1. 1/25  s with XD & Kaluza-Klein excitation of gluon at ATLAS Exotic signals at Hadron Colliders 04,Durham Exotic signals at Hadron Colliders 04 Marc Escalier, LPNHE Paris Results within the ATLAS experiment

2. 2/25 XD: the models ADD large XD (~mm) R c >>1 TeV -1 Small XD (TeV -1 ) (Antoniadis) Randal-Sandrum MSSM M GUT =10 16 GeV MSSM + XD Hierarchy problem can be solved! In our model, gauge bosons can propagate in XD  modification of the RGE (E. Dudas, R. Dienes, T. Ghergetta, hep/ph 9803466 and hep/ph9807522) for (4+2) D and R=1/10 TeV -1 strong M GUT ~30 TeV weak em   i strong   i em weak

3. 3/25 Detection of KK excitations of gauge bosons gluon  qq, most abundant  ~  s  difficult to detect over QCD jet bck , Z G. Azuelos and G. Polesello – proceedings of the Workshop “Physics at TeV colliders”,Les Houches, May 2001 – hep-ph/0204031, ATL-COM-PHYS-2003-004 W G. Polesello, M. Prata Observation of deviations of  Observation of resonances Feynman diagrams for dijets production involving KK excitations q i q i  q i q i q i q j  q i q j q i q i  q i q i q i q j  q i q j q i q i  q i q i - -- - --

4. 4/25 Modification of the coupling constant SM : MSSM+XD : Jacobi function : High Energy theory at (4+  )D  Effective theory at 4D with Kaluza-Klein excitations of gauge bosons (fermions can also exist but are not considered in the following)

5. 5/25 Data analysis at LHC M min What can we measure ? 2 competitive effects: KK excitations make the cross-section to increase decrease of  s makes  decrease at high M c (counterbalance effect of KK) Influence of  s (dominant for high M c ) M min (pair of jet) (GeV) M max ( we’ll take 14 TeV )

6. 6/25 This is NOT a resonance Reachable R -1 (GeV) for different scenarii (N s max > 5) Limits: influence of KK in the propagator ?

7. 7/25 propagator of n-KK resonance c n >0=2m n =n/R  n =2  s m n c0=1, n=0: SM gluon Cross-sections  |M| 2 (amplitude square) KK gluon propagator n=0  SM  n =f(  s )  s =f(  n )

8. 8/25 Implementing XD into Pythia XD function from C. Balazs (done at Les Houches 2003) m,n=0  massless gluon IF(ISUB.EQ.11.OR.ISUB.EQ.12)THEN SQDQQT=EffGluProp(TH,TH,XKKL(1),XKKL(2)) REDQST=EffGluProp(SH,TH,XKKL(1),XKKL(2)) SQDQQU=EffGluProp(UH,UH,XKKL(1),XKKL(2)) REDQTU=EffGluProp(UH,TH,XKKL(1),XKKL(2)) SQDQQS=EffGluProp(SH,SH,XKKL(1),XKKL(2)) ENDIF M c is compactification scale M s cutoff scale M s /M c Only some processes have XD Propagator T, T Propagator S, T Propagator U,U Propagator U,T Propagator S, S  n =2  s m n

9. 9/25 Us: CTEQ6L1 Dicus et al: CTEQ3M Sigma deviation Observation up to M c ~15 TeV Cross-section deviations No running of alpha_s here  KK -  SM (pb) Pt min (GeV)

10. 10/25 No  s running With  s running 2 contribs: propagator+coupling (  s ) Processes 11, 12 only All processes

11. 11/25 No  s running  s running Processes 11, 12 only All processes  s =f(  ) and  =f(  s )  iterative process

12. 12/25 Process 11 Process 12 KK excitation KK equally spaced spectrum (log scale) 1TeV Observation of resonance

13. 13/25 S/sqrt(B):1599±7,9  Sqrt(s) events lumi=100 fb -1 Very large resonance  difficult to observe over qcd background Signif= s channel (XD resonance) t channel (SM+XD)

14. 14/25 Search for extra-dimensions : Kaluza-Klein resonance production in s-channel background QCD background is t-channel idea: use (s,t) Mandelstam variables distributions to reject s channel from t channel contributions ?  s (s) ^  s (?) Strategy : enhance s-channel contribution

15. 15/25 leptons:E=cst t Mandelstam variable (t or u=  ) s channel t channel

16. 16/25 P3P3 P2P2 P4P4 t1t1 P1P1 t’ 1 P3P3 P2P2 P4P4 t2t2 t’ 2 P1P1 ? Protons: need to reconstruct x 1, x 2 Take best reconstructed variable t or u For min{|t 1 -t’ 1 |;|t 2 -t’ 2 |}, take: t = (t i +t’ i )/2 4-momentum conservation : P 1 +P 2 =P 3 +P 4 s = (P 1 +P 2 ) 2 =(P 3 +P 4 ) 2 : unambigiuous t : ambigiuous t 1 =(P 1 -P 3 ) 2 t’ 1 =(P 2 -P 4 ) 2  t ? t 2 =(P 1 -P 4 ) 2 t’ 2 =(P 2 -P 3 ) 2  u ? idea : impose s, look at t

17. 17/25 kinematics with jets: reconstruction of x protons x resolution: 6% Ev. #

18. 18/25 «S»/«T-U» channels The idea is not to separate s channels from t/u, it is just to see if there is special behaviour for s channel and t/u channels

19. 19/25 s=1 TeV, Cteq6L1,  QCD correct ^

20. 20/25 gg  gg interference normalised qg  qg

21. 21/25  distributions for s=1TeV S/sqrt(B)=1690.07± 8.98  gain 5,6 % 1,2 10 5 9,9 10 5 low cuthigh cut Low cut high cut Search for optimal cuts XD resonance processes Others processes

22. 22/25  pdf distributions Likelihood ratio ponderation using  distributions XD resonance process Other processes

23. 23/25 After likelihood S/sqrt(B):2177 ± 17 likelihood S/sqrt(B):1599±7,9  Sqrt(s) events lumi=100 fb -1 before likelihood 36 %

24. 24/25 Conclusion Cross-section deviations Resonances  consequences on others resonances (KK gravitons ?) statistics ~1 10 6 files to be generated NLO computation ? full simulation ? LES HOUCHES 'PHYSICS AT TEV COLLIDERS 2003' BEYOND THE STANDARD MODEL WORKING GROUP: SUMMARY REPORT. By Beyond the Standard Model Working Group (B.C. Allanach et al.). SLAC-PUB-10365, Mar 2004. 114pp. Contributed to 3rd Les Houches Workshop: Physics at TeV Colliders, Les Houches, France, 26 May - 6 Jun 2003. e-Print Archive: hep-ph/0402295 More information: