2. B.E.A.CH., Vancouver, june 24-28, 2002 B.E.A.CH., Vancouver, june 24-28, 2002 SERGIO P. RATTI INFN and Dipartimento di Fisica Nucleare e Teorica – PAVIA (for the FOCUS Collaboration) NEW RESULTS ON CHARMED BARYONS INFOCUS

3. Univ. of California-Davis,CBPF-Rio de Janeiro,CINVESTAV-Mexico City, Univ.Colorado-Boulder,FERMILAB, Laboratori Nazionali di Frascati, Univ. ofIllinois-Urbana-Champaign,Indiana Univ.-Bloomington, Univ. ofNorth Carolina-Asheville, INFN and Univ.-Pavia, Univ. ofPuerto Rico-Mayaguez, Univ. ofSouth Carolina-Columbia, Univ. ofTennessee-Knoxville, Vanderbilt Univ.-Nashville, Univ. ofWisconsin-Madison Univ.-Seoul, Korea, Kyungpook N.Univ,Taegu, Korea INFN and Univ.-Milano, The Collaboration

4. -  c + production asymmetry (no) -  c + decays into  ’s -  c + high multiplicity decays - double-charmed baryons - Conclusions -  c + production asymmetry (no) -  c + decays into  ’s -  c + high multiplicity decays - double-charmed baryons - Conclusions Outline of the talk

5. PRODUCTION ASYMMETRY PRODUCTION ASYMMETRY

6.  c + signals large and clean samples make precision studies possible large and clean samples make precision studies possible INVESTIGATE PRODUCTION ASYMMETREY ASYMMETREY y = 3024 ± 74  c + pK -  + c+c+ c+c+ 5292±69

7. R(E691)= 0.79 ±.17 R(E687)= 0.93 ±.14 R FOCUS = 0.725±.021±.021 R(E691)= 0.79 ±.17 R(E687)= 0.93 ±.14 R FOCUS = 0.725±.021±.021 A(E691)= 0.110 ±.089 A(E687)= 0.035 ±.076 A FOCUS = 0.155±.014±.014 A(E691)= 0.110 ±.089 A(E687)= 0.035 ±.076 A FOCUS = 0.155±.014±.014 preliminary  c + -  c + R =  c + /  c + ; A = -----------------  c + +  c +  c + +  c +  c + -  c + R =  c + /  c + ; A = -----------------  c + +  c +  c + +  c +  c + -  c + asymmetry

8.  c + DECAYS WITH  ’s

9. The most aboundant final states containing the  hyperons are:  and  + K - K + and the Cabibbo Suppressed channels:  K  The most aboundant final states containing the  hyperons are:  and  + K - K + and the Cabibbo Suppressed channels:  K  We measured the relative B.R.   (                We measured the relative B.R.   (                 + c into  K  KK

10. or  + c  + K +  - Cabibbo suppressed decay:  + c  + K +  - Cabibbo suppressed decay: 2 body dominant K* o (892) K+-K+- K-+K-+withoutFSI ~ the same withoutFSI dd - u u ++ -- ++ u u sc - u W+W+ s d c -- s d - s - uu K+K+ u d d ++ W+W+ s u u ++ c W+W+ - s u d d

11. -K++-K++-K++-K++ Y=10.1±10.9 ev  + c + K +  -  + c  + K +  - < 0.40  + c (892))  (  + c   (892))  + c  )  (  + c        ) 95% cl Y=49±10 ev 832MeV<K* o (892 )<960MeV + K ±   + K* o (892) K ±  ±

12.  + c + K *o (892)  + c  + K *o (892)  + c +  +  -  + c  +  +  -  + c + K *o (892)  + c  + K *o (892)  + c +  +  -  + c  +  +  -       Using       as refence channel we minimize systematic errors       Using       as refence channel we minimize systematic errors  m (        Y=1706±88  (  + c  + K *o (892))  (  + c  +  +  - ) =(7.8±1.8±1.3)x10 -2

13.  + c  + K + K -  (  + c  + K + K - )  (  + c  +  +  - ) =(7.3±1.1±1.1) 10 -2  + c  + K + K - Y= 103± 15 ++ s s - c uu s d u W+W+ oo ++ ++ -- - u dc u u u u s s - W+W+ s  * 1690 s c ++ u d W+W+ u u s - s or but also

14.  + c  +  o Y=57±10 ev  (  + c  +  )  (  + c  +  +  - ) =(8.7±1.6±0.6) 10 -2  (  + c  +  +  ) xBR(  * ( 1690)  + K - )  (  + c   K + ) =R=R R=(2.2±.6±.1)10 -2  + c  * K +

15. Conclusions - 1 FOCUS results compared to other experiments

16. Some high multiplicity  + c decays Some high multiplicity   + + c c decays

17. Selection criteria  CLS > 5 %  P(  c )> 50 GeV/c  P(   c )> 50 GeV/c  Picon on 4  ’s > -8  iso2 < 0.1 %  Out of Target > -2 L/  L > 5.5 N. Events: N. Events: 18.6 ± 5.8 Mass=(2.281±.004) MeV    c 1  + event on PDG 1 st evidence PRELIMINARY

18. Primary vertex Secondary vertex First attempt to reconstruct a decay containing a neutron First attempt to reconstruct a decay containing a neutron 5*10 7    n   candidates Five charged particles  - to cut combinatoric Five charged particles  - to cut combinatoric

19. Cherenkov selectionVertex selection  + c n K -  -  +  +  + analysis

20. Y=24 ± 6  =11 ± 3 S/n=5.9 Y=24 ± 6  =11 ± 3 S/n=5.9 Preliminary results B.R. might come soon Kind of nice to see the decay!  + c n K -  -  +  +  + n K -  -  +  +  + M( n K -  -  +  +  + ) 1 st evidence

21. The  o c

22.  c CHARM BARYON CLEO  c CHARM BARYON CLEO       K                  K    KK   c  TOTAL no    K    Y=40.4  9.0

23.   c CHARM BARYON FOCUS   c CHARM BARYON FOCUS M(  -  + ) Y=23±7 M(  - K -  + )  + ) Y=38±9 Y=64±14 M=2697.5±2.2

24. The  +,++ cc It was year 2000

25. The  +,++ general topology -select charm candidates (D o,D +,  + c ) in golden modes (K , K , k  and pK  ; -combine either D’s or  + c momentum vectors to meet additional tracks; -cc candidate momentum vector to seed primary vertex; -CL>1% for all 3 vertices; l/  >0 + Cherenkov cut K,p, . -select charm candidates (D o,D +,  + c ) in golden modes (K , K , k  and pK  ; -combine either D’s or  + c momentum vectors to meet additional tracks; -cc candidate momentum vector to seed primary vertex; -CL>1% for all 3 vertices; l/  >0 + Cherenkov cut K,p, . We searched for cc baryons in year 2000

26. Y=19994±262 S/  s=74 Y=1167305±3011 M(k ,k ,k  ) GeV SAMPLES ABOUT 1.2 MILLION EVENTS TO BEGIN WITH

27. 14  cc (D o,± X) decays and 7  cc (  + c X) decays

28. Combined distribution The 2 channels searched by SELEX The 2 channels searched by SELEX Sum of all our channels Sum of all our channels Selex areas in green

29. Conclusions – 2 No evidence of  cc. May be  prod in SELEX is 40 to 100 times our  prod ? No evidence of  cc. May be  prod in SELEX is 40 to 100 times our  prod ?

30. Final conclusions With ~ 20,000 + ~ 1.2 million D +,o, no evidence With ~ 20,000  + c + ~ 1.2 million D +,o, no evidence for production of neither nor for production of neither  + cc nor  ++ cc double charm baryons seen by SELEX -BR’s. of several  + c decays containing  ’s, relative to  + c  +  +  - : i.e.(  + K +  -,  - K +  +,  +  +  -,  +  o,  + K  +,  +o (1690)K +,…); -preliminary 1st evidence of  + c decay containing n (no,ev in PDG); -preliminary 1st evidence of  + c  - 3  +  - (1 ev in PDG); -BR’s. of several  + c decays containing  ’s, relative to  + c  +  +  - : i.e.(  + K +  -,  - K +  +,  +  +  -,  +  o,  + K  +,  +o (1690)K +,…); -preliminary 1st evidence of  + c decay containing n (no,ev in PDG); -preliminary 1st evidence of  + c  - 3  +  - (1 ev in PDG);