=== modified file 'Template/LO/Source/dsample.f'
--- old/Template/LO/Source/dsample.f	2015-03-26 08:58:13 +0000
+++ new/Template/LO/Source/dsample.f	2015-04-24 15:44:19 +0000
@@ -2052,7 +2052,7 @@
 
                xxmean = tmean/tsigma
                if (cur_it.ne.2)then
-                  xchi2 = (chi2/xxmean/xxmean-tsigma)/dble(cur_it-2)               
+                  xchi2 = dabs(chi2/xxmean/xxmean-tsigma)/dble(cur_it-2)               
                else
                   xchi2 = 0d0
                endif
@@ -2171,7 +2171,7 @@
                endif
                tmean = tmean / tsigma
                trmean = trmean / tsigma
-               chi2 = (chi2 / tmean / tmean - tsigma) / dble(itm - 1)
+               chi2 = dabs(chi2 / tmean / tmean - tsigma) / dble(itm - 1)
                tsigma = tmean / sqrt(tsigma)
                write(*, 80) real(tmean), real(tsigma), real(trmean), real(chi2)
  80            format(/1X,79(1H-)/1X,23HAccumulated results:   ,

=== modified file 'madgraph/iolibs/template_files/addmothers.f'
--- old/madgraph/iolibs/template_files/addmothers.f	2015-04-07 12:11:42 +0000
+++ new/madgraph/iolibs/template_files/addmothers.f	2015-04-24 16:20:19 +0000
@@ -692,6 +692,7 @@
      $        mo_color.eq.8.and.i3.eq.2.and.i3bar.eq.2) then
 c     Replace the maximum index with the minimum one everywhere
 c     (we don't know if we should replace i3 with i3bar or vice versa)
+
          maxcol=max(max3,max3bar)
          if(maxcol.eq.max3) then
             mincol=min3bar
@@ -704,23 +705,70 @@
      $              icol(j,i)=mincol
             enddo
          enddo
+
+         if (mincol.eq.0.and.mo_color.eq.3) then
+c            situation like (possible if they are epsilon in the gluon decay
+c            (503,0)----------+ggggggggggggg (509,508)
+c                             |
+c                             |(x,y)
+c            in this case maxcol=509 and mincol=0
+c            The correct solution in this case is:
+c            (503,0)----------+ggggggggggggg (503,508)
+c                             |
+c                             |(0,508)
+            if(icolmp(2,1).eq.0)then
+               maxcol = icolmp(1,2)
+               mincol = icolmp(1,1)
+               icol(1,ires) = 0
+               icol(2,ires) = icolmp(2,2)
+            elseif(icolmp(1,1).eq.0)then
+               maxcol = icolmp(2,2)
+               mincol = icolmp(2,1)
+               icol(1,ires) = icolmp(1,2)
+               icol(2,ires) = 0 
+            elseif(icolmp(2,2).eq.0)then
+               maxcol = icolmp(1,1)
+               mincol = icolmp(1,2)
+               icol(1,ires) = 0
+               icol(2,ires) = icolmp(2,1)
+            elseif(icolmp(1,2).eq.0)then
+               maxcol = icolmp(2,1)
+               mincol = icolmp(2,2)
+               icol(1,ires) = icolmp(1,1)
+               icol(2,ires) = 0
+            else
+               !should not happen
+               write(*,*) "weird color combination in addmothers.f"
+               write(*,*) icolmp(1,1), icolmp(2,1), icolmp(1,2), icolmp(2,2)
+               stop 1
+            endif
+c           now maxcol=509 and mincol=503 so replace all occurence of 509-> 503
+c            print *,'Replaced ',maxcol,' by ',mincol
+            do i=ires+1,nexternal
+               do j=1,2
+                  if(icol(j,i).eq.maxcol)
+     $                 icol(j,i)=mincol
+               enddo
+            enddo
+         else
+c        standard case
 c     Fix the color for ires (remember 3<->3bar for t-channels)
-         icol(1,ires)=0
-         icol(2,ires)=0
+            icol(1,ires)=0
+            icol(2,ires)=0
 c         print *,'Replaced ',maxcol,' by ',mincol
-         if(max3.eq.maxcol)then
-            if(i3-i3bar.ge.0) icol(2,ires)=min3
-            if(i3bar-i3.ge.0) icol(1,ires)=max3bar
-         else
-            if(i3-i3bar.ge.0) icol(2,ires)=max3
-            if(i3bar-i3.ge.0) icol(1,ires)=min3bar
+            if(max3.eq.maxcol)then
+               if(i3-i3bar.ge.0) icol(2,ires)=min3
+               if(i3bar-i3.ge.0) icol(1,ires)=max3bar
+            else
+               if(i3-i3bar.ge.0) icol(2,ires)=max3
+               if(i3bar-i3.ge.0) icol(1,ires)=min3bar
+            endif
          endif
-c         print *,'Set mother color for ',ires,' to ',(icol(j,ires),j=1,2)
+c     print *,'Set mother color for ',ires,' to ',(icol(j,ires),j=1,2)
       else
 c     Don't know how to deal with this
          call write_error(i3,i3bar,mo_color)
       endif
-
       fix_tchannel_color=maxcolor
       
       return