1. 08/09/2007 Tania Moulik, B Spectroscopy at Tevatron, ISMD 2007 1 International Symposium of Multiparticle Dynamics 2007 International Symposium of Multiparticle Dynamics 2007 09 Aug 2007 Tania Moulik (University of Kansas) On behalf of CDF & DØ collaboration

2. 08/09/2007 Tania Moulik, B Spectroscopy at Tevatron, ISMD 2007 2  Protons :LINAC  Booster  Main Injector  Tevatron 400 MeV  8 GeV  150 GeV  ~1.00 TeV  Antiprotons : 120 GeV protons (MI)  Ni Target  antiprotons  debuncher+accumulator+recycler  Tevatron 6 Km 3 Km 150 m Accelerator chain

3. 08/09/2007 Tania Moulik, B Spectroscopy at Tevatron, ISMD 2007 3 Overview of Detectors

4. 08/09/2007 Tania Moulik, B Spectroscopy at Tevatron, ISMD 2007 4 QCD simplifies in the limit of one heavy quark mass  Heavy Quark effective field theory (HQET). Mass scale for heavy baryons different from quark confinement scale  ~ 400 MeV governing physics of light hadrons.  mt, mb, mc >>  QCD >> ms, mu, md Heavy baryons good way to study non-perturbative QCD (Quark interactions inside hadrons described by non-perturbative QCD) HQET successful in describing Qq systems. Continue to test it for Qqq systems. Features of HQET:  Treat heavy quark as static source of color field.  In case of baryons, view Light quarks forming a diquark pair and independent of the heavy quark in the limit of infinite heavy quark mass and it looks the same for any flavor or spin orientation of the heavy quark Also test Heavy baryon predictions from other theoretical models (approximations to QCD) :  1/Nc expansion, sum rules, lattice QCD B spectroscopy Motivation

5. 08/09/2007 Tania Moulik, B Spectroscopy at Tevatron, ISMD 2007 5 Experimental timeline of heavy B baryons For a long time only known heavy B baryon was  b.  Semileptonic decays observed at LEP between 1992-1998 and also at Tevatron.  Hadronic decay modes (Fully reconstructed == Measure mass precisely) ª(J/   ) (1991)@UA1 ª (1997)@CDF ª  c  (2006) @ CDF and continued to be studied at Tevatron. Recent discoveries at Tevatron of  b and  b, and the excited B states lead to an exciting new era of testing theories describing quark systems with a heavy baryon. Potential to discover other new B baryons, …and so on…

6. 08/09/2007 Tania Moulik, B Spectroscopy at Tevatron, ISMD 2007 6 The quest for b Baryons Light diquark system : spin 0 (  ) (I=0, Jp=0 - ) / spin 1 (  ) (I=1, Jp=1 + ) state  state (0+)  heavy Quark (1/2+),   state (1+)  heavy Quark (1/2+)  Host of hadron discoveries led Enrico Fermi to exclaimEnrico Fermi "Had I foreseen that, I would have gone into botany "

7. 08/09/2007 Tania Moulik, B Spectroscopy at Tevatron, ISMD 2007 7 Mass predictions and hierarchies Why are  and  masses different?  uus  –  (uds) mass difference believed to be due to difference between u-d and u-s hyperfine interactions : And other predictions : Hyperfine splittings Zeldovich, Sakharov, Sov. J. Nucl. Phys. 4(1967) 283 Predicted mass hierarchy: M(Λ b )< M(  b ) < M(  b ) Karliner, Lipkin, hep-ph/0307243, Phys. Lett. B 575, 249(2003)

8. 08/09/2007 Tania Moulik, B Spectroscopy at Tevatron, ISMD 2007 8 Observation of  b In  b  light quarks in symmetric state Together with heavy quark leads to doublet of baryons Ground state  decays strongly to  -type baryons (antisymmetric configuration of quarks) emitting pions. Look for  b in decay mode  b . Number of theoretical predictions: 180 – 210 MeV 10-40 MeV (Mass splitting) 5-7 MeV 0.40  0.07 MeV (Isospin splitting)

9. 08/09/2007 Tania Moulik, B Spectroscopy at Tevatron, ISMD 2007 9  b   b ,  b   c ,  c  p K  Start with constructing  b Then, Search for narrow resonances in the mass difference distribution Backgrounds:  tracks from  b fragmentation (e.g. hadronization of the b quark) and underlying event.  Physics background, ª B 0  D-  +; D-   -K+  - ª Also B 0 ’s from B ** decays. Optimize cuts with  b signal region blinded.  b c  PDG  = 422  m, Cut requirement: c  (  b ) > 250  m 5.565 < m(  b ) < 5.670 GeV

10. 08/09/2007 Tania Moulik, B Spectroscopy at Tevatron, ISMD 2007 10  b Results Fit to breit-wigner convoluted with double gaussian. Width of breit-wigner : No isospin splitting sensitivity Measure average

11. 08/09/2007 Tania Moulik, B Spectroscopy at Tevatron, ISMD 2007 11 Observation of  b (dsb) Vertex Prob  2 > 1 % pT (  ) > 1.5 GeV 2.80 GeV < M (  ) < 3.35 GeV pT (J/  ) > 5 GeV Vertex Prob  2 > 1 % Track with higher mom. Assumed pion 1.05 GeV < M (p  ) < 1.125 GeV At most 2 hits in tracker before p  vertex. Imp. Param sig. > 3(both tracks) At least > 4 (for one track) Imp. Param sig. > 3(pion track) Decay length (  ) > 4 * uncertainty  Decay length (  ) > 4 * uncer tainty

12. 08/09/2007 Tania Moulik, B Spectroscopy at Tevatron, ISMD 2007 12 Special techniques..   p  For particles like the  b -, usual impact parameter cut requirement for track reconstruction could result in missing the  and proton tracks from the  and  - decays. At DØ entire J/  dataset was processed with “special” extended tracking: Impact parameter cut from 2.5 cm  10.0 cm Maximum acceptance angle  0.08 rad  0.2 rad At CDF  candidate tracks are refitted, with Si hit requirements.   →p-→p- ----

13. 08/09/2007 Tania Moulik, B Spectroscopy at Tevatron, ISMD 2007 13  b Results Likelihood Fit Results : M (DØ) = 5774  11 (stat.)  15 (syst.) MeV -- [1] M (CDF)= 5792.9  2.4 (stat.)  1.7 (syst.) GeV ) – [2] ( Theory : 5.793 - 5.814) Likelihood Fit Results : M (DØ) = 5774  11 (stat.)  15 (syst.) MeV -- [1] M (CDF)= 5792.9  2.4 (stat.)  1.7 (syst.) GeV ) – [2] ( Theory : 5.793 - 5.814) 15.2  4.4 17.5  4.3 [1] PRL 99, 1052001 (2007) [2] arXiv:0707.0589

14. 08/09/2007 Tania Moulik, B Spectroscopy at Tevatron, ISMD 2007 14 Observation B 1 and B 2 * Among B mesons,  Only ground 0 - states B+,B0,Bs,Bc  and excited 1- state B* considered established. Quark models predict 2 broad and 2 narrow P-states:  Broad states difficult to distinguish  Width ~ 100 MeV (Decay through an S wave).  Narrow states easier to identify  Width ~ 10 MeV (Decay through D wave) M..Di Pierro and E. Eichten, Phys. Rev. D 64 (2001)

15. 08/09/2007 Tania Moulik, B Spectroscopy at Tevatron, ISMD 2007 15 Observation B 1 and B 2 * Look for mesons in decay modes Reconstruct Look for  track from primary vertex. Combine with B+ Plot Breit-wigner convoluted with gaussian. Resolution in  M determined from simulation PDG, J. Phys. G 33 1 (2006)

16. 08/09/2007 Tania Moulik, B Spectroscopy at Tevatron, ISMD 2007 16 Observation B 1 and B 2 * D0CDF M(B 1 ) (MeV)5720.6  2.4  1.4 M(B 2 *) (MeV)5746.8  2.4  1.7 Unable to resolve the B2* decaying through B* and emission of  and through B. Masses agree to within 1 

17. 08/09/2007 Tania Moulik, B Spectroscopy at Tevatron, ISMD 2007 17 Observation of B s * Analysis similar to previous mode Look for the decay B * s2  B+K- Where is B * s2  B * K ? should be here Claim : Suppressed due to L=2 orbital angular momentum and small mass difference D0 does not observe the Bs1 peak. Would be interesting to look at more data.

18. 08/09/2007 Tania Moulik, B Spectroscopy at Tevatron, ISMD 2007 18 B s * Interpretation and Theory Theory predicts equal branching ratios of B s2 *  B*+K- and B+K-. Experimentally should be observed as resonance displaced to lower  M by photon energy 45.78+-0.35 MeV. Rate supressed by a factor (No signal expected with current statistics) What about B s1  B*K+?  In (bd) system, M(B2*) – M(B1) = 26.2+-3.1+-0.9,..Applying to Bs system…  Expect B s1 = 5813 MeV i.e. < M(B*)+M(K-) (5819 MeV)…In this case, no Bs1 signal expected. C.M. Momentum of K in B*K decay C.M. momentum of K in B K decay

19. 08/09/2007 Tania Moulik, B Spectroscopy at Tevatron, ISMD 2007 19 Results B s *

20. 08/09/2007 Tania Moulik, B Spectroscopy at Tevatron, ISMD 2007 20 B Quest began … and continues @ Fermilab Celebrating 30 years of the b quark discovery @ Fermilab A fitting anniversary celebration: Discovery of new B baryons…and the search goes on…! 1977