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0795afa3 | 1 | * |

2 | * $Id$ | |

3 | * | |

4 | * $Log$ | |

5 | * Revision 1.2 1996/12/04 17:39:53 cernlib | |

6 | * Version 7.22 from author | |

7 | * | |

8 | * | |

9 | * This directory was created from /afs/cern.ch/user/m/mclareni/isajet/isajet.car patch isassdoc | |

10 | ISASUSY 7.21 | |

11 | Decay Modes in the Minimal Supersymmetric Model | |

12 | ||

13 | Howard Baer | |

14 | Florida State University | |

15 | Talahassee, FL 32306 | |

16 | ||

17 | Frank E. Paige | |

18 | Brookhaven National Laboratory | |

19 | Upton, NY 11973 | |

20 | ||

21 | S.D. Protopopescu | |

22 | Brookhaven National Laboratory | |

23 | Upton, NY 11973 | |

24 | ||

25 | Xerxes Tata | |

26 | University of Hawaii | |

27 | Honolulu, HI 96822 | |

28 | ||

29 | ||

30 | ||

31 | The code in patch ISASUSY of ISAJET calculates decay modes of | |

32 | supersymmetric particles based on the work of H. Baer, M. Bisset, D. | |

33 | Dzialo (Karatas), X. Tata, J. Woodside, and their collaborators. The | |

34 | calculations assume the minimal supersymmetric extension of the | |

35 | standard model. Supersymmetric grand unification is assumed by | |

36 | default in the chargino and neutralino mass matrices, although the | |

37 | user can override this by specifying arbitrary U(1) and SU(2) gaugino | |

38 | masses at the weak scale. The squark, left and right slepton and | |

39 | sneutrino masses are treated as arbitrary. Soft breaking masses are | |

40 | input for the 3rd generation; mass eigenstates are computed from | |

41 | these. Most calculations are done at the tree level, but one-loop | |

42 | results for gluino loop decays, H -> GM GM and H -> GL GL, loop | |

43 | corrections to the Higgs mass spectrum and couplings, and QCD | |

44 | corrections to H -> q qbar are included. The Higgs masses have been | |

45 | calculated using the effective potential approximation including both | |

46 | top and bottom Yukawa and mixing effects. Mike Bisset and Xerxes Tata | |

47 | have contributed the Higgs mass, couplings, and decay routines. Note | |

48 | that e+e- annihilation to SUSY particles and SUSY Higgs bosons have | |

49 | been included in ISAJET versions >7.11. The following are NOT included | |

50 | in this version: | |

51 | ||

52 | * WH and ZH Higgs production mechanisms in hadronic collisions | |

53 | ||

54 | * Large tan(beta) solution (tan(beta)<=10 should be chosen) | |

55 | ||

56 | * Non-degenerate 1st and 2nd generation sfermions | |

57 | ||

58 | These and other processes may be added in future versions as the physics | |

59 | interest warrants. Note that the details of the masses and the decay | |

60 | modes can be quite sensitive to choices of standard model parameters | |

61 | such as the QCD coupling ALFA3 and the quark masses. To change these, | |

62 | you must modify subroutine SSMSSM. By default, ALFA3=.12. | |

63 | ||

64 | All the mass spectrum and branching ratio calculations in ISASUSY | |

65 | are performed by the call to | |

66 | ||

67 | SUBROUTINE SSMSSM(XM1,XM2,XMG,XMS,XMTL,XMTR,XMLL,XMLR,XMNL | |

68 | $,XTANB,XMHA,XMU,XMT,XAT,XMBR,XAB,IALLOW) | |

69 | ||

70 | where the following are taken to be independent parameters: | |

71 | ||

72 | XM1 = U(1) gaugino mass | |

73 | = computed from XMG if > 1E19 | |

74 | XM2 = SU(2) gaugino mass | |

75 | = computed from XMG if > 1E19 | |

76 | XMG = gluino mass | |

77 | XMS = common u,d,s,c squark mass | |

78 | XMTL = left soft breaking stop mass | |

79 | XMTR = right soft breaking stop mass | |

80 | XMBR = right soft breaking sbottom mass | |

81 | XMLL = left slepton mass | |

82 | XMLR = right slepton mass | |

83 | XMNL = sneutrino mass | |

84 | XTANB = tan(beta) = ratio of vev's | |

85 | = 1/R (of old Baer-Tata notation). | |

86 | XMU = mu = SUSY Higgs mass | |

87 | = -2*m_1 of Baer et al. | |

88 | XMHA = pseudo-scalar Higgs mass | |

89 | XMT = top quark mass | |

90 | XAT = stop squark trilinear term | |

91 | XAB = sbottom squark trilinear term | |

92 | ||

93 | The variable IALLOW is returned: | |

94 | ||

95 | IALLOW = 1 if Z1SS is not LSP, 0 otherwise | |

96 | ||

97 | All variables are of type REAL except IALLOW, which is INTEGER, and all | |

98 | masses are in GeV. The notation is taken to correspond to that of Haber | |

99 | and Kane, although the Tata Lagrangian is used internally. All other | |

100 | standard model parameters are hard wired in this subroutine; they are | |

101 | not obtained from the rest of ISAJET. The theoretically favored range of | |

102 | these parameters is | |

103 | ||

104 | 50 < M(gluino) < 2000 GeV | |

105 | 50 < M(squark) < 2000 GeV | |

106 | 50 < M(slepton) < 2000 GeV | |

107 | -1000 < mu < 1000 GeV | |

108 | 1 < tan(beta) < mt/mb | |

109 | 100 < M(top) < 200 GeV | |

110 | 50 < M(HA) < 1000 GeV | |

111 | M(t_l), M(t_r) < M(squark) | |

112 | M(b_r) ~ M(squark) | |

113 | -1000 < A_t < 1000 GeV | |

114 | -1000 < A_b < 1000 GeV | |

115 | ||

116 | It is assumed that the lightest supersymmetric particle is the lightest | |

117 | neutralino Z1. Some choices of the above parameters may violate this | |

118 | assumption, yielding a light chargino or light stop squark lighter than | |

119 | Z1SS. In such cases SSMSSM does not compute any branching ratios and | |

120 | returns IALLOW = 1. | |

121 | ||

122 | SSMSSM does not check the parameters or resulting masses against | |

123 | existing experimental data. SSTEST provides a minimal test. This routine | |

124 | is called after SSMSSM by ISAJET and ISASUSY and prints suitable warning | |

125 | messages. | |

126 | ||

127 | SSMSSM first calculates the other SUSY masses and mixings and puts | |

128 | them in the common block /SSPAR/: | |

129 | ||

130 | #include "sspar.inc" | |

131 | ||

132 | It then calculates the widths and branching ratios and puts them in the | |

133 | common block /SSMODE/: | |

134 | ||

135 | #include "ssmode.inc" | |

136 | ||

137 | Decay modes for a given particle are not necessarily adjacent in this | |

138 | common block. Note that the branching ratio calculations use the full | |

139 | matrix elements, which in general will give nonuniform distributions in | |

140 | phase space, but this information is not saved in /SSMODE/. In | |

141 | particular, the decays H -> Z + Z* -> Z + f + fbar give no indication | |

142 | that the f + fbar mass is strongly peaked near the upper limit. | |

143 | ||

144 | All IDENT codes are defined by parameter statements in the PATCHY | |

145 | keep sequence SSTYPE: | |

146 | ||

147 | #include "sstype.inc" | |

148 | ||

149 | These are based on standard ISAJET but can be changed to interface with | |

150 | other generators. Since masses except the t mass are hard wired, one | |

151 | should check the kinematics for any decay before using it with possibly | |

152 | different masses. | |

153 | ||

154 | Instead of specifying all the SUSY parameters at the electroweak | |

155 | scale using the MSSMi commands, one can instead use the SUGRA parameter | |

156 | to specify in the minimal supergravity framework the common scalar mass | |

157 | M_0, the common gaugino mass M_(1/2), and the soft trilinear SUSY | |

158 | breaking parameter A_0 at the GUT scale, the ratio tan(beta) of Higgs | |

159 | vacuum expectation values at the electroweak scale, and sign(mu), the | |

160 | sign of the Higgsino mass term. The renormalization group equations are | |

161 | solved iteratively using Runge-Kutta numerical integration, as follows: | |

162 | ||

163 | (1) The RGE's are run from the weak scale M_Z up to the GUT scale, | |

164 | where alpha_1 = alpha_2, taking all thresholds into account. We use | |

165 | two loop RGE equations for the gauge couplings only. | |

166 | ||

167 | (2) The GUT scale boundary conditions are imposed, and the RGE's | |

168 | are run back to M_Z, again taking thresholds into account. | |

169 | ||

170 | (3) The masses of the SUSY particles and the values of the soft | |

171 | breaking parameters B and mu needed for radiative symmetry are | |

172 | computed, e.g. | |

173 | mu**2(M_Z) = (M_H1**2 - M_H2**2 * tan**2(beta)) | |

174 | /(tan**2(beta)-1) - M_Z**2/2 | |

175 | ||

176 | (4) The 1-loop radiative corrections are computed. | |

177 | ||

178 | (5) The process is then interated until stable results are | |

179 | obtained. | |

180 | ||

181 | This is essentially identical to the procedure used by several other | |

182 | groups. Other possible constraints such as b-tau unification and limits | |

183 | on proton decay have not been included. | |

184 | ||

185 | Patch ISASSRUN of ISAJET provides a main program SSRUN and some | |

186 | utility programs to produce human readable output. These utilities must | |

187 | be rewritten if the IDENT codes in /SSTYPE/ are modified. To create the | |

188 | stand-alone version of ISASUSY with SSRUN, run YPATCHY on isajet.pam | |

189 | with the following cradle: | |

190 | ||

191 | \+USE,*ISASUSY. Select all code | |

192 | \+USE,NOCERN. No CERN Library | |

193 | \+USE,IMPNONE. Use IMPLICIT NONE | |

194 | \+EXE. Write everything to ASM | |

195 | \+PAM. Read PAM file | |

196 | \+QUIT. Quit | |

197 | ||

198 | Compile, link, and run the resulting program, and follow the prompts for | |

199 | input. Patch ISASSRUN also contains a main program SUGRUN that reads | |

200 | the SUGRA parameters, solves the renormalization group equations, and | |

201 | calculates the masses and branching ratios. To create the stand-alone | |

202 | version of ISASUGRA, run YPATCHY with the following cradle: | |

203 | ||

204 | \+USE,*ISASUGRA. Select all code | |

205 | \+USE,NOCERN. No CERN Library | |

206 | \+USE,IMPNONE. Use IMPLICIT NONE | |

207 | \+EXE. Write everything to ASM | |

208 | \+PAM. Read PAM file | |

209 | \+QUIT. Quit | |

210 | ||

211 | To produce the documentation, run YPATCHY with the following cradle: | |

212 | ||

213 | \+USE,CDESUSY,ISASSDOC | |

214 | \+EXE | |

215 | \+PAM | |

216 | \+QUIT | |

217 | ||

218 | This documentation is automatically appended to that for ISAJET. | |

219 | ||

220 | ISASUSY is written in ANSI standard Fortran 77 except that | |

221 | IMPLICIT NONE is used if +USE,IMPNONE is selected in the Patchy cradle. | |

222 | All variables are explicitly typed, and variables starting with | |

223 | I,J,K,L,M,N are not necessarily integers. All external names such as | |

224 | the names of subroutines and common blocks start with the letters SS. | |

225 | Most calculations are done in double precision. If +USE,NOCERN is | |

226 | selected in the Patchy cradle, then the Cernlib routines EISRS1 and its | |

227 | auxiliaries to calculate the eigenvalues of a real symmetric matrix and | |

228 | DDILOG to calculate the dilogarithm function are included. Hence it is | |

229 | not necessary to link with Cernlib. | |

230 | ||

231 | The physics assumptions and details of incorporating the Minimal | |

232 | Supersymmetric Model into ISAJET have appeared in a conference | |

233 | proceedings entitled | |

234 | ||

235 | H. Baer, F. Paige, S. Protopopescu and X. Tata, | |

236 | "Simulating Supersymmetry with ISAJET 7.0/ISASUSY 1.0", | |

237 | ||

238 | which has appeared in the proceedings of the workshop on "Physics at | |

239 | Current Accelerators and Supercolliders", ed. J. Hewett, A. White and | |

240 | D. Zeppenfeld, (Argonne National Laboratory, 1993). Detailed | |

241 | references may be found therein. Users wishing to cite an appropriate | |

242 | source may cite the above report. | |

243 | ||

244 | ||

245 |