1 The STARlight Monte Carlo models 2-photon and photon-Pomeron interactions
2 in ultra-peripheral heavy ion collisions. The physics approach for the photon-Pomeron
3 interactions is described in Klein and Nystrand, Phys. Rev. C60, 014903 (1999),
4 with the p_t spectrum (including vector meson interference) discussed in Phys. Rev.
5 Lett. 84, 2330 (2000). The 2-photon interactions are described in Baltz, Gorbunov,
6 Klein, Nystrand, Phys.Rev. C80 (2009) 044902.
8 STARlight has several input files, all of which are expected to be in the
9 same directory as the starlight code. User-specified input parameters are
10 read from a file named "slight.in"; these parameters are described
13 The output of the STARlight Monte Carlo will be written to an ascii file
16 ----------------------------------------------------------------------------
18 The contents of a sample slight.in file are listed below, with
19 explanation. The user should modify this file according to his or her
21 BEAM_1_Z = 82 #Z of projectile
22 BEAM_1_A = 208 #A of projectile
23 BEAM_2_Z = 82 #Z of target
24 BEAM_2_A = 208 #A of target
25 BEAM_GAMMA = 1470 #Gamma of the colliding ions
27 W_MAX = 12.0 #Max value of w
28 W_MIN = -1 #Min value of w
29 W_N_BINS = 40 #Bins i w
30 # maximum and minimum values for w (the gamma-gamma center of mass
31 # energy, w = 4(E1)(E2), (Setting W_MIN = -1 tells STARlight to use the default values
32 # specified in inputParameters.cpp; otherwise, specify wmin here, and the number
33 # of w bins in the lookup tables
35 RAP_MAX = 8. # max rapidity
36 RAP_N_BINS = 80 # Number of y bins used in the cross section calculation
38 CUT_PT = 0 #Cut in pT? 0 = (no, 1 = yes)
39 PT_MIN = 1.0 #Minimum pT in GeV
40 PT_MAX = 3.0 #Maximum pT in GeV
41 CUT_ETA = 0 #Cut in pseudorapidity? (0 = no, 1 = yes)
42 ETA_MIN = -10 #Minimum pseudorapidity
43 ETA_MAX = 10 #Maximum pseudorapidity
45 PROD_MODE = 2 #gg or gP switch (1 = two-photon, 2 = coherent vector meson, 4 = incoherent vector meson )
47 N_EVENTS = 10 #Number of events produced
49 PROD_PID = 443013 #Channel of interest (in PDG notation); currently supported options listed below
50 RND_SEED = 34533 #Random number seed
52 OUTPUT_FORMAT = 2 #Form of the output (not considered at this state)
54 BREAKUP_MODE = 5 #Controls the nuclear breakup
55 # Note that this option only works for lead or gold; it should work at any energy
56 # 1 = hard sphere nuclei (b>2R)
57 # 2 = require that both nuclei break up (Xn,Xn)
58 # 3 = a single neutron from each nucleus (1n,1n)
59 # 4 = require that neither nucleus breaks up (0n,0n)
60 # 5 = require that there be no hadronic break up
61 # (This is similar to option 1, but with the actual hadronic interaction
63 # 6 = require break up of one or both nuclei (Xn)
64 # 7 = require break up of one nucleus (Xn,0n)
66 INTERFERENCE = 0 #Interference (0 = off, 1 = on)
67 IF_STRENGTH = 1. #% of intefernce (0.0 - 0.1)
68 COHERENT = 1 #Coherent=1,Incoherent=0 production for assym collisions
69 INCO_FACTOR = 1. #percentage of incoherence
70 BFORD = 9.5 #Deuteron slope parameter (dsig/dt = exp(BFORD*t))
71 INT_PT_MAX = 0.24 #Maximum pt considered, when interference is turned on
72 INT_PT_N_BINS =120 #Number of pt bins when interference is turned on
75 ----------------------------------------------------------------------------
77 Currently supported 2-photon channel options:
79 ---------------------------------
92 Currently supported vector meson options:
94 ---------------------------------
100 443013 J/Psi --> mu+mu-
101 444011 Psi(2S) --> e+e-
102 444013 Psi(2S) --> mu+mu-
103 553011 Upsilon(1S) --> e+e-
104 553013 Upsilon(1S) --> mu+mu-
105 554011 Upsilon(2S) --> e+e-
106 554013 Upsilon(2S) --> mu+mu-
107 555011 Upsilon(3S) --> e+e-
108 555013 Upsilon(3S) --> mu+mu-
109 913 rho0 + direct pi+pi- (with interference)
110 The direct pi+pi- fraction is from the ZEUS results
116 fixed types for class Particle
119 autoconfig will appear in the future .. make sure paths are fixed before compiling
120 this is for includes and libraries in Makefile
121 - don't forget about link to pythia xml doc
122 This is located in main.cpp
124 - changed PID of the charged KAON to 321 and neutral kaon to 310 .. it should work now for phi -> kk
126 - incoherent formfactor was hardcoded for dAu events, it should now accept coherent too.
127 - Had hardcoded narrow and wide resonances for VMs. The user can again select gg_or_gp (2 or 3)
128 except for the psi family. This is still always narrow.
129 - Changed the spin dependence for VMs going to ee/mumu(gammaavectormeson::gettheta). It was only for psi and now upsilon will follow too
130 inretrospect, i should probably have done this first and merge psifamily back into gammaavm.cpp