Is it Exotics?

1. Is it Exotics? Samir FERRAG University of Glasgow ATLAS UK Physics Meeting

2. Hinchliffe’s Theorem When a title is in the form of a question, the answer is always: “No”

3. Outline • Motivation • Summary of ATLAS Exotic activities • Fake discoveries: • Theoretical uncertainties from the Standard Model • Experimentation • Natural strategies (careful approach) • Conclusion

4. Introduction: Exotics is not a whim… • Why 3 generations? • Larger symmetry group, compositeness, lepton flavour violation • Why left-handed weak interaction ? • Left-Right Symmetric model • Why all these parameters • Compositeness… • What about gravity, cosmological constraints • SUSY, Extra-dimensions… • EWSB: no Higgs found (yet) ? • Strong symmetry breaking, Little Higgs… • Hierarchy of scales • Instability in the EW calculations. Higgs mass • ... I want my discovery ! …but it requires a carefull approach

5. Non SUSY BSM • Ingredients for BSM physics: • Space time + Geometry+ Fundamental fields & Gauge Symmetry + Symmetry Breaking • Space-Time: • Extra dimensions?: another fundamental Mp scale • Factorized and non-factorized • Large, Small, Universal or no • Consequences of low Mp: Black Holes • Larger Gauge symmetries: • New gauge bosons and new heavy fermions • Flavour violation • Fundamental Fields: • Standard Fermions and Bosons or Compositeness • new fundamental particles, larger symmetries... • Symmetry breaking: excluding SUSY • Dynamical Breaking: Vector Boson interactions, non Higgs mechanism

6. Classification by topics and models • Extended gauge symmetries: • Heavy Gauge bosons: Z’,W’ • LRSM: H++, Z’, W’, Majorana N… • Heavy fermions • Isosinglet quarks (E6 down, Top) • Flavor Changing Neutral Current (FCNC) • Compositeness: • Excited fermions (electrons, quarks) • Leptoquarks • Extra dimensions • Large extra dimensions: • direct Graviton production, Virtual exchange of Gravitons • Black Holes • Small extra dimensions: • KK excitations of gauge bosons: W, Z and g • Universal extra dimensions • Coupling unification • Warped extra dimensions: • RS Radion, Narrow Graviton resonance • Dynamical symmetry breaking: • Little Higgs, Technicolor • Vector Boson scattering: WW, WZ

7. Outsider’s a priories…(sometimes real!) • Two Exotic behaves in Exotics: • Study the phenomenology of models which are sufficiently new, bizarre, or baroque that nobody had looked at them yet: • “Collider signals of neutrino-mediated SUSY with breaking of R-parity, T-parity, G-parity, P-parity, CP, CPT, Lorentz invariance and Unitarity” • Study increasingly obscure phenomenological details of well developed models, preferably those which will only be accessible to colliders or collider upgrades that will never happen. • Follow a healthy strategy for Exotics. J. Lykken @ les Houches 2005

8. Experience from the past • Exotic physics has always been the first physics to be discovered… …and the only one never discovered ? • Is our approach a healthy one to Exotics ? • May be, the common sens is to: • first, discover ATLAS/LHC: • Machine backgrounds, Min Bias, Energy scale at high energies, Calibration, Trigger, alignment, Cal linearity… • second, discover Standard Model: • Electroweak physics, PDF uncertainties… • third, discover new physics: it has to be there • May be the corresponding model exists, may be not…

9. Why are we going to discover ”Exotics” the first year of data taking and how the discovery will be delayed for later (never)?

10. When the Standard Model is not certain… CTEQ hep-ph/0303013 • Excess interpreted as new physics in early days • Today, Tevatron jet data are considered to lie within PDF uncertainties. • The high-xgluon uncertainties has increased by including the high Et data

11. SM 2XD 4XD 6XD …and when Joey says: “I’m not sure!” Mc= 2 TeV Mc= 4 TeV Mc= 2 TeV PDF uncertainties S. Ferrag • Without PDF uncertainties, XD predictions are well separated from the SM ones • With PDF uncertainties Standard Model prediction become band • By increasing Mc, some of the XD predictions fall into the SM band • Predictions of XD model are absorbed in the SM zone by new PDF fit • Discovery power is cancelled by PDF uncertainties above Mc=4TeV •  But: are we sure about these uncertainties ?

12. But “uncertainty estimations” is not an exact science ! S. Ferrag & A. Djouadi Disagreement at more then 3 sigma between Alekhin and MRST/CTEQ at low Higgs masses  low x anti-quarks…

13. Boundary effect with a Toy MC + Cross section Resolution ATLAS: Another source of new physics… • Exponentially decreasing cross section example: jet cross section • Bin transfer: Gaussian + flat tail @ 0, 0.25, 0.5, 0.75 and 1% • Correction: Gaussian only • We can make an artificial excess if we don’t handle our apparatus • …Strange resemblance with the Tevatron excess !!! • Are we sure to have enough manpower to understand our detector • at high energy?

14. And many other examples of discoveries… • Leptoquarks @ HERA (~1996) • First discovery of the top quark @ 40 GeV Even the Standard Model can be (re)discovered… • …. • We would like strategies where we minimise such waist of energy, manpower…and faith !

15. Here, we can do “nothing” Version: “n” of the LHC schedule (without uncertainties) • LHC start-up will be slow and gradual • The discoveries announced in 2009-2010 will be made from • Data sets with L<5 fb-1 and not the 30-300 fb-1 that you see • in all the studies (constraints!) • Non-demanding studies are Suitable

16. Simple final state topologies • Strategy: • Understand the SM predictions and establish their uncertainty band • Responsibility in uncertainty calculations • Mature experimental tools • Every prediction outside this band is a signature of new physics • Choice of 1st years @ LHC: • Simple topologies and robust analyses: • Di-leptons, di-photons, dijets…over large energy range

17. 2 parts: Limits of the SM & possible BSM signatures SM uncertainty zone Non SM measurement mll • But: • Even for the simplest topologies (dileptons, diphotons…), • Nobody tried to estimate the total theoretical uncertainties • (PDFs, mRen, mFac, higher orders QCD, EW… ) • In ATLAS: most of the tools are tuned for low energy physics

18. Responsibility game: Standard Model predictions • Question: What is the SM prediction on the simple topology ?  what will we measure at ATLAS when we in this topology ? • Theoretical side: • simple final state topology (2e, 2g, 2jets…) • observables (may be by interacting with BSM) • list and estimate all the uncertainties (PDF, (N)NLO, mfact, mrenor…) • GOAL: Make the SM uncertainty band • Experimental side: • Experimental considerations: (Reconstruction efficiencies, Machine backgrounds, Min Bias, Energy scale at high energies, Calibration, Trigger, alignment, Cal linearity…) • Mis-Identification: ZZ or WW like DY…(composition of the measured sample with given set of cut) Establish the shape and the composition of measured sample and its uncertainty band

19. Exotics: which underlying model ? • For a chosen simple topology @ high energy: • Report of all the existing models in the market • Other observables to disentangle the models and make priority between them • For the first years data: since no excess • Only limits on these models will be measured

20. Exotics CSC activities https://twiki.cern.ch/twiki/bin/view/Atlas/CSCExoticsAnalyses • Reclassifying by final state topologies • Diletons, Diphotons and lepton+photon • Z’ (several models), RS Graviton, Virtual ADD Graviton • Virtual Leptoquarks, Leptogluons, Heavy scalar • (GraviScalar, Radion, Heavy Higgs…), Excited Leptons… • Dileptons + jets • Majorana Neutrino, Leptoquarks… • Lepton + missing Et • W’ • Boson Boson: • WW and WZ final state • Multi-Everything: • Black Holes

21. Dileptons as a simple topology study Full simulation F. Heinmann

22. Reconstruct hadronic + leptonic W pair Require forward jets Veto jets in central region Dibosons final state: WW scattering • The ultimate test of electroweak symmetry breaking • Not unitary above ~1 TeV if no new physics BG BG signal 5- significance with 30 fb-1in most difficult case Most difficult case: continuum signal

23. Conclusion • We need to understand the Detector and the Standard Model before looking for new physics • Why simple topologies at high energies ? • Study programme is luminosity independent • Robust analyses  first publications (tradition in PP) • Nobody estimated the total theoretical uncertainties • Nobody look at them in ATLAS • Complementary to SM group activities (low energy) • Good candidate to a UK collaboration for the next 5 years.