BEYOND THE STANDARD MODEL AT THE TEVATRON? OR, WHAT YOU SEE OFTEN DEPENDS ON WHAT YOU LOOK FOR Gordy Kane Fermilab Oct 2006

Introduction/perspectives (More general) supersymmetry signatures Is it susy?

String theory is exciting because it’s a framework that addresses how to explain why the SM particles and forces are what they are, it incorporates all the forces in a quantum theory, and it addresses many questions the SM cannot address Why and how is the electroweak symmetry of the SM broken? Why is parity not conserved? What is the dark matter? How does the matter asymmetry originate? Why are there families of particles? How is supersymmetry broken? How does the hierarchy between the weak scale and the string scale or gravity arise? What caused inflation Most other approaches to physics BTSM address few or none of these, and have little or no theoretical motivation

The natural scale for string theory is at or above the unification scale, of order GeV– but we need to connect it with experiment Supersymmetry stabilizes our scale against quantum corrections from this high scale, in a perturbative theory that allows us to relate physics at the two scales – and –It provides a candidate for dark matter –It may explain electroweak symmetry breaking perturbatively –It implies accurate unification of force strengths so the idea of a simple, unified description of forces can make sense –It provides ways to explain the matter asymmetry – let’s us make string based predictions for LHC and Tevatron and other low scale data (EDMs, DM, rare decays…) – let’s us extrapolate collider and other low scale data to the string scale and get clues to stringy physics – is suggested by string theory solutions SO WE CAN TRY TO STUDY AND TEST STRINGY PHYSICS IN A SUPERSYMMETRIC WORLD

Let’s assume the world is simple and understandable, and that we can answer or at least address all the basic questions – of course it could be more complicated, but why give up the simple and comprehensive picture until we are forced to?? So – assume we live in the best of all possible string vacua – supersymmetric one(s) – optimism about discoveries and understanding well justified

General picture suggests/predicts light Higgs boson, lighter than about 200 GeV in a general supersymmetric theory -- two independent (indirect) experimental confirmations No deviation from SM predictions at LEP unless superpartners directly seen Unification of gauge couplings at high scale Cold dark matter swimps OK! Main test – superpartners exist around EW scale

So default should be to focus resources on supersymmetry searches

Are there light superpartners to detect at Tevatron?

Assume ILC with total energy 500 GeV can produce new particles – then very likely Tevatron can too  at FNAL no need to argue for light superpartners Tevatron can also produce light gluinos, up to few hundred GeV – good theoretical motivation for light gluinos [Theory motivated benchmark models and superpartners at the Tevatron. G.L. Kane, Joseph D. Lykken, Stephen Mrenna, Brent D. Nelson, Lian-Tao Wang, Ting T. Wang, Phys.Rev.D67:045008,2003; hep-ph/ , and also recent stringy model building]G.L. KaneJoseph D. LykkenStephen MrennaBrent D. NelsonLian-Tao WangTing T. Wang

Are there light superpartners to detect at Tevatron? Assume ILC with total energy 500 GeV can produce new particles – then very likely Tevatron can too  at FNAL no need to argue for light superpartners Tevatron can also produce light gluinos, up to few hundred GeV – good theoretical motivation for light gluinos [Theory motivated benchmark models and superpartners at the Tevatron. G.L. Kane, Joseph D. Lykken, Stephen Mrenna, Brent D. Nelson, Lian-Tao Wang, Ting T. Wang, Phys.Rev.D67:045008,2003; hep-ph/ , and also recent stringy model building]G.L. KaneJoseph D. LykkenStephen MrennaBrent D. NelsonLian-Tao WangTing T. Wang If LHC finds light superpartners that could have been found at the Tevatron…

Parameters? -- So far no parameters with dimensions of mass calculable from first principles – in SM must measure all quark and lepton masses, and higgs mass (or vev) – same in supersymmetry Supersymmetry full Lagrangian quantum field theory – gauge couplings same as for the SM, known – families, so more possible (complex) masses than in SM, so more parameters Imagine high scale underlying theory – still can’t calculate masses, but high scale theory has few mass parameters – then can calculate all the mass parameters of supersymmetry in terms of those few Also, any particular physics only sensitive to subset of parameters Also, same parameters at hadron colliders, rare decays, DM …

Are there problems with this picture? Could have found effects by now in g µ -2, FCNC – most do show σ effects – squarks, sleptons in loops so perhaps clue that these are heavier than ~ 1 TeV – note recent Becher and Neubert analysis of b  s γ “ This opens a window for significant New Physics contributions in rare radiative B decays” EDMs too small? – problem only if assume phases random parameters ~1, but that’s unlikely if an underlying theory – would be great if one could learn all observable phases ~0 Given experimental constraints, and radiative EWSB for Higgs physics, should have found m h  100 GeV – serious fine tuning?? -- only in MSSM -- LEP limits not general -- fine tuning smaller if light gluinos -- accident? – e.g. 4sin 2 θ W -1 << 1 for sin 2 θ=0.23 Maybe, but not clear there are any problems

How do we find a signal BTSM ?? The experts are experimenters + SM theorists, simulators They will get it right wherever they look carefully Many places to look – where you look is crucial

What are good signatures of supersymmetry? (Datta, GK, Toharia hep-ph/ ) Should be very phenomenological, unbiased –Form of supersymmetry need not be MSSM – will contain MSSM so MSSM spectrum will be there, but MSSM constraints need not be –Do NOT impose EWSB, lower limit on DM relic density, rare decays, g-2, etc – all are very model dependent –No general lower limit on LSP mass exists –Don’t assume gaugino mass unification (7-2-1at low scale) -- not so likely at high scale in string theories, can have different RGE running, puts artificial lower limit on gluino mass These don’t directly affect search for BTSM signal, but may lead one to not focus on all good signals

Some very good signatures – presumably Run2 papers on all of them by now… Same-sign dileptons, or same-sign t or b -- but suppressed if charginos heavy, or if LH squarks > gluinos > RH squarks, or gluinos  g+LSP [HK 1984, TW] Trileptons -- but suppressed if N 2 decays radiatively or to sneutrino + neutrino Large missing transverse energy b-rich events if stop or sbottom lighter than other squarks Recent string model building suggests light gaugino masses (gluinos, charginos, neutralinos) – all could be in tevatron range with few fb -1

But if the more obvious signals are not there, the events more into different categories

Note single lepton and trijet signals more robust

Is it susy?

(Datta, GK, Toharia, hep-ph/ ) Can we tell various models with KK excitations, etc from susy after a signal is found? Can we tell susy from something we haven’t yet thought of? At hadron colliders? I think so…

Cross sections determined by mass, spin, charges – measure mass kinematically, and measure or know charges for a given model  spin So can distinguish spin 0, ½, 1,… and therefore models, at hadron collider [measure top spin same way  spin ½] Basic method robust, may need work for some mass patterns

Also, BR -- fix spectrum as same for MSSM, UED, and fix gluino decay BR to be same as gluon recurrence BR Then: MSSMUED And signature fractions: OS 2 lepton SS 2 lepton trilepton

So experimental program whose goals are physics BTSM should strongly emphasize Find superpartners if they are there – look broadly and systematically Lab dark matter detectors Signals that require new weak scale particles or significantly constrain approaches -- EDMs -- FCNC rare decays or those with large non-SM windows (g-2, µ->e γ, etc)

What if LHC makes discoveries first? Tevatron data often adds info, probes different info

Suppose a susy signal – very difficult to deduce nature of LSP at hadron collider – leptons soft – flippers, etc – assume squark and gluino masses measured Several ways to remove higgsino/wino LSP degeneracy by observing other channels, e.g. using Tevatron data! Note quark partons, better at tevatron Light gluino Light squark

Good theoretical and phenomenological motivation for light superpartners, particularly gluinos, charginos, neutralinos – in Tevatron range Best signatures not known because cannot calculate masses from first principles yet – so examine all signatures thoroughly

CPV AT HADRON COLLIDERS Doesn’t matter if initial state CP invariant – just calculate SM baseline Similarly, doesn’t matter if detector invariant Can study with leptons in final state – study triple scalar products etc Can use jet charges for light quarks (u,d) and for gluons to greatly increase statistics – done at LEP – I am confident it can be done with appropriate jets at hadron colliders