1. B c mass, lifetime and BR’s at CDF Masato Aoki University of Tsukuba For the CDF Collaboration International Workshop on Heavy Quarkonium 2006 @ BNL

2. Masato AokiInternational Workshop on Heavy Quarkonium 2006 @ BNL2 Outline 1.Introduction a.The B c meson b.Tevatron and CDF 2.  (B c )B(B c  J/  l )/  (B u )B(B u  J/  K) measurement 3.Lifetime measurement 4.Mass measurement 5.Summary

3. Masato AokiInternational Workshop on Heavy Quarkonium 2006 @ BNL3 Ground state of bottom-charm quark bound system  Both quarks are heavy  Similar to cc and bb families  But the two quarks have different flavor  Only weak decay is possible  B c has measurable lifetime B c provides unique features of heavy quark bound states In the future…  As a B s generator  CP asymmetry measurement in D 0 D s decay mode The B c Meson

4. Masato AokiInternational Workshop on Heavy Quarkonium 2006 @ BNL4 B c in CDF Run I (1991~1996) B c signal search using B c  J/  l  (l=e,  ) channel ~20 B c signal events were observed in 0.11 fb -1 of J/    data [PRL 81, 2432 (1998) and PRD 58, 112004 (1998)] M=6.4±0.39±0.13 GeV/c 2  =0.46 ±0.03 ps +0.18 –0.16 =0.132 ±0.031 +0.041 –0.037 +0.032 –0.020  (B c )  B(B c  J/  l )  (B u )  B(B u  J/  K) * harder p T (B c ) was assumed

5. Masato AokiInternational Workshop on Heavy Quarkonium 2006 @ BNL5 The Tevatron Collider √s=1.98 TeV proton-antiproton collider Tevatron has already delivered 1.6 fb -1  CDF has ~1 fb -1 available for analysis We anticipate 4~8 fb -1 by the end of Run II Record peak luminosity : 1.82  10 32 cm -2 s -1

6. Masato AokiInternational Workshop on Heavy Quarkonium 2006 @ BNL6 B field : 1.4 T HAD calorimeter Muon system Drift chamber Silicon microstrip detector EM calorimeter The CDF II detector

7. Masato AokiInternational Workshop on Heavy Quarkonium 2006 @ BNL7 Heavy Flavor Physics at CDF Huge production cross sections at Tevatron   b ~30  b Large backgrounds as well qb q b b g g b q q b g b b g g g b B triggers  lepton trigger  displaced track trigger  and combined trigger Trigger requirements  large bandwidth  background suppression  deadtimeless primary vertex secondary vertex d0 B J/    Used for current B c analysis

8. Masato AokiInternational Workshop on Heavy Quarkonium 2006 @ BNL8 B c Production and Decay B c has differently flavored heavy quarks  Much smaller production rate  Unique decay (b  c,c  s,annihilation…)  Rich decay modes SpeciesProd. Fraction B+B+ 40% B0B0 BsBs 10% b-baryons10% BcBc ~0.05% Theoretical calculation : 7.4nb Phys. Lett. B605, 311(2005) DecayBR bcbc B c  J/  e ~1.9% B c  J/  ~0.13% cscs B c  B s  ~16.4% BcBs*BcBs* ~20.2% ann. BcBc ~1.6% B c  cs ~4.9% hep-ph/0308214(2003)

9. Masato AokiInternational Workshop on Heavy Quarkonium 2006 @ BNL9 Production Rate Measurement B c  J/  e and J/  semileptonic decays  Use J/    trigger data (0.36 fb -1 )  Large BR  statistical advantage  No narrow mass peak due to missing neutrino (4~6GeV/c 2 )  Need to understand all of backgrounds  fake J/  …………………..J/  mass sideband  fake e,  and DIF………...J/  +track & fake rate  bb (b  J/  X,b  l X)….....PYTHIA Monte Carlo  photon conversion e……...tagged conv. e & its efficiency  prompt J/  ……………….require to have a displaced vertex Use B u  J/  K as a normalization mode  Topologically similar  Measure  (B c )B(B c  J/  l )/  (B u )B(B u  J/  K)  Cancel out most of uncertainties

10. Masato AokiInternational Workshop on Heavy Quarkonium 2006 @ BNL10  (B c )B(B c  J/  l )/  (B u )B(B u  J/  K) Measurement : 0.36 fb -1 electron mode : 0.282 ± 0.038(stat.) ± 0.035(yield) ± 0.065(acceptance) (p T (B)>4GeV/c) 0.242 ± 0.036(stat.) ± 0.031(yield) ± 0.051(acceptance) (p T (B)>6GeV/c) muon mode : 0.245 ± 0.045(stat.) ± 0.066(syst.) +0.080/-0.032(life.) (p T (B)>6GeV/c) J/  e J/  5.9  5.2  * softer p T (B c ) was assumed

11. Masato AokiInternational Workshop on Heavy Quarkonium 2006 @ BNL11 Lifetime Three major decay diagrams Lifetime should be  B c   1/(0.6+1.2+0.1)  0.5 ps if all the three diagrams contribute to the decay

12. Masato AokiInternational Workshop on Heavy Quarkonium 2006 @ BNL12 Lifetime Measurement B c  J/  e semileptonic decay Perform a maximum likelihood fit to J/  e decay length Correct neutrino’s momentum using Monte Carlo Background shapes Estimate # of BKGs fake J/  conversion fake e bb Constrained during the fitting (same way as  B ratio measurement)

13. Masato AokiInternational Workshop on Heavy Quarkonium 2006 @ BNL13 Lifetime Measurement  (B c ) = 0.463 +0.073/-0.065(stat.) ± 0.036(syst.) ps B c  J/  e channel Data : ~  fb -1 accepted by PRL

14. Masato AokiInternational Workshop on Heavy Quarkonium 2006 @ BNL14 Mass Theoretical calculations predict M(B c )  6.3GeV/c 2 B c full reconstruction is necessary for precise mass measurement CDF searches for the B c  J/  decay : (BR~0.1%) PRL94,172001(2005)

15. Masato AokiInternational Workshop on Heavy Quarkonium 2006 @ BNL15 Observation of the B c  J/  decay and Mass Measurement Data : ~1.1 fb -1 J/  selection is optimized using B u  J/  K events 7.5  M(B c ) = 6276.5 ± 4.0(stat.) ± 2.7(syst.) MeV/c 2 N(B c )  50 Close up

16. Masato AokiInternational Workshop on Heavy Quarkonium 2006 @ BNL16 Summary The B c signal has been observed in B c  J/  e  modes with >5  significance in CDF Run II Measured B c meson properties   (B c )B(B c  J/  l )/  (B u )B(B u  J/  K)  e : 0.282 ± 0.038 ± 0.035 ± 0.065 (p T (B)>4GeV/c)   : 0.245 ± 0.045 ± 0.066 +0.080/-0.032 (p T (B)>6GeV/c)  Lifetime  0.463 +0.073/-0.065 ± 0.036 ps  Mass  6276.5 ± 4.0 ± 2.7 MeV/c 2 Other studies are to follow soon… Lifetime measurements from J/ , J/ 

17. Masato AokiInternational Workshop on Heavy Quarkonium 2006 @ BNL17 Backup slides

18. Masato AokiInternational Workshop on Heavy Quarkonium 2006 @ BNL18 Residual photon conversions Electrons coming from photon conversion event are removed from the J/  e candidate list Find colinear partner track miss-tracking in low p T region not 100% finding efficiency  residual photon conversion electrons Estimate using found conversions and its efficiency