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## /mesonWidthVacuum [ Modules ]

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NAME

module mesonWidthVacuum

NOTES

Module which calculates the partial and full widths of the meson resonances in dependence of their mass. Their pole mass is given by their mass in 'particleProperties' and the widths at this pole mass as well. Everything corresponds to the vacuum situation. The resulting width is therefore always the width in vacuum! As mass of the resonance we use the four-vector definition: p_mu p^mu= mass**2 Prescription according to Manley et al. Phys. Rev. D45 (1992) 4002. The In-Width is assumed to be the outwidth.

## mesonWidthVacuum/omega_width [ Global module-variables ]

SOURCE

```  integer, save :: omega_width = 1
```

PURPOSE

Select a parametrization for the omega vacuum width:

• 1 = GiBUU default (a la Manley)
• 2 = Muehlich

[ Top ] [ mesonWidthVacuum ] [ Subroutines ]

NAME

PURPOSE

Reads input in jobcard out of namelist "MesonWidthVacuum".

## mesonWidthVacuum/MesonWidthVacuum [ Namelists ]

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NAME

NAMELIST /MesonWidthVacuum/

PURPOSE

Includes the input switches:

## mesonWidthVacuum/vacuumWidth [ Subroutines ]

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NAME

function vacuumWidth (mass, partID, ratio) result (gammaTotal)

NOTES

This routine calculates the total vacuum decay width of a mesonic resonance, i.e. the sum of all partial decay widths, and the branching ratios for each channel as a function of the offshell mass (m^2 = p_mu p^mu). Parameters taken from Manley et al. Phys. Rev. D45 (1992) 4002 and PDG. The mass dependence of the resonances is treated according to Manley.

INPUTS

• real, intent(in) :: mass -- offshell mass of Resonance in GeV
• integer, intent(in) :: partID -- ID of resonance

OUTPUT

• real, dimension(1:nDecays), optional :: ratio -- branching ratio, i.e. partial width / full width for all decay channels of the mesons
• real :: gammaTotal -- full width (mass) in GeV at the mass of "mass"

## mesonWidthVacuum/stableFinalState [ Functions ]

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NAME

real function stableFinalState(mass, poleMass, mass1, mass2, L, partialWidth_pole)

NOTES

Resonance decays into stable particles. Decay only allowed if:

• (1) decay width > widthCutOff and ...
• (2) mass of resonance > Sum of masses of decay products

Manley et al. Phys. Rev. D45 (1992) 4002.

OUTPUT

• returns the partial width for the specified channel at the given mass

## mesonWidthVacuum/semistableFinalState [ Functions ]

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NAME

real function semistableFinalState(mass,polemass,ID,L,partialWidth_pole)

NOTES

Resonance decays into one stable and one unstable particle. Calculates the partial width dependend on mass of a meson resonance decaying into one stable and one unstable decay product. According to Manley and Effenberger' Dr. Thesis equation 2.76.

OUTPUT

• returns the partial width for the specified channel at the given mass

## mesonWidthVacuum/rho_AB_Integrand [ Functions ]

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NAME

real function rho_AB_Integrand (mu)

NOTES

This is the integrand of rho_ab(mu) in Effenbergers Dr.-Thesis, page 27, formula 2.76. Only in the case of only one unstable particle, currently only used for decays into "rho pi"!

## mesonWidthVacuum/omegaVacuum [ Functions ]

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NAME

real function omegaVacuum (s, r)

INPUTS

real, intent(in) :: s ! m^2 of the omega meson integer, intent(in) :: r ! select channel

NOTES

Returns the partial omega widths in the vacuum:

• r=0 : total width
• r=1 : omega -> pi pi
• r=2 : omega -> pi0 gamma
• r=3 : omega -> rho pi (as an approximation for omega -> 3pi)

See: Pascal Muehlich, PhD thesis, chapter 8.2.1.

## mesonWidthVacuum/dileptonWidth [ Subroutines ]

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NAME

real function dileptonWidth (ID, mass)

NOTES

Calculate the dilepton decay width of the vector mesons rho, omega and phi (V -> e+e-) according to strict vector-meson dominance (VMD). References:

```  * http://arxiv.org/abs/1203.3557v2, eq. (11) and table 3.
* Effenberger PhD, chapter 2.7.1
```

INPUTS

• integer, intent(in) :: ID --- vector meson ID (should be 103, 105 or 107)
• real, intent(in) :: mass --- vector meson mass in GeV

OUTPUT