ITEP Meeting on the future of heavy flavour physics 1 Experimental methods for precise determination of CKM matrix sides Marie-Hélène Schune Member of the BaBar and LHCb collaborations LAL-Orsay Introduction Present status V td, V ts : B mixing Rare B decays V cb, V ub : Semileptonic decays B Charm physics Overall status and future B factories : LHCb : Radiative B decays B s mixing

ITEP Meeting on the future of heavy flavour physics 2 Introduction

ITEP Meeting on the future of heavy flavour physics 3 Mass eigenstates  weak interaction eigenstates  mixing matrix : the Cabbibo-Kobayashi-Maskawa matrix Weak interaction eigenstates Mass eigenstates CKM matrix Transition amplitude between the quarks i and j : V ij bu W V ub V ij complex  CP violation Framework : the CKM matrix V ud V us V ub V cd V cs V cb V td V ts V tb d’ s’ b’ = dsbdsb 1- 2 A 3 (-i) /2 A 2 A 3 (1- -i) -A O( 4 ) Wolfenstein parametrisation

ITEP Meeting on the future of heavy flavour physics 4 3 families + CKM matrix unitarity  4 parameters Relations between the CKM matrix elements The unitarity triangle /2/2  /  1  /  3 (,)(,) (0,0) (1,0)   1- 2 A 3 (-i) /2 A 2 A 3 (1- -i) -A parameters known with different precisions : =sin( c ) ~0.4 % A ~ 1.7 %  ~ 15 %  ~ 5 % CKM : present status

ITEP Meeting on the future of heavy flavour physics 5 Some of the experiments BELLE CDF D0 BABAR e + e - (4s) pp s=1.96 TeV LHCb pit june 2006 pp s=14 TeV

ITEP Meeting on the future of heavy flavour physics 6 Present status

ITEP Meeting on the future of heavy flavour physics 7 V td and V ts top quark couplings  loop or box diagrams Search for New Physics V tb V ts b d s b d s W W V td t t V tb V td V ts Bd,sBd,s 0 Bd,sBd,s 0 b d s d s b W W V tb V td V ts t V tb V td V ts Bd,sBd,s 0 Bd,sBd,s 0 B B mixing : t Top quark contribution dominates d s  K* Radiative B decays Top quark contribution dominates

ITEP Meeting on the future of heavy flavour physics 8 B 0 -B 0 oscillations Time-dependent probability for a produced at t=0 to be observed as a or at time t Can be predicted in the SM framework Non-perturbative QCD perturbative QCD  Reconstruct the decay time (t) Tag the B production state : Other B information (B factories and pp colliders) Same side tagging (for pp colliders only/ B s )

ITEP Meeting on the future of heavy flavour physics 9 B 0 -B 0 Oscillations: m d SU(3) flavour breaking smaller theoretical uncertainties HFAG =1 m d : a high precision measurement (~0.8%) dominated by B factories results  m d =  ps -1 Asymmetry  cos(  m d t) |  t| (ps) Weak constraint on the UT triangle due to the knowledge of BELLE BB. Full B reconstruction  use Due to the size of the CKM elements m s >> m d

ITEP Meeting on the future of heavy flavour physics 10 Several analysis from LEP, SLD, Tevatron Combine different limits : the amplitude method measurement of A at each m s At a given m s : A=0 : no oscillation A=1 : oscillation m s excluded at 95% CL : A+1.645 A <1 Sensitivity : same relation with A=0 ( ) First limit was set in 1993 at m s >1.8 ps -1 at 95%CL !  B s -B s oscillations: m s HFAG LEP/SLD 1999 LEP/SLD 2002 m s : already a high precision measurement (~2.3%) CDF 2006

ITEP Meeting on the future of heavy flavour physics 11 Implications of m d / m s measurements on the CKM parameters determinations Two very precise measurements : (~0.8 % and 2%) Indirect measurement of m s (prediction) : But it does not translate into a precise determination of the SM parameters …  known to 5-8%

ITEP Meeting on the future of heavy flavour physics 12 Radiative B decays BR(b  d )  |V td | 2 BR(b  s ) |V ts | 2 d s Semi-inclusive analysis (~55% of the modes reconstructed) K* peak visible due to the good resolution  New Physics  BF of b  s and b  d  Standard Model  E  spectrum in b  s | V cb | and | V ub |  BF(b  s)/BF(b  d)  |V td | 2 /|V td | 2 Inclusive photon energy spectrum sensitive to b-quark motion inside B meson  reduces the systematic uncertainty in the V cb and V ub extractions bsbs

ITEP Meeting on the future of heavy flavour physics 13 B/  First observation: 5.5 signal qq K*  other B SU(3) breaking correction weak annihilation diagram for BR(B   ) Experiment BF(B  ) BaBar (211 x 10 6 BB) Belle (386 x 10 6 BB)  68%CL 95%CL Full UT fit With the present statistics : use of all the modes, in future  only ? < at 90% CL Expect new BaBar results at ICHEP

ITEP Meeting on the future of heavy flavour physics 14 V cb or V ub Exclusive and inclusive semileptonic approaches : different theoretical uncertainties Weak decay of a free quark : free quark decay Perturbative +non-perturbative corrections At the hadron level : Exclusive decays : depend on QCD form factors from eg LQCD, quark models... Inclusive decays : use Heavy Quark symmetry+ OPE measure OPE parameters from data (spectra and moments of bs and b  cℓ distributions) Complication for charmless decays:  need to apply kinematic cuts to suppress b  cℓ background  measurements of partial branching fractions in restricted phase space regions  theoretical uncertainties more difficult to evaluate  Semileptonic decays: V ub and V cb

ITEP Meeting on the future of heavy flavour physics 15 V cb inclusive (Buchmüller/Flächer): V cb from semileptonic decays Good agreement |V cb |F(1)= (37.60.8)10 -3 V cb exclusive ~5% precision |V cb |= (41.960.23 exp 0.35 HQE 0.59 SL )10 -3 ~2% precision |V cb |= (41.32.0)10 -3 22 with F(1) = 0.91  0.04 theo Does not contain the latest result from BaBar : |V cb |=

ITEP Meeting on the future of heavy flavour physics 16 V ub in inclusive B decays In these regions the theory (OPE) breaks down, acceptance sensitive to Fermi motion of b quark inside the B meson Several approaches : MethodS/BPros & Cons Untagged Electron spectrum endpoint 0.050.2 High statistics Bkg subtraction Untagged E e vs q 2 neutrino reconstruction ~0.5High statistics Lower syst. on shape functions Bkg subtraction Breco Tags m X vs q 2 analysis ~2Low background Very small syst. on SF param Small statistics signal

ITEP Meeting on the future of heavy flavour physics 17 B  0 ℓ B  + ℓ V ub exclusive : Bℓ Bℓ = missing of the event ; can add Breco tag to improve S/B Missing mass 2   ℓ   ℓ   ℓ   ℓ Measure the form factor q 2 dependance. Compare with theoretical calculations BF(B ℓ ) precision~8% Various experimental results in good agreement signal Yields : 36  - ℓ, 34  0 ℓ

ITEP Meeting on the future of heavy flavour physics 18 V ub from semileptonic decays summary V ub inclusive (HFAG) V ub determination from exclusive decays BF precision~8% but |V ub | precision ~20%  theory dominated ~8% precision |V ub |~ (4.40.2 0.3 )10 -3 inclusive |V ub |~ (3.70.2 0.7 )10 -3 exclusive Understanding of the difference ?

ITEP Meeting on the future of heavy flavour physics 19 B     In the SM it measures f B |V ub |  Direct measurement of f B when using |V ub | from SL decays (to be compared to LQCD predictions)  Test of NP (e.g.: charged Higgs could enhance BF)  Experimental technique  One B fully reconstructed (hadronic or semileptonic)  Search for  in the rest of the event (2) BR(B) BABAR BB< 2.6 at 90% CL BELLE BB 4.2  Electromagnetic energy not associated with the B tag nor the  0 from the  decay (GeV) V ub ~216 signal events Using |V ub | from HFAG :

ITEP Meeting on the future of heavy flavour physics 20 Charm physics Measurements of f D+ and f Ds improved prediction of f B /f Bs precise measurements of m d and m s precise determination of V td /V ts parameters + D BF measurements V cd Extraction of D form factors Validation of LQCD (DK ℓ ) B form factors (D /ℓ) precise determination of V ub /V cb parameters

ITEP Meeting on the future of heavy flavour physics 21 Recent lattice result (hep-lat/ ) Measuring f D and f Ds Pseudo scalar decay : V cd  wave function overlap CLEO-c 281 pb events N Bkgd =2.920.50 D* S  D S  and normalize to D s   D s →  signal N  = 489±55 Preliminary stat syst D s →  LQCD Aubin et al. PRL (2005)

ITEP Meeting on the future of heavy flavour physics 22 Semi-leptonic D decays DK ℓ form factor : comparison of recent experimental results with LQCD calculation CLEO BF relative to PDG (~117 events) Events / 10 MeV U ( = Emiss – |Pmiss| ) CLEO-c

ITEP Meeting on the future of heavy flavour physics 23 Overall status and future

ITEP Meeting on the future of heavy flavour physics 24 Phases and sides measurements in good agreement The CKM mechanism works well… NP should appear as correction to this framework Preferred region using only the sides measurements

ITEP Meeting on the future of heavy flavour physics 25 Future from the sides point of view : the B factories The existing B factories will collect about 1 ab -1 ( X 2 present samples) per experiment B measurement will improve  confrontation with LQCD predictions B/  determination will improve V ub analyses will be able to discriminate between theoretical models  improved V ub extraction B factories : charm factories ! Super B factory ? Japanese project, based on KEK2 experience : 40 ab -1 before 2020 More futuristic : Italian project (linked to ILC development) : 50 ab -1 before 2015 Improvement of all the above points : eg : expect few thousands BR(B) signal events !

ITEP Meeting on the future of heavy flavour physics 26 Future from the sides point of view : LHCb Use of radiative B decays :  N/yearB/S at 90% CL BdK*BdK* ~0.41%35k<0.7 B s  ~0.64%9.3k<2.4 B d ( 0 ) ~0.03%40<3.5 Analysis complicated by the presence of a  0 B d  0  should be easier BELLE has ~6 signal events in this mode LHCb But the extraction of |V td /V ts | is not completely clean from a theoretical point of view (SU(3) breaking, presence of a weak annihilation diagram in   (and not in K*) Full simulation of bb inclusive events

ITEP Meeting on the future of heavy flavour physics 27 Very precise measurement of m s using B s  D s (KK ) events : One year of data taking (2fb -1 ) : 80k fully reconstructed events with B/S~0.3 and (t) ~40 fs m s (ps -1 ) 20  stat (m s ) (ps -1 ) (m s ) will be dominated by the systematics (eg knowledge of the time scale) LHCb The tagging performances will be checked on data (similar self tagging decay modes, double tagging technique K same ) Tag  eff (%) Opposite Side 3.90.3 (1.50.1 CDF) Same Side 2.10.3 (3.40.5 CDF) Recent NN approaches lead to ~9% for B s Expected unmixed B s D s    sample in one year of LHCb data taking

ITEP Meeting on the future of heavy flavour physics 28 And then … Preferred region determined by sides measurements 2010 : B factories 2 x 1 ab -1 LHCb : 4 fb -1 V ub ~ 5% V cb ~ 1% (m s ) = 0.3 ps -1 f B B B ~ 5%  ~ 3% B K ~ 5% Lattice QCD  < 1°  ~ 7 °  ~ 5°(half B-factories/half LHCb) Experimental inputs Theoretical inputs Sides and angles determination of () : similar precision Hopefully this picture will not be the one we will see in 2010 and sides and angles measurements will be incompatible !

ITEP Meeting on the future of heavy flavour physics 29 Summary B factories : V cb and V ub determinations More and more inputs from data to constraint the theory  improved V ub and V cb measurements. f B extraction from B measurement Increasing role of charm physics which provide high-quality “lattice calibration”  improvement on the precision of the CKM parameters Hadronic colliders : Very precise measurement of the B s –B s mixing frequency Measurements of BK * , B s  and B/  All modes with neutrinos are difficult in hadronic environment Many new results expected for ICHEP !

ITEP Meeting on the future of heavy flavour physics 30 Backup slides

ITEP Meeting on the future of heavy flavour physics 31 b  cℓ and b  uℓ B d and B s mixing  K : CPV in K decays B  ccs :  1 /  B  /  /  :  2 /  B  DK :  3 /  2 sides ; 3 angles  aim : to overconstrain this unitarity triangle precision test of the Standard Model Constraints in the (,) plane

ITEP Meeting on the future of heavy flavour physics 32 The “B” experiments : main characteristics ExperimentIntegrated luminosity BoostMain points CDF/D0 1.6 fb -1 2 large  bb / had small  trigger  bb large Incoherent production ( extra tagging dilution) All B species Many particles not associated with the 2 b hadrons LHCb2 fb -1 (/year) BaBar/BELLE fb -1 small  bb / had ~ 0.2 Coherent BB production Only B  and B d BB pair alone

ITEP Meeting on the future of heavy flavour physics 33 Experimental techniques at B factories B-Flavour tagging t=1.6 ps  z 200, 250 m Exclusive B meson reconstruction coherent BB production Beam Energy-substituted massEnergy difference Event shape (m ES )  3 MeV (E) : mode dependent qq events (q=u,d,s,c) BB events Exploit kinematic constraints from beam energies  (4S) rest frame