### TABLE OF CONTENTS

- 1. /shadowing
- 1.1. shadowing/AeffCalc
- 1.2. shadowing/pathint
- 1.2.1. pathint/inipath

## /shadowing [ Modules ]

NAME

module **shadowing**

PURPOSE

This module provides the calculation of **shadowing** for
the vector meson components of a (high energetic) virtual photon:
The couplings are rescaled...

(cf. Th.Falter, PhD thesis)

## shadowing/AeffCalc [ Subroutines ]

[ Top ] [ shadowing ] [ Subroutines ]

NAME

subroutine **AeffCalc**(targetNuc,position,egamma,qsq2,shadfac)

PURPOSE

calculate shadowing factor R_V for vector meson components:

e^2/g_V^2 -> e^2/g_V^2* R_V

INPUTS

- type(tNucleus) :: targetNuc -- nucleus to consider
- real,dimension(1:3) :: position -- spatial coordinate
- real :: egamma -- energy of photon (=nu)
- real :: qsqs2 -- transfered momentum (=Q2)

OUTPUT

- real,dimension(4) :: shadfac -- the shadowing factors for rho0, omega, phi, J/psi

NOTES

- cf. PyVP[ScaleVMD]: Pythia stores the inverse of the couplings, therefore f_V^2/4pi -> f_V^2/4pi / shadfac
- cf. Th.Falter, PhD thesis, p.88ff, p117ff
- the underlying assumptions seem not to hold for small A (i.e. He): assumption (5.13) is not very important; assumption (5.11) not tested!

## shadowing/pathint [ Functions ]

[ Top ] [ shadowing ] [ Functions ]

NAME

real function **pathint**(targetNuc,r,cost,zprime)

PURPOSE

calculates \int_{z'}^z\rho(\vec b,z'')dz'' with z=r*cos(\theta)

INPUTS

OUTPUT

- function value -- as given

## pathint/inipath [ Subroutines ]

[ Top ] [ pathint ] [ Subroutines ]

NAME

subroutine **inipath**

PURPOSE

Initialise pathint

NOTES