1.    (Episodio II)

2. Signal/Background Reaction:             0   e  e        0 e  e   0 X-section  [  b]: 2.04  10 -3 9.87  10 -3 0.30  10 -3 0. 46 0.14  10 -3 Most frequent charged  decays: BR(      ) = (22.73±0.28)  10 -2 BR(      0) = (4.60±0.16)  10 -2 BR(  e  e   ) = (6.8±0. 8)  10 -3 09/04/282

3. Analysis versus EVCL ALL RAD RPI KPM 09/04/283 Stream correlation for MC charged RAD investigated: run RAD, RPI & RAD, KPM & RAD & RPI

4. Selection Criteria (see Marek J. talk)  Event Signature:   2 PNC: |t cl -l cl /c|<5  t  Recoil photon: most energetic cluster with E   250 MeV  2 tracks closest to IP (using PCA, no vertex requirement)  Kinematical Constraints:  Two body  decay kinematics to calculate E  recoil   kinematics to calculate      : |E t -P t |<10 MeV (EtPt)  Best Photon: we choose one PNC with  <0.2 rad to the calculated   (OPAN) Main background is      0 (B:S=200:1): M(      M    Background hypothesys:  in the  0 rest frame cos     >-0.98  in the plane     versus E  good S/B separation 09/04/284

5. 5 E    (MeV) Background rejection Main background is      0 (B:S=200:1): M(      M    Background hypothesys:  in the  0 rest frame cos       in the plane     versus E  good S/B separation     Signal Bkg cos     (   sys) Signal Bkg E    (MeV)     E    (MeV)    

6.   : BestPhoton 09/04/286 RADRPI Black: Pre-Selected Blue: EtPt +OPAN Green: (PI0) cos      Red: (Inside) plane     versus E  MeV RAD&RPI

7.   : BestPhoton, PI0 09/04/287 Black: cos     (RAD & RPI)/Selected(RAD & RPI) Red: cos     (RAD)/Selected(RAD&RPI) Blue: cos     (RPI)/Selected(RAD&RPI) MeV 

8.   : BestPhoton, Inside 09/04/288 Black: Inside Cut  (RAD & RPI)/ cos     (RAD & RPI) Red: Inside Cut (RAD)/cos     (RAD&RPI) Blue: Inside Cut  (RPI)/ cos     (RAD&RPI) MeV 

9.    09/04/289 RADRPI M  MeV) Black: Pre-Selected Blue: EtPt +OPAN Green: (PI0) cos      Red: (Inside) plane     versus E 

10. Cos    sys) 09/04/2810 RAD RPI Cos   Black: Pre-Selected Blue: EtPt +OPAN Green: (PI0) cos      Red: (Inside) plane     versus E 

11.       RAD+RPIEvent SignatureFull Selection Signal : Bkg1:10017:1 Signal58%42% Background53%2.5 10 -4 L (run 2005) = 130 pb -1 N(      )  10 5 09/04/2811 Efficiency study: going on…

12.      

13. Signal/Background Reaction:             (  )             0   e  e        0 e  e   0 X-section  [  b]: 6.04  10 -5 8.80  10 -5 2.04  10 -3 9.87  10 -3 0.30  10 -3 0. 46 0.14  10 -3 09/04/2813

14. Selection Criteria  Event Signature:   2 PNC: |t cl -l cl /c|<5  t  Recoil photon: less energetic cluster with E  >20 MeV (89%)  2 tracks closest to IP (using PCA, no vertex requirement)  Kinematical Constraints or Kinematic Fit ?:  Two body  decay kinematics to calculate E  recoil  Best Photon: we choose one PNC with  <0.2 rad to the calculated     …….. 09/04/2814

15. MC Simulation V00: official MC only with  -contribution V01: PMCC using the matrix element as from Gormley et al. [PRD2(1970)] V02: PMCC Pure phase space E  (MeV) 09/04/2815 V00

16. Comparison with  Background investigation: from      we learn how to reject      0 ; Stream versus two photon invariant mass M  (MeV) 09/04/2816 V00

17. E  and E  E  (MeV) E  (MeV) 09/04/2817 After Pre-Selection

18. Outlooks… Work on selection efficiency is going on Data-MC looks promising Preliminary investigation on  Selection to be optimize Improve MC Simulation ? QCD Anomaly  P      unitary effects via final state interactions: –WZW in the context of HLS –Chiral unitarity approach Bethe-Salpeter-equation –Omnes function 09/04/2818

19. SPARE 09/04/2819

20.  kinematics to calculate   From 2-body  decay  E  recoil: From  decay we disentangle our control sample:      0 09/04/2820

21. Control Sample:      0 09/04/2821

22. Physics Motivations Gormley et al. Phys. Rev. D2 (1970) 501 Angular distribution expected QCD Anomaly      unitary effects via final state interactions: –WZW in the context of HLS –Chiral unitarity approach Bethe-Salpeter-equation –Omnes function 09/04/2822

23. Past Results:  +  -  1970-BNL: Gormley et. Al Phys. Rev. D2, 501 (1970) 7250 events spectra agree with simple  -dominant model 1973: Layter et. al Phys. Rev. D7, 2565 (1973) 18150 events spectra agree with  -dominance of the  +  - final state Gormley Layter 09/04/2823

24. Past Results:  +  -  1975: A.Grigorian et. al Nucl. Phys. B91, 232 (1975) 474 events 1984-TASSO: 130 events 1987-ARGUS: 795 (1990: 2626) events 1987-TPC-  : 321 events 1984-PLUTO: 195 events 1990-CELLO: 586 events 1992-WA76: 401 events 1991-Serpukhov: 2491 events 1997-Crystal Barrel: 7392 events Box Anomaly evidence (independent of any assumption on  ) 1998-L3: 2123 events well described by resonant contribution (published spectra no background subtracted) CB 09/04/2824

25. Conclusions and Outlooks KLOE  KLOE2: unique opportunity to search for Box Anomaly       : analysis with full KLOE data set, good results from background suppression and promising MC-Data comparison       : very very preliminary work on MonteCarlo (toy!), insert element matrix in GEANFI; analysis with KLOE2 data set KLOE2 data set …. 09/04/2825  L =2.5 fb -1  L =5 fb -1   P  10 8 5·10 5 2x10 8 10 6 P   +  -  5·10 6 15·10 4 10 7 3·10 5 Efficiency  40% 2·10 5 6·10 4 4·10 5 1.2·10 5 Efficiency  20% 3·10 4 6·10 4