Constants#
Physical and mathematical constants and related functions used throughout the package. Most masses and widths are taken by the Review of Particle Physics by the Particle Data Group [14]. The base unit is taken to be GeV.
- dispersionrelations.constants.MeV = 0.001#
Megaelectronvolt, numerically defined as \(10^{-3}\) as a default (so that
GeV\(=1\)).
- dispersionrelations.constants.eV = 1e-09#
Electronvolt, numerically defined as \(10^{-6}\times\)
MeV.
- dispersionrelations.constants.keV = 1e-06#
Kiloelectronvolt, numerically defined as \(10^{-3}\times\)
MeV.
- dispersionrelations.constants.GeV = 1.0#
Gigaelectronvolt, numerically defined as \(10^{3}\times\)
MeV.
- dispersionrelations.constants.TeV = 1000000.0#
Teraelectronvolt, numerically defined as \(10^{6}\times\)
MeV.
- dispersionrelations.constants.E_almost_zero = 1e-05#
A small energy, used in order to avoid division by zero.
- dispersionrelations.constants.alpha_fs = 0.0072973525205055605#
Electromagnetic fine structure constant \(\alpha_{\text{fs}}\approx1/137\).
- dispersionrelations.constants.e2 = 0.09170123627630092#
Electric charge squared, \(e^2 = 4\pi\alpha_{\text{fs}}\).
- dispersionrelations.constants.to_nb = 389379.2904730569#
Conversion factor from natural units to nanobarns.
Note: a “natural unit” is defined by whatever is equal to 1 by default. If \(\text{GeV}=1\), then the constant
to_nbwill convert \({\text{GeV}}^{-2}\) to nanobarns.
- dispersionrelations.constants.degrees = 0.017453292519943295#
Conversion factor from radians to degrees \(=\pi/180\).
- dispersionrelations.constants.M_RHO = 0.7625000000000001#
Mass of the \(\rho\) meson, obtained from the pole position [7].
- dispersionrelations.constants.M_RHO_STD = 0.0017#
Standard deviation of the \(\rho\) meson mass, obtained from the pole position [7].
- dispersionrelations.constants.G_RHO = 0.1464#
Width of the \(\rho\) meson, obtained from the pole position [7].
- dispersionrelations.constants.G_RHO_STD = 0.0022#
Standard deviation of the \(\rho\) meson width, obtained from the pole position [7].
- dispersionrelations.constants.M_RHO_BW = 0.7752600000000001#
Mass of the \(\rho\) meson, obtained as a Breit–Wigner parameter [14].
- dispersionrelations.constants.M_RHO_BW_STD = 0.00023#
Standard deviation of the \(\rho\) meson mass, obtained as a Breit–Wigner parameter [14].
- dispersionrelations.constants.G_RHO_BW = 0.1474#
Width of the \(\rho\) meson, obtained as a Breit–Wigner parameter [14].
- dispersionrelations.constants.G_RHO_BW_STD = 0.0008#
Standard deviation of the \(\rho\) meson width, obtained as a Breit–Wigner parameter [14].
- dispersionrelations.constants.M_OMEGA_STD = 0.00013000000000000002#
Standard deviation of the \(\omega\) meson mass [14].
- dispersionrelations.constants.G_OMEGA_STD = 0.00013000000000000002#
Standard deviation of the \(\omega\) meson width [14].
- dispersionrelations.constants.M_PHI_STD = 1.6e-05#
Standard deviation of the \(\phi\) meson mass [14].
- dispersionrelations.constants.G_PHI_STD = 1.3e-05#
Standard deviation of the \(\phi\) meson width [14].
- dispersionrelations.constants.M_ETA_STD = 1.7000000000000003e-05#
Standard deviation of the \(\eta\) meson mass [14].
- dispersionrelations.constants.G_ETA_STD = 5e-08#
Standard deviation of the \(\eta\) meson width [14].
- dispersionrelations.constants.M_A1_POLE = 1.209#
Mass of the \(a_1\), obtained from the pole position [11].
- dispersionrelations.constants.M_A1_POLE_STD = 0.016#
Standard deviation of the \(a_1\) mass, obtained from the pole position [11].
- dispersionrelations.constants.G_A1_POLE = 0.5760000000000001#
Width of the \(a_1\), obtained from the pole position [11].
- dispersionrelations.constants.G_A1_POLE_STD = 0.1#
Standard deviation of the \(a_1\) width, obtained from the pole position [11].
- dispersionrelations.constants.BR_OMEGA_TO_3PI = 0.892#
Branching ratio of \(\omega \to 3\pi\) decay [14].
- dispersionrelations.constants.BR_OMEGA_TO_3PI_STD = 0.006999999999999999#
Standard deviation of the branching ratio of \(\omega \to 3\pi\) decay [14].
- dispersionrelations.constants.G_OMEGA_TO_3PI = 0.00774256#
Partial width of \(\omega \to 3\pi\) decay.
- dispersionrelations.constants.G_OMEGA_TO_3PI_STD = 0.00013091409091461472#
Standard deviation of the partial width of \(\omega \to 3\pi\) decay.
- dispersionrelations.constants.BR_OMEGA_TO_PI0GAMMA = 0.0833#
Branching ratio of \(\omega \to \pi^0 \gamma\) decay [14].
- dispersionrelations.constants.BR_OMEGA_TO_PI0GAMMA_STD = 0.0025#
Standard deviation of the branching ratio of \(\omega \to \pi^0 \gamma\) decay [14].
- dispersionrelations.constants.G_OMEGA_TO_PI0GAMMA = 0.000723044#
Partial width of \(\omega \to \pi^0 \gamma\) decay.
- dispersionrelations.constants.G_OMEGA_TO_PI0GAMMA_STD = 2.4251953344009224e-05#
Standard deviation of the partial width of \(\omega \to \pi^0 \gamma\) decay.
- dispersionrelations.constants.G_RHO_TO_ETAGAMMA = 4.4200000000000004e-05#
Partial width of \(\rho \to \eta \gamma\) decay [13].
- dispersionrelations.constants.G_RHO_TO_ETAGAMMA_STD = 3.1e-06#
Standard deviation of the partial width of \(\rho \to \eta \gamma\) decay [13].
- dispersionrelations.constants.BR_KSTAR_TO_KGAMMA_CHARGED = 0.00098#
Branching ratio of the charged \(K^* \to K \gamma\) decay [5].
- dispersionrelations.constants.BR_KSTAR_TO_KGAMMA_CHARGED_STD = 8.999999999999999e-05#
Standard deviation of the branching ratio of the charged \(K^* \to K \gamma\) decay [5].
- dispersionrelations.constants.BR_KSTAR_TO_KGAMMA_NEUTRAL = 0.00246#
Branching ratio of the neutral \(K^* \to K \gamma\) decay [5].
- dispersionrelations.constants.BR_KSTAR_TO_KGAMMA_NEUTRAL_STD = 0.00021#
Standard deviation of the branching ratio of the neutral \(K^* \to K \gamma\) decay [5].
- dispersionrelations.constants.G_KSTAR_TO_KGAMMA_CHARGED = 5.096e-05#
Partial width of the charged \(K^* \to K \gamma\) decay.
- dispersionrelations.constants.G_KSTAR_TO_KGAMMA_CHARGED_STD = 1.265701386583739e-05#
Standard deviation of the partial width of the charged \(K^* \to K \gamma\) decay.
- dispersionrelations.constants.G_KSTAR_TO_KGAMMA_NEUTRAL = 0.00012792#
Partial width of the neutral \(K^* \to K \gamma\) decay.
- dispersionrelations.constants.G_KSTAR_TO_KGAMMA_NEUTRAL_STD = 3.147501866560209e-05#
Standard deviation of the partial width of the neutral \(K^* \to K \gamma\) decay.