Split SUSY at Colliders

1. Durham University Split SUSY at Colliders Peter Richardson Work done in collaboration with W. Kilian, T. Plehn and E. Schmidt, Eur.Phys.J.C39:229-243,2005, hep-ph/0408088. Susy05, Durham 21st July

2. Introduction • We have had a lot of talks on Split SUSY and the theoretical motivations (or lack of them.) • I will not repeat those arguments now. • From a phenomenological point of view Split SUSY is interesting because it predicts very different collider signatures. • We need to investigate these signatures to ensure we don't miss SUSY if it’s there. Susy05, Durham 21st July

3. Introduction • In Split SUSY due to the high mass scale the only SUSY particles which can be produced in colliders are • Gluinos • Charginos • Neutralinos Susy05, Durham 21st July

4. Hadron Collider Signals • At hadron colliders the only production mechanisms are • Gluino pairs • Gaugino pairs due to the large scalar masses associated production mechanisms are negligible. • The signals from the gauginos may be observable but it is hard at both the Tevatron and LHC unless the masses are close to the LEP limits. Susy05, Durham 21st July

5. Gauginos at Hadron Colliders • For a sample Split SUSY point with • The masses are Susy05, Durham 21st July

6. Gauginos at Hadron Colliders • The dominant cross sections are • 2910fb • 1498fb • 2099fb • The trilepton signal is hard as the decay is mediated by the Z. • Other modes might be possible. Susy05, Durham 21st July

7. Gluinos at Hadron Colliders • There is however a large cross section for the production of gluino pairs. • In the Split SUSY model this only depends on the mass of the gluino. • There are three scenarios • Gluino decays promptly • Gluino decays in the detector. • Gluino is stable on collider timescales Susy05, Durham 21st July

8. Gluinos at Hadron Colliders • The first two scenarios should be similar to the models already studied, with the addition of displaced vertices in the second case. • Therefore we studied the case of the stable gluino. • There have been previous studies of this for the Tevatron Baer, Cheung, Gunion PRD 59,075002 and we used many of the same ideas. Susy05, Durham 21st July

9. Gluinos at Hadron Colliders • When the gluino hadronizes it will form either • Glueball-like state • Mesonic state • Baryonic state • General opinion is that • Rg is the lightest state • Rqqq is unlikely to be directly produced. Susy05, Durham 21st July

10. Gluinos at Hadron Colliders • We included the production of these states in the cluster hadronization model of HERWIG. • Due to the modelling of the hadronization the relative probability, ,, of producing the gluonic and mesonic R-hadrons is undetermined. • This parameter and the gluino mass determined the phenomenology at hadron colliders. Susy05, Durham 21st July

11. Gluinos at Hadron Colliders • There are two signals we considered • Charged R-hadron production • Signal much like stable weakly interacting particles. • R-hadron looks like a muon but deposits more energy in the calorimeter. • Arrives later at the muon chambers due to the mass. • Can measure the mass using the time-delay. Susy05, Durham 21st July

12. Gluinos at Hadron Colliders • Neutral R-hadron production • Some energy loss in calorimeter • Monojet type signals • In both cases we used HERWIG interfaced to AcerDet for fast detector simulation together with simple modelling of the R-hadron interactions based on Baer, Cheung, Gunion PRD 59,075002. Susy05, Durham 21st July

13. Energy Loss • We used a range of different models of the hadronic cross section to estimate the uncertainty of this simple approach. • The more accurate results of Kraan hep-ex/0404001 are within this range. Susy05, Durham 21st July

14. Energy Loss Susy05, Durham 21st July

15. Charged R-hadrons • Applied a simple efficiency for reconstruction for 85% as with muons. • Required the charged R-hadron to have transverse momentum greater than 50 GeV. • The time delay at the muon detectors between 10ns and 50 ns. • Required the observation of 10 events. Susy05, Durham 21st July

16. Charged R-hadrons Susy05, Durham 21st July

17. Mass Measurement Susy05, Durham 21st July

18. Mass Measurement Susy05, Durham 21st July

19. Neutral Searches • The neutral search was based on an optimised analysis using the same cuts as the experimental analysis in Barr et. al. JHEP 0303:045,2003. • This requires at least 100 GeV missing transverse energy and one jet with transverse momentum greater than 100 GeV which should be sufficient to pass the trigger. Susy05, Durham 21st July

20. Neutral Searches Susy05, Durham 21st July

21. LHC • Charged R-hadron signal can be seen up to above 2 TeV. • Neutral signal is worse. • Needs more detailed experimental study. • There have been other studies • Hewett et. al. JHEP 0409:070,2004 considered the charge flipping which we neglected. • STOPPING GLUINOS. • Arvanitaki et. al. hep-ph/0506242 consider gluinos which are stopped in the detector. Susy05, Durham 21st July

22. ILC • Chargino and Neutralino sector is the same as usual. • Masses can be extracted using standard techniques. • The integrating out of the heavy degrees of freedom leads to different neutral/chargino Yukawa couplings. Susy05, Durham 21st July

23. ILC • Assume mass measurements to 0.5% • Cross sections with statistical error only. • Fit the anomalous Yukawa couplings. • At larger values possible to distinguish weak-scale MSSM from SpS. Susy05, Durham 21st July

24. Conclusions • Split SUSY has different and interesting experimental signals. • Should be observable at the LHC for gluino masses less than 2 TeV. • At a linear collider can be verified by looking at gaugino yukawa couplings. • In general looking at the gaugino yukawa couplings would be an interesting test of the MSSM. Susy05, Durham 21st July