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/XsectionRatios [ Modules ]

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NAME

module XsectionRatios

NOTES

Computes and stores the ratios of the in-medium and vacuum BB -> BB + mesons cross sections (see M. Wagner et al., PRC 71, 034910 (2005).


XsectionRatios/flagScreen [ Global module-variables ]

[ Top ] [ XsectionRatios ] [ Global module-variables ]

SOURCE

  logical, save :: flagScreen = .false.

PURPOSE

  • If .true. -- in-medium screening is applied to the input cross section.
  • If .false. -- no cross section modification.


XsectionRatios/ScreenMode [ Global module-variables ]

[ Top ] [ XsectionRatios ] [ Global module-variables ]

SOURCE

  integer, save :: ScreenMode = 1

PURPOSE

possible values:

  • 1: in-medium screening of NN total cross section according to Li and Machleidt, PRC 48 (1993) 1702 and PRC 49 (1994) 566
  • 2: in-medium screening of BB total cross section according to P. Daniewlewicz, NPA 673, 375 (2000); Acta. Phys. Pol. B 33, 45 (2002)

NOTES

relevant when flagScreen = .true.


XsectionRatios/flagInMedium [ Global module-variables ]

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SOURCE

  logical, save :: flagInMedium = .false.

PURPOSE

  • If .true. -- In-medium ratios are used to decide whether an event is accepted or not.
  • If .false. -- The event is always accepted


XsectionRatios/InMediumMode [ Global module-variables ]

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SOURCE

  integer, save :: InMediumMode = 2

PURPOSE

possible values:

  • 1: all events of the type BB -> BB (+ mesons) are subject to in-medium reduction following Eqs.(194),(195) of GiBUU review paper [currently works in RMF mode only]
  • 2: NN -> NN elastic scattering events are modified according to Li and Machleidt all other BB -> BB (+ mesons events are subject to in-medium reduction according to Eq. (33) from T. Song, C.M. Ko, PRC 91, 014901 (2015) [works in all modes (Skyrme, RMF, cascade)]

NOTES

relevant when flagInMedium = .true.


XsectionRatios/flagVacEL [ Global module-variables ]

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SOURCE

  logical, save ::  flagVacEL = .false.

PURPOSE

  • If .true. -- no in-medium modification for NN -> NN elastic

NOTES

relevant for flagInMedium = .true.


XsectionRatios/flagVacHRES [ Global module-variables ]

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SOURCE

  logical, save ::  flagVacHRES = .false.

PURPOSE

  • If .true. -- no in-medium modification for BB <-> BB with at least one participating resonance higher than P33(1232) or with more than one P33(1232)

NOTES

relevant for flagInMedium = .true.


XsectionRatios/flagVacMesProd [ Global module-variables ]

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SOURCE

  logical, save :: flagVacMesProd = .false.

PURPOSE

  • If .true. -- no in-medium modification for BB -> BB + meson(s)

NOTES

relevant for flagInMedium = .true.


XsectionRatios/alpha [ Global module-variables ]

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SOURCE

  real, save :: alpha = 1.2

PURPOSE

Parameter which controls the density dependence of the NN <-> N Delta cross section via suppression factor of exp(-alpha*(rho/rho_0)**beta)

for the density dependence from: Song/Ko, arXiv:1403.7363 (InMediumMode=2)


XsectionRatios/beta [ Global module-variables ]

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SOURCE

  real, save :: beta = 1.

PURPOSE

Parameter which controls the density dependence of the NN <-> N Delta cross section via suppression factor of exp(-alpha*(rho/rho_0)**beta)

for the density dependence of the type of arXiv:2107.13384 (InMediumMode=2)


XsectionRatios/shift0 [ Global module-variables ]

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SOURCE

  real, save :: shift0 = 0.

PURPOSE

Mass shift m-m^* (GeV) for using in elementary particle collision mode.


XsectionRatios/getSigmaScreened [ Functions ]

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NAME

real function getSigmaScreened(pair,sigma,srts,mediumAtColl)

PURPOSE

Returns in-medium screened/reduced cross section (mbarn). See:

  • Li and Machleidt, PRC 48 (1993) 1702 and PRC 49 (1994) 566,
  • P. Daniewlewicz, NPA 673, 375 (2000); Acta. Phys. Pol. B 33, 45 (2002)

INPUTS

  • type(particle), dimension(1:2) :: pair -- incoming particles
  • real, intent(in) :: sigma -- not screened cross section
  • real, intent(in) :: srts -- c.m. energy
  • type(medium), intent(in) :: mediumAtColl -- medium info

NOTES

srts and mediumAtColl only needed for ScreenMode=1


XsectionRatios/getSigmaTotal [ Functions ]

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NAME

real function getSigmaTotal(pair)

PURPOSE

Returns the total in-medium cross section (mbarn).

INPUTS

  • type(particle), dimension(1:2) :: pair -- incoming particles

NOTES

The total in-medium pp cross section is used for all types of colliding baryons/antibaryons.

Returns zero if there is at least one incoming meson.


XsectionRatios/accept_event [ Functions ]

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NAME

logical function accept_event(pair,finalState)

PURPOSE

Accepts or rejects the event randomly, using the in-medium cross section ratios:

  • returns .true. --- if the event is accepted
  • returns .false. --- if the event is rejected

INPUTS

  • type(particle), dimension(1:2) :: pair -- incoming particles
  • type(particle), dimension(:) :: finalState -- outgoing particles

NOTES

the procedure is as follows: first, a particle collision is chosen with the default cross sections. Then, in a second step, the ratio of the in-medium and the vacuum cross section is calculated. If smaller than 1, then the event generated in step 1 is rejected by a Monte Carlo decision.


XsectionRatios/init [ Subroutines ]

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NAME

subroutine init

PURPOSE

Reads in input switches from namelist XsectionRatios_input.


XsectionRatios/XsectionRatios_input [ Namelists ]

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NAME

NAMELIST /XsectionRatios_input/

PURPOSE

Includes the switches:


XsectionRatios/Ratio [ Functions ]

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NAME

real function Ratio(srtsStar,mStar,mass)

PURPOSE

Compute the ratio of the in-medium and vacuum B_1 + B_2 -> B_3 + B_4 + M_5 + M_6 + M_7 + M_8 cross sections

INPUTS

  • real :: srtsStar -- c.m. energy (GeV),
  • real dimension(:) :: mStar -- Dirac masses of all particles (GeV)
  • real dimension(:) :: mass -- vacuum masses of all particles (GeV)

OUTPUT

  • real :: Ratio -- ratio of the in-medium and vacuum cross sections

NOTES

The particles 1 and 2 are incoming baryons, the particles 3 and 4 are outgoing baryons, the particles M_5, ..., M_8 are outgoing mesons. The routine will compute one of the ratios:

  • B_1 + B_2 -> B_3 + B_4,
  • B_1 + B_2 -> B_3 + B_4 + M_5,
  • ...,
  • B_1 + B_2 -> B_3 + B_4 + M_5 + ...+ M_8

depending on the the size n of the arrays mStar and mass, which must be in the interval [4:8].


XsectionRatios/Ratio_BaB [ Functions ]

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NAME

real function Ratio_BaB(pair,finalState)

PURPOSE

Compute the ratio of the in-medium and vacuum cross sections baryon + antibaryon -> mesons

INPUTS

  • type(particle), dimension(1:2) :: pair -- incoming particles
  • type(particle), dimension(:) :: finalState -- outgoing particles

OUTPUT

  • real :: Ratio_BaB -- ratio of the in-medium and vacuum cross sections

NOTES

Maximum 6 mesons can be treated (otherwice returns Ratio_BaB=1.).


XsectionRatios/RatioNNPion_NN [ Functions ]

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NAME

real function RatioNNPion_NN(nucleon1,nucleon2,pionPart)

PURPOSE

Compute the ratio of the in-medium and vacuum absorption rates N1 N2 pi --> N3 N4

INPUTS

  • type(particle), intent(in) :: nucleon1,nucleon2,pionPart

OUTPUT

  • real :: RatioNNPion_NN -- ratio of the in-medium and vacuum absorption rates