B hadrons Tevatron By Eduard De La Cruz Burelo University of Michigan On behalf of the CDF and D0 collaborations Lancaster University UK, 2-8 July, 2006

CDF and DØ Detectors Complete description in other talks :  S. Donati, CDF detector and triggers for B Physics  L. Welty, D0 detector and triggers for B Physics

Outline In this talk B s lifetime in semileptonic decays B c lifetime Λ b lifetime CDF/D0 measurements no presented here B +,B 0, and B s lifetime in B→J/ ψX decays B +,B 0, and B s lifetime in hadronic decays B + and B 0 lifetime in semileptonic decays B s lifetime in B s →K + K - Summary, conclusions and future measurements…

Motivation EXPERIMENT THEORY Testing HQE, where light quarks are included via 1/m b perturbative expansions.  Expect some differences between lifetimes of different species: τ(B + ) ≥ τ(B 0 ) ≈ τ(B s ) > τ(Λ b ) >> τ(B c )  Lifetime ratios are usually reported since it reduces uncertainties Currently b-baryons are accessible at high statistics at the Tevatron. C. Tarantino, hep-ph/

Current status HFAG hep-ex/ B +,B 0 and B s mesons, excl. reconstructed in hadronic decays (CDF 360 pb -1 ) τ(B + ) = 1.66 ± 0.03(stat) ± 0.01(syst) ps τ(B 0 ) = 1.51 ± 0.02(stat) ± 0.01(syst) ps τ(B s ) = 1.60 ± 0.10(stat) ± 0.02(syst) ps τ(B + )/τ(B 0 ) = 1.10 ± 0.02(stat) ± 0.01(syst) τ(B s )/τ(B 0 ) = 1.06 ± 0.07(stat) ± 0.01(syst) Direct measurement of the lifetime ratio (D0 440 pb -1 ) τ(B + )/τ(B 0 ) = ± 0.016(stat) ± 0.014(syst) Measurements from CDF/D0 no presented in this talk (just to compare):

Lifetime measure techniques  Fully reconstructed decay:  Using proper decay length method: LBLB Primary vertex B decay Vertex Transverse component of the boost The distribution of is related to the lifetime of the B “R” is the resolution function

Lifetime measure techniques  Partially reconstructed decay:  Using pseudo-proper decay length method:  p T (semi) : Transverse momentum of the semi-reconstructed decay  K : factor to account for the momentum of missing particles in the B decay. Extracted from MC “R” is the resolution function Signal p.d.f.:

B s system Most general eigenstates: Schrödinger equation: Heavy (H) and light (L) B s eigenstates are expected to have different widths  Relation of matrix elements to decay and oscillation parameters:  Kin Yip, Measurements of Bs lifetime difference at Tevatron  J. Walder, B s oscillation measurements at D0  G. Salamanna, B s oscillation measurements at CDF

B s lifetime in semileptonic decays CDF and D  have measured the B s lifetime in the semileptonic decay B s →D s l X, l=e,  (DØ use only  )  It is a equal mixture of CP states, extra constraint to ΔΓ/Γ:  Large statistics from muon triggers τ m (B s ) is the mean B s lifetime obtained from a fit assuming a single exponential decay – I. Dunietz et al, Phys. Rev. D (2001) -.

signal ~ 1232 D0: Muons with pT>2 GeV CDF: 8 GeV single lepton trigger (muons and electrons) B s semileptonic samples

Primary vertex  K factor is extracted from MC  Charm and bottom background are included in the fit Pseudo-proper decay length:

Bs lifetime results: CDF 360 pb -1 D0 400 pb -1 World average(2006): Best world measurement !!!. Hep-ex/

Constraining ΔΓ/Γ R. Van Kooten: hep-ex/ hep-ex/ One sigma contours of flavor-specific decays lifetime, including D0 measurement. For ΔΓ/Γ and Bs→K + K - lifetime see:  Kin Yip, Measurements of B s lifetime difference at Tevatron

Λ b lifetime in the fully reconstructed decay Λ b →J/ ψΛ Lightest b baryon (udb) World average lifetime dominated by measurements in semileptonic decay channels, where Λ b is not fully reconstructed. Currently produced in high statistics only at Tevatron, (no produced in B factories) Testing Heavy Quark Expansion theory in three quarks system.

R is the detector resolution  Λ πp Beam line distribution related to the Λ b lifetime:

Measurement method λ + mass distribution (signal + bkg) Models for λ + mass distribution Simultaneous Mass & lifetime likelihood fit Signal selection Fitting procedure B 0  J/  K S is used as a control sample due to its similar topology, lifetime measured at the same time. It can be used to compute the lifetime ratio τ(Λ b )/ τ (B 0 ) Background p.d.f.:  Resolution for zero lifetime component  Exponential decays for short and long-lived bkg. Signal p.d.f.:  Exponential decay convoluted with the resolution function

Λ b mass signal PRL 94, (2005) DØDØ L=250 pb -1

D0 Λ b lifetime measurement V.M Abazov et al, PRL 94, (2005) DØDØ DØDØ Measurement in 250 pb -1 of data, in the decay:

New CDF’s Λ b lifetime measurement First time the Λ b lifetime is measured as large as to the B 0 lifetime. New precision is at the level of the world average. World average: τ(Λ b )=1.23 ± 0.08 ps

Cross check for lifetime measurement (CDF)

PDG 2004 Excludes new CDF result

B c lifetime  Bound state of two heavy quarks (b and c)  B c is the only meson with different heavy flavors  Only weak decays possible  Low production rate B 0 :B + :B s :Λ b ≈ 40:40:10:10, B c ~0.5%  Difficult to select due to its short lifetime bcbc cccc e  udud  J/ Ψ→µµ See dedicated talk to B c :  A. Rahaman, New results on B c in Tevatron

Lifetime extracted from B c → J/Ψ l ν samples CDF in J/Ψe channel (360 pb -1 ) DØ in J/Ψµ channel (210 pb-1 )

B c lifetime measurement CDF: lifetime measured in J/Ψe channel (360 pb -1 ) DØ: lifetime measured in J/Ψµ channel (210 pb -1 ) Prediction: 0.55 ±0.15 ps V. Kiselev, hep-ph/ Lifetime measurement using pseudo-proper decay length, K factor from MC

Summary A lot of lifetime measurements from the Run II of Tevatron. No possible to cover all of them in this talk. New CDF Λ b lifetime is surprising high compare to the world average. New measurements in complementary channels to come to support or cross check this. Best world measurement of B s lifetime in semileptonic decay, an extra constraint to ΔΓ/Γ and the possibility of new physics in the B s system. B c lifetime measurement consistent with prediction. Measurements in fully reconstructed decay channels in the future will help to improve the precision.

Future measurements… More results in the future:  DØ Updated  b  J/  Lifetime with 1 fb -1 Measurement of  b Lifetime in semileptonic decays using 1 fb -1  CDF Lifetime measurement in  b  c  Update of lifetime of B hadrons in B  J/  X channels using 1 fb -1 This measurements will cross check the CDF lifetime measurement what is 3σ away from the world average.