| 1 | #!/usr/bin/env python
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| 2 | ################################################################################
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| 3 | #
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| 4 | # Requires python v2.7
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| 5 | #
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| 6 | # Simple script for generation of a LHE file containing events distributed with a flat (log)pt and eta spectrum.
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| 7 | #
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| 8 | # For help type:
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| 9 | # python FlatSpectrumProducer.py -h
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| 10 | #
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| 11 | ################################################################################
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| 12 |
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| 13 | import os, random, math, argparse, sys
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| 14 |
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| 15 | def print_params(args):
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| 16 |
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| 17 | print 'sqrt(s) : ', args.ecm
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| 18 | print 'ptmin : ', args.ptmin
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| 19 | print 'ptmax : ', args.ptmax
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| 20 | print 'etamin : ', args.etamin
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| 21 | print 'etamax : ', args.etamax
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| 22 | print 'size : ', args.size
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| 23 | print 'seed : ', args.seed
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| 24 | print 'flat log : ', args.log
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| 25 | print 'output : ', args.output
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| 26 |
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| 27 | def write_init(args):
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| 28 |
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| 29 | ebeam = args.ecm/2.
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| 30 |
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| 31 | out = open(args.output, "a")
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| 32 | out.write('<LesHouchesEvents version="3.0">\n')
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| 33 | out.write('<init>\n')
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| 34 | out.write('2212 2212 {0} {1} 0 0 1 1 -4 1\n'.format(ebeam, ebeam))
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| 35 | out.write('1000. 1. 1000. 1\n')
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| 36 | out.write('</init>\n')
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| 37 | out.close()
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| 38 |
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| 39 | def write_event(args, pt, eta, phi):
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| 40 |
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| 41 | e = pt*math.cosh(eta)
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| 42 |
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| 43 | # compute particles 4-vectors (for massless particles): px, py, pz, e
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| 44 |
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| 45 | p1 = [0., 0., e, e]
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| 46 | p2 = [0., 0., -e, e]
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| 47 | p3 = [pt*math.cos(phi), pt*math.sin(phi), pt*math.sinh(eta), e]
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| 48 | p4 = [- pt*math.cos(phi), - pt*math.sin(phi), - pt*math.sinh(eta), e]
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| 49 |
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| 50 | if args.pdg == 21:
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| 51 | pdg = 0
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| 52 | else:
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| 53 | pdg = args.pdg
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| 54 |
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| 55 | cf_list = []
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| 56 |
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| 57 | ########## quarks
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| 58 | if pdg > 0:
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| 59 |
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| 60 | cf_list.append([501, 501, 502, 502])
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| 61 | cf_list.append([501, 502, 501, 502])
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| 62 |
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| 63 | color = cf_list[random.randint(0, 1)]
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| 64 |
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| 65 | # assume massless quarks
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| 66 | out = open(args.output, "a")
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| 67 | out.write('<event>\n')
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| 68 | out.write(' 4 1 +1000. {:.8e} 0.78186083E-02 0.11800000E+00\n'.format(2*e))
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| 69 | out.write(' 1 -1 0 0 {} 0 {:+.8e} {:+.8e} {:+.8e} {:.8e} {:.8e} 0.0000e+00 1.0000e+00\n'.format(color[0], p1[0], p1[1], p1[2], p1[3], 0.))
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| 70 | out.write(' -1 -1 0 0 0 {} {:+.8e} {:+.8e} {:+.8e} {:.8e} {:.8e} 0.0000e+00 -1.0000e+00\n'.format(color[1], p2[0], p2[1], p2[2], p2[3], 0.))
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| 71 | out.write(' {} 1 1 2 {} 0 {:+.8e} {:+.8e} {:+.8e} {:.8e} {:.8e} 0.0000e+00 1.0000e+00\n'.format(pdg, color[2], p3[0], p3[1], p3[2], p3[3], 0.))
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| 72 | out.write(' -{} 1 1 2 0 {} {:+.8e} {:+.8e} {:+.8e} {:.8e} {:.8e} 0.0000e+00 -1.0000e+00\n'.format(pdg, color[3], p4[0], p4[1], p4[2], p4[3], 0.))
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| 73 | out.write('</event>\n')
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| 74 |
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| 75 | ########## gluons
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| 76 | else:
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| 77 |
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| 78 | cf_list.append([503, 501, 504, 502, 503, 502, 504, 501])
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| 79 | cf_list.append([504, 501, 503, 502, 503, 501, 504, 502])
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| 80 |
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| 81 | color = cf_list[random.randint(0, 1)]
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| 82 |
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| 83 | out = open(args.output, "a")
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| 84 | out.write('<event>\n')
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| 85 | out.write(' 4 1 +1000. {:.8e} 0.78186083E-02 0.11800000E+00\n'.format(2*e))
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| 86 | out.write(' 21 -1 0 0 {} {} {:+.8e} {:+.8e} {:+.8e} {:.8e} {:.8e} 0.0000e+00 1.0000e+00\n'.format(color[0], color[1], p1[0], p1[1], p1[2], p1[3], 0.))
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| 87 | out.write(' 21 -1 0 0 {} {} {:+.8e} {:+.8e} {:+.8e} {:.8e} {:.8e} 0.0000e+00 1.0000e+00\n'.format(color[2], color[3], p2[0], p2[1], p2[2], p2[3], 0.))
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| 88 | out.write(' 21 1 1 2 {} {} {:+.8e} {:+.8e} {:+.8e} {:.8e} {:.8e} 0.0000e+00 1.0000e+00\n'.format(color[4], color[5], p3[0], p3[1], p3[2], p3[3], 0.))
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| 89 | out.write(' 21 1 1 2 {} {} {:+.8e} {:+.8e} {:+.8e} {:.8e} {:.8e} 0.0000e+00 1.0000e+00\n'.format(color[6], color[7], p4[0], p4[1], p4[2], p4[3], 0.))
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| 90 | out.write('</event>\n')
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| 91 |
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| 92 |
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| 93 |
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| 94 | #__________________________________________________________
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| 95 |
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| 96 | if __name__=="__main__":
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| 97 |
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| 98 | parser = argparse.ArgumentParser()
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| 99 | parser.add_argument("--pdg", type=int, help='available: 1/2/3/4/5/21 i.e: [uubar/ddbar/ssbar/ccbar/bbbar/gg] (default: 1)', default='1')
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| 100 | parser.add_argument("--ptmin", type=float, help="minimum pt [GeV] (default: 1.)", default=1.)
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| 101 | parser.add_argument("--ptmax", type=float, help="maximum pt [GeV] (default: 50000.)", default=50000.)
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| 102 | parser.add_argument("--etamin", type=float, help="minimum eta (default: 6.)", default=-6.)
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| 103 | parser.add_argument("--etamax", type=float, help="maximum eta (default: 6.)", default=6.)
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| 104 | parser.add_argument("--ecm,", dest='ecm', type=float, help="center of mass energy (default: 13000)", default=13000)
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| 105 | parser.add_argument("--size", type=int, help="number of events to generate (default: 1000)", default=1000)
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| 106 | parser.add_argument("--seed", type=int, help="random seed (default: 0)", default=0)
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| 107 | parser.add_argument('--log', dest='log', help="flat in log pt (default: yes)", action='store_true')
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| 108 | parser.add_argument('--nolog', dest='log', help="flat in pt (default: false)", action='store_false')
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| 109 | parser.set_defaults(log=True)
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| 110 | parser.add_argument("--output", help="output LHE file (default: events.lhe)", default='events.lhe')
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| 111 |
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| 112 | args = parser.parse_args()
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| 113 |
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| 114 | # check if provided pdgCode is allowed
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| 115 | allowed_pdgCodes = [1, 2, 3, 4, 5, 21]
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| 116 | if args.pdg not in allowed_pdgCodes:
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| 117 | print args.pdg ,'Please provide a supported pdgCode : 1, 2, 3, 4, 5 or 21'
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| 118 | sys.exit(0)
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| 119 |
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| 120 | # print user-defined parameters
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| 121 | print_params(args)
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| 122 | print ''
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| 123 |
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| 124 | # intialize file and write LHE file header
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| 125 | out = open(args.output, "w+")
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| 126 | out.close()
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| 127 | write_init(args)
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| 128 |
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| 129 | # initialize random seed
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| 130 | random.seed(args.seed)
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| 131 |
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| 132 | print 'Start event generation ...'
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| 133 |
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| 134 | ebeam = args.ecm/2.
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| 135 | count = 0
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| 136 |
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| 137 | # start event loop
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| 138 | while count < args.size:
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| 139 |
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| 140 | phi = random.uniform(0., math.pi)
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| 141 | eta = random.uniform(args.etamin, args.etamax)
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| 142 |
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| 143 | # flat in pt or in logpt
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| 144 | if args.log:
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| 145 | pt = math.pow(10, random.uniform(math.log10(args.ptmin), math.log10(args.ptmax)))
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| 146 | else:
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| 147 | pt = random.uniform(args.ptmin, args.ptmax)
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| 148 |
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| 149 | # generating "balanced" collision, i.e x1 = x2 = 2*energy/sqrt(s)
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| 150 | e = pt*math.cosh(eta)
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| 151 |
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| 152 | # write event corresponding to required process
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| 153 | if e < ebeam/2.:
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| 154 | write_event(args, pt, eta, phi)
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| 155 | count += 1
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| 156 | if (count+1)%1000 == 0:
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| 157 | print ' ... processed {} events ...'.format(count+1)
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| 158 |
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| 159 | print ''
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| 160 | print 'Event generation completed.'
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| 161 | print 'Output file:'
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| 162 | print '{}'.format(os.path.abspath(args.output))
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| 163 |
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| 164 |
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| 165 | out = open(args.output, "a")
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| 166 | out.write('</LesHouchesEvents>\n')
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| 167 | out.close()
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