MRS_charm#

class MCEq.charm_models.MRS_charm(e_grid, csm)[source]#

Bases: CharmModel

Martin-Ryskin-Stasto charm model.

The model is described in A. D. Martin, M. G. Ryskin, and A. M. Stasto, Acta Physica Polonica B 34, 3273 (2003). The parameterization of the inclusive \(c\bar{c}\) cross-section is given in the appendix of the paper. This formula provides the behavior of the cross-section, while fragmentation functions and certain scales are needed to obtain meson and baryon fluxes as a function of the kinematic variable \(x_F\). At high energies and \(x_F > 0.05\), where this model is valid, \(x_F \approx x=E_c/E_{proj}\). Here, these fragmentation functions are used:

\(D\)-mesons \(\frac{4}{3} x\)

\(\Lambda\)-baryons \(\frac{1}{1.47} x\)

The production ratios between the different types of \(D\)-mesons are stored in the attribute cs_scales and D0_scale, where D0_scale is the \(c\bar{c}\) to \(D^0\) ratio and cs_scales stores the production ratios of \(D^\pm/D^0\), \(D_s/D^0\) and \(\Lambda_c/D^0\).

Since the model employs only perturbartive production of charm, the charge conjugates are symmetric, i.e. \(\sigma_{D^+} = \sigma_{D^-}\) etc.

Parameters:

e_grid (np.array) – energy grid as it is defined in MCEqRun.
csm (np.array) – inelastic cross-sections as used in MCEqRun.

Attributes Summary

`D0_scale`	D0 cross-section wrt to the ccbar cross-section
`allowed_proj`	hadron projectiles, which are allowed to produce charm
`allowed_sec`	charm secondaries, which are predicted by this model
`cs_scales`	fractions of cross-section wrt to D0 cross-section

Methods Summary

`D_dist`(x, E, mes)	Returns the Feynman-\(x_F\) distribution of \(\sigma_{D-mesons}\) in mb
`LambdaC_dist`(x, E)	Returns the Feynman-\(x_F\) distribution of \(\sigma_{\Lambda_C}\) in mb
`dsig_dx`(x, E)	Returns the Feynman-\(x_F\) distribution of \(\sigma_{c\bar{c}}\) in mb
`get_yield_matrix`(proj, sec)	Returns the yield matrix in proper format for `MCEqRun`.
`sigma_cc`(E)	Returns the integrated ccbar cross-section in mb.
`test`()	Plots the meson, baryon and charm quark distribution as shown in the plot below.

Attributes Documentation

D0_scale = 0.47619047619047616#: D0 cross-section wrt to the ccbar cross-section

allowed_proj = [2212, -2212, 2112, -2112, 211, -211, 321, -321]#: hadron projectiles, which are allowed to produce charm

allowed_sec = [411, 421, 431, 4122]#: charm secondaries, which are predicted by this model

cs_scales = {411: 0.5, 421: 1.0, 431: 0.15, 4122: 0.45}#: fractions of cross-section wrt to D0 cross-section

Methods Documentation

D_dist(x, E, mes)[source]#

Returns the Feynman-\(x_F\) distribution of \(\sigma_{D-mesons}\) in mb

Parameters:

x (float or np.array) – \(x_F\)
E (float) – center-of-mass energy in GeV
mes (int) – PDG ID of D-meson: \(\pm421, \pm431, \pm411\)

Returns:

\(\sigma_{D-mesons}\) in mb

Return type:

float

LambdaC_dist(x, E)[source]#

Returns the Feynman-\(x_F\) distribution of \(\sigma_{\Lambda_C}\) in mb

Parameters:

x (float or np.array) – \(x_F\)
E (float) – center-of-mass energy in GeV
mes (int) – PDG ID of D-meson: \(\pm421, \pm431, \pm411\)

Returns:

\(\sigma_{D-mesons}\) in mb

Return type:

float

dsig_dx(x, E)[source]#

Returns the Feynman-\(x_F\) distribution of \(\sigma_{c\bar{c}}\) in mb

Parameters:

x (float or np.array) – \(x_F\)
E (float) – center-of-mass energy in GeV

Returns:

\(\sigma_{c\bar{c}}\) in mb

Return type:

float

get_yield_matrix(proj, sec)[source]#

Returns the yield matrix in proper format for MCEqRun.

Parameters:

proj (int) – projectile PDG ID \(\pm\) [2212, 211, 321]
sec (int) – charmed particle PDG ID \(\pm\) [411, 421, 431, 4122]

Returns:

yield matrix if (proj,sec) combination allowed,: else zero matrix

Return type:

np.array

sigma_cc(E)[source]#: Returns the integrated ccbar cross-section in mb.

Note

Integration is not going over complete phase-space due to limitations of the parameterization.

test()[source]#: Plots the meson, baryon and charm quark distribution as shown in the plot below.