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PYTHIA
8.317
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#include <SigmaQCD.h>
Public Member Functions | |
| TopThreshold () | |
| Trivial constructor and destructor. | |
| void | setup (int topModelIn, double mtIn, double gammatIn, double gammatGreenIn, double thresholdRegionIn, double singletFracIn, int alphasOrder, double alphasValue) |
| Initialization setup - read in necessary settings. More... | |
| double | multiplySigmaBy (double mHat, double m3, double m4, double m3Orig, double m4Orig, double eThr) |
| Cross section enhancement factor, combined. More... | |
| double | imGreenSin (double eNow, double mtNow) |
| Imaginary part of Green's function for singlet state. More... | |
| double | imGreenOct (double eNow, double mtNow) |
| Imaginary part of Green's function for octet state. More... | |
| double | weightTopDecay (Event &process) |
| Set up information to handle angular distributions in toponium decay. More... | |
| double | matrixElementP2bbveevmumu (const Event &work, int ib, int ibb, int ive, int ie, int ivm, int im) |
| Matrix element for decay angles in pseudoscalar toponium-like state. More... | |
Auxiliary class for top threshold corrections, based on V. Fadin, V. Khoze and T. Sjostrand, Z. Phys. C48 (1990) 613.
| double imGreenOct | ( | double | eNow, |
| double | mtNow | ||
| ) |
Imaginary part of Green's function for octet state.
Basic expressions.
Sum over resonance contributions.
Combine with non-resonant terms and done.
| double imGreenSin | ( | double | eNow, |
| double | mtNow | ||
| ) |
Imaginary part of Green's function for singlet state.
Basic expressions.
Sum over resonance contributions.
Combine with non-resonant terms and done.
| double matrixElementP2bbveevmumu | ( | const Event & | work, |
| int | ib, | ||
| int | ibb, | ||
| int | ive, | ||
| int | ie, | ||
| int | ivm, | ||
| int | im | ||
| ) |
Matrix element for decay angles in pseudoscalar toponium-like state.
Four-vectors, with their squares and products.
Note: overall factor mtSq omitted.
| double multiplySigmaBy | ( | double | mHat, |
| double | m3, | ||
| double | m4, | ||
| double | m3Orig, | ||
| double | m4Orig, | ||
| double | eThr | ||
| ) |
Cross section enhancement factor, combined.
Cross section enhancement factor.
No rescaling where not defined.
Calculate key kinematics variables.
alpha_strong value.
Initial values.
Coulomb threshold factors for attractive (singlet) and repulsive (octet).
Green's function factors for attractive (singlet) and repulsive (octet).
Damping for eThr < -thrRegion.
Recalculate kinematics relative to original quark masses.
Alternative definition of eThr agrees with beta factor for Gamma_t = 0.
Mix of attractive and repulsive channels.
Since the threshold cross section contains a beta factor (with m3/m4, not m3Orig/m4Orig) this must be removed in the final answer.
| void setup | ( | int | topModelIn, |
| double | mtIn, | ||
| double | gammatIn, | ||
| double | gammatGreenIn, | ||
| double | thrRegionIn, | ||
| double | singletFracIn, | ||
| int | alphasOrder, | ||
| double | alphasValue | ||
| ) |
Initialization setup - read in necessary settings.
TopThreshold. Auxiliary class to Sigma2gg2QQbar and Sigma2qqbar2QQbar, which allows simulation of top threshold enhancement factors according to V. Fadin, V. Khoze and T. Sjostrand, Z. Phys. C48 (1990) 613.
| double weightTopDecay | ( | Event & | process | ) |
Set up information to handle angular distributions in toponium decay.
Create working copy of process record to simplify setup.
Order ttbar system and the decay products (treg = t, breg = b).
The W+- decay products, ferm = fermion, anti = antifermion.
Convert massive W decay products to massless ones, along unchanged axis in the W rest frame.
Weight for pseudoscalar ttbar state.
1.8.11
