1. The Top Quark Beyond the SM at ATLAS Granada 29 th June 2006 António Onofre LIP / UCP Universidad de Granada Departamento de Física Teórica y del Cosmos

2. Outline I) What do we know about the top quark? top quark? II) The top quark at ATLAS III) Conclusions Granada, 29 th June 2006

3. I) What do we know about the top quark? I) What do we know about the top quark? N ν = 2.9841±0.0083 n The top quark completes the 3 family structure of the SM n It has spin=1/2, n Charge=+2/3, n It´s the weak-isospin partner of the b-quark,  =1.42GeV (including m b,M W,  s,EW corr.)  =1.42GeV (including m b,M W,  s,EW corr.) n It’s a massive particle (special role in SM?) From the SM we know that:  QCD -1 =(100MeV) -1 =10 -23 s M t =>  t < 10 -23 s Hadronization time NO top hadrons Granada, 29 th June 2006

4. From e + e, e ± p and pp Colliders we have top quark data - LEP ALEPH, DELPHI, OPAL and L3 (e + e - Collider) HERA H1 and ZEUS (e ± p Collider) TEVATRON D0 and CDF (pp Collider) - I) What do we know about the top quark? I) What do we know about the top quark? Granada, 29 th June 2006 Beyond SM SM+Beyond

5. The TEVATRON The TEVATRON The present experimental knowledge on top quark physics is dominated by the TEVATRON data Run I (1992-1996)  s = 1.8 TeV Discover top quark in 1995 Integrated luminosity 120pb -1 Run II (2001-present)  s = 1.96 TeV Total Int.Luminosity Delivered: ~1.5fb -1 /exp Recorded ~1.2fb -1 /exp Futur: ~2fb -1 (by 2006) ~4fb -1 (by 2007) ~8fb -1 (by 2009) 2 multi-purpose detectors D  and CDF I) What do we know about the top quark? I) What do we know about the top quark? Granada, 29 th June 2006

6. A) The top mass (TEVATRON,LEP,SLD) A) The top mass (TEVATRON,LEP,SLD) I) What do we know about the top quark? I) What do we know about the top quark? Granada, 29 th June 2006 measuredinferred

7. A) The top mass at RUN II (TEVATRON) A) The top mass at RUN II (TEVATRON) Summary of Top Mass Results I) What do we know about the top quark? I) What do we know about the top quark? Granada, 29 th June 2006 m t =172.5±2.3 GeV/c 2

8. ~85% g g ~15% Diagrams:Dependence with Energy: B) The pp tt cross section (TEVATRON)  (pp tt)@NLL=6.7pb (15% uncertainty) at M t =175GeV I) What do we know about the top quark? I) What do we know about the top quark? Granada, 29 th June 2006 Top quarks are rare events: 1 in 10 10 events !!!

9. CDF Run 2 Preliminary:D0 RUN 2 Preliminary: B) The pp tt cross section (TEVATRON) I) What do we know about the top quark? I) What do we know about the top quark? Granada, 29 th June 2006

10. C) The t bW decay and W polarization t W 0 Longitudinal fraction F 0 W b +1/2 0 W - Left-Handed fraction F - t b W +1/2 -1/2 +1 W + Right-Handed fraction F + t W b +1/2 +1 -1/2 V-A SUPPRESSED W boson has three helicity states: “Left-handed”, “Longitudinal”, “Right-handed” Top quark decay is the most significant source of Longitudinal Ws. I) What do we know about the top quark? I) What do we know about the top quark? Granada, 29 th June 2006

11. By measuring the fraction of longitudinal Ws we are: Testing a Standard Model prediction: F 0 =0.7 F - =0.3 Probing the structure of the tWb vertex C) The t bW decay and W polarization I) What do we know about the top quark? I) What do we know about the top quark? Granada, 29 th June 2006  W(cos  *)=F 3 (1-cos  *) 2 + F 3 (1-cos 2  *) + F 3 (1+cos  *) 2 848 -+ 0

12. D) Top Rare decays n The top quark almost always decays to a b quark, B(t  Wb)~1 n Most of the SM rare decays of the top are really rare u B(t  Ws)<0.18%, B(t  Wd)<0.02% n The Ratio of Events with b-tagged and no b-tagged jets is: R=B(t  Wb)/B(t  Wq) = |V tb | 2 / (|V td | 2 + |V ts | 2 + |V tb | 2 ) =99.8% FCNC Decays: B(t   c) +B(t   u)<3.2% at 95% CL B(t  Zc) +B(t  Zu)<33% at 95% CL I) What do we know about the top quark? I) What do we know about the top quark? Granada, 29 th June 2006

13. A) The Most Exciting Discoveries are the Unexpected Ones Unfortunately it Seems Difficult To Predict the Unexpected… Unfortunately it Seems Difficult To Predict the Unexpected… Why Going Beyond the SM? Why Going Beyond the SM? B) Physics Beyond the SM Required for Unification SuperSymetry at TeV scale modifies evolution of couplings SuperSymetry at TeV scale modifies evolution of couplings  Unification and Agreement with Data  Unification and Agreement with Data Granada, 29 th June 2006 II) The top quark at ATLAS II) The top quark at ATLAS C) New Physics is also a test of the SM… It is mandatory to measure the top quark quantum numbers It is mandatory to measure the top quark quantum numbers

14. ATLAS at CERN Geneve Airport LHC CERN SPS Accelerator CERN (Prevessin) 27 km ATLAS, CMS, LHCb e ALICE 20 Member States + USA, Canada, Japan, Russia, China, India,... II) The top quark at ATLAS II) The top quark at ATLAS Granada, 29 th June 2006 Proton-Proton Collisions Ecm = 7000 + 7000 GeV 800 million collisions/s The biggest cryogenic system in the world (1.8K, superfluide helium) 27 km of magnets with B=8T

15. II) The top quark at ATLAS II) The top quark at ATLAS ATLAS at CERN Granada, 29 th June 2006

16. σ(W→lν) σ(tt) m t =175 GeV   (pp tt): 10% g g 90% u High Collision Rate F LHC (Tevatron) – every 25ns (396ns) u High Cross-Sections ~0.1b F 2-3 interactions per collision LHC low/high lumi L=10 33 cm -2 s -1 F 20 interactions per collision LHC design/high lumi L=10 34 cm -2 s -1 u W, Z, top are rare events F Requires High Luminosity F Trigger is crucial: sel. Leptons High pT II) The top quark at ATLAS II) The top quark at ATLAS Granada, 29 th June 2006 Cross-sections at the LHC

17. pp tt bbW + W - (833pb) pp tt bbW + W - (833pb) 1 Lepton p T >20 GeV, | η |<2.5 E T >20 GeV ≥ 4 jets E T >40 GeV, | η |<2.5 ≥ 2 b-tags Signal: tt bbqq´ l l + (l=e,  ) Signal: tt bbqq´ l l + (l=e,  ) II) The top quark at ATLAS II) The top quark at ATLAS Granada, 29 th June 2006 A) The top mass at ATLAS proton beam W b t q q|q| Jet Jet (b) Semileptonic Topology neutrino e, 

18. M t (had) M W (had) Selected 87000 events for 10fb -1 (S/B~78) Most Important Systematic Errors: n Energy Jet Calibration n FSR Systematic Errors: SN-ATLAS-2004-040 Tot(sys) = 1.3 GeV Tot(stat) = 0.1 GeV II) The top quark at ATLAS II) The top quark at ATLAS Granada, 29 th June 2006 A) The top mass at ATLAS

19. II) The top quark at ATLAS II) The top quark at ATLAS Granada, 29 th June 2006 B) Anomalous Couplings in the t  bW decay Angular Asymmetries: A FB, A + and A - Angular Asymmetries: A FB, A + and A - A FB A+A+A+A+ A-A-A-A- cos(  l *) A FB [t=0] A ± [t= (2 2/3 -1)] ±

20. II) The top quark at ATLAS II) The top quark at ATLAS Granada, 29 th June 2006 B) Anomalous Couplings in the t  bW decay

21. II) The top quark at ATLAS II) The top quark at ATLAS Granada, 29 th June 2006 M t-lep M t-had Log 10 (L s /L B ) Sig. BacK. L=10fb -1 Pre-Selection (Probabilistic): 1 lepton pT>25GeV,|  | 25GeV,|  |<2.5  4 jets, pT>20GeV,|  | 20GeV,|  |<2.5 n 2 b-tag jets n Missing pT>20GeV Final Selection: n Log 10 (L s /L B ) > -0.2 B) Anomalous Couplings in the t  bW decay

22. II) The top quark at ATLAS II) The top quark at ATLAS Granada, 29 th June 2006 n The measured Angular Distributions are affected by detector related effects (resolutions, triggers, selection criteria, etc.) n To recover the “True” signal (S) Angular Distributions, reference MC samples for signal (S ref ) and back. (B ref ) were generated to estimate the expected Correction Function used to compensate for experimental effects (f C =G/S ref ); n The signal is extracted from “Data” (S 0 +B 0 ) by: S = (S 0 + B 0 - B ref ) x G/S ref B) Anomalous Couplings in the t  bW decay

23. II) The top quark at ATLAS II) The top quark at ATLAS Granada, 29 th June 2006 B) Anomalous Couplings in the t  bW decay L=10fb -1 n SM (LO): A FB = -0.2226 A + = 0.5482 A - = -0.8397  /A FB = 6.0%  /A + = 1.9%  /A - = 0.4% Systematic Errors:

24. II) The top quark at ATLAS II) The top quark at ATLAS Granada, 29 th June 2006 B) Anomalous Couplings in the t  bW decay The dependence of A FB on the Anomalous Couplings The dependence of A FB on the Anomalous Couplings The b-quark mass must be taken into account (differences up to 17% in g L and 9% in V R ) The b-quark mass must be taken into account (differences up to 17% in g L and 9% in V R )

25. II) The top quark at ATLAS II) The top quark at ATLAS Granada, 29 th June 2006 B) Anomalous Couplings in the t  bW decay 1) Anomalous Couplings with W polarization: 2) The helicity fractions are related to A FB, A + and A - : SM(LO): 3) Best Results: (careful with definitions when comparing to TEVATRON)

26. II) The top quark at ATLAS II) The top quark at ATLAS Granada, 29 th June 2006 B) Anomalous Couplings in the t  bW decay Best 1  Results: Working Going on…

27. C) Top Quark FCNC decays (tt events) C) Top Quark FCNC decays (tt events) Highly Suppressed in the SM: II) The top quark at ATLAS II) The top quark at ATLAS Granada, 29 th June 2006

28. II) The top quark at ATLAS II) The top quark at ATLAS Granada, 29 th June 2006 C) Top Quark FCNC decays (tt events) C) Top Quark FCNC decays (tt events) Probabilistic Type of Analysis after Pre-selection Probabilistic Type of Analysis after Pre-selection Pre-Selection: Pre-Selection:

29. II) The top quark at ATLAS II) The top quark at ATLAS Granada, 29 th June 2006 C) Top Quark FCNC decays (tt events) C) Top Quark FCNC decays (tt events) Specific Criteria: Specific Criteria:

30. II) The top quark at ATLAS II) The top quark at ATLAS Granada, 29 th June 2006 C) Top Quark FCNC decays (tt events) C) Top Quark FCNC decays (tt events) Specific Criteria: Specific Criteria:

31. II) The top quark at ATLAS II) The top quark at ATLAS Granada, 29 th June 2006 C) Top Quark FCNC decays (tt events) C) Top Quark FCNC decays (tt events) Specific Criteria: Specific Criteria:

32. II) The top quark at ATLAS II) The top quark at ATLAS Granada, 29 th June 2006 C) Top Quark FCNC decays (tt events) C) Top Quark FCNC decays (tt events)

33. A) ATLAS Sensitivity (5  ): B) Absence of Signal (95% C.L.): C) Dominant Systematic Errors: M t e  b-tag < 20% II) The top quark at ATLAS II) The top quark at ATLAS Granada, 29 th June 2006 C) Top Quark FCNC decays (tt events) C) Top Quark FCNC decays (tt events)

34. Combined Plot: II) The top quark at ATLAS II) The top quark at ATLAS Granada, 29 th June 2006 C) Top Quark FCNC decays (tt events) C) Top Quark FCNC decays (tt events)

35. Conclusions èThere is no doubt that colliders are doing a Great Job up to now… Wait for the next data at the LHC... èMany analysis are under preparation for the LHC and a strong collaboration between Theoreticians and Experimentalists is necessary èThe Top Quark Physics is one of the best places to look for New Physics (at least it is there…)

36. The best way to access the top spin is to study de angular distribution of its decay products:  i = analysing power of particle i Spin Correlations in pp tt: Spin Correlations in pp tt: II) The top quark at ATLAS II) The top quark at ATLAS Granada, 29 th June 2006 B) Top spin correlations (asymmetries)  X=l XX XX SM C(LO) C(NLO) 0.319 0.326

37. Double Differential Distributions: Double Differential Distributions: Opening Angle Distributions: Opening Angle Distributions: II) The top quark at ATLAS II) The top quark at ATLAS Granada, 29 th June 2006 SM D(LO) D(NLO) -0.217 -0.237 SM Predictions: SM Predictions: l +, t  l, q t qq l +, t  lq q t Asymmetries Definitions: Asymmetries Definitions: B) Top spin correlations (asymmetries) We have considered: A lj, Ã lj, A j

38. II) The top quark at ATLAS II) The top quark at ATLAS Granada, 29 th June 2006 B) Top spin correlations (asymmetries) (asymmetries) A lj A j à lj L=10fb -1

39. II) The top quark at ATLAS II) The top quark at ATLAS Granada, 29 th June 2006 B) Top spin correlations (asymmetries) Systematic Errors (probabilistic):

40. II) The top quark at ATLAS II) The top quark at ATLAS Granada, 29 th June 2006 E) Top Quark FCNC decays (Single top Events) E) Top Quark FCNC decays (Single top Events) A) Diagrams For Single top production: B) Decays under study: e

41. A) B) II) The top quark at ATLAS II) The top quark at ATLAS Granada, 29 th June 2006 E) Top Quark FCNC decays (Single top Events) E) Top Quark FCNC decays (Single top Events)

42. A) ATLAS Sensitivity (5  ): B) Absence of Signal (95% C.L.): II) The top quark at ATLAS II) The top quark at ATLAS Granada, 29 th June 2006 E) Top Quark FCNC decays (Single top Events) E) Top Quark FCNC decays (Single top Events)

43. New Interactions Quark Radius at Colliders èHERA (H1) f q (Q 2 ) Results Interpreted in terms of f q (Q 2 ) Result: R<1.7x10 - 16 cm q-form factor: d  /dQ 2 = d  SM /dQ 2 x f q (Q 2 )  Tevatron (CDF, DY e + e -,  +  - ) Result: R<1.0x10 - 16 cm Result: R<1.0x10 - 16 cm f q (Q 2 )=1- 1 Q 2 6

44.  In SM (m t =175GeV/c 2 ) B(t  c) 5.2x10 -13 B(t  c) ~ 5.2x10 -13 B(t  Zc) 1.5x10 -13 B(t  Zc) ~ 1.5x10 -13 èSM extensions lead to large enhancements: 1). 2HDM  g ij  (m qi m qj ) 1). 2HDM  g ij  (m qi m qj ) 2). k , k Z èCDF searched for: t  c(u)  and t  Zc(u) t  c(u)  and t  Zc(u) B  t  c  B  t  u  < 3,2%  B  t  c  B  t  u  < 33% CDF  k 2  <0.176 CDF  k 2  <0.176 k 2 Z <0.533 at  =m t k 2 Z <0.533 at  =m t èAt LEP are Anomalous Couplings k   k Z are Anomalous Couplings c(u)te- e+ Z,  k , k Z Top Quark and FCNC At e + e -, pp Colliders _

45. èDELPHI, OPAL, L3, ALEPH searched at LEP for e + e -  tc(u)  bWc(u) e + e -  tc(u)  bWc(u) Hadronic: W  qq´ Hadronic: W  qq´ Leptonic: W  l ± Leptonic: W  l ± Top Quark and FCNC At e + e -, pp Colliders _