Computing unintegrated gluon by interpolating an input grid
The form of the 2d grid is assumed to be:
# logx logkt2 xg
i1 j1 val1
... ... ...
i1 jn valn
i2 j1 valn+1
... ... ...
i2 jn valn*m
and both variables have to grow monotonically.
IMPORTANT: normalization of gluon
In case of problems in gluon evaluation a corresponding error is written to the
unintegratedgluon.err file which is always produced by this class. The possible error codes are
- Err001 : Evaluation outside the domain of the grid.
- Err002 : Negative value of the gluon.
In each of the above cases the return value of the xg(double logx, double logkt2) function is set to zero.
- add description of normalization, perhaps remove functions _norm_f/F
|vector<pair <double, double> > UnintegratedGluon::grid_limits
return grid limits in form of 2d vector of pairs: [[x1min,x1max], [x2min, x2max]]
Min and max values in each dimension can be obtained by using first or second pair data members.
Referenced by grid_limits(), and xg().
value of the unintegrated gluon
|logx||ln(x) where x is the longitudinal momentum fraction of the gluon |
|logkt2||ln(kt^2) where kt is the transverse momentum of the gluon |
|logmu2||ln(^2) where is the factorization scale; this parameter is relevant only for some gluons like e.g. the KShardscale gluon; it also implies that 3d grid is used as input |
References count1, count4, count5, first, grid3d, and grid_limits().
Referenced by TMDlib::ksBHKSPDF(), TMDlib::ksDLCPDF(), and TMDlib::ksPDF().