New results from B A B AR, Marie-Hélène Schune, BNL, May 20th New results from B A B AR Marie-Hélène Schune Laboratoire de l’Accélérateur Linéaire Orsay, France All numbers are preliminary Brookhaven National Laboratory Particle Physics Seminar May 20, 2002

New results from B A B AR, Marie-Hélène Schune, BNL, May 20th New results from B A B AR I will not talk about –sin2  in charmonium modes : 1.B A B AR and PEPII 2.Charmless B decays : –B 0 , K  or KK –B 0  0  0 3.The “B recoil” physics : –semileptonic branching fractions of B + and B 0 –D meson production in B decays sin2  0.75  0.09  fb -1 Winter 2002 conferences

New results from B A B AR, Marie-Hélène Schune, BNL, May 20th –CKM matrix has 4 real parameters (one phase included) –2 are well known : =|V us |=sin(  Cabbibo )=  A =|V cb |/ 2 =0.83  0.06 –unitarity of the CKM matrix leads to constraints that can be tested: CKM matrix for 3 generations B d    ,    , … B d  J/  K s, D* + D* -,… B  D* , DK, K  B , ,  l,  l,… B d  B d, B d  B  D ( * ) l,D ( * ) ,… Unitarity Triangle  

New results from B A B AR, Marie-Hélène Schune, BNL, May 20th ) DIRC (PID) 1.5T solenoid CsI(Tl) EMC Instrumented Flux Return Silicon Vertex Tracker Drift Chamber e + (3.1GeV) e - (9GeV) SVT: 97% efficiency, 15  m z resol. (inner layers, perpendicular tracks) Tracking :  p T )/p T = 0.13% P T  0.45% DIRC : K-  separation >3  for P<3.5GeV/c EMC:  E /E = 1.33% E -1/4  2.1% The B A B AR detector

New results from B A B AR, Marie-Hélène Schune, BNL, May 20th 20025

New results from B A B AR, Marie-Hélène Schune, BNL, May 20th PEP-II asymmetric B Factory 9GeV e - on 3.1GeV e + :  s~10.58 GeV for B 0 : coherent neutral B pair production and decay (p-wave) boost of  (4S) in lab frame :  =0.55

New results from B A B AR, Marie-Hélène Schune, BNL, May 20th Running at the  (4S) Off On PEP-II B A B AR

New results from B A B AR, Marie-Hélène Schune, BNL, May 20th May 2 nd : –PEPII delivered : 87 fb -1 –BABAR recorded : 83 fb -1 (including 9 fb -1 off peak ) results for 55 fb -1 B factory performances daily integrated luminosity

New results from B A B AR, Marie-Hélène Schune, BNL, May 20th Charmless B decays Study of penguins diagrams Possible direct CP violation   B 0 , K  or KK –Branching fractions (  eff ,  ) –CP violations measurements (  eff,  ) B 0  0  0 (  eff  ) (,)(,)    

New results from B A B AR, Marie-Hélène Schune, BNL, May 20th B 0  and CP violation (1) BF(B 0  ) << BF(B 0  K  ) penguins contributions may be large Hadronic Penguin Amplitude (P) Tree amplitude (T) Tree only : =  f e 2i   C  =0 S  =sin(2  ) Tree+Peng. C   0 S  =sin(2  eff ) mixing e -2i 

New results from B A B AR, Marie-Hélène Schune, BNL, May 20th B 0  and CP violation (2) perfect flavour tagging & time resolution realistic mis-tagging & finite time resolution S  =0.7  and C  =0. f + : B 0 tag

New results from B A B AR, Marie-Hélène Schune, BNL, May 20th Main variables : –|cos  S | : angle between the B 0 sphericity axis and the sphericity axis of the rest of the event – F : Fisher discriminant based on “energy flow cones” (CLEO) B 0 , K  or KK kinematics “Jets” Candidate Axis of “Rest Event” Candidate |cos  S | Candidate

New results from B A B AR, Marie-Hélène Schune, BNL, May 20th Signal MC  ~2.6 MeV background B 0 , K  or KK : m ES and  E Energy substituted mass : –dominated by the beam energy knowledge  E : assume  mass –dominated by the tracking resolution  (  E)~26 MeV  KK KK ~325 MeV background m ES 45 MeV

New results from B A B AR, Marie-Hélène Schune, BNL, May 20th B 0 , K  or KK : the PID (1) The DIRC Measure Angle of Cherenkov Cone in quartz –Transmitted by internal reflection –Detected by PMTs Particle Quartz bar Cherenkov light Active Detector Surface

New results from B A B AR, Marie-Hélène Schune, BNL, May 20th DIRC PMT +light catchers DIRC stand-off box, magnetic shielding and electronic crates

New results from B A B AR, Marie-Hélène Schune, BNL, May 20th B 0 , K  or KK : the PID (2) DIRC performances measured on data using D*  D 0  and D 0  K   (  c )  2.2 mrad K/  separation 2.5  p range of 2-body B decays at B A B AR

New results from B A B AR, Marie-Hélène Schune, BNL, May 20th B 0 , K  or KK : analysis strategy Start with a B 0  h + h - (no PID) m ES ~17600 events for ~56 fb -1 unbinned max L with  E, m ES, F,  1c,  2c measure N  N K  N KK and add  t and tagging information (as for sin2  ), fix the yields extract S  and C 

New results from B A B AR, Marie-Hélène Schune, BNL, May 20th B 0  B0KB0K B 0 , K  or KK :branching fractions results ModeYield Branching Fraction (10 -6 ) K  Asymmetry (A K   B 0  +  - B0K-+B0K-+ B 0  K + K - Likelihood projections : remove one 1 variable from fit ; cut on L proba m ES  E small cross-feed ~83 B 0  ~356 B 0  K 

New results from B A B AR, Marie-Hélène Schune, BNL, May 20th B 0 , K  or KK : BF comparison CLEO 9 fb -1 B A B AR 56 fb -1 BELLE 31fb -1 BF( B 0  +  - )(10 -6 ) 4.3  1.6   0.7   1.1  0.4 BF( B 0  K -  + )(10 -6 ) 17.2  2.5   1.1   1.8  1.5 BF( B 0  K - K + )(10 -6 ) <1.9 at 90%CL<1.1 at 90%CL<0.5 at 90%CL AKAK   0.05   0.08  0.01 BF(B 0  ) << BF(B 0  K  )

New results from B A B AR, Marie-Hélène Schune, BNL, May 20th B 0 , K  or KK : CP analyses  t Time information  t : –resolution dominated by B tag vtx (  (  z) ~ 180  m) –extracted from data B reco sample (D (*) ,D (*) ,D (*) a 1 …) –Background shape : side bands Similar to sin(2  ) analyses

New results from B A B AR, Marie-Hélène Schune, BNL, May 20th NN output Not Used Prob(B 0 ) B Flavour tagging methods For electrons, muons and kaons use the charge correlation b c dd l-l- B0B0 D, D* W- Lepton Tag b d B0B0 W- W+ cs K *0 d Kaon Tag Each category is characterized by the probability of giving the wrong answer (mistag fraction w ) Multivariate analysis exploiting the other kinematic information of the event, e.g.,  Momentum spectrum of the charged particles  Information from non-identified leptons and kaons  Soft  from D* decay Neural Network Hierarchical, mutually exclusive, tagging categories

New results from B A B AR, Marie-Hélène Schune, BNL, May 20th B 0 , K  or KK : CP analyses tagging Split the events into 4 tagging categories : –leptons –kaons –NT1 –NT2 Performances obtained on data (B reco sample) Similar to sin(2  ) analyses NN type tagging leptons kaons NT1 NT2 m ES

New results from B A B AR, Marie-Hélène Schune, BNL, May 20th B 0 , K  or KK : CP analyses validation Validation : measure  B on  /K  sample : Validation : measure  m d  B =1.66  0.09 ps  m d =0.517  ps -1 Select the K  events and plot A mix

New results from B A B AR, Marie-Hélène Schune, BNL, May 20th B 0 , K  or KK : CP analyses results S  =-0.01  0.37  0.07 S   [-0.66,+0.62] at 90 % CL C  =-0.02  0.29  0.07 C   [-0.54,+0.48] at 90 % CL ~ 27 B 0  ~9 Background ~25 B 0  ~9 Background Select the B 0  events Plot the asymmetry between B 0 tag and B 0 tag events

New results from B A B AR, Marie-Hélène Schune, BNL, May 20th BBNS: QCD FACTORISATION APPROACH: M. Beneke, G. Buchalla, M. Neubert and C.T. Sachrajda Nucl.Phys.B606 (2001) 245 ( ,  ) constraints from S  and C  CKM Fitter H. Höcker, H. Lacker, S. Laplace and F. Le Diberder Eur. Phys. J. C (2001)

New results from B A B AR, Marie-Hélène Schune, BNL, May 20th B 0 , K  or KK : CP comparisons Belle (K Trabelsi Moriond): -C  (BABAR)  2 (S   C   A 

New results from B A B AR, Marie-Hélène Schune, BNL, May 20th Search for B 0  0  0 BF(B 0  0  0 ) : –measured  isospin analysis to get  from B 0  +  - (M. Gronau, D. London Phys Rev Lett (1990)) –upper bound  still a useful constraint: (Y. Grossman, H. Quinn Phys Rev D (1998)) Experimentally challenging : –low BF expected (th. predictions : few ) –purely neutral final state Recent results : Yieldlimit (10 -6 ) (90% CL) CLEO (9 fb -1 ) BELLE (30 fb -1 ) 12  6 5.6

New results from B A B AR, Marie-Hélène Schune, BNL, May 20th Main variables : –|cos  S | : angle between the B 0 sphericity axis and the sphericity axis of the rest of the event – F : Fisher discriminant based on the “energy flow cones” –m EC : energy constrained mass –  E = E * B –  s/2 in the CMS Search for B 0  0  0 : analysis (1) “Jets” Candidate Axis of “Rest Event” F Candidate

New results from B A B AR, Marie-Hélène Schune, BNL, May 20th Search for B 0  0  0 : analysis (2) The B     0 background : –event shape similar to the signal one –m EC only slightly wider (small   missing) –  E is the only discriminating variable –in the fit : fix BF( B     0 )= (from CLEO upper limit)  E (GeV) B 0B 0 B000B000

New results from B A B AR, Marie-Hélène Schune, BNL, May 20th Unbinned maximum L fit using F PDF and (m EC,  E ) PDF Compare with an optimized cut and count analysis : Fit yield : Search for B 0  0  0 : results BF(B 0  0  0 ) < at 90 % CL Main systematics : neutral efficiency continuum m EC param. F param. B     0 yield 54 fb -1

New results from B A B AR, Marie-Hélène Schune, BNL, May 20th The “B recoil” physics generic B decay B type known  should allow (in principle !) to measure all B BF Will show : leptonic studies D 0 and D  production

New results from B A B AR, Marie-Hélène Schune, BNL, May 20th The “B recoil” physics B factories : the world’s largest sample of reconstructed B mesons 56 fb -1 B 0 sample N signal =13743  125 B + sample N signal =12909  120 Reconstruct the Cabibbo-favored hadronic decays :

New results from B A B AR, Marie-Hélène Schune, BNL, May 20th Inclusive semileptonic B decays Inclusive rate is large –Sides of the unitarity triangle |V cb | and |V ub | –B  X c e is large –B  X u e is an experimental challenge (0,0) (  )    (1,0)

New results from B A B AR, Marie-Hélène Schune, BNL, May 20th Compare b + /b 0 with  (B + )/  (B 0 ) : Extract the prompt and cascade lepton spectrum from the charge correlation with the B reco : –B -  X c e - –B +  X c e + –B 0 : correct for mixing CLEO results (2.4 fb -1 ) using B 0 tagged sample and  (4S)  l : –b 0 = (10.78  0.60  0.69)% –b + = (10.25  0.57  0.65)% –b + /b 0 = Inclusive semileptonic B decays

New results from B A B AR, Marie-Hélène Schune, BNL, May 20th Electron identification Variables : –E/p –Shower shapes –DCH and DIRC Performances measured on data: 90% Backgrounds : -  conversions  0 dalitz decays -J/  decays p (GeV)

New results from B A B AR, Marie-Hélène Schune, BNL, May 20th Background subtracted electrons spectra Rightsign Wrong sign B  N right sign = N + p B 0 N right sign =N 0 p (1-  d )+N 0 c  d N wrong sign =N 0 p  d +N 0 c (1-  d ) results on 21 fb -1

New results from B A B AR, Marie-Hélène Schune, BNL, May 20th b + /b 0 =.950 .080 .091 b + /b 0 =.99 .10 .03 b 0 and b + results BF results :ratio : B+B+ B0B0

New results from B A B AR, Marie-Hélène Schune, BNL, May 20th Inclusive branching fractions of B 0 and B + to charmed hadrons –Enters in the n c (= mean charm per B decay ) computation For each B specie two measurements are performed : The absolute BF : BF(B  DX) with D = D 0 or D + –“large statistics” –Need  (D) from MC The wrong D ratio : –Wrong D sample statistically limited –Need to correct for mixing for the B 0 –More MC independant D production in B decays DDDsc,…DDDsc,… b c s DDDsc,…DDDsc,… WRONG RIGHT q c B 0 or B - ( )

New results from B A B AR, Marie-Hélène Schune, BNL, May 20th D production in B decays reconstruction Hadronic : –B 0  D*  D*  D*a 1 Semileptonic : B 0  D  l fit to cos  B-D*l variable m ES cos  B-D*l D reconstruction : D 0  K  and D   K  50 fb -1

New results from B A B AR, Marie-Hélène Schune, BNL, May 20th BF(B  DX) Fit N( D ) and correct for B rec background  BF(B  DX) ( ) Brec : B 0  D*l M(K  ) M(K  ) Brec : B 0  D*  D*  D*a 1 BF( B 0  D 0 X)(%) Semilep  3.3  4.6 Hadronic 59.3  5.9  3.9 Combined 57.9  2.9  2.1 (*)  3.5 (**) ( ) BF( B 0  D  X)(%) Semilep  2.8  3.9 Hadronic 35.3  4.3  3.8 Combined 35.6  2.3  1.1 (*)  3.6 (**) (*) Correlated syst. (**) Uncorrelated syst.

New results from B A B AR, Marie-Hélène Schune, BNL, May 20th w (D) for neutral B mesons Correlate the D and the B flavours : –For B 0 : should correct for mixing done on an optimized time interval (|  t|<2.5 ps)  reduced statistical uncertainty,  m d dependance  obs = Mix Mix+Unmix =  d + w (1  2  d ) Unmix Mix Brec : B 0  D*l Brec : B 0  D*  D*  D*a 1 M(K  ) w ( B 0  D  X) (%) Semilept. 7.3  3.7  1.9 Hadronic 8.9  7.1  1.8 Combined 7.7  3.3  1.4  0.8 w ( B 0  D 0 X ) (%) Semilept  3.5  2.4 Hadronic 9.6  4.7  1.1 Combined 13.1  2.8  1.5  0.6

New results from B A B AR, Marie-Hélène Schune, BNL, May 20th Results suggest B 0 spectator quark effect negligible in wrong D production Results consistent with world data (“ B admixture”) In the future : –Add the B  sample –100 fb -1 – start to look for D s and  c (looser B reco selection ?) BF( B 0  D 0 X ) = ( 50.3  3.0  3.7 ) % BF( B 0  D 0 X ) = ( 7.6  1.7  1.1 ) % BF( B 0  D + X) = ( 32.8  2.5  3.5 ) % BF( B 0  D - X) = ( 2.7  1.2  0.6 ) % D production in B decays Better understanding of the overall picture of the B decays Compare BF( B 0  D 0 + D + X) = (83.1  6.4) % with world data: BF( B admixt  D 0 + D + X) = (78.5  3.4) % 30 or 51 fb -1

New results from B A B AR, Marie-Hélène Schune, BNL, May 20th Summary A true factory of B mesons : –BF(B 0  +  - ) = (5.4  0.7  0.4) –BF(B 0  K +  - ) = (17.8  1.1  0.8) Unfortunately not enough to get B 0  0  0 –BF(B 0  0  0 ) < at 90 % CL CP violation results : –S  =-0.01  0.37  0.07 –C  =-0.02  0.29  0.07 “B recoil” physics is starting : –Semi leptonic measurements –D mesons production in B decays BF( B 0  D 0 X ) = ( 50.3  3.0  3.7 ) % BF( B 0  D 0 X ) = ( 7.6  1.7  1.1 ) % BF( B 0  D + X) = ( 32.8  2.5  3.5 ) % BF( B 0  D - X) = ( 2.7  1.2  0.6 ) %