, R)
PURPOSE
Calculate R=sigma_L/sigma_T according:
- L.W.Whitlow et al., ``A Precise extraction of R = sigma-L / sigma-T from a global analysis of the SLAC deep inelastic e p and e d scattering cross-sections,'' Phys.Lett.B250:193-198,1990.
NOTES
We corrected a typo in the constant b1 from the paper.