BaBar Physics Results and UCSD Contributions Vivek Sharma University of California, San Diego 4/23/2019 V.Sharma DOE Review 2000

BaBar Physics Highlights Measurement of Sin2b with 9 fb-1 (Osaka) Precise measurements of time-dependent B0 Oscillations with inclusive dilepton Exclusive fully reconstructed B Samples Precise measurement of B0 and B- Meson lifetime Measurement of B0 -> p+ p- and B0 -> K+ p- Rates Measurement of B -> K*g Search for B (K, K*)l+l- B Meson Reconstruction and measurement of Branching Fractions Time dependent Measurements Future CP Physics 4/23/2019 V.Sharma DOE Review 2000

BaBar Physics Talks Today Soeren Prell will describe time-dependent B Mixing analysis (headed to be the world’s best measurement) and measurement of mistag fractions for CP measurements Riccardo Faccini will describe the Sin2b Measurement I will summarize Highlights of Babar Physics results B reconstruction Effort and Physics with it Future physics directions and timeline for publications 4/23/2019 V.Sharma DOE Review 2000

Observation of B0pp & Kp Sensitive to angles Sin2a via time dep. CP asymmetry B0 -> K+pi- Vs B- -> K0Pi- possibly sensitive to g Require excellent Pi Vs K discrimination (DIRC) Precursor to other quasi-two body, three-body and four-body charmless B decay analysis needed for Sin2a N() = 25+-8 N(K) = 26+-8 N(KK) = 1+-4 Cut-based analysis using kaon selector 4/23/2019 V.Sharma DOE Review 2000

Likelihood analysis Good News for Sin2a ? Global likelihood fit using mES, E, event topology and energy flow based discriminant, and track Cherenkov angle Mode Ns Stat. Sig. (s) BaBar B (10-6) CLEO p+p- 5.7 K+p- 6.7 K+K- 2.1 <6.6 <1.9 Good News for Sin2a ? 4/23/2019 V.Sharma DOE Review 2000

Br(B0 -> K*0g) = (5.42 +- 0.82(stat) +-0.47(sys)) x 10-5 Electroweak Penguins Vital for measurements of V_td/V_ts Direct CP violation searches First step : Measurement of Exclusive mode B –K*g g t w S/d signal = 48 +- 7 events BaBar (8.6 x 106 BB) Br(B0 -> K*0g) = (5.42 +- 0.82(stat) +-0.47(sys)) x 10-5 4/23/2019 V.Sharma DOE Review 2000

Search for B (K, K*)l+l- B K e+e- B K m+m- B K* e+e- B K* m+m- e+e- K+ e+e- K*0 2 m+m- K+ m+m- K*0 1 Mode # obs. evts Total 3 # bkg. evts 0.25 0.50 0.33 1.3 0.20 90% C.L. limit < 12.8 x 10 -6 < 24.7 x 10 -6 < 25.2 x 10 -6 < 8.3 x 10 -6 3.15 fb-1 4/23/2019 V.Sharma DOE Review 2000

B Meson Lifetimes B0/B0 7.4 fb-1 B+/B- B0 = 1.506  0.052 (stat)  0.029 (syst) ps B+ = 1.602  0.049 (stat)  0.035 (syst) ps B+/ B0 = 1.065  0.044 (stat)  0.021 (syst) 4/23/2019 V.Sharma DOE Review 2000

B0 Mixing with Dilepton Sample POCA B20 Lepton 1 True B1 vertex True U(4s) Estimated Y(4S) vertex (4S) <z> = 250 µm B0 l+ l- Dmd = (0.507 ± 0.015(stat) ± 0.022 (syst))  ps-1 4/23/2019 V.Sharma DOE Review 2000

B Meson Reconstruction A variety of measurements are done best with a large fully reconstructed sample of B mesons B Oscillation B lifetime Study of Flavor tagging calibration (for CP) Null CP measurements (calibration check for sin2beta) With rising accumulated luminosity, a large sample of fully reconstructed events will change the way we do many key measurements in B physics B decays with missing neutrino b-> Tau nu and b -> s nu nubar B-> u l nu inclusive and exclusive rates (Vub) Reconstructing large B samples are non-trivial Individual branching ratios are small (~0.2%) Many “drops in the bucket” Large multiplicity in B decay requires good particle reconstruction efficiency and background control (PID) Requires good software coordination (~40-60 decay modes need to be reconstructed) Babar has the largest sample of fully reconstructed B mesons Reconstructed and analyses within weeks of data taking 4/23/2019 V.Sharma DOE Review 2000

B0 Meson Reconstruction B0  D(*) -p+  D(*) -r+  D(*) -a1+  J/Y K*0 2577±59 B0 4/23/2019 V.Sharma DOE Review 2000

B- Meson Reconstruction B -D0 p + B -D*0 p + 2636±56 B± 4/23/2019 V.Sharma DOE Review 2000

Fully Reconstructed (4S) p- K- p+ m+ m- B0 y(2S)K0s ( ) B0D*+p- D*+D0p+ y(2S)  m+ m- K0s p+ p- D0K-p+ 4/23/2019 V.Sharma DOE Review 2000

B0  D* -l+ nl D*-  D0 - D0  K-p+ , D0  K-p+ p0 , D0  K-p+ p- p+ 7517104 4/23/2019 V.Sharma DOE Review 2000

Fully Reconstructed B Decays at DOE Review last year From 18 to 14000 Reconstructed B Mesons in 1 year 4/23/2019 V.Sharma DOE Review 2000

UCSD Contributions to Sin2b Measurement 4/23/2019 V.Sharma DOE Review 2000

Time Dependent CP Asymmetry Measurement Btag Bcp lepton Kaon Z  Four Requirements Large samples of reconstructed “CP-interesting” decays of B Mesons 2. Measure the Z between the tag B and the CP B  Precision tracking and Vertexing 3. Tag flavor of the other B(tag) and measure “mistag” rates from data  Time-dependent Mixing with “non-CP” B decay modes 4. “null” CP measurements using non-CP B samples UCSD group has played an important role in each of these issues 4/23/2019 V.Sharma DOE Review 2000

UCSD Role in Babar Physics Riccardo Faccini : Sin2b Technical Coordinator Responsible for integrating all aspects of physics necessary for CP Asymmetry measurement Convenor, Charmonium Group Micro-DST database design and implementation for Physics analysis, New Data Model Taskforce Gerhard Raven Babar Tracking Coordinator (till ~June 2000) Vertex Reconstruction Data Delivery Model Soeren Prell Fitting algorithm (tFit) for Sin2b, time-dependent mixing and Lifetime (BaBar Standard) Babar Statistics task force Shahram Rahatlou Author of analysis packages for B reconstruction (Babar Standard) Thesis on Sin2b Measurement David MacFarlane Chair, Publication Board B Reconstruction Vivek Sharma Convenor, B reconstruction (BRECO) Group B Mixing and Sin2b 4/23/2019 V.Sharma DOE Review 2000

UCSD Role In Babar Physics Infrastructure Developed and maintained Micro-DST for physics analysis used by all Babar analyses Author of first (and only) B meson reconstruction and analysis packages: CharmUser, BrecoUser and DstarlnuUser heavily used in Babar Copied for other analyses with technical input from UCSD Author of CPFramework : Data-mining and delivery Algorithm to “tune” MC with data performance to study systematic errors Charged Particle tracking Particle Identification : Leptons & Kaon Taskforce to develop new Computing/analysis model for data analysis with ever-increasing data samples tFIT: Framework for time-dependent CP asymmetry, B mixing and lifetime analysis is a Babar Standard B & D meson vertex reconstruction and error evaluation : Is 1 m measured by Babar the same as the standard Critical for all time-dependent measurements Critical Role in facilitating BaBar Physics 4/23/2019 V.Sharma DOE Review 2000

Publications on 2000 Data First publication based on 2000 data targeted for spring 2001 Sin2b measurement targeted for BCP4 and Moriond And validation (time-dependent) measurements which exercise relevant algorithms B mixing with fully reconstructed B sample B lifetime with fully reconstructed B samples Expected to be the World’s best measurements Expect a flurry of publication between spring and fall2001 4/23/2019 V.Sharma DOE Review 2000

Data Sample Accumulated and Projected Osaka Data 20 fb-1 Future Luminosity Projections Year 2000  20 fb-1 Year 2001  +40 fb-1 Year 2002  +80 fb-1 Year 2003  +115 fb-1 Expect very precise test of Sin2b end 2001 and significant measure of Sin2a 4/23/2019 V.Sharma DOE Review 2000

UCSD Physics Goals Continue with successful & singular focus on Sin2b and B0 mixing measurements Develop CP fitting to include more decay modes with their specific physics issues Transversity (angular) analysis for PsiK*, D*D* Sin2a Continue to build large samples of fully reconstructed B Mesons B- -> Tau nu B-> X_u l nu Final states 4/23/2019 V.Sharma DOE Review 2000