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/photonXS [ Modules ]

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NAME

module photonXS

PURPOSE

This module collects some routines for cross-section parametrizations for the photon-induced reactions (gamma+N).

photonXS/iParam [ Global module-variables ]

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SOURCE

  integer, save :: iParam = 2

PURPOSE

Switch to select the kind of parametrization for gamma N -> V N:

  • 1: "old parametrization", fit to experimental data, cf. Effenberger PhD, p.53
  • 2: Pythia, cf. Friberg/Sjöstrand hep-ph/0007314
  • 3: Donnachie, Landshoff [citation needed]

photonXS/omega_saphir [ Global module-variables ]

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SOURCE

  logical, save :: omega_saphir = .true.

PURPOSE

If .true. an improved fit (to SAPHIR data) will be used for gamma N -> omega N. cf. "calcXS_omega_saphir"

photonXS/setIParam [ Subroutines ]

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NAME

subroutine setIParam(i,os)

PURPOSE

switching by hand between some parametrisations

INPUTS

  • integer :: i -- new value of "iParam"
  • integer, OPTIONAL :: os -- new value of "omega_saphir"

photonXS/readInput [ Subroutines ]

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NAME

subroutine readInput

PURPOSE

Reads input out of jobcard. Namelist 'photonXS'.

photonXS/photonXS [ Namelists ]

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NAME

NAMELIST photonXS

PURPOSE

Includes the parameters:

photonXS/gammaN2VN_matrix [ Subroutines ]

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NAME

subroutine gammaN2VN_matrix(srts,i,spot,matrix)

PURPOSE

Calculates squared matrix elements for gamma N -> V N with different parametrizations, cf. 'iParam'.

INPUTS

  • real, intent(in) :: srts -- SQRT(s)
  • integer, intent(in) :: i -- select vector meson V: 1=rho, 2=omega, 3=phi, 4=J/Psi
  • real, intent(in) :: spot -- scalar potential for vector meson in final state

OUTPUT

NOTES

For rho, omega and phi this routine returns matrix elements, for J/Psi it directly returns the cross section.

The used coupling constants gV are not modified due to shadowing!

photonXS/calcXS_gammaN2VN [ Subroutines ]

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NAME

subroutine calcXS_gammaN2VN(srts,media,sig,sigi)

PURPOSE

Produces cross section for 

     gamma N -> V  N

and 

    gamma N -> V pi N

INPUTS

OUTPUT

  • real, dimension(1:4) :: sig -- cross section for gamma N -> (rho,omega,phi,JPsi) N
  • real, dimension(1:4), OPTIONAL :: sigi -- cross section for gamma N -> (rho,omega,phi,JPsi) N Pion

NOTES

Returned cross sections are in microbarn.

photonXS/calcXS_gammaN2VDelta [ Subroutines ]

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NAME

subroutine calcXS_gammaN2VDelta(srts,sigi,media)

PURPOSE

Calculates the cross section for gamma N -> V Delta, where V is a vector meson.

INPUTS

OUTPUT

  • real, dimension(1:4) :: sigi ! cross sections
  • sigi(1) -> rho Delta
  • sigi(2) -> omega Delta
  • sigi(3) -> phi Delta
  • sigi(4) -> JPsi Delta

NOTES

Units of cross sections: microbarn

photonXS/calcXS_gammaN2strange [ Subroutines ]

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NAME

subroutine calcXS_gammaN2strange(srts,sigma)

PURPOSE

Produces cross section for 

     gamma N -> Lambda K, Sigma K, N K Kbar

OUTPUT

  • real, dimension(1:3 :: sigma ! cross section
  • sigma(1) :: Lambda K
  • sigma(2) :: Sigma K
  • sigma(3) :: N K Kbar

NOTES

UNITS of cross sections????

photonXS/calcXS_omega_saphir [ Subroutines ]

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NAME

subroutine calcXS_omega_saphir(srts,cs)

PURPOSE

Calculates the cross section for gamma + N -> omega + N (fit to SAPHIR data). See P. Muehlich, diss., chapter 9.3.3. The data can be found in J.Barth, Eur. Phys. J. A18 (2003) 117-127

INPUTS

  • real,intent(in):: srts --- sqrt(s) for gamma + nucleon (in GeV)

OUTPUT

  • real,intent(out):: cs --- cross section in microbarn

NOTES

The matrix element for the process is tabulated in the file "gammaN_omegaN_ME_saphir.dat". It is computed from the (splined) SAPHIR cross sections.