2 C*********************************************************************
4 FUNCTION PYHFTH(SH,SQM,FRATT)
6 C...Gives threshold attractive/repulsive factor for heavy flavour
8 COMMON/LUDAT1/MSTU(200),PARU(200),MSTJ(200),PARJ(200)
9 COMMON/PYPARS/MSTP(200),PARP(200),MSTI(200),PARI(200)
10 COMMON/PYINT1/MINT(400),VINT(400)
12 SAVE /PYPARS/,/PYINT1/
14 C...Value for alpha_strong.
15 IF(MSTP(35).LE.1) THEN
20 Q2BN=SQRT(MAX(1.,SQM*((SQRT(SH)-2.*SQRT(SQM))**2+PARP(36)**2)))
25 C...Evaluate attractive and repulsive factors.
26 XATTR=4.*PARU(1)*ALSSG/(3.*SQRT(MAX(1E-20,1.-4.*SQM/SH)))
27 FATTR=XATTR/(1.-EXP(-MIN(50.,XATTR)))
28 XREPU=PARU(1)*ALSSG/(6.*SQRT(MAX(1E-20,1.-4.*SQM/SH)))
29 FREPU=XREPU/(EXP(MIN(50.,XREPU))-1.)
30 PYHFTH=FRATT*FATTR+(1.-FRATT)*FREPU