Tunable switches and parameters in LEPTO 6.4

Last updated: 960111

Lepto switches:

Switch: Short description: Default & alt. values:

LST(8) QCD effects D=12
LST(11) F_L, (targetmass, higher twist) D=0, alt. 1 -> F_L
LST(15) Parton distributions D=9, alt. any recent distr.
LST(16) Parton distributions D=1, alt. any recent distr.
LST(20) Cut-off scheme for ME D=5, alt. 6
LST(34) Soft Colour Interactions D=1 = on, alt. 0 = off
LST(35) Seaquark treatment D=1 = on, alt. 0 = off

Lepto parameters:

Parameter: Short description: Default & range of values:

PARL(3) Primordial k_T D=0.44 GeV, 0.3-0.8 GeV
PARL(7) Prob. for SCI D=0.5 , 0.0-0.5
PARL(8) Cut-off in matrix element D=0.01
PARL(9) Cut-off in matrix element D=1 GeV^2, 1.0-4.0 GeV^2 for LST(20)=6 use PARL(8)=0.001, 0.0001-0.1 PARL(9)=1.0 GeV^2
PARL(14) p_T in target remnant split D=0.35 GeV, 0.0-0.8 GeV
PARL(20) Mass red. for complex remnant D=0.10 GeV, 0.0-0.25 GeV
PYPAR(21) Lambda_QCD in initial shower D=from parton densities, range = 0.1-0.4 GeV
PYPAR(22) Cut-off in initial shower D=1 GeV^2 , 0.5-4.0 GeV^2 should preferable be the same as PARJ(82)^2, other values may require changing PARJ(41) and PARJ(42).

Jetset 7.4.07 parameters:

Parameter: Short description: Default & range of values:

PARU(112) Lambda_QCD in alpha_s D=from parton densities, range = 0.1-0.4 GeV
PARJ(41) a in fragmentation fcn D=0.3 , *
PARJ(42) b in fragmentation fcn D=0.58 GeV^-2, *
PARJ(81) Lambda_QCD in final shower D=0.29 GeV, *
PARJ(82) Cut-off in final shower D=1.0 GeV , *

* changing these parameters should be done with caution since they have been tuned from LEP measurements. A change of one of the parameters may require simultaneous changes of the other parameters as well.

Leif Lönnblad