Vectorlike Confinement and its Signatures at the LHC

1. Vectorlike Confinement and its Signatures at the LHC Can Kılıç work done with Takemichi Okui and Raman Sundrum arXiv: 0906.0577

2. Introduction • LHC coming, expectations shaped by the hierarchy problem. • Known solutions constrained by experiment. Possible scenarios. • Concept of meso-tuning. Impact on discovery potential at the LHC. Part of NP may be accessible. Need guiding principle. • Theoretical simplicity / safety from PO at low energy. (rich phenomenology at higher energies) • Define Vectorlike Confinement: • new vectorlike fermions • a new strong gauge force • (very weak interactions relevant for decay) • LHC phenomenology dominated by hyperhadrons.

3. Attractive features • Precedent: Analogy to QED + low energy QCD. Signatures: pair production, resonance. can decay, is stable up to weak interactions. Mirrored in VC. • Safety: “Gauge-mediation” is flavor blind. Mass scale set by confinement, separated from EWSB. • Rich phenomenology: A minimal theory naturally gives rise to an array of distinct collider signatures (multi GB, CHAMPs, other exotica), some new features.

4. Deja-Vu? • Not TC. Different motivation / structure / signatures. • TC must have chiral fermions for EWSB, which impacts PEW. • Generating masses leads to flavor problems in TC. • Connected in the bigger picture? • Can use same tools (analog computer) • VC as a strawman model

5. Outline • Theoretical Structure • Phenomenological Lagrangian • Representative Case Studies • A subtlety in the minimal model • CHAMPs and EW gauge bosons • Multijets • R Hadrons • DM, cascades, other possibilities • Conclusion

6. A Brief History of QCD • Begin by strongest interactions (u,d only) • Focus on ,ρ • Confinement, flavor symmetry • (Pseudo) Goldstones: transform in adjoint of flavor group. • ’s and baryons stable • ρ lightest state, decays to 2 , becomes special once we add U(1)em

7. A Brief History of QCD Consequences of turning on U(1)em (qu = 2/3 , qd = -1/3) • ρ is the lightest meson which can be interpolated by • ρ/γ mixing • resonant production •  charges • anomalous,

8. A Brief History of QCD • Both up and down number still conserved, stable, turn on weak interactions. (4-fermion operators) • Up and down numbers no longer conserved, baryon number still conserved. • Need light particles for to decay, introduce non-strongly interacting particles. induces as well as neutron decay (proton stable)

9. Could Lightning Strike Twice?From a simple UV theory to rich IR Physics • Hypercolor: SU(N) gauge theory with F vectorlike flavors in the fundamental representation. Scale ΛHC. (F chosen such that theory confines) • Flavor symmetry Conserved number for each flavor. • (Pseudo)Goldstones: we consider • and baryons stable at this point • is the lightest meson, decays to 2 , becomes special as we turn on SM.

10. Could Lightning Strike Twice?From a simple UV theory to rich IR Physics • Turn on hyperfermions charged under SM. • SM breaks many of the flavor numbers, introduce “species” of hyperfermions. (e.g. color triplet) • Changes running of SM couplings, for one species in to avoid QCD Landau-pole in the UV. • interpolated by can mix with SM gauge bosons, resonant production. • charges. • Radiative masses for • Anomaly of can decay with zero species number ( - short) • Species number unbroken. Leads to stable .

11. Could Lightning Strike Twice?From a simple UV theory to rich IR Physics • - long stable, SM charged. UV physics analogous to weak interactions can decay them to non-hypercolored particles (SM). or breaks species numbers. • Straightforward to break hyperbaryon number as well. Model dependent. • Models constrained, there must exist a SM final state with matching quantum numbers. (simple choice: GUT-like representations)

12. Constraints (I) • Vectorlike fermions: Confinement preserves vector part of flavor symmetry, SM unaffected. Choose quantum numbers such that Yukawa terms with the SM Higgs forbidden, PEW safe. • “Gauge mediation” means that flavor violating effects from renormalizable part of the VC theory suppressed relative to the SM by loop factor. • Nonrenormalizable operators can induce flavor violating SM operators. For generic coefficients, need M ~ O(104) TeV. For special flavor structure, M can be anything consistent with EFT description.

13. Phenomenological Lagrangian The • Not literal EFT. Large N estimates. • Mixing/production: where • Shift induces • Production from gluons • Dominant decay from where • Rare decays

14. Phenomenological LagrangianMasses Three sources of mass: • SM gauge groups break the flavor symmetry • Fundamental hyperquark masses • From EWSB

15. Phenomenological Lagrangian-short and -long • Chiral anomalies induce those with no net species numbers decay to a pair of gauge bosons. Here • Higher dimensional operators decay with nonzero species number.

16. Phenomenological Lagrangian-long Decay Length • Current-current decays suppressed by fermion masses • Scalar-scalar decays are less suppressed • Prospects for visibility tied to flavor structure.

17. Phenomenological LagrangianOverview

18. Constraints (II) • Many exotic states with SM charges. Ocean bottom searches for charged particles: Plenty of room between bounds from cosmology and flavor. • Fermion compositeness: worst case is eeqq , OK as long as • -short decays at the Tevatron OK as long as • Resonant production and decay to SM: electroweak has too small cross section/branching fraction, color is interesting – search strategy in a few slides. • Singlet are axions. For we have (safe for SN cooling, beam dump) decay not observable not observable (BF too small)

19. A Few Simple ModelsSU(2) Doublet • representation • Spectrum contains with • , bleak collider phenomenology • There is a special that could keep the from decaying because axial current is odd: • MDM candidate? • If decays, adding a singlet gives more generic structure, without losing any features.

20. A Few Simple ModelsWhat a Singlet Can Do • SM charge assignment: • The singlet as “strange” • Masses (singlet is axion): • After EWSB: • -strahlung at LEP?

21. A Few Simple ModelsWhat a Singlet Can Do • Resonances: • Short-lived pions: Lepton-rich, very good reconstruction in the channel. • Long lived pions decays through the current operator (heavier states preferred). When suppression scale is low, prompt or displaced same-sign tau-pair +MET as well as , otherwise CHAMP pairs. too soft to see

22. A Few Simple ModelsCHAMPs • Triggers like a muon. • Experimental handles: curvature, dE/dx,ToF • Tevatron Limits dictate • Distributions • more advanced analysis by Chen & Adams (200 pb-1 at 10 TeV)

23. A Few Simple ModelsMulti-photons • Associated production gives mode.(BF ~35% in CN) • Resonant as well as nonresonant channels. (~65% in CC) (GMSB searches) – work in progress. (~32% in CN) • Distributions • Hyperbaryon decay

24. A Few Simple ModelsSU(3) Triplet • Color triplet gives rise to color octet , . • Without any electroweak charges, can be as light as 300GeV. Possibly in Tevatron data, not excluded, discoverable. still easy at LHC, harder.

25. A Few Simple ModelsSU(3) Triplet + Singlet • Add a singlet • Spectrum • Decay modes • Axion mode interesting but unobservable

26. A Few Simple ModelsR-Hadrons • Triplet collider stable or decays through current-current operator, 3rd generation leptoquark • R-hadrons will be charged with O(1) probability. Resonance easier to observe compared to EW model. • 4 R-hadrons (leptoquarks) if g’ pair produced – fb cross section • Hyperbaryon decay

27. A Few Simple ModelsSpectators • DM candidates generic in VC models. • Exotic species have a much harder time decaying • and make up DM candidate • can decay to “Squark” pair production with subsequent decay to “LSP” • More general cascades

28. Conclusions • VC: New confining gauge interactions with vectorlike matter are theoretically simple and generic. • “Gauge-mediated” setup with vectorlike matter ensures safety from low energy precision tests. • Vector states can be resonantly produced, decay to naturally light PGB’s. • Scalars have short-lived and collider stable species. • Short-lived scalars decay to a pair of SM gauge bosons. 4 GB final states can be spectacular. • Long lived scalars appear as CHAMPs / R-hadrons. Resonance reconstruction possible. Decays into heavy flavors can be preferred. (leptoquarks, di-taus, di-tops…) • Unbroken species number or spectators can give DM candidates. Cascades possible.