************************************************************************ * * integrandspDIS.f: * * This functions return the integrands need to compute the polarised DIS * structure functions. * In order to wrap it in a form that can be fed to the integration * function DGAUSS, it is an explicit function only of the integration * variable y while it depends on the other variables: * * 1) the perturbatibe order pt, * 2) the number of active flavours wnf, * 3) the grid indices walpha and wbeta, * 4) the particular plitting function denoted by k such that: * * k combination * -------------------------- * 1 gluon * 2 pure-singlet * 3 non-singlet-plus * 4 non-singlet-minus * * 5) the structure function index: * * sf Structure Function * -------------------------- * 1 g1 * 2 gL * 3 g4 * * that are contained in the common block wrapDIS.h * ************************************************************************ * * Zero Mass coefficient functions for polarised DIS * ************************************************************************ function integrandspDISzm(y) * implicit none * include "../commons/grid.h" include "../commons/wrapDIS.h" ** * Input Variables * double precision y ** * Internal Variables * double precision z,w_int,fR,fS,fL double precision CR,CS double precision G1G1PA, G1NS1PA, G1NS1PB double precision GLNS1PA double precision G4NS1PA, G4NS1PB ** * Output Variables * double precision integrandspDISzm * * Interpolant functions * z = xg(igrid,wbeta) / y * fL = 0d0 if(walpha.eq.wbeta) fL = 1d0 * fR = w_int(inter_degree(igrid),walpha,z) fS = fR - fL * * Contructing integrands order by order * CR = 0d0 CS = 0d0 * * NLO * if(wipt.eq.1)then * g4 if(sf.eq.3)then * Non-singlet-plus/minus if(k.eq.3.or.k.eq.4)then CR = G4NS1PA(y) CS = G4NS1PB(y) endif * gL elseif(sf.eq.2)then * Non-singlet-plus/minus if(k.eq.3.or.k.eq.4)then CR = GLNS1PA(y) endif * g1 elseif(sf.eq.1)then * Gluon if(k.eq.1)then CR = G1G1PA(y) * Non-singlet-plus/minus elseif(k.eq.3.or.k.eq.4)then CR = G1NS1PA(y) CS = G1NS1PB(y) endif endif endif * integrandspDISzm = CR * fR + CS * fS * return end