There’s Something About SUSY

1. There’s Something About SUSY m. spiropulu EFI/UofC oct 3 2002

2. Something Heavy Supersymmetry is the most plausible solution of the hierarchy (issue)  about SUSY Something Light low energy Supersymmetry is required  Something Dark might provide the missing matter of the universe if the lightest neutralino is stable Something Beautiful the symmetry between fermions and bosons Something Cool they couple with known and sizable strengths Something Exotic a component of string theory Something Urgent testable at high enough energies (now)

3. SUSY SUSY is not a (super)model SUSY is a spontaneously broken spacetime symmetry

4. bosons-fermions I Bosons: Commuting fields Integer spin particles Bose statistics Fermions: Anticommuting fields Half-integer spin particles Fermi statistics [anticommutativity ab=-ba and aa=-aa=a2=0 If a is the operator that creates an electron into a given state, a2 creates two electrons into the same state.] A superspace has extra anticommuting coordinates q

5. bosons-fermions II If we Taylor expand an electron (anticommuting field) in the extra coordinates electron field in superspace = selectron(boson) + electron(fermion) For each boson of spin J there is a fermion of spin J±½ of equal mass  This picture is not telling the whole story:SUSY is broken  The masses of the superparticles are not equal with their corresponding particles (or we would have seen them already).  So we start SUSY with a few new parameters and introduce a bunch more of what are called “soft breaking terms”: the masses of all the superparticles. Photon W,Z gluon Squark slepton quark Photino Wino,Zino gluino quark lepton quark gluino gluon squark quark equal couplings

6. general MSSM:370 parameters

7. particle content M1 M2 M3

8. supersymmetry in colliders  Tevatron mass reach: 400 – 600 GeV for gluinos, 150 – 250 GeV for charginos and neutralinos 200 – 300 GeV for stops and sbottoms  LHC reach: 1 – 3 TeV for almost all sparticles If SUSY has anything to do with generating the electroweak scale, we will discover sparticles soon. ( no experimental direct evidence for SUSY today)

9. 16 orders of magnitude puzzle What kind of physics generates and stabilizes the 16 orders of magnitude difference between these two scales hierarchy of scales 10-17 cm Electroweak scale range of weak force mass is generated (W,Z) strong, weak, electromagnetic forces have comparable strengths 10-33 cm Planck scale GN ~lPl2 =1/(MPl)2 1028 cm Hubble scale size of universe lu 1027 eV 1011 eV 10-33 eV

10. bosons-fermions IIIBose-Fermi Cancellation SUSY SM and the solution to the higgs naturalness problem (the radiative corrections to the higgs mass can not be 32 orders of magnitude larger than the higgs mass)

11. what’s up with that? unification of couplings The gauge couplings of the Standard Model converge to an almost common value at very high energy.

12. For MSUSY=1 TeV, unification appears at 3x1016 GeV unification of couplings • SUSY changes the slopes of the coupling constants

13. Proton’s (don’t) decay (fast) • In generic SUSies the proton could decay • We have measurements to the contrary effect • Satisfy this by conserving R-parity R=(-1)3(B-L)+2S

14. With R-parity conservation • 370107 (soft breaking) parameters • The end of the decay chain of all SUSY particles is the lightest supersymmetric particle (LSP) • The properties of the LSP, generally determine the signature of SUSY • LSP is stable – great dark matter candidate; In many SUSY models it also weakly interacting.

15. example of mSUGRA SUSY tanb m A squarks/sleptons gauginos higgses

16. example collider signatures

17. example backgrounds

18. more SUSY models • Gauge mediated SUSY (LSP is the gravitino) photon-lepton signatures. M1:M2:M3=1:2:7 • Anomaly mediated SUSY (LSPs are the Winos) disappearing tracks. M1:M2:M3=3:1:-8 • String inspired models

19. SUSY mass clues Upper bound (stau coanihilation) TeVII reach Red : most natural mass* D0 220 CDF 190 TeVII reach D0 TeVII reach Mass (GeV/c2) 170 CDF D0 GMSB CDF LEP2 97 LEP2 LEP2 CDF D0 LEP2 LEP2 GMSB LEP2 LEP2 LEP2 45 LEP2 DM LEP2 LEP2 * Anderson/Castano

20. the dark side of SUSY Cosmology needs sources of non-baryonic dark matter SUSies provide weakly interacting massive particles to account for the universe’s missing mass • neutralinos • sneutrinos • gravitinos  • We are closing in fast on either discovery or exclusion! • There is a good complementarity between direct, indirect, and collider searches  

21. CDMS, CRESST, GENIUS Tevatron reach LHC does the rest already excluded GLAST 0.1 < Wc < 0.3 0.025 < Wc < 1 J. Feng, K. Matchev, F. Wilczek

22. How do we detect neutralino DM at colliders? look at missing energy (LSP) signatures: QCD jets + missing energy like-sign dileptons + missing energy trileptons + missing energy leptons + photons + missing energy b quarks + missing energy etc. 

23. CDF 300 GeV gluino candidate: gluino pair strongly produced, decays to quarks + neutralinos

24. detectors

25. Booster p source Main Injector and Recycler machines Tevatron pp 14 TeV 1034 LHC (27 Km) ~2 x Tevatron (3.2 Km)

26. gluino decay path example

27. example cross sections L is the Luminosity e is the acceptance (trigger included) B is the Background s is the cross section (unit is area: the effective scattering size of a process) Total p/antip cross section is 7x10-30 m2 Unit of Barns (b) = 10-28m2 s(ppX)=70 mb Run I L ~ 1031 crossings/cm2/sec N/sec ~ sL = 7x105/sec >1 interactions per beam crossing! Cross Section for top production: s(pptt+X)=70 mb This is around 1/1010 of total N/sec ~ sL = 7x10-5/sec A couple were created/day but we only saw a small % ~100 events in 3 ys in two experiments

28. recording the physics: triggering

29. recording the physics: triggering

30. recording the physics: triggering

31. Calorimeter energy Central Tracker (Pt,f) Muon stubs Cal Energy-track match E/P, Silicon secondary vertex Multi object triggers Farm of PC’s running fast versions of Offline Code  more sophisticated selections

32. f q Missing ET + multijets(CDF) Missing Energy provides R-parity conserving SUSY signatures (R=(-1)3B+L+2S) and also appears in many other phenomenological paradigms MET + 3 jets (squarks,gluinos) MET + dileptons + jets (squarks gluinos) MET + c-tagged jets (scalar top) MET + b-tagged jets (scalar bottom,Higgs) MET + monojet (gravitino, graviton) MET + photons (gravitino)

33. Production/Decay Graphs

34. cosmic QCD gap Main Ring Use to define fiducial jets “Fake” MET MAIN RING  DETECTOR NOISE  COSMICS eliminated with a set of timing and good jet quality requirements & QCD mismeasurements

35. Standard Model Missing Energy +jets Z/W +jets MC norm to Z data  QCD MC norm to jet data  top, dibosons MC norm using theory cross section

36. Analysis HT=ET(2)+ET(3)+MET Number of High PT isolated tracks 0 >0 “blind analysis” approach where you expect your signal don’t look until you are ready

37. Optimization for SUSY

38. Z(inv) W(t) W(m,e) top Q C D comparisons around the “box”

39. “The BOX” The Box: SM Expected 76±13 Found in data 74

40. “The other BOXes” A/D SUSY boxes: SM Expected 33±7 Found in data 31

41. “The other BOXes” SUSY box C: SM Expected 10.6±1 Found in data 14

42. LIMITS

43. Candidate Event Knowledge from this analysis applied in monojet+MET analysis with RunI data that can search for associate gluino-neutralino production (also KK graviton etc).

44. susy – electroweak connection favors lighter gluinos to avoid tuning (G. Kane et al) look at models with nonuniversal gaugino masses There’s Something About the gluino mass(why we think we’ll see it sooner than later) The required cancellation is easier if the gluino mass is not “too large”.

45. chargino/neutralino trilepton signature If this signal is observed , the structure in the l+l- mass distribution will constrain the c01 and c02 masses (difficult). LHC will take it from there.

46. stop signatures Aided by improved CDF/D0 lepton coverage and heavy flavor tagging

47. colliders, SUSY and baryogenesis since colliders will thoroughly explore the electroweak scale, we ought to be able to reach definite conclusions about EW baryogenesis EW baryogenesis in SUSY appears very constrained, requiring a Higgs mass less than 120 GeV, and a stop lighter than the top quark Baryogenesis requires new sources of CP violation besides the CKM phase of the Standard Model (or, perhaps, CPT violation). B physics experiments look for new CP violation by over-constraining the unitarity triangle SUSY models are a promising source for extra phases

48. such a light stop will be seen at the Tevatron

49. SUSY@LHC • LHC is a SUSY factory. • If LHC does not find SUSY forget about (weak scale) SUSY. • High rates for direct squark and gluino production. • Model independent measurement OK- • Model independent limit DIFFICULT.

50. SUSY@LHC • Use consistent model in simulations to study different cases. • Combinatorial SUSY is the dominant background to SUSY. • Guess and scan over the most difficult points of the multi-parameter-multi-model SUSY space. • Ultimately you want to measure all the parameters of the model.