GenEv
                      an event generator for inelastic electro-scattering

 Genev works in 4 steps:

                                          Channels list
1) V_Gamma + P ---> N + PI+
2) V_Gamma + P ---> P + PI0
3) V_Gamma + N ---> P + PI-
4) V_Gamma + N ---> N + PI0
5) V_Gamma + P ---> DELTA++ + PI-
6) V_Gamma + P ---> DELTA+ + PI0
7) V_Gamma + P ---> DELTA0 + PI+
8) V_Gamma + N ---> DELTA+ + PI-
9) V_Gamma + N ---> DELTA0 + PI0
10) V_Gamma + N ---> DELTA- + PI+
11) V_Gamma + P ---> RHO0 + P
12) V_Gamma + P ---> RHO+ + N
13) V_Gamma + N ---> RHO- + P
14) V_Gamma + N ---> RHO0 + N
15) V_Gamma + P ---> P + PI + PI-
16) V_Gamma + P ---> N + PI0 + PI+
17) V_Gamma + N ---> N + PI+ + PI-
18) V_Gamma + N ---> P + PI0 + PI-
19) V_Gamma + P ---> OMEGA + P
20) V_Gamma + N ---> OMEGA + N
21) V_Gamma + P ---> P + PI+ + PI- + PI0
22) V_Gamma + P ---> N + PI+ + PI+ + PI-
23) V_Gamma + N ---> N + PI+ + PI- + PI0
24) V_Gamma + N ---> P + PI+ + PI- + PI-
     25) V_Gamma + P ---> PHI + P
26) V_Gamma + N ---> PHI + N
27) V_gamma + P ---> pi+ + pi+ + pi- + pi- + p
28) V_gamma + P ---> pi+ + pi+ + pi- + pi- + pi0 + p
29) V_gamma + P ---> pi+ + pi+ + pi+ + pi- + pi- + n

                           Decay of unstable particles
 
 
    Particle
    Decay Channel
    Branching Ratio
      D++
      p p+
      1.0
      D+
      p p0
      0.66
      D+
      n p+
      0.33
      D0
      n p0
      0.66
      D0
      p p-
      0.33
      D-
      n p-
      1.0
      r+
      p+ p0
      1.0
      r0
      p+ p-
      1.0
      r-
      p- p0
      1.0
      F0
      K+ K-
      0.49
      F0
      KS KL
      0.35
      F0
      p+ p- p0
      0.16
 


                            - Inelastic cross-section
 
- w and q fixed bin
- W and Q2 fixed bin
 

- Q2 dependence

One can chose between:
 
- tabulated cross sections (10 MeV W steps)
- phenomenological fit for 1 pion
- phenomenological calculation + data fit for 2 pions
- w and multipions production obtained interpolating available data
 
 
 

Total cross section

 


 

 2 pions total cross section
 


 
Angular distributions
Theta in C.M
- tabulated angular distribution (9 degrees steps)
- for 1- 2 pions, w and F channels experimental data are used
- for multipions channels phase sspace extraction (GENBOD)
phi distributions: all channels have uniform distr. but single pion
                               a + bcos(j) + c cos2(j)



 
Rho decay distribution
theta, phi of pion in rho rest frame
All other channels have an uniform distribution for decaying particles


   
genev_hp.lund     ! lund file name
10000                  ! events number
4.045                   ! Ebeam (GeV)
0.1                      ! omega_min/Eo
0.95                     ! omega_max/Eo
12.5                     ! teta_min electron (degrees)
55.                       ! teta_max electron (degrees)
0                         ! flag to fix Q2 (1=read Qmin,Qmax; 0=ignore them)
0.6                       ! Q2min WARNING!! If Q2 and W flags are BOTH=1 extraction
4.0                       ! Q2max is made in Q2,W bin; elsewere in Omega,theta bin
1                         ! flag to fix W (1=read Wmin,Wmax; 0=ignore them)
1.                        ! Wmin (GeV)
2.8                     ! Wmax (GeV)
0                       !flag to fix phi of e- (1=read phi_min,phi_max;0=ignore them)
30                     ! phi_min (degrees)
90                     ! phi_max (degrees)
16                     ! number of activated channels channels
1,2,5,6,7,11,12,15,16,19,21,22,25,27,28,29             ! channels ID (in one line, ID
                                                                          ! separeted by a coma e.g 1,3,4..)
0                        ! 0/1 LUND file no/yes
0                        !Flag Rho ds/dt (0=ds/dt true; 1=uniform 2=flat 3=fixed angle)
931132                ! random number
CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC
C                                                          CHANNEL ID
 1) V_Gamma + P ---> N + PI+
 2) V_Gamma + P ---> P + PI0
 3) V_Gamma + N ---> P + PI-
 4) V_Gamma + N ---> N + PI0
 5) V_Gamma + P ---> DELTA++ + PI-
 6) V_Gamma + P ---> DELTA+ + PI0
 7) V_Gamma + P ---> DELTA0 + PI+
 8) V_Gamma + N ---> DELTA+ + PI-
 9) V_Gamma + N ---> DELTA0 + PI0
 10) V_Gamma + N ---> DELTA- + PI+
 11) V_Gamma + P ---> RHO0 + P
12) V_Gamma + P ---> RHO+ + N
13) V_Gamma + N ---> RHO- + P
14) V_Gamma + N ---> RHO0 + N
15) V_Gamma + P ---> P + PI + PI-
16) V_Gamma + P ---> N + PI0 + PI+
17) V_Gamma + N ---> N + PI+ + PI-
 18) V_Gamma + N ---> P + PI0 + PI-
 19) V_Gamma + P ---> OMEGA + P
 20) V_Gamma + N ---> OMEGA + N
 21) V_Gamma + P ---> P + PI+ + PI- + PI0
 22) V_Gamma + P ---> N + PI+ + PI+ + PI-
 23) V_Gamma + N ---> N + PI+ + PI- + PI0
 24) V_Gamma + N ---> P + PI+ + PI- + PI-
 25) V_Gamma + P ---> PHI + P
 26) V_Gamma + N ---> PHI + N
 27) V_gamma + p ---> pi+ + pi+ + pi- + pi- + p
 28) V_gamma + p ---> pi+ + pi+ + pi- + pi- + pi0 + p
 29) V_gamma + p ---> pi+ + pi+ + pi+ + pi- + pi- + n

 

(left)SIMULATION w, q fixed and Q2>0.5            (right)  Run 9158 (4GeV low field)

 


SIMULATION w, q fixed and 1<W>2.8
 
  

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