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/NbarN_to_NbarDelta [ Modules ]

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NAME

module NbarN_to_NbarDelta

PURPOSE

Includes the Nbar N <-> Nbar Delta cross sections according to the one-pion exchange model. NOTES: This module has a similar structure as the module dimi. AUTHOR: Alexei Larionov, 04.2008

NbarN_to_NbarDelta/initNbarN_to_NbarDelta [ Namelists ]

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NAME

NAMELIST initNbarN_to_NbarDelta Includes the input variables:

NbarN_to_NbarDelta/delta_mass [ Global module-variables ]

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SOURCE

  real, save :: delta_mass=0.01

PURPOSE

NbarN_to_NbarDelta/maxPoints_mass [ Global module-variables ]

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SOURCE

  integer, save :: maxPoints_mass=150

PURPOSE

  • number of the grid points on the delta mass

NbarN_to_NbarDelta/delta_srts [ Global module-variables ]

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SOURCE

  real, save :: delta_srts=0.01

PURPOSE

  • grid step on an invariant energy (GeV)

NbarN_to_NbarDelta/maxPoints_srts [ Global module-variables ]

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SOURCE

  integer, save :: maxPoints_srts=100

PURPOSE

  • number of the grid points on the invariant energy

NbarN_to_NbarDelta/init [ Subroutines ]

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NAME

subroutine init

PURPOSE

Reads data out of namelist 'initNbarN_to_NbarDelta'

NbarN_to_NbarDelta/massNbarN_NbarDelta [ Subroutines ]

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NAME

subroutine massNbarN_NbarDelta(srts,massDelta)

PURPOSE

Evaluates masses in Nbar N -> Nbar Delta process using NbarN_to_NbarDelta_dm This is done by a Monte-Carlo process utilizing dsigma/dm.

NOTES

NbarN_to_NbarDelta/NbarN_to_NbarDelta_Integrated [ Subroutines ]

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NAME

subroutine NbarN_to_NbarDelta_Integrated(dsdm_Integrated,srts)

PURPOSE

Returns the cross section for pbar n --> nbar delta^- scattering, integrated over the Delta mass.

NbarN_to_NbarDelta/NbarDelta_to_NbarN [ Subroutines ]

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NAME

subroutine NbarDelta_to_NbarN(sigma,srts,mdel)

PURPOSE

Returns the cross section for nbar delta^- --> pbar n scattering.

NbarN_to_NbarDelta/NbarN_to_NbarDelta_dm [ Subroutines ]

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NAME

subroutine NbarN_to_NbarDelta_dm(dsdm,dsdm_Integrated,sigma,srts,mdel)

PURPOSE

this subroutine calculates the cross sections for pbar n <--> nbar delta^- Stores cross sections at first call to a field and then it only returns those field values.

INPUTS

real srts =sqrt(s) in the process real mdel= mass of delta

RESULT

real :: sigma= total cross section (for reaction with incoming delta) real :: dsdm= mass differential cross section as function of mdel and srts 

               (for reaction with outgoing delta)

real :: dsdm_Integrated= mass differential cross section integrated over mass as function 

                          of srts (for reaction with outgoing delta)

NOTES

Actual cross section is computed by subroutine calculate below.

NbarN_to_NbarDelta/calculate [ Subroutines ]

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NAME

subroutine calculate(dsdm,sigma,srts,mdel)

PURPOSE

Calculate the cross sections for pbar n <--> nbar delta^-

INPUTS

real srts =sqrt(s) in the process real mdel= mass of delta

RESULT

real :: sigma= total cross section (for reaction with incoming delta) real :: dsdm= mass differential cross section as function of mdel and srts 

               (for reaction with outgoing delta)

NbarN_to_NbarDelta/calculate1 [ Subroutines ]

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NAME

subroutine calculate1(s,t,dsigdt,mass_min,mass_max)

PURPOSE

Compute d sigma(pbar_1 n_2 -> nbar_3 delta_4^-) / d t (mb/GeV^2) integrated over mass of delta.

INPUTS

  • s=(p1+p2)^2
  • t=(p1-p3)^2=(p4-p2)^2 --- Mandelstam variables (GeV^2)

RESULT

  • dsigdt = d sigma(pbar_1 n_2 -> nbar_3 delta_4^-)
  • mass_min,mass_max --- delta mass integration limits (GeV)

NbarN_to_NbarDelta/mNbarN_to_NbarD2 [ Subroutines ]

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NAME

real function mNbarN_to_NbarD2 (t, m_1, m_2, m_3, m_4)

PURPOSE

Matrix element squared and averaged over initial and summed over final spins for pbar_1 n_2 -> nbar_3 delta_4^- within OPEM with effective nucleon and delta masses.

INPUTS

  • t=(p1-p3)^2 -- Mandelstam variable (GeV^2)
  • m_1,m_2,m_3,m_4 -- effective masses of particles (GeV)