Les Houches Project on a Natural SUSY Scan

How to do this

On uaf in /home/users/fkw/generators/susy/ there are two subdirectories: softsusy-3.3.8 susyhit-1.3 and a README.sezen file.

First go into the softsusy-3.3.8 directory. Check out the README.fkw there. It tells you how to take a file that specs the parameters, and create a spectrum file.

Second go into susyhit-1.3 directory. Use the spectrum file you made, and produce from it a full fledged slha file, including all the BRs. Check out the README.fkw to see how.

Input to softsusy-3.3.8

At the softsusy stage, we only vary one parameter: mu This is set to 100,200,300,400,500GeV. The corresponding slha files are on the webserver

Block MODSEL                 

# Select model  1    0                        

# Low energy MSSM Block SMINPUTS               

# Standard Model inputs  1   1.27908953E+02       

# alpha_em^(-1)(MZ) SM MSbar  2   1.16637000E-05       

# G_Fermi   3   1.18400000E-01       

# alpha_s(MZ) SM MSbar  5   4.19000000E+00       

# mb(mb) SM MSbar  6   1.73300000E+02       

# mtop(pole)  7   1.77700000E+00       

#  Mtau      Block MINPAR                 

# Input parameters  3   1.00000000E+01       

# tanb Block EXTPAR  0   -1        

# EWSB  1   1.00000000E+03      

# MG1  2   1.00000000E+03      

# MG2  3   1.00000000E+03      

# MG3  11  2.00000000E+03      

# At   12  0.00000000E+00      

# Ab   13  0.00000000E+00      

# Atau  23  1.00000000E+02      

# mu  26  1.00000000E+03      

# MA  31  5.00000000E+03      

# Ml1  32  5.00000000E+03      

# Ml2  33  5.00000000E+03      

# Ml3  34  5.00000000E+03      

# MR2  35  5.00000000E+03      

# MR2  36  5.00000000E+03      

# MR3  41  5.00000000E+03      

# Mq1  42  5.00000000E+03      

# Mq2  43  5.00000000E+02      # Mq3  44  5.00000000E+03      # Mu1  45  5.00000000E+03      # Mu2  46  1.20000000E+03      # Mu3  47  5.00000000E+03      # Md1  48  5.00000000E+03      # Md2  49  1.50000000E+03      # Md3 Block SOFTSUSY               # SOFTSUSY specific inputs          2   0                    # quark mixing option 

Table of higgsino masses vs mu

All masses and mass differences are in GeV?

Checked the neutralino and chargino mixing matrices for mu=100,500 and they don't differ in substance, i.e. are as expected.

Quick orientation of stop and sbottom BRs

pick mu = 200GeV and gain some quick orientation.

angles in degree. mStop = 477GeV, mSbottom = 536GeV To keep BRs for gluino and sb2 from going into NAN, I stay away from angles that are exactly 0 or 180 degrees. Instead am using costheta = 0.999975 and sintheta = 2.2e-3 or some such.

I don't have to fill in the complete set of options, because the picture is already obvious.

In fact, staring at this makes it pretty obvious that there isn't much diversity from an experimental standpoint. Let me try to summarize what I think is going on.

• Assumption Set 1:
  • pick gluino, st2, sb2 and everything else high enough in mass that they don't matter
  • higgsinos are the only charginos/neutralinos that matter
    • they are fine split by a couple GeV? or so because of M1,M2 >> mu
  • pick stop and sbottom masses to be degenerate enough to not allow sb to st W nor st to sb W decays.
  • no compressed spectra: i.e. pick st, sb masses significantly larger than mu + mTop.
    • anytime you have compressed spectra the detailed kinematics tends to influence the sensitivity significantly.
• Conclusions for this set of assumptions:
  • There's really only 5 numbers that matter for the experimental reach
    • cross section into events with 2 top + 2 higgsino
    • cross section into events with 1 top + 1 b + 2 higgsinos
    • cross section into events with 2 b + 2 higgsinos
    • the average mass between st and sb
    • the value of mu
    • the last two matter only mildly. In fact, to 1st order only the difference between the colored masses and mu matters.
  • This means practically that we can get away with a very coarse scan, as long as we generate these 3 SMS.
    • T2tt i.e. 2 top + 2 LSP
    • T2bb i.e. 2 b + 2 LSP
    • T2tb i.e. 1 top + 1 b + 2 LSP (we are missing this SMS).
    • Having these 3 SMS we can compute whether or not a given model is excluded (as long as it follows the Set 1 assumptions).
    • Having a modest number of grid points within this range is good enough to prove that this indeed works.
• Assumption Set 2:
  • Everything the same as for set 1 except:
    • stop and sbottom masses are no longer degenerate. I.e. abs(mStop - mSbottom) >> mW
• Conclusions for Set 2:
  • This adds additional fnal states: * 2 top or 2b or 1b 1 top + 2 higgsinos as before * for each of the above + 1 W or + 2 W in addition to the final state. * the extra W's must come from somewhere, i.e. these final states are cross section suppressed. * they thus probably don't matter much once hadronic and 1-lepton searches are combined.
• Assumption Set 3:
  • Same as for set 1 except:
    • allow compressed spectra.
• Conclusions for Set 3:
  • all hell breaks loose. Whether or not a given model is excluded depends on the details of the BRs and spectrum.
• Assumption Set 4:
  • Same as for set 1 except:
    • allow compressed spectra AND abs(mStop - mSbottom ) >> mW
• Conclusions for Set 4:
  • Here the final states with the extra W's become crucial. There'll be cases where sensitivity exists only because of them.

Overall, it seems to me that Set 3 and Set 4 are the most interesting here, and we should try to generate a brought variety of them. Whereas, we can probably prune the total set of models to a smaller, more manageable number by being coarse in the region of parameter space of Set 1.

Following set of SLHA files for the scan are generated

Current location of the SLHA files: Werner Porods home directory.

Following text describes the structure of the directories and what is contained inside them.

The following archives contain several SLHA input files for the scan range. In all files the following parameters can take the foolowing values (all masses in GeV? )

• m_stop_1: 150, 200, 300, 400, 500, 600, 700, 800, 900, 1000
• m_sbottom_1: 150, 200, 300, 400, 500, 600, 700, 800, 900, 1000 (see however the comment below)
• mu: 100, 200, 300, 400, 500
• tan(beta): 10, 50
• theta_sbottom: 0, 45, 90 degree (comment: if theta_stop = 90 thne also theta_sbottom is fixed to 90 degree)

The archives differ in the combinations of therea_stop and m_gluino

1. input_run1.tgz
   • m_gluino: 2000
   • theta_stop: 0, 45, 90 (see also comment for theta_sbottom)
     • in case of a theta_stop = 0 one has a pure left-stop in the game and thus, also the left-sbottom. We compute the mass of sbottom_L using the tree level mass relation. IN case that this mass is below m_sbottom_1 e have to flip the ordering of the sbottom-masses and change the mixing matrix accordingly. The corresponding file-names have as addiotional string '_flipped' before the '.spc'. The files namges contain all relevant information e.g. Spheno_mst0150_tht045_msb0150_thb090_mu100_mg2000_tb10.spc, implies m_stop = 150GeV, theta_stop = 45, m_sbottom = 150 GeV? , theta_sbottom = 90, mu = 100, m_gluino - 2000 and tan(beta) = 10
2. Input_run1_optional.tgz
   • m_gluino:2000
   • theta_stop: 135,180 (see also comment for theta_sbottom and the one above replacing theta_stop =0 by theta_stop = 180)
3. input_run2.tgz
   • m_gluino: 1000
   • theta_stop: 0.45, 90 (see also commet for theta_sbottom and theta_stop above)
4. input_run2_optional.tgz
   • m_gluino: 1000
   • theta_stop: 135, 180 (see also comment for theta_sbottom and theta_stop above)
5. input_run3.tgz
   • m_gluino: 750
   • theta_stop:
   • theta_stop: 0.45, 90 (see also commet for theta_sbottom and theta_stop above)
6. input_run3_optional.tgz
   • m_gluino: 750
   • theta_stop: 135, 180 (see also comment for theta_sbottom and theta_stop above)

-- FkW - 2013/06/23