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Published byKathlyn Black Modified over 9 years ago
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A big success with more than 200 participants
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AIM OF THE WORKSHOP Make an overall status of our knowledge of the CKM parameters at the end of the era of CLEO, LEP, SLD, TeVatron I (reach consensus to start from common base) Try to define priorities for theoretical developments and future measurements : - in a short timescale (B-Factories/TeVatron II) - in a longer timescale (bridging today LHC)
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Working Group I : V ub, V cb and Lifetimes Working Group II : V td, V ts Working Group III : CKM Fits Lattice Data Group (LDG) Forum on Averaging (for PDG + users) Talks on : Charm and Kaon Physics Structure of the Workshop
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1- 2 /2 A 3 ( i ) 1- 2 /2A 2 A 3 (1- -i ) - A 2 1 u c t dsb b d, s b V td,V ts B Oscillations d, s V tb c,u B decays b V ub,V cb The CKM Matrix In the Wolfenstein parameterization 4 parameters :, A,
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To be continued at B-Factories and TeVatron Theoretical assumptions Theoretical uncertainties Possible measurements Theory UT parameters Measurements Error Meaning (discussion) Statistical Methods to extract UT parameters Analysis Methods Analysis Systematic
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WORKING GROUP I Lifetimes V cb V ub c,u B decays b V ub,V cb
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Inclusive Determination of V cb b c l V cb Average by LEP Working Groups BR sl + b V cb
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Determination of V cb limited by theoretical uncertainties ….. The expression of V cb in the low scale running HQ masses formalism (as an example)* Can these parameters be determined experimentally ? V cb = 0.0415 ( 1 - 0.012 2 0.010 m b + 0.006 s + 0.007 mbmb ( Fermi movement inside the hadron) ( also named ) 22 V cb m b pert * In “Upsilon expansion” formalism :
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From CLEO measurements
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Other experiments should perform this analysis …….
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Value agreed at the end of the Workshop Part of theoretical error on V cb becomes experimental from the determination of 2 and m b V cb (inclusive)= ( 40.7 ± 0.7 ± 0.8 ) 10 -3 It was ± 2.0 and of theo. origin !
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Exclusive Determination of V cb G(w) contains kinematics factors and is known (also 1 and ) F(w) is the form factor describing the B D * transition At zero recoil (w=1), as M Q F(1) 1 Strategy : Measure d /dw and extrapolate to w=1 to extract F(1) V cb
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Syst. dominated by the knowledge of the D** (for LEP) F(1) |V cb | 2 22
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F(1) At the Workshop agreement on F(1) = 0.91±0.04 (Gauss.) 3 determinations
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What’s next to improve V cb Experimental side: More and new moment analyses B-factories can perform both exclusive and inclusive analyses Theory side : More work on the theory for the 2 ,m b extraction Unquenched F(1) calculations Studies of eventual correlation between inclusive and excluive determinations Form factors measurements in B D*l
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Combing the inclusive and the exclusive measurements : V cb = (41.8 ± 1.0 ) 10 -3
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Challenge measurement from LEP Inclusive determination of Vub Using several discriminant variables to distinguish between the transitions : b c b u V ub B X u l
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Results from all the LEP experiments
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At the Workshop we agreed on V ub (inclusive) = (4.09 ± 0.46 ± 0.36) 10 -3 New determination
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Exclusive determination of Vub B l V ub = (3.68 ± 0.55 +0.28 (syst.))10 -3 (in ISGW2 Model) - 0.37 V ub = (3.68 ± 0.14 +0.21 (syst.)± 0.55(theo.))10 -3 - 0.29 Babar CLEO Important theoretical uncertainties from different models NOW, Lattice QCD calculations start to be precise
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What’s next to improve V ub Experimental side: B-factories can perform inclusive/end-point/exclusive analyses Theory side : More work on the theory for the extraction of inclusive/end-point analyses Lattice QCD calculations for exclusive form factors Correlations between the different V ub determinations Correspondence between D l and B l
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All lifetimes of weakly decaying B hadrons have been precisely measured Very important test of the B decay dynamics Lifetimes
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(B 0 d ) = 1.543 ± 0.015 ps ( 1.0%) (B + ) = 1.658 ± 0.014 ps ( 0.9%) (B 0 s ) = 1.464 ± 0.057 ps ( 3.9%) ( B ) = 1.208 ± 0.051 ps ( 4.2%) Averages from LEP/SLD/Tevatron (+ B-Factories) The hierarchy was correctly predicted ! (B + )/ (B 0 ) about 5 effect in agreement with theory (B 0 s )/ (B 0 ) about 1 effect in agreement with theory Is there a problem for B ?
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Theory News…..
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Next improvements : (B + )/ (B 0 ) from B factories But more important (B 0 s ) and ( B ) from TeVatron …. and B B c, c Experiment side: Theory side: Improvements of the Lattice QCD calculations
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mdmd msms WORKING GROUP II Radiative and Leptonic B decays Rare K decays d, s b b V td,V ts B Oscillations
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Present Future
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Study of the time dependent behaviour of the Oscillation B 0 - B 0 TextBook Plot
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Before B-Factories mdmd LEP/SLD/CDF precisely measured the m d frequency m d = 0.498 ± 0.013 ps -1 LEP/SLD/CDF (2.6 %) B-factories confirmed the value improving the precision by a factor 2 m d = 0.496 ± 0.007 ps -1 LEP/SLD/CDF/B-factories (1.4%) The final B-factories precision will be about 1% ( 0.004 ps -1 )
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Combination of different limits using the amplitude methods Combination using A and A msms m s excluded at 95% CL A + 1.645 A < 1 At given m s A = 0 no oscillation A = 1 oscillation Sensitivity same relation with A = 0 1.645 A < 1 Measurement of A at each m s
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m s > 14.9 ps -1 at 95% CL Sensitivity at 19.3 ps -1 “Hint of signal” at m s =17.5 ps -1 but with significance at 1. Expectation in The Standard Model m s [14.1-21.6] ps -1 at 95% CL
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Very important achievement. The m s information has to be included in the CKM Fits using the Likelihood Method. ( in the past this was a source of differences between the groups performing CKM fits)
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WORKING GROUP III CKM Fits Strategies the angle V ud,V us Two subgroups :
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1- 2 /2 A 3 ( i ) 1- 2 /2A 2 A 3 (1- -i ) - A 2 1 u c t dsb b d, s b V td,V ts B Oscillations d, s V tb c,u B decays b V ub,V cb The CKM Matrix In the Wolfenstein parameterization 4 parameters :, A,
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b u / b c | V ub \ V ub | 2 2 + m d |V td | 2 f B d 2 B B d f(m t ) 2 + m d \ m d |V td \ V td | 2 f Bd 2 B B d \ f B s 2 B B s 2 + K f(A, B K..)
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Ex : B K = 0.87 ± 0.06 (gaus) ± 0.13 (theo.) Treatment of the inputs Rfit Bayesian p.d.f. from convolution (sum in quadrature) Likelihood Delta Likelihood Likelihood obtained summing linearly the two errors Delta Likelihood [0.68-1.06] [0.76-0.98]At 68% CL
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Where the difference is coming from ? Difference comes from how the inputs are treated : At present mainly from: F(1), inclusive V cb, B K Breakdown of the error is important The splitting between Gaussian and theoretical error is crucial and somehow arbitrary Results of the Workshop : theoretical error reduced and origin of the error better defined K ( V cb 4 * B K )
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Differences are small and physics conclusions quantitatively the same
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The difference ( which is by the way small ) on the CKM quantities coming from the different methods, is essentially due to the different treatment of the theoretical errors Using Likelihoods as obtained from linear sum of Exp.+Theo. errors Using Likelihoods as obtained from convolution of Exp. Theo. errors Both methods use the same likelihood Differences almost disappears
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Another example with sin2 (without K )
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[0.14-0.30] [0.24-0.39] at 95%CL = 0.220 ± 0.040 = 0.315 ± 0.038 at 68%CL
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Which are the predictions : sin2 , , m s sin2 [0.57-0.81] [43.6-67.3] o at 95%CL m s [14.1-21.6] ps -1 sin2 = 0.78 ± 0.08From B J/ K 0 s First crucial test done
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Winter 2002 1995 1988 Mainly thanks to measurements done at LEP after the end of data taking
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What will happen next ? Proceedings by Summer : Yellow Book + simultaneous publication in other laboratories (Slac/Tevatron/Cornell..) We hope with significant improvement from B-factories Next Workshop, late Spring 2003 in UK ( Lake District ) Aim is to have a LHC preparation workshop in year B LHC -2 But may well be need for a further a Workshop before…. B Physics has been intensively studied during last 10 years at LEP/SLD/TeVatron and CLEO and spectacular improvements have been obtained in the last years
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