StRoot  1
WeakShowerMEs.cc
1 // WeakShowerMEs.cc is a part of the PYTHIA event generator.
2 // Copyright (C) 2014 Torbjorn Sjostrand.
3 // PYTHIA is licenced under the GNU GPL version 2, see COPYING for details.
4 // Please respect the MCnet Guidelines, see GUIDELINES for details.
5
7 // WeakShowerMEs class.
8
9 #include "Pythia8/WeakShowerMEs.h"
10
11 namespace Pythia8 {
12
13 //==========================================================================
14
15 // The WeakShowerMEs class.
16
17 //--------------------------------------------------------------------------
18
19 // Calculate the 2 to 2 ME uG -> uG, with an overall factor of
20 // g_s^4 / 9 was removed.
21
22 double WeakShowerMEs::getTchanneluGuGME(double sHat, double tHat,
23  double uHat) {
24
25  double sH2 = sHat* sHat;
26  double sH3 = sH2 * sHat;
27  double tH2 = tHat * tHat;
28  double uH2 = uHat * uHat;
29  return (18.*sH3*uHat - 4*tH2*uH2 + 9*sHat*uH2*(tHat + 2*uHat) +
30  sH2*(-4.*tH2 + 9*tHat*uHat + 18*uH2))/(sHat*tH2*uHat);
31
32 }
33
34 //--------------------------------------------------------------------------
35
36 // Calculate the 2 to 2 ME ud -> ud, with an overall factor of
37 // g_s^4 / 9 was removed.
38
39 double WeakShowerMEs::getTchannelududME(double sHat, double tHat,
40  double uHat) {
41
42  double sH2 = sHat * sHat;
43  double tH2 = tHat * tHat;
44  double uH2 = uHat * uHat;
45  return 4.*(sH2+uH2)/tH2;
46
47 }
48
49 //--------------------------------------------------------------------------
50
51 // Calculate the 2 to 2 ME uu -> uu, with an overall factor of
52 // g_s^4 / 9 was removed.
53
54 double WeakShowerMEs::getTchanneluuuuME(double sHat, double tHat,
55  double uHat) {
56
57  double sH2 = sHat * sHat;
58  double tH2 = tHat * tHat;
59  double uH2 = uHat * uHat;
60  return 4./2.*((sH2+uH2)/tH2 + (sH2+tH2)/uH2 - 2.*sH2/(3.*tHat*uHat));
61
62 }
63
64 //--------------------------------------------------------------------------
65
66 // Calculate the 2 to 3 ME uG -> uGZ, with an overall factor of
67 // \frac{(g_s^4 * 4\pi \alpha_{em} * (lU^2 + rU^2))}{
68 // 9 * \cos^2(\theta_W) \sin^2(\theta_W)}$was removed. 69 // p1 = incoming quark, p2 = incoming gluon, p3 = outgoing gluon, 70 // p4 = outgoing Z, p5 = outgoing quark. 71 72 double WeakShowerMEs::getTchanneluGuGZME(Vec4 p1, Vec4 p2, Vec4 p3, 73 Vec4 p4, Vec4 p5) { 74 75 double p12 = p1*p2; 76 double p13 = p1*p3; 77 double p14 = p1*p4; 78 double p23 = p2*p3; 79 double p24 = p2*p4; 80 double p44 = p4*p4; 81 double p12P = (p1 + p2).m2Calc(); 82 double p13M = (p1 - p3).m2Calc(); 83 double p14M = (p1 - p4).m2Calc(); 84 double p23M = (p2 - p3).m2Calc(); 85 double p25M = (p2 - p5).m2Calc(); 86 double p35P = (p3 + p5).m2Calc(); 87 double p45P = (p4 + p5).m2Calc(); 88 double p44S = p44*p44; 89 90 double dia1 = (-4*p12*(p12* (p44 - 2*p24) -p23 * (p44 - 2*p24) +2*p13*p24)) 91 / pow2(p12P * p45P); 92 93 double dia2 = -(((p12 - p13 - p23) * (p12 * (p44 - 2*p14) 94 - p13 * (p44 - 2*p14) + 2*p14*p23)) / (p12P * p13M * pow2(p45P))); 95 96 double dia3 = (8*(p44 - 2*p12) * p12 * (p12 - p23 - p24)) 97 / (pow2(p12P) * p35P * p45P); 98 99 double dia4 = -(8*pow3(p12) + 2*pow2(p12) * (p44 - 6*p13 - 6*p14 - 6*p23 100 - 4*p24) + 4*pow2(p13) * (p44 - 2*p14 - p24) - 2*p14*p23 101 * (-p44 + 2*p14 + 2*p23 + 4*p24) + 2*p13 * (-4*pow2(p14) 102 + 2*p14 * (p44 - 3*p23 - 3*p24) + 2*p23 * (p44 - p24) + p44*p24) 103 + p12* (p44S + 4*pow2(p13) + 4*pow2(p14) + 4*pow2(p23) - 4*p14 104 * (p44 - 4*p23 - 3*p24) - 4*p13* (p44 - 4*p14 - 4*p23 - 3*p24) 105 - 2*p44*p24 + 4*p23*p24)) / (4. * p12P * p13M * p25M * p45P); 106 107 double dia5 = (-9*(2*pow3(p12) + (p13 + p23) * (-(p14* p23) 108 + p13 * (p44 - 2*p14 - p24)) + pow2(p12)* (2*p44 - 4*p13 - 3*p14 109 - 4*p23 - 3*p24) + p12 * (2*pow2(p13) + p23 * (-p44 + 4*p14 110 + 2*p23 + 3*p24) + p13 * (-2*p44 + 5*p14 + 4*p23 + 4*p24)))) 111 / (p12P * p23M* pow2(p45P)); 112 113 double dia6 = (-4*(2*pow3(p12) + pow2(p12)* (7*p44 - 4*p13 - 6*p14 114 - 2*p23 - 4*p24) + p12 * (2*pow2(p13) + 4*pow2(p14) - 2*p44*p23 115 - 3*p44*p24 + 2*p23* p24 + 2*pow2(p24) + p14 * (-8*p44 + 6*p23 + 2*p24) 116 + p13* (-7*p44 + 10*p14 + 6*p23 + 6*p24)) + 2*(pow2(p13) * (p44 117 - 2*p14 - p24) + p14* (p14* (p44 - 2*p23) + p23 * (p44 - p24) + p44*p24) 118 + p13 * (-2*pow2(p14) + p23 * (p44 - 2*p24) + p14* (2*p44 - 3*p23 119 - 2*p24) + (p44 - p24)* p24)))) / (p12P * p14M * p35P * p45P); 120 121 double dia7 = ((p12 - p13 - p14) * (p44 - 2*p23) * (p12 - p13 - p14 122 - p23 - p24)) / (p12P * p14M * p25M * p45P); 123 124 double dia8 = (9*(2*pow2((p1*p2))* (p44 - 10*p14 - 16*p23 + 4*p24) 125 + p12* (p44S + 20*pow2(p14) - 6*p44*p23 + 16*pow2(p23) 126 + p13* (-18*p44 + 28*p14 + 32*p23 - 8*p24) + 2*p44*p24 127 + 16*p23* p24 - 8*pow2(p24) + p14* (-8*p44 + 52*p23 + 4*p24)) 128 + 2*(4*pow2(p13)* (p44 - p14 - 2*p23) - p14*p23* (-3*p44 + 10*p14 129 + 8*p23 + 8*p24) + p13* (-4*pow2(p14) - 8*pow2(p23) + 4*p23* (p44 - p24) 130 + 2*p14* (2*p44 - 8*p23 + p24) + p24* (p44 + 4*p24))))) 131 / (8. * p12P * p23M * p14M * p45P); 132 133 double dia9 = (-4*p13* (2*pow2(p12) + p12* (p44 - 4*p13 - 2*p14 134 - 4*p23 - 2*p24) + 2*(p13 + p23)* (p13 + p14 + p23 + p24))) 135 / (pow2(p13M) * pow2(p45P)); 136 137 double dia10 = (4*pow3(p12) - 4*pow2(p12) * (3*p13 + 2*p14 + 2*p23 + p24) 138 + p12* (p44S + 8*pow2(p13) + 4*pow2(p14) + 4*pow2(p23) 139 - 4*p14* (p44 - 3*p23 - 3*p24) - 2*p44*p24 + 4*p23*p24 140 + p13* (-6*p44 + 20*p14 + 4*p23 + 12*p24)) + 2*(p14*p23* (p44 141 - 2*p14 - 2*p23 - 4*p24) + 2*pow2(p13)* (p44 - 2*p14 - 2*p24) 142 + p13* (-4*pow2(p14) + 2*p14* (p44 - 2*p23 - 3*p24) 143 + 2*p23* (p44 - p24) + p44*p24))) / (4. * p12P * p13M * p35P* p45P); 144 145 double dia11 = (4*p13* (p44 + 2*p13)* (p44 + 2*p12 - 2*p14 - 2*p24)) 146 / (pow2(p13M)* p25M * p45P); 147 148 double dia12 = (-9*(-2*pow3(p12) + 2*pow3(p13) - 2*p14* pow2(p23) 149 + pow2(p12)* (p44 + 6*p13 - 2*p14 + 4*p23 + 2*p24) + p13*p23 150 * (-p44 - 2*p14 + 2*p23 + 6*p24) + pow2(p13)* (p44 + 4*p23 + 6*p24) 151 - p12* (6*pow2(p13) + p23* (p44 - 4*p14 + 2*p23 + 2*p24) 152 + p13* (-2*p14 + 8*(p23 + p24))))) / (2.* p13M * p23M * pow2(p45P)); 153 154 double dia13 = -((p12 - p13 - p14)* (p44 - 2*p23)* (p44 - 2*p24)) 155 / (2. * p13M * p14M * p35P * p45P); 156 157 double dia14 = (2*(-8*pow2(p13)* (p44 - p14) - 2*pow2(p12) 158 * (p44 - 2*p14 + 2*p23 - 2*p24) + 2*p14* (-p44S - 2*pow2(p23) 159 + p23 * (p44 + 2*p14 - 2*p24) + 2*p44*p24) + p12* (p44S 160 - 4*pow2(p14) + 4*pow2(p23) + 2*p13* (3*p44 - 6*p14 - 2*p23 - 2*p24) 161 - 4*pow2(p24)) + p13* (-2*p44S + 8*pow2(p14) + 2*(p44 + 2*p23)* p24 162 + 4*pow2(p24) + p14* (-8*p44 + 8*p23 + 4*p24)))) 163 / (p13M * p14M * p25M * p45P); 164 165 double dia15 = (-9*(8*pow3(p12) + 2*pow2(p12)* (p44 - 8*p13 - 2*p14 166 - 4*p23 - 8*p24) + p12* (3*p44S + 8*pow2(p13) - 4*pow2(p14) 167 - 6*p44*p23 - 10*p44*p24 + 24*p23* p24 + 8*pow2(p24) + 4*p14 168 * (p23 + 3*p24) + 2*p13 * (3*p44 - 2*p14 + 8*p23 + 12*p24)) 169 + 2*(p14*p23 * (p44 + 2*p14 - 8*p24) + 4*pow2(p13)* (p14 170 + p23 - p24) + p13* (4*pow2(p14) - 4*pow2(p23) 171 + 4*p23* (p44 - 4*p24) - 10*p14* p24 + (3*p44 - 4*p24)* p24)))) 172 / (8. * p13M * p23M * p14M * p45P); 173 174 double dia16 = (4*p12*p23* (p44 + 2*p12 - 2*p14 - 2*p24)) 175 / (pow2(p12P) * pow2(p35P)); 176 177 double dia17 = ((p12 - p13 - p14)* (p44 - 2*p24) 178 * (p12 - p13 - p14 - p23 - p24)) / (p12P * p13M * p25M * p35P); 179 180 double dia18 = (9*(-20*pow3(p12) + 4*pow2(p12)* (4*p44 + p13 + 2*p14 181 + p23) + 2*p14*p23* (p44 + 2*p14 - 4*p23 - 2*p24) + 8*pow2(p13) 182 * (p44 - p14 - p24) + p13* (-8*pow2(p14) + 8*p44*p23 183 + 4*p14* (2*p44 - 2*p23 - 5*p24) + 6*p44*p24 - 4*pow2(p24)) 184 + p12* (p44S - 4*pow2(p14) - 14*p44*p23 + 8*pow2(p23) 185 - 8*p14* (p44 - p23 - 2*p24) - 12*p44*p24 + 12*p23* p24 186 + 4*pow2(p24) + p13 * (-22*p44 + 20*p14 - 8*p23 + 24*p24)))) 187 / (8. * p12P * p23M * p35P * p45P); 188 189 double dia19 = (-8*p13* (p44 + 2*p12 - 2*p14 - 2*p24)*(p12 - p14 - p24)) 190 / (p12P * p14M * pow2(p35P)); 191 192 double dia20 = (-8*pow3(p12) - p12* (4*pow2(p13) + 4*pow2(p14) 193 - 4*p14* (p44 - 3*p23 - 4*p24) - 4*p13* (p44 - 4*p14 - 3*p23 - 4*p24) 194 + (p44 - 2*p24)* (p44 - 2*p23 - 2*p24)) - 2*pow2(p12) 195 * (p44 - 6*p13 - 6*p14 - 4*p23 - 6*p24) + 2*p14*p23 196 * (-p44 + 2*p14 + 2*p24) + pow2(p13) * (-4*p44 + 8*p14 + 4*p24) 197 + p13* (8*pow2(p14) - 4*p14* (p44 - 3*p23 - 3*p24) - 2*(p44 - 2*p24) 198 * (2*p23 + p24))) / (4. * p12P * p14M * p25M* p35P); 199 200 double dia21 = (-9*(14*pow3(p12) + pow2(p12)* (7*p44 - 10*p13 - 30*p14 201 - 10*p23 - 22*p24) + 2*p12 * (2*pow2(p13) + 12*pow2(p14) - p44*p23 202 - 3*p44*p24 + 2*p23* p24 + 4*pow2(p24) + p13* (-4*p44 + 10*p14 203 + 6*p23 + 5*p24) + p14* (-5*p44 + 7*p23 + 16*p24)) + 2*(2*pow2(p13) 204 * (p44 - 2*p14 - p24) + p13* (-4*pow2(p14) + 2*p23* (p44 - 2*p24) 205 + 2*p14* (p44 - 3*p23 - 2*p24) + p44*p24) + p14* (-4*pow2(p14) 206 + 2*p14* (p44 - p23 - 3*p24) + p23* (p44 - 2*p24) 207 + 2*(p44 - p24)* p24)))) / (4. * p12P * p23M * p14M* p35P); 208 209 double dia22 = (-8*p13*p23* (-p12 + p23 + p24)) 210 / (pow2(p13M)* pow2(p25M)); 211 212 double dia23 = (-9*(2*pow3(p12) - pow2(p12)* (p44 + 10*p13 + 6*p14) 213 + p12* (p44S + 8*pow2(p13) + 4*pow2(p14) + 3*p44*p23 - 2*pow2(p23) 214 - p44*p24 - 4*p23 * p24 - 2*pow2(p24) + 2*p13* (6*p14 + 7*p23 + 2*p24) 215 + p14* (-2*p44 + 4*p23 + 6*p24)) - 2*(4*pow3(p13) + 2*pow2(p13) 216 * (p44 + 2*p14 + p23 - p24) + p14*p23* (2*p14 - p23 + p24) 217 + p13 * (p44S + 4*pow2(p14) + (-2*p44 + p23)* p24 - pow2(p24) 218 + p14* (-2*p44 + 4*p23 + 2*p24))))) / (4. * p13M * p23M * p25M * p45P); 219 220 double dia24 = (-2*pow2(p12)* (p44 + p13 + p23 - p24) + p12* (2*pow2(p13) 221 - p13* (p44 - 6*p14) + (p44 + 2*p14 + 2*p23 - 2*p24)* (p23 + p24)) 222 + 2*(pow2(p13)* (p44 - 2*p14 - p24) - p14*p23 * (p23 + p24) 223 + p13* (-2*pow2(p14) + p14 * (p44 - p23 - 2*p24) + p24* (p23 + p24)))) 224 / (2. * p13M * p14M * p25M* p35P); 225 226 double dia25 = (8*p12* (p44 + 2*p12 - 2*p23 - 2*p24)*(p12 - p23 - p24)) 227 / (p13M * p14M * pow2(p25M)); 228 229 double dia26 = (9*(4*pow3(p12) + 2*pow2(p13)* (p44 - 2*p14 - 3*p24) 230 - 2*pow2(p12)* (p13 + 6*p23 + 2*p24) + p12* (p44S + 6*pow2(p13) 231 - 2*p44*p14 + 4*pow2(p14) - 2*p44*p23 + 8*pow2(p23) + 3*p13 232 * (p44 + 2*p14 - 2*p23 - 2*p24) - 2*p44*p24 + 8*p23*p24) 233 + p14* (-p44S + 2*p14* (p44 - 2*p23 - 2*p24) + 4*p23* p24 234 + 4*pow2(p24)) - p13 * (p44S + 4*pow2(p14) - 4*pow2(p23) 235 + 2*p23 * (p44 - 6*p24) + 2*p44*p24 - 8*pow2(p24) 236 + p14* (-4*p44 + 2*p23 + 8*p24)))) / (4. * p13M * p23M * p14M * p25M); 237 238 double dia27 = (-9*(3*pow3(p12) - pow3(p13) + p14 * pow2(p23) 239 + pow2(p12)* (p44 - 7*p13 - 3*p14 - 6*p23 - 2*p24) - p13*p23 240 * (2*p44 + p23 - 2*p24) - pow2(p13)* (p14 + 2*p23 - 2*p24) 241 + p12 * (5*pow2(p13) + p13* (p44 + 4*p14 + 8*p23) 242 + p23 * (p44 + 2*p14 + 3*p23 + 2*p24)))) / (pow2(p23M) * pow2(p45P)); 243 244 double dia28 = (9*(2*pow3(p12) - pow2(p12)* (p44 + 4*p13 + 10*p14 245 + 8*p23 - 2*p24) + 2*pow2(p13)* (p44 - 2*p14 - p24) + p14* (p44S 246 + 2*p44*p23 + 2*pow2(p23) - 2*p14* (p44 + 6*p23) - 4*p44*p24) 247 + p12* (-p44S + 2*pow2(p13) + 8*pow2(p14) + p13 * (-5*p44 + 14*p14) 248 - 3*p44*p23 - 2*pow2(p23) + 2*p14* (p44 + 10*p23) + 6*p44*p24 249 + 2*p23* p24 - 4*pow2(p24)) + p13* (-4*pow2(p14) + pow2(p44 - 2*p24) 250 + 2*p23* (p44 + p24) + p14* (-6*p23 + 4*p24)))) 251 / (4. * p23M * p14M * p35P * p45P); 252 253 double dia29 = (-9*(6*pow3(p12) - 2*pow2(p13)* (p44 - 2*p14 + 3*p24) 254 - pow2(p12)* (p44 + 12*p13 + 2*p14 + 8*p23 + 10*p24) + p14* (p44S 255 - 2*p14* (p44 - 6*p23) - 6*p44*p23 - 2*pow2(p23) - 4*p44*p24) 256 + p13* (p44S + 4*pow2(p14) - 8*pow2(p23) - 2*p44* p24 - 4*pow2(p24) 257 - 2*p14* (2*p44 - 5*p23 + 4*p24) - 2*p23* (2*p44 + 5*p24)) 258 + p12* (6* pow2(p13) - 4*pow2(p14) + 3*p44*p23 + 2*pow2(p23) 259 + 6*p23* p24 + 4*pow2(p24) + p14 * (6*p44 - 4*p23 + 4*p24) 260 + p13* (7*p44 - 2*p14 + 16*p23 + 16*p24)))) 261 / (4. * p23M * p14M * p25M * p45P); 262 263 double dia30 = (-9*(4*pow3(p12) + 2*pow2(p12)* (p44 - 4*p13 + 2*p14 264 - 6*p24) + p12* (p44S + 4*pow2(p13) - 8*pow2(p14) - 6*p44*p23 265 + 12*pow2(p23) - 6*p44 *p24 + 4*p23* p24 + 8*pow2(p24) + 2*p14 266 * (p44 - 4*p23 + 2*p24) + 8*p13* (p44 - p14 + 2*p23 + 2*p24)) 267 - 2*(-2*p14* (p44 + 2*p14 - 3*p23)* p23 + pow2(p13)* (p44 - 2*p14 268 + 2*p24) + p13 * (-2*pow2(p14) + 8*pow2(p23) - 3*p23* (p44 - 2*p24) 269 + p24* (-p44 + 4*p24) + p14* (p44 + 6*p24))))) 270 / (2. * pow2(p23M) * p14M * p45P); 271 272 double dia31 = (-2*(p13* (p44 - 2*p14) + p14* (p44 + 2*p12 - 2*p14 273 - 2*p23 - 2*p24))* (p44 + 2*p12 - 2*p14 - 2*p24)) 274 / (pow2(p14M) * pow2(p35P)); 275 276 double dia32 = -((p44 - 2*p14)* (p12* (p44 - 2*p14) - p13* (p44 - 2*p14) 277 + 2*p14*p23)) / (2. * pow2(p14M) * p25M * p35P); 278 279 double dia33 = (-9*(4*pow3(p14) + 2*pow2(p12)* (p44 + 2*p14) 280 - 4*pow2(p14)* (p44 + p23 - 3*p24) - 2*p44*p13* p24 281 + p14* (p44S + 2*p44*p23 + (-6*p44 + 4*p13)* p24 + 8*pow2(p24)) 282 + p12 * (2*p13* (p44 - 2*p14) + p44*(3*p44 + 2*p23 - 2*p24) 283 - 2*p14* (3*p44 + 2*p23 + 6*p24)))) / (4. * p23M * pow2(p14M) * p35P); 284 285 double dia34 = (-4*(p12 - p23 - p24)* (p44*p12-2*p14*p24)) 286 / (pow2(p14M)* pow2(p25M)); 287 288 double dia35 = (-9*(2*pow2(p12)* (p44 + 2*p14) - 2*p13 * (p44 - 2*p14) 289 * (p44 - 2*p14 + 2*p23 + p24) + 2*p14* (4*pow2(p23) + 8*p23* p24 290 + p24* (-p44 + 2*p14 + 4*p24)) + p12* (2*p13* (p44 - 2*p14) 291 + p44*(p44 - 2*p23 - 2*p24) - 2*p14* (p44 + 6*p23 + 6*p24)))) 292 / (4. * p23M * pow2(p14M) * p25M); 293 294 double dia36 = (-9*(4*pow2(p12)* (p44 + 2*p14) - p13 * (p44 - 2*p14) 295 * (p44 - 2*p14 + 8*p23 + 4*p24) + p14* (-p44S - 4*pow2(p14) 296 + 16*pow2(p23) - 4*p23 * (p44 - 4*p24) - 8*p44*p24 + 16*pow2(p24) 297 + 4*p14* (p44 + 2*p23 + 4*p24)) + p12* (4*p13 * (p44 - 2*p14) 298 - 4*pow2(p14) + p44*(3*p44 + 4*p23 - 4*p24) - 4*p14* (p44 + 6*p23 299 + 6*p24)))) / (4. * pow2(p23M) * pow2(p14M)); 300 301 return dia1 + dia2 + dia3 + dia4 + dia5 + dia6 + dia7 + dia8 + dia9 302 + dia10 + dia11 + dia12 + dia13 + dia14 + dia15 + dia16 + dia17 + dia18 303 + dia19 + dia20 + dia21 + dia22 + dia23 + dia24 + dia25 + dia26 + dia27 304 + dia28 + dia29 + dia30 + dia31 + dia32 + dia33 + dia34 + dia35 + dia36; 305 306 } 307 308 //-------------------------------------------------------------------------- 309 310 // Calculate the 2 to 3 ME ud -> udZ, with the coupling between Z and d 311 // set to zero. An overall factor of 312 // \frac{(g_s^4 * 4\pi \alpha_{em} * (lU^2 + rU^2))}{ 313 // 9 * \cos^2(\theta_W) \sin^2(\theta_W)}$ was removed.
314 // p1 = incoming u, p2 = incoming d, p3 = outgoing Z,
315 // p4 = outgoing d, p5 = outgoing u.
316
317 double WeakShowerMEs::getTchannelududZME(Vec4 p1,Vec4 p2,Vec4 p3,
318  Vec4 p4,Vec4 p5) {
319
320  double p12 = p1*p2;
321  double p13 = p1*p3;
322  double p14 = p1*p4;
323  double p23 = p2*p3;
324  double p24 = p2*p4;
325  double p33 = p3*p3;
326  double p13M = (p1 - p3).m2Calc();
327  double p24M = (p2 - p4).m2Calc();
328  double p35P = (p3 + p5).m2Calc();
329  double p33S = p33*p33;
330
331  double dia1 = (-4*(2*pow3(p12) + pow2(p12) * (p33 - 2*p13 - 4*p14
332  - 2*p23 - 4*p24) + p14* (2*p14* p23 - (p33 - 2*p23)* p24)
333  + p12 * (2*pow2(p14) + 2*p24* (p13 + p23 + p24)
334  + p14* (p33 + 2*p13 + 4*p24)))) / pow2(p24M* p35P);
335
336  double dia2 = (-2*(4*pow3(p12) + 4*pow2(p12)
337  * (p33 - 2*p14 - 3*p23) + p12 * (p33S - 4*pow2(p13) + 4*pow2(p14)
338  - 6*p33*p23 + 8*pow2(p23) + 4*p13 * (p23 - p24) - 4*p33*p24 + 4*p23
339  * p24 + 4*pow2(p24) + 4*p14* (p33 + 4*p23 + 4*p24)) + 2*(-2*pow2(p14)
340  * p23 + p13* (p33 + 2*p13 - 2*p24) * p24 + p14* (-4*pow2(p23) + p23
341  * (p33 - 6*p13 - 6*p24) + 2*(p33 - p13 - 2*p24)* p24))))
342  / (p13M * pow2(p24M) * p35P);
343
344  double dia3 = (-2*(2*pow2(p12)* (p33 + 2*p13)
345  - 2*p33*p14* (p23 + p24) + 4*pow2(p13)* (2*p23 + p24) + p12
346  * (-4*pow2(p13) + p33*(p33 + 2*p14 - 2*p23) - 4*p13* (p14 + 3*p23
347  + 2*p24)) + p13* (8*pow2(p23) + 2*p24 * (-p33 + 2*p14 + 2*p24) + p23
348  * (-4*p33 + 4*p14 + 8*p24)))) / pow2(p13M * p24M);
349
350  return dia1 + dia2 + dia3;
351
352 }
353
354 //==========================================================================
355
356 } // end namespace Pythia8