Predefined Banks

Many parameters, like the particle density function and the number of events, have to be set for all programs, these parameters are collected and can be set by the use of a steering card bank called MOCA.

Below you see the complete MOCA bank. Some of the entries are described in detail below.

MOCA 0              ! NLO Monte Carlo steering card, Version 0
  'TYPE' 2          ! NLO program (1=Mepjet, 2=Disent, 3=Disaster++)
  'NEVE' 10000      ! Number of Events (required)
  'Q2MI' 10.        ! (D=100.) Q**2 min
  'Q2MA' 100.       ! (D=4000.) Q**2 max
  'XMIN' 0.         ! (D=0.) x min
  'XMAX' 1.         ! (D=1.) x max
  'XIMI' 0.         ! (D=0.) xi min
  'XIMA' 1.         ! (D=1.) xi max
  'YMIN' 0.         ! (D=0.) y min
  'YMAX' 0.7        ! (D=1.) y max
  'W2MI' 0.         ! (D=0.) Minimum W**2
  'W2MA' 100000.    ! (D=100000.) Maximum W**2
* PDFL and PDFH give the PDF libs used for LO (L,SET.eq.0) and 
* NLO (H,SET.ne.0) calculations, should be identical for MRS and 
* of corresponding type for CTEQ and GRV, 
* example : PDFL=5005 (GRV94 LO) and PDFH=5006 (GRV94 NLO) for
* MSbar scheme and PDFH=5007 (GRV94 NLO) for DIS scheme
  'PDFL' 3035       ! (D=3035=MRSH MSbar) PDF lib, 
  'PDFH' 3035       !   NGROUP*1000+NSET as in pdflib manual
  'ECMS' 90200.     ! (D=90200.=27.5*820.*4.) CMS energy
  'EP  ' 820.       ! (D=820) Proton energy
  'LEPT' 1          ! (D=1) incoming lepton (1: e-, 2: e+)
* The following values (upto * end) are given in the lab frame
  'ELMI' 11.        ! (D=0.) Minimum energy of scattered electron
* 'ELMA' 11.        ! (D=1000.) Maximum energy of scattered e-
  'TLMI' 150.       ! (D=0.) Minimum angle of scattered electron
  'TLMA' 172.5      ! (D=180.) Maximum angle of scattered e-
* end
  'NFL ' 5          ! (D=5) number of flavours
  'SFQ2' 1.         ! (D=1.) factorization scale factor for Q**2
  'SRQ2' 1.         ! (D=1.) renormalization scale factor for Q**2
  'SFKT' 0.         ! (D=0.) factorization scale factor for kt**2
  'SRKT' 0.         ! (D=0.) renormalization scale factor for kt**2
  'SFPT' 0.         ! (D=0.) factorization scale factor for pt**2
  'SRPT' 0.         ! (D=0.) renormalization scale factor for pt**2
  'SFCO' 0.         ! (D=0.) factorization scale factor for 1
  'SRCO' 0.         ! (D=0.) renormalization scale factor for 1
  'IAEL' 0          ! (D=0) switch for alpha_electromagnetic
                    ! 0 : fixed, 1 : running
  'AELM' 0.00729735308 ! (D=0.00729735308) alpha_electromagnetic
  'MASS' 0.15       ! (D=0.15) mass of strange quark in GeV
  'MASC' 1.4        ! (D=1.4) mass of charm quark in GeV
  'MASB' 4.4        ! (D=4.4) mass of bottom quark in GeV
  'MAST' 174        ! (D=174) mass of top quark in GeV
  'ALOO' 2          ! (D=2) number of loops for alpha_s running,
                    ! -1: pdf routine, 0: fixed, 1|2|3: 1|2|3 loop 
  'LAM4' 0.3        ! (D=0.3) Lambda_4_MSbar for running alphas
                    ! or alphas for fixed alphas

• ITYPE is coded as follows :

  ITYPE=0 :

  unknown

  ITYPE=1 :

  MEPJET

  ITYPE=2 :

  DISENT

  ITYPE=3 :

  DISASTER++

• NEVE is the only field required for each run. It gives the number of events to be generated¹.

• PDFL and PDFH specify the parton density functions used. Two values are given in order to enable the distinction of leading order and next-to-leading order processes. The format of each of the values is NGROUP * 1000 + NSET where NGROUP and NSET are given by the PDFLIB.
• The renormalization and factorization scale can be set using the formula
  $$\mu_{s}^{}$$ = f_Q2Q² + f_PTp_t² + f_KTk_t² + f_CO
  where the factors f_xy are set with the steering parameter Ssxy.
• IAEL and AELM steer the running of $\alpha_{\mbox{\scriptsize el.mag.}}^{}$ and ALOO and LAM4 steer the running of $\alpha_{s}^{}$ accordingly. When ALOO is set to -1, the $\alpha_{s}^{}$ calculation included in the pdf library is used. If it is 0, $\alpha_{s}^{}$ $\equiv$LAM4 for every scale, otherwise LAM4 corresponds to $\Lambda^{4}_{\overline{MS}}$ and the masses MASx are used for calculating $\Lambda^{(3,5,6)}_{\overline{MS}}$.

Some parameters are still program specific, therefore for each generator an additional steering card exists. Below you can find the steering card of DISASTER++[3] and DISENT[2].

DISE 0              ! DISENT specific steering card
* 'SEDL' -1         ! (12345) Lower seed value for random generator
                    ! if set to negative value a time-depended
                    !  value will be used
* 'SEDH' -1         ! (678900) Higher seed value for random generator
                    ! if set to negative value a process-depended
                    !  value will be used
  'SCHE' 0          ! (D=0) 0 : MSbar, 1 : DIS
                    ! Please note : the PDF has to be chosen equivalent
  'NPO1' 2          ! (D=2) The parameters NPO1 and NPO2 are internal
  'NPO2' 4          ! (D=4) parameters used by Disent, please refer
                    ! to the program manual
DISA 0              ! DISASTER++ specific steering card
  'BORN' 2          ! (D=2) number of particles in born term
  'PROC' 0          ! (D=1) order of process (0 : LO, 1 : NLO)
  'FPRE' 1.5        ! (D=1.5) factor for # points in preparation run
  'FFIN' 1.5        ! (D=1.5) factor for # points in final run

MEPJ 0              ! MEPJET specific steering card
  'BOSO' 1          ! exchange boson (1:gamma, 2:Z, 3:gammaZ, 4:W)
  'BORN' 2          ! (D=2) number of particles in born term
  'PROC' 0          ! (D=1) order of process (0 : LO, 1 : NLO)
  'NPRO' 100        ! (D=100) process number (quark+gluon, unpolarized)
                    ! see Mepjet manual for details (iproc)
  'IMAS'            ! (D=0) massive calculation (0=no, 1=yes)
  'IPDF'            ! (D=4) pdf crossing function
  'ITER'            ! (D=4) number of iterations for vegas adaptation
  'SMIN'            ! (D=0.1) smin cone size
  'PTIN'            ! (D=0.1) minimal p_t in lab frame for partons
  'AMIN'            ! (D=-10) minimal pseudo rapidity in lab for partons
  'AMAX'            ! (D=-10) maximal pseudo rapidity in lab for partons

Please note, that due to the usage of crossing functions the parton density functions for Mepjet is not set with PDFL, PDFH, but by the IPDF switch.