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Version: SMASH-3.1
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Version: SMASH-3.1
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Helper function that creates the oscar output with the format selected by create_oscar_output (except for dileptons and photons).
| Contents | Determines what infomration will be written to the output |
| [in] | modern_format | Use the 1999 or 2013 format |
| [in] | path | Path of output |
| [in] | out_par | Output parameters that hold the output configuration |
| [in] | name | (File)name of ouput |
Within Collision_Term section, the String_Parameters section can be used to modify a series of parameters which affect the string fragmentation.
Diquark_Supp — double, optional, default = 0.036
Diquark suppression factor. Defines the probability to produce a diquark antidiquark pair relative to producing a qurk antiquark pair.
Form_Time_Factor — double, optional, default = 1.0
Factor to be multiplied with the formation time of string fragments from the soft string routine.
Formation_Time — double, optional, default = 1.0
Parameter for formation time in string fragmentation, in fm.
Gluon_Beta — double, optional, default = 0.5
Parameter \(\beta\) in parton distribution function for gluons,
\[\mathrm{PDF}_g(x) \propto \frac{1}{x}(1-x)^{\beta+1}\;.\]
Gluon_Pmin — double, optional, default = 0.001
Smallest possible scale for gluon lightcone momentum in GeV. This is divided by \(\sqrt{s}\) to get the minimum fraction to be sampled from PDF shown in Gluon_Beta.
Mass_Dependent_Formation_Times — bool, optional, default = false
Whether the formation time of string fragments should depend on their mass. If it is set to true, the formation time is calculated as \(\tau = \sqrt{2}\frac{m}{\kappa} \).
Quark_Alpha — double, optional, default = 2.0
Parameter \(\alpha\) in parton distribution function for quarks,
\[\mathrm{PDF}_q\propto x^{\alpha-1}(1-x)^{\beta-1}\;.\]
Quark_Beta — double, optional, default = 7.0
Parameter \(\beta\) in PDF for quarks shown in Quark_Alpha.
Popcorn_Rate — double, optional, default = 0.15
Parameter StringFlav:popcornRate, which determines production rate of popcorn mesons in string fragmentation. It is possible to produce a popcorn meson from the diquark end of a string with certain probability (i.e., diquark to meson + diquark).
Power_Particle_Formation — double, optional, default = ±1
The default value of this parameter is +1 if \(\sqrt{s}<200\,\mathrm{GeV}\) and -1 otherwise. If positive, the power with which the cross section scaling factor of string fragments grows in time until it reaches 1. If negative, the scaling factor will be constant and jump to 1 once the particle forms.
Prob_proton_to_d_uu — double, optional, default = 1./3
Probability of splitting an (anti)nucleon into the quark it has only once and the diquark it contains twice in terms of flavour in the soft string routine.
Separate_Fragment_Baryon — bool, optional, default = true
Whether to use a separate fragmentation function for leading baryons in non-diffractive string processes.
Sigma_Perp — double, optional, default = 0.42
Parameter \(\sigma_\perp\) in GeV in the distribution for transverse momentum transfer between colliding hadrons \(p_\perp\) and string mass \(M_X\),
\[ \frac{d^3N}{dM^2_Xd^2\mathbf{p_\perp}}\propto \frac{1}{M_X^2} \exp\left(-\frac{p_\perp^2}{\sigma_\perp^2}\right)\;. \]
Strange_Supp — double, optional, default = 0.16
Strangeness suppression factor \(\lambda\),
\[\lambda= \frac{P(s\bar{s})}{P(u\bar{u})\vphantom{\bar{d}}}= \frac{P(s\bar{s})}{P(d\bar{d})}\;. \]
Defines the probability to produce a \(s\bar{s}\) pair relative to producing a light \(q\bar{q}\) pair.
String_Sigma_T — double, optional, default = 0.5
Standard deviation in GeV in Gaussian for transverse momentum distributed to string fragments during fragmentation.
String_Tension — double, optional, default = 1.0
String tension \(\kappa\) in GeV/fm connecting massless quarks in Hamiltonian,
\[H=|p_1|+|p_2|+\kappa |x_1-x_2|\;.\]
This parameter is only used to determine particles' formation times according to the yo-yo formalism (in the soft string routine for now).
StringZ_A — double, optional, default = 2.0
Parameter \(a\) in Pythia fragmentation function \(f(z)\),
\[f(z) = \frac{1}{z} (1-z)^a \exp\left(-b\frac{m_T^2}{z}\right)\;.\]
StringZ_A_Leading — double, optional, default = 0.2
Parameter \(a\) in Lund fragmentation function (see StringZ_A) used to sample the light cone momentum fraction of leading baryons in non-diffractive string processes.
StringZ_B — double, optional, default = 0.55
Parameter \(b\) in 1/GeV² in Pythia fragmentation function shown in StringZ_A.
StringZ_B_Leading — double, optional, default = 2.0
Parameter \(b\) in 1/GeV² in Lund fraghmentation function (see StringZ_B) used to sample the light cone momentum fraction of leading baryons in non-diffractive string processes.
Use_Monash_Tune — bool, optional, default = (Modus == "Collider" && Sqrtsnn >= 200)
Whether to use the monash tune Skands:2014pea [12] for all string processes. If nothing is specified, this option will be generally false unless SMASH is run in the collider modus with an energy per nucleon pair \(\mathtt{Sqrtsnn}\geq 200\,\mathrm{GeV}\).
Collision_Term:
Strings: True
String_Parameters:
String_Tension: 1.0
Gluon_Beta: 0.5
Gluon_Pmin: 0.001
Quark_Alpha: 2.0
Quark_Beta: 7.0
Strange_Supp: 0.16
Diquark_Supp: 0.036
Sigma_Perp: 0.42
StringZ_A_Leading: 0.2
StringZ_B_Leading: 2.0
StringZ_A: 2.0
StringZ_B: 0.55
String_Sigma_T: 0.5
Prob_proton_to_d_uu: 0.33
Separate_Fragment_Baryon: True
Popcorn_Rate: 0.15