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5* Revision 1.2 1996/12/04 17:39:53 cernlib
6* Version 7.22 from author
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10 ISASUSY 7.21
11 Decay Modes in the Minimal Supersymmetric Model
13 Howard Baer
14 Florida State University
15 Talahassee, FL 32306
17 Frank E. Paige
18 Brookhaven National Laboratory
19 Upton, NY 11973
21 S.D. Protopopescu
22 Brookhaven National Laboratory
23 Upton, NY 11973
25 Xerxes Tata
26 University of Hawaii
27 Honolulu, HI 96822
31 The code in patch ISASUSY of ISAJET calculates decay modes of
32supersymmetric particles based on the work of H. Baer, M. Bisset, D.
33Dzialo (Karatas), X. Tata, J. Woodside, and their collaborators. The
34calculations assume the minimal supersymmetric extension of the
35standard model. Supersymmetric grand unification is assumed by
36default in the chargino and neutralino mass matrices, although the
37user can override this by specifying arbitrary U(1) and SU(2) gaugino
38masses at the weak scale. The squark, left and right slepton and
39sneutrino masses are treated as arbitrary. Soft breaking masses are
40input for the 3rd generation; mass eigenstates are computed from
41these. Most calculations are done at the tree level, but one-loop
42results for gluino loop decays, H -> GM GM and H -> GL GL, loop
43corrections to the Higgs mass spectrum and couplings, and QCD
44corrections to H -> q qbar are included. The Higgs masses have been
45calculated using the effective potential approximation including both
46top and bottom Yukawa and mixing effects. Mike Bisset and Xerxes Tata
47have contributed the Higgs mass, couplings, and decay routines. Note
48that e+e- annihilation to SUSY particles and SUSY Higgs bosons have
49been included in ISAJET versions >7.11. The following are NOT included
50in this version:
52 * WH and ZH Higgs production mechanisms in hadronic collisions
54 * Large tan(beta) solution (tan(beta)<=10 should be chosen)
56 * Non-degenerate 1st and 2nd generation sfermions
58These and other processes may be added in future versions as the physics
59interest warrants. Note that the details of the masses and the decay
60modes can be quite sensitive to choices of standard model parameters
61such as the QCD coupling ALFA3 and the quark masses. To change these,
62you must modify subroutine SSMSSM. By default, ALFA3=.12.
64 All the mass spectrum and branching ratio calculations in ISASUSY
65are performed by the call to
70where the following are taken to be independent parameters:
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
93The variable IALLOW is returned:
95 IALLOW = 1 if Z1SS is not LSP, 0 otherwise
97All variables are of type REAL except IALLOW, which is INTEGER, and all
98masses are in GeV. The notation is taken to correspond to that of Haber
99and Kane, although the Tata Lagrangian is used internally. All other
100standard model parameters are hard wired in this subroutine; they are
101not obtained from the rest of ISAJET. The theoretically favored range of
102these parameters is
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
116It is assumed that the lightest supersymmetric particle is the lightest
117neutralino Z1. Some choices of the above parameters may violate this
118assumption, yielding a light chargino or light stop squark lighter than
119Z1SS. In such cases SSMSSM does not compute any branching ratios and
120returns IALLOW = 1.
122 SSMSSM does not check the parameters or resulting masses against
123existing experimental data. SSTEST provides a minimal test. This routine
124is called after SSMSSM by ISAJET and ISASUSY and prints suitable warning
127 SSMSSM first calculates the other SUSY masses and mixings and puts
128them in the common block /SSPAR/:
130#include ""
132It then calculates the widths and branching ratios and puts them in the
133common block /SSMODE/:
135#include ""
137Decay modes for a given particle are not necessarily adjacent in this
138common block. Note that the branching ratio calculations use the full
139matrix elements, which in general will give nonuniform distributions in
140phase space, but this information is not saved in /SSMODE/. In
141particular, the decays H -> Z + Z* -> Z + f + fbar give no indication
142that the f + fbar mass is strongly peaked near the upper limit.
144 All IDENT codes are defined by parameter statements in the PATCHY
145keep sequence SSTYPE:
147#include ""
149These are based on standard ISAJET but can be changed to interface with
150other generators. Since masses except the t mass are hard wired, one
151should check the kinematics for any decay before using it with possibly
152different masses.
154 Instead of specifying all the SUSY parameters at the electroweak
155scale using the MSSMi commands, one can instead use the SUGRA parameter
156to specify in the minimal supergravity framework the common scalar mass
157M_0, the common gaugino mass M_(1/2), and the soft trilinear SUSY
158breaking parameter A_0 at the GUT scale, the ratio tan(beta) of Higgs
159vacuum expectation values at the electroweak scale, and sign(mu), the
160sign of the Higgsino mass term. The renormalization group equations are
161solved iteratively using Runge-Kutta numerical integration, as follows:
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.
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.
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
176 (4) The 1-loop radiative corrections are computed.
178 (5) The process is then interated until stable results are
179 obtained.
181This is essentially identical to the procedure used by several other
182groups. Other possible constraints such as b-tau unification and limits
183on proton decay have not been included.
185 Patch ISASSRUN of ISAJET provides a main program SSRUN and some
186utility programs to produce human readable output. These utilities must
187be rewritten if the IDENT codes in /SSTYPE/ are modified. To create the
188stand-alone version of ISASUSY with SSRUN, run YPATCHY on isajet.pam
189with the following cradle:
191\+USE,*ISASUSY. Select all code
192\+USE,NOCERN. No CERN Library
194\+EXE. Write everything to ASM
195\+PAM. Read PAM file
196\+QUIT. Quit
198Compile, link, and run the resulting program, and follow the prompts for
199input. Patch ISASSRUN also contains a main program SUGRUN that reads
200the SUGRA parameters, solves the renormalization group equations, and
201calculates the masses and branching ratios. To create the stand-alone
202version of ISASUGRA, run YPATCHY with the following cradle:
204\+USE,*ISASUGRA. Select all code
205\+USE,NOCERN. No CERN Library
207\+EXE. Write everything to ASM
208\+PAM. Read PAM file
209\+QUIT. Quit
211To produce the documentation, run YPATCHY with the following cradle:
218This documentation is automatically appended to that for ISAJET.
220 ISASUSY is written in ANSI standard Fortran 77 except that
221IMPLICIT NONE is used if +USE,IMPNONE is selected in the Patchy cradle.
222All variables are explicitly typed, and variables starting with
223I,J,K,L,M,N are not necessarily integers. All external names such as
224the names of subroutines and common blocks start with the letters SS.
225Most calculations are done in double precision. If +USE,NOCERN is
226selected in the Patchy cradle, then the Cernlib routines EISRS1 and its
227auxiliaries to calculate the eigenvalues of a real symmetric matrix and
228DDILOG to calculate the dilogarithm function are included. Hence it is
229not necessary to link with Cernlib.
231 The physics assumptions and details of incorporating the Minimal
232Supersymmetric Model into ISAJET have appeared in a conference
233proceedings entitled
235 H. Baer, F. Paige, S. Protopopescu and X. Tata,
236 "Simulating Supersymmetry with ISAJET 7.0/ISASUSY 1.0",
238which has appeared in the proceedings of the workshop on "Physics at
239Current Accelerators and Supercolliders", ed. J. Hewett, A. White and
240D. Zeppenfeld, (Argonne National Laboratory, 1993). Detailed
241references may be found therein. Users wishing to cite an appropriate
242source may cite the above report.