lnstrf.F

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C ********************************************************************

      SUBROUTINE lnstrf(X,Q2,XPQ)

      IMPLICIT NONE

C...Structure function per nucleon for a proton/neutron mixture
C...according to defined nucleus.
CGI-001122 Updated to save and mix total d- and u-quark distributions
C...instead of only the valence parts.

*
* to avoid variable conflictions, a second keep element is necessary
* with the same common block name (see LEPTO2)
*

      COMMON /leptou/ cut(14),lst(40),parl(30),
     &                xlp,ylp,w2lp,q2lp,ulp
      REAL cut,parl,xlp,ylp,w2lp,q2lp,ulp
      INTEGER lst
      SAVE /leptou/


      COMMON /linter/ pari(50),ewqc(2,2,8),qc(8),zl(2,4),zq(2,8),pq(17)
      REAL  pari,ewqc,qc,zl,zq,pq
      SAVE /linter/

      REAL x,q2,xpq,xdv,xuv,xd,xu,xub,xdb
      dimension xpq(-6:6)

      CALL lystfu(2212,x,q2,xpq)

      IF(pari(11).LE.1.e-06) RETURN
C...Total d- and u-quark densities in proton, save for use in LEPTOX
      xd=xpq(1)
      xu=xpq(2)
      pari(12)=xd
      pari(13)=xu
CMM-010306 Saving the anti d- and anti u-quark densities
Cstep1
C...anti-d- and anti-u-quark densities in proton, save for use in LEPTOX
      xdb=xpq(-1)
      xub=xpq(-2)
      pari(42)=xdb
      pari(43)=xub
      IF(lst(39).EQ.0) THEN
C...For nuclear target, mix d- and u-quark distributions.
        xpq(1)=(1.-pari(11))*xd+pari(11)*xu
        xpq(2)=(1.-pari(11))*xu+pari(11)*xd
C...mix anti-d- and anti-u-quark distributions.
        xpq(-1)=(1.-pari(11))*xdb+pari(11)*xub    
        xpq(-2)=(1.-pari(11))*xub+pari(11)*xdb
      ENDIF
      RETURN
      END