22 July 2005Mauro Donega HEP20051 B s lifetimes in hadronic decays at CDF Mauro Donegà Université de Genève on behalf of the CDF collaboration

22 July 2005Mauro Donega HEP20052 Outline CDF II detector Trigger on fully hadronic B decays Trigger shaping Correct for the trigger shaping Results

22 July 2005Mauro Donega HEP20053 CDF II – subdetectors used for these analyses LAYER 00: 1 layer of radiation-hard silicon at very small radius (1.5 cm) COT: large radius (1.4 m) Drift Chamber 96 layers, 200ns drift time Precise P T above 400 MeV/c Precise 3D tracking in |  |<1  (1/P T ) ~ 0.1%GeV –1 ;  (hit)~150  m dE/dx info provides >1.4 sigma K/  separation above 2 GeV/c SVX-II + ISL: (2) layers of double-side silicon (3cm < R < 30cm) Standalone 3D tracking up to |  |= 2 Very good I.P. resolution: ~30  m (~20  m with Layer00) TIME OF FLIGHT B =1.4 T

22 July 2005Mauro Donega HEP20054 Silicon Vertex Trigger   35  m  33  m  47  m (resolution  beam) Pt(trk) >2 GeV/c  Pt >5.5 GeV/c 100  m<IP(trk)<1 mm |  | <1 on-line Fully hadronic B decays

22 July 2005Mauro Donega HEP20055 Trigger bias - features SVT = high purity b-samples but…there’s a price to pay: proper time distribution is distorted Dashed = before trigger Solid = after trigger Toy demonstration 100  m<IP(trk)<1 mm

22 July 2005Mauro Donega HEP20056 Trigger shaping - correction decaydetector smearingefficiency function Likelihood Typical efficiency function Monte Carlo L sig (ct) = [exp(ct, c  )  G(ct,0,  ct )] x  TTT (ct) event by event resolution

22 July 2005Mauro Donega HEP20057 Tests: Check the range of validity of the efficiency function MC MC – data proper time distribution: Check the SVT decision on the B + → J/ψ K + unbiased sample and compare the proper time distributions

22 July 2005Mauro Donega HEP20058 Charmed Signals B ± → D 0  ± (D 0 → K -  + ) B 0 → D ±  ± (D - → K +  -  - ) B 0 → D ± 3  ± (D - → K +  -  - ) B S → D S ±  ± (D S - → Φ  - ) ( Φ → K + K - ) B S → D S ± 3  ± (D S - → Φ  - ) ( Φ → K + K - ) L = 360 pb -1

22 July 2005Mauro Donega HEP20059 Typical B-mass Distribution for hadronic final states Partially reconstructed decays Combinatorial background Cabibbo suppressed mode Less than 0.1% contamination in the signal region

22 July 2005Mauro Donega HEP Simultaneous Mass-Lifetime fit c  = 479 ± 32  m Mass = ± 1.1 MeV/c 2  =17.8 ± 1.1 MeV/c 2 B S → D S ±  ± (D S - → Φ  - ) ( Φ → K + K - )

22 July 2005Mauro Donega HEP Fit Results Systematic errors World Averages  (B + ) = ± ps  (B 0 ) = ± ps  (B s ) = ± ps HFAG Winter 2005

22 July 2005Mauro Donega HEP ±47 B  hh’ events Charmless Signals Invariant mass  hp (GeV/c 2 ) Unbinned maximum likelihood fit variables: Invariant mass  = q 1 (1-p 1 /p 2 ) BdBd BsBs Bd kBd k Bs kkBs kk B d   Bs  kBs  k B s  kk: almost pure CP even state  s 360 pb -1 underway ) L = 180pb -1 (

22 July 2005Mauro Donega HEP KinematicsParticle Identification = j BKG fraction (float) BKG Likelihood Sum over the 4 channels  B d  K +  - Bd  K-+Bd  K-+ e p k    T(ct,  ct ) Unbalance Momentum P(A|B)P(B)

22 July 2005Mauro Donega HEP Conclusions ● All the measurements agree with World Averages:  (B ± ) = 1.66 ± 0.03 ± 0.01 ps (W.A ± ps)  (B 0 ) = 1.51 ± 0.02 ± 0.01 ps (W.A ± ps)  (B S ) = 1.60 ± 0.10 ± 0.02 ps (W.A ± ps) B s -> K + K - important to get to  s The capability of measuring lifetime in fully reconstructed hadronic B decays at CDF has been demonstrated A Monte Carlo based way to correct for the trigger bias has been developed (and a MC independent one is well under development)

22 July 2005Mauro Donega HEP200515

22 July 2005Mauro Donega HEP TeVatron 1 fb -1 delivered

22 July 2005Mauro Donega HEP Decays topology B 0 → D ±    ( D - → K +      B ±  D 0    (D 0  K -    ) B S  D S ± 3  ± (D S -  Φ    ) ( Φ  K + K - ) PV D B B D D  Intermediate states are reconstructed B and D meson vertexes decay reconstructed Primary vertex from Beamline information ct = M B * L XY /p T B

22 July 2005Mauro Donega HEP B 0 → D ±  ± (D - → K +  -  - )

22 July 2005Mauro Donega HEP B 0 → D ± 3  ± (D - → K +  -  - )

22 July 2005Mauro Donega HEP B ± → D 0  ± (D 0 → K -  + )

22 July 2005Mauro Donega HEP B S → D S ± 3  ± (D S - → Φ  - ) ( Φ → K + K - )