B Production and Decay at DØ Brad Abbott University of Oklahoma BEACH 2004 June 28-July 3

B physics at DØ Will be presenting latest results on: –D** –B** –B s      –  (1S) production –X(3872) Keys to DØ B physics program –Muon system and trigger –Silicon vertex detector and fiber tracker L= 115 – 250 pb -1

SMT Muon System and Tracker New forward muon system with |  |<2 and good shielding 4-layer Silicon and 8 doublet-layer Fiber Trackers in 2 T magnetic field

Observation of B   D** X D** are orbitally excited D meson states In heavy quark limit –Two narrow states (D-wave) –Two broad states(S-wave) Search for narrow states via –D 0 1 (2420)  D* +  - –D* 0 2 (2460)  D* +  -

D 0 sample D 1 0 and D 2 * 0 observed in several experiments, most recently by BaBar/Belle in B -  D** 0  - DØ is studying D 1 0 and D 2 *0 in B semileptonic decays Start with B  D 0 X (D 0  K  )

D* sample Add a pion (charge correlated with the muon) with P T >0.18 GeV

D** Measure invariant mass of D* -  + system See merged D 1 0 (2420) and D 2 * 0 (2460) Wrong sign combinations

Interference effects Two interfering Breit-Wigner D** states with mass/width as measured by Belle (no resolution effects included) Work in progress to extract separate amplitude for each state and relative phase of interference.

Branching ratio Take experimentally measured number of D 1 0 and D 2 * 0 : N(D 1 )+N(D 2 *)=523  40 Measure branching ratio of B  D**(narrow) X, normalizing to known branching ratio (B  D* +  X) Br(B  {D 1 0,D 2 * 0 }  X Br({D 1 0,D 2 * 0 }  D* +  - ) =  0.021(stat) ± (sys) % Compare to LEP measurement of total D** Br (B  D* +  X) = (0.48  0.10)% ~ half the rate through narrow states

Future measurements = predicted by HQET World average =0.4 ± 0.15 DØ can measure: R Br(B   D 1 X ) Br(B   D* 2 X) Interference effects Helicity

B** Heavy quark symmetry predicts 4 B* J states J P = 0 +, 1 +, 1 +, 2 + Parity and angular momentum require B* J to decay to B*  or B  B** provide a good test of heavy quark symmetry Many properties of the B** unknown Large B cross section at Tevatron allows for precise measurements with large statistics

B** Search for B** d  B +  - B +  J/  K + Allows one to charge correlate the pion and the B to reduce combinatoric background 115 pb -1 PDG Average  GeV

Additional Channels Are adding in more decays to increase statistics B** +  B d   –B d  J/  K* –B d  J/  K S With increased statistics should be able to resolve the narrow B** states.

B d,s      Forbidden at Tree Level in SM BR(B d  l + l - )BR(B s  l + l - ) e(3.4 ± 2.3) (8.0 ± 3.5)  (1.5 ± 0.9) (3.4 ± 0.5)  (3.1 ± 1.9) (7.4 ± 1.9) Theoretical predictions Experimental limits at 90% CL BR(B d  l + l - )BR(B s  l + l - ) e < <  < <  < 2.5 %< 5.0%

B s     in SUSY(Two Higgs-Doublet Model) BR depends only on charged Higgs mass and tan  BR increases as tan 4  (tan 6  ) in 2HDM (MSSM) R parity violating models can give tree level contributions

Dimuon Data sample

Cut optimization Signal box is blinded Use a random grid search optimizing the ratio   = reconstruction efficiency of signal MC B= expected background extrapolated from sidebands a = number of sigmas corresponding to confidence level (set to 2 for this analysis, corresponding to ~ 95% CL (Following proposal from G. Punzi physics/ Test of hypothesis and limits)

Discriminating variables Isolation of the muon pair Opening angle between momentum vector of  pair and vector pointing from primary vertex to  vertex Decay length Box not opened yet180 pb -1

Expected upper limit Since box not opened, calculate expected upper limit Expected signal normalized to B +  J/  K + Expect 7.3 ± 1.8 background events in signal region Current expected limit using Feldman-Cousins: Br(B s     ) < % CL (stat + sys) Reoptimization still in progress. Further improvements expected

 (1S) Production Measuring the  (1S) production cross section provides a test of our understanding of the production mechanism of heavy quarks Extend measurement of  (1S) cross section to rapidities of 1.8 Color octet model predicts an increase in transverse polarization with increasing P T (Measurements so far are inconclusive)

Analysis Measure the  (1S) cross-section as a function of P T in three rapidity regions 0< |y| < <|y|< <|y|<1.8 Signal fit to 3 Gaussians  (1S),  (2S),  (3S) Background: 3 rd order polynomial m(  (2/3S) = m(  (1S) +  m pdg (  (2/3S)-  (1S))  (  (2/3S) =  (  (1S) + m  (2/3S)/m(  (1S))*  (  (1S)) 5 parameters: m,   (1S) Number of  (1S),  (2S),  (3S )

Normalized cross section 159 pb -1

Normalized Cross section

Normalized cross section Normalized cross section shows little dependence on rapidity Good agreement with published results Absolute cross section nearly ready Next: Polarization measurement

X(3872)  J/   +  - First observed by Belle B +  K + X(3872) decays Signal confirmed by CDF, DØ and BaBar Nature of X(3872) unknown Theories include: –Another charmonium state –D D* molecular state Since the X(3872) lies very close in mass to the Ψ(2S) charmonium state, and has a common decay mode (X  J/     , we compare production and decay properties of these two states through this decay mode

X(3872)   M=774.9 ± 3.1 (stat)  3.0 (sys) MeV  522 ± 100 X candidates  Significance = pb -1

Separate data into different regions Compare  (2S) yield to X yield in different regions Study production and decay characteristics

a) P T > 15 GeV b) |y| <1 c) |cos(   )| < 0.4 d) decay length < 0.01 cm e) isolation=1 f) |cos (   )| < 0.4 (   : boost one of the pions and the X(3872) into dipion rest frame.   is the angle between them) To within uncertainties, production of X(3872) found to be consistent with the production of the Y(2S) I.e producted both directy and via B decays, Future: look for radiative decays and charge analog of X Compare Submitted to PRL: hep-ex/

Summary Observation of B  D** X Observation of B** Sensitivity to Bs      Normalized Upsilon(1S) Cross section Observation of X(3872) Many new analyses on the way