Changes between Version 2 and Version 3 of MSSM


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Timestamp:
02/21/10 17:24:57 (8 years ago)
Author:
BenjF
Comment:

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  • MSSM

    v2 v3  
    1111One popular Beyond the Standard Model theory is the Minimal Supersymmetric Standard Model (MSSM). Its main features are to link bosons with fermions and unify internal and external symmetries. Moreover, it allows for a stabilization of the gap between the Planck and the electroweak scale and for gauge coupling unification at high energies, provides a dark matter candidate as the lightest supersymmetric particle and appears naturally in string theories. However, since supersymmetric particles have not yet been discovered, supersymmetry must be broken at low energies, which makes the superpartners massive in comparison to their Standard Model counterparts. 
    1212 
    13 Our !MSSM implementation in !FeynRules is the most general one in a sense that it is keeping all the flavour-violating and helicity-mixing terms in the Lagrangian and also all the possible additional CP-violating phases. This yields thus 105 new free parameters. In order to deal in a transparent way with all of those, our implementation will follow the commonly used universal set of conventions provided by the Supersymmetry Les Houches Accord, except for some minor points (see instructions below). 
     13Our MSSM implementation in FeynRules is the most general one in a sense that it is keeping all the flavour-violating and helicity-mixing terms in the Lagrangian and also all the possible additional CP-violating phases. This yields thus 105 new free parameters. In order to deal in a transparent way with all of those, our implementation will follow the commonly used universal set of conventions provided by the Supersymmetry Les Houches Accord, except for some minor points (see instructions below). 
    1414 
    1515   * [http://www.slac.stanford.edu/spires/find/hep/www?rawcmd=FIND+A+NILLES+AND+D+1983+and+j+phys+rept&FORMAT=www&SEQUENCE= Phys.Rept.110 (1984) 1]: H. P. Nilles, ''Supersymmetry, Supergravity and Particle Physics''.  
     
    2121=== Model files & extensions === 
    2222 
    23 '''The !MSSM implementation:''' 
    24    * Main !FeynRules files (as a tar-ball): [attachment:susy1.0.1.tgz susy1.0.1.tgz (05.07.09)].  
     23'''The MSSM implementation:''' 
     24   * Main FeynRules files (as a tar-ball): [attachment:susy1.0.1.tgz susy1.0.1.tgz (05.07.09)].  
    2525   * Example of parameter file: [attachment:FRT_paramcard.dat SPS 1a], with the corresponding [attachment:sps1a.rst restriction file].  
    26    * Parameter file translator, SLHA format ↔ !FeynRules format: [attachment:translator1.1.8.tgz Translator1.1.8].  
     26   * Parameter file translator, SLHA format-FeynRules format: [attachment:translator1.1.8.tgz Translator1.1.8].  
    2727   *  
    2828   * Example of a Mathematica® notebook loading the model and the parameters: [attachment:SUSY.nb SUSY.nb].  
     
    3434=== Instructions === 
    3535 
    36 The !MSSM is implemented in '''unitary gauge'''. 
     36The MSSM is implemented in '''unitary gauge'''. 
    3737   * The switch <font color="saddlebrown" class="WYSIWYG_COLOR">FeynmanGauge</font> (future devlopments) must thus be set to <font color="saddlebrown" class="WYSIWYG_COLOR">False</font>,  
    3838   * The flag <font color="saddlebrown" class="WYSIWYG_COLOR">$sWScale</font> can be set to the value <font color="saddlebrown" class="WYSIWYG_COLOR">"weak" </font>or <font color="saddlebrown" class="WYSIWYG_COLOR">"susy"</font>, depending on the scale to which the electroweak parameters have to be evaluated,  
     
    5050 
    5151In order to validate our implementation, we have performed the following tests. 
    52    * '''FeynArts model file generated by !FeynRules''': recalculation of the helicity amplitudes related to the hadroproduction of a pair of supersymmetric particles and comparison with the three references:  
     52   * '''FeynArts model file generated by FeynRules''': recalculation of the helicity amplitudes related to the hadroproduction of a pair of supersymmetric particles and comparison with the three references:  
    5353      * [http://www.slac.stanford.edu/spires/find/hep/www?rawcmd=FIND+A+B+FUKS+AND+T+SQUARK+and+t+flavour&FORMAT=www&SEQUENCE= Nucl. Phys. B787 (2007) 1]: G. Bozzi, B. Fuks, B. Herrmann and M. Klasen, ''Squark and gaugino hadroproduction and decays in non-minimal flavour violating supersymmetry.''  
    5454      * [http://www.slac.stanford.edu/spires/find/hep/www?rawcmd=FIND+A+B+FUKS+AND+t+gauge-mediated&FORMAT=www&SEQUENCE= Nucl. Phys. B810 (2009) 266]: B. Fuks, B. Herrmann and M. Klasen, ''Flavour Violation in Gauge-Mediated Supersymmetry Breaking Models: Experimental Constraints and Phenomenology at the LHC.''  
    5555      * B. Fuks '', private communication''.  
    56    * '''Comparison of the built-in !CalcHEP (CH-ST) and !MadGraph (MG-ST) model files with the !FeynRules generated ones, MG-FR and CH-FR,''' through the calculation of various quantities. For each implementation, we have fixed all the parameters to those of <font color="saddlebrown" class="WYSIWYG_COLOR">SPS 1a</font> and set the<font color="saddlebrown" class="WYSIWYG_COLOR"> widths of the particles to zero</font> *.*  
     56   * '''Comparison of the built-in CalcHEP (CH-ST) and MadGraph (MG-ST) model files with the FeynRules generated ones, MG-FR and CH-FR,''' through the calculation of various quantities. For each implementation, we have fixed all the parameters to those of <font color="saddlebrown" class="WYSIWYG_COLOR">SPS 1a</font> and set the<font color="saddlebrown" class="WYSIWYG_COLOR"> widths of the particles to zero</font> *.*  
    5757      * '''1 &rarr; 2''' decay widths for all Standard Model particles and their superpartners (320 channels), for MG-FR and MG-ST: [attachment:decay.tgz decay.tgz].  
    58       * '''2 &rarr; 2''' cross sections related to the production of any pair of particles from a Standard Model initial state of <font color="saddlebrown" class="WYSIWYG_COLOR">2x600 !GeV</font> and<font color="saddlebrown" class="WYSIWYG_COLOR"> 2x1000 !GeV</font>, and for the four implementations CH-ST, CH-FR, MG-ST and MG-FR. <font color="saddlebrown" class="WYSIWYG_COLOR">CalcHEP is run in unitary gauge. </font>  
     58      * '''2 &rarr; 2''' cross sections related to the production of any pair of particles from a Standard Model initial state of <font color="saddlebrown" class="WYSIWYG_COLOR">2x600 GeV</font> and<font color="saddlebrown" class="WYSIWYG_COLOR"> 2x1000 GeV</font>, and for the four implementations CH-ST, CH-FR, MG-ST and MG-FR. <font color="saddlebrown" class="WYSIWYG_COLOR">CalcHEP is run in unitary gauge. </font>  
    5959         * Leptonic initial states (twice 149 channels): [attachment:ee600.jpg ee600.jpg], [attachment:ee1000.jpg ee1000.jpg], [attachment:tautau600.jpg tautau600.jpg], [attachment:tautau1000.jpg tautau1000.jpg], [attachment:enu600.jpg enu600.jpg], [attachment:enu1000.jpg enu1000.jpg], [attachment:taunu600.jpg taunu600.jpg], [attachment:taunu1000.jpg taunu1000.jpg].  
    6060         * Quark initial state (twice 181 channels): [attachment:uu600.jpg uu600.jpg], [attachment:uu1000.jpg uu1000.jpg], [attachment:dd600.jpg dd600.jpg], [attachment:dd1000.jpg dd1000.jpg], [attachment:bb600.jpg bb600.jpg], [attachment:bb1000.jpg bb1000.jpg], [attachment:bt600.jpg bt600.jpg], [attachment:bt1000.jpg bt1000.jpg].