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High Energy Physics

Department of Physics and Astronomy

Faculty of Technology and Science

Tunable switches and parameters in LEPTO 6.5

Last updated: 961101

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=2, alt. 1 or 0=off
LST(35)         Seaquark treatment              D=1 = on, alt. 2 or 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=0.04    , 0.0001-0.1  
PARL(9)         Cut-off in matrix element       D=4 GeV^2 , 1.0-100.0 GeV^2
                                                for LST(20)=6 use
                                                PARL(8)=0.001
                                                PARL(9)=1.0 GeV^2
PARL(10)        width of the virtuality         PARL(10)=0.44 GeV, 0.1-1.0 GeV
                distribution of the sea quark 
                partner for LST(34)=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,
                                                            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, 
                                                             ,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.



Constructed by AE and JR