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Recent CP violation results from BaBar

This presentation explores recent findings on CP violation from the BaBar experiment, focusing on the CKM unitarity triangle and its implications for understanding quark sector violations. Presenting data on D and B meson decays, we discuss new results that indicate approximately 2.8σ tension between specific measurements, revealing potential new physics in low-energy flavor processes. Emphasizing the need for precise measurements of CP asymmetries and CKM parameters, we analyze our strategies and the BaBar detector's capabilities that contributed to these groundbreaking observations.

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Recent CP violation results from BaBar

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  1. Recent CP violation results from BaBar F. Martínez-Vidal • IFIC – Universitat de València-CSIC • Representing the BaBar Collaboration at Supersymmetry 2011 (SUSY 2011) FNAL, Batavia, Illinois (USA) 28th August to 2nd September 2011

  2. CP violation CKM unitarity triangle • Leading source of quark-sector CP violation established (mostly by BaBar and Belle) • CKM mechanism • Overall good consistency between measurements and predictions within CKM • ~2.8s tension for sin2bB(cc)K and BF(B+t+n) • New physics (NP) can be revealed in low-energy flavor processes…especially in loops • Particularly fruitful are processes with (very) small effects predicted by the SM • NP in generalinduces (additional) FCNC and CP-violating phases PRD 84, 033005 (2011) • Yet, need more and precise CP asymmetries sensitive to NP(loop level) • …and more precise SM candle (tree level)measurements (CKM angle g, or |Vub|) • The particle can be very heavy…can probe NP at the multi-TeV scale, but need huge data sets…Luminosity frontier • Complementary to direct searches at energy frontier 1 SUSY 2011, FNAL Recent CP violation results from BaBar F. Martínez-Vidal, IFIC-Valencia

  3. Outline • The BaBar detector & data set • CP violation in D decays • D+ p+K0s • D+(s)K+K0sp+p- and D0K+K-p+p- • CP violation in t decays • t-p-K0snt • CP violation in Charmless B decays • B+ (r0/f0)K*+ and B0 r-K*+ • B0 K+p-p0 and B+ K+p0p0 • Conclusions • BffK New CP violation results related to the measurement of the CKM angle g have been presented also in the last year, but will not be discussed in this talk 2 SUSY 2011, FNAL Recent CP violation results from BaBar F. Martínez-Vidal, IFIC-Valencia

  4. BaBar detector 1.5T solenoid EMC 6580 CsI(Tl) crystals DIRC (PID) 144 quartz bars 11000 PMs e+ (3.1 GeV) Drift Chamber 40 stereo layers e- (8-9 GeV) Silicon Vertex Tracker 5 layers, double sided strips Instrumented Flux Return iron / RPCs / LSTs (muon / neutral hadrons) • Asymmetric B-factory: Ecms = 10.58 GeV • Performed a wide range of flavor physics results in B, Cham and t sectors • General purpose detector in e+e- environment: precision tracking, photon/electron detection, particle ID, muon/KL identification. Very stable over the 9 years of operation 3 3 SUSY 2011, FNAL Recent CP violation results from BaBar F. Martínez-Vidal, IFIC-Valencia

  5. B factories Data set • 530 fb-1 recorded in the 9 years of operation 14.5 fb-1 30.2 fb-1 430 fb-1 54 fb-1 Off-(nS) 4 fb-1 above (4S) ≈ 470106 BB (0.5Belle) ≈ 690106 cc ≈ 500106 ≈ 1.2108 (3S) (7Belle+Cleo) ≈ 1.0108 (2S) (0.5Belle+Cleo) 4 SUSY 2011, FNAL Recent CP violation results from BaBar F. Martínez-Vidal, IFIC-Valencia

  6. Recent CP violation results: • D decays 5 SUSY 2011, FNAL Recent CP violation results from BaBar F. Martínez-Vidal, IFIC-Valencia

  7. D decays: motivation csud(CF) and cdus(DCS) cudd(SCS) and cuss(SCS) c u W+ • Direct CP violation in D decays arises through interference between: • In the SM is CKM suppressed O(10-3) or less • NP can increase or reduce the effect • e.g. additional CP phase from charged Higgs boson • SCS decays are more likely to show the effect if present • Current experimental sensitivity O(10-3) c s , d Vcs s Vcs W+ u g d , s d, s d, s Penguin Tree PRD 75, 036008 (2007) hep-ph/0104008 (2001) PRD 51, 003478 (1995) 6 SUSY 2011, FNAL Recent CP violation results from BaBar F. Martínez-Vidal, IFIC-Valencia

  8. D+p+K0s: experimental technique • Due to CPV in mixing in the kaon sector, the direct CP asymmetry is expected to be • Signal yields from likelihood fit to m(p+K0s), with selection based on a Boosted Decision Tree with 7 variables: • 807K D±signal events • Measure J. Phys. G 37, 075021 (2010) hep-ph/0104008 (2001) Forward-Backward asymmetry Detector charge asymmetry • Data-driven method to correct for Ae • Use tracks from e+e-(4S)BB decays (isotropic in rest frame) to map the ratio of p+/p- detection efficiencies • Offset on ACP+0.05% 7 SUSY 2011, FNAL Recent CP violation results from BaBar F. Martínez-Vidal, IFIC-Valencia

  9. D+p+K0s: results 470 fb-1 • Use data-driven method to extract AFB, and ACP in bins of polar angle Consistent with SM prediction (-0.332±0.006)% PRD 83, 071103(R) (2011) 8 SUSY 2011, FNAL Recent CP violation results from BaBar F. Martínez-Vidal, IFIC-Valencia

  10. D+(s)K+K0sp+p- : experimental technique • Measure a T-odd observable • If we assume CPT invariance  CP violation • Define T-odd triple products for D+(s) and D-(s) • Define the T-odd asymmetries • FSI could introduce fake T-odd asymmetries. To remove, define • Signal selection optimized by means of likelihood ratio with 3 variables • Yields obtained from simultaneous likelihood fit to m(K+Ksp+p-) distributions for D+, D-, Ds+, Ds-, for >0 and < 0 triple products (8 samples in total) T-violating asymmetry PRD 66, 094004 (2002) PRD 64, 116003 (2001) PLB 538, 309 (2002) Int.J.M.Phys. A24, 657 (2009) 9 SUSY 2011, FNAL Recent CP violation results from BaBar F. Martínez-Vidal, IFIC-Valencia

  11. D+(s)K+K0sp+p-: results 520 fb-1 • ~21K D± and 30K Ds± signal events • Results • Similar BaBar analysis using D0K+K-p+p- • ~47K D0/D0 signal events FSI seem to be larger in D+s than D+ decays 1107.1232 [hep-ph] (2011) T-violating asymmetry consistent with 0 10 improvement wrt previous result 1105.4410 [hep-ex] (2011). Accepted by PRD(RC) PRD 81, 111103(R) (2010) 10 SUSY 2011, FNAL Recent CP violation results from BaBar F. Martínez-Vidal, IFIC-Valencia

  12. Recent CP violation results: • t decays 11 SUSY 2011, FNAL Recent CP violation results from BaBar F. Martínez-Vidal, IFIC-Valencia

  13. t-p-K0snt: motivation t- nt W- • SM model predicts the decay amplitude and its CP conjugate to be the same  no direct CP V is expected • However, like in D+p-Ks, due to CPV in the kaon sector, the CP asymmetry is expected to be • A deviation of the measured AQfrom AQSM would be a hint of NP • e.g. an additional CP violating phase from an exotic charged Higgs boson • Can consider • p0s are expected not to change the asymmetry u p- d Tree s d K0 PLB 625, 47 (2005) Note: the sign of the asymmetry is opposite to that of D+p+K0s PLB 398, 407 (1997) 12 SUSY 2011, FNAL Recent CP violation results from BaBar F. Martínez-Vidal, IFIC-Valencia

  14. t-p-K0snt:experimental technique Selected event topology e+orm+ • Reconstruct up to 3p0s • Electron andmuon tags • pl* > 4 GeV to reduce background from non-t-pairs • Reconstructed hadronic mass < 1.8 GeV • Rejects qq background Invariant mass of the hadronic final state (0p0s) • Remaining qq and K0s background further reduced using likelihood ratio technique • Visible energy, number of neutral clusters, thrust, total transverse momentum • Displaced vertex, invariant mass, momentum and polar angle of the K0s candidate Preliminary 13 SUSY 2011, FNAL Recent CP violation results from BaBar F. Martínez-Vidal, IFIC-Valencia

  15. t-p-K0snt:results 437x106t+t- pairs • Measured raw ACP value (after subtraction of qq background and non-K0st decays) has to be corrected by • Different nuclear reaction cross-section of K0 and K0 with material detector • (0.14±0.03)% for e-tag, (0.14±0.02)% for m-tag • Errors include uncertainties from kaon-nucleon cross-sections and isospin • Dilution from background modes including K0s • Result Systematic uncertainties 3s from the SM prediction Preliminary. To be submitted to PRD(RC) 14 SUSY 2011, FNAL Recent CP violation results from BaBar F. Martínez-Vidal, IFIC-Valencia

  16. Recent CP violation results: • Charmless B decays 15 SUSY 2011, FNAL Recent CP violation results from BaBar F. Martínez-Vidal, IFIC-Valencia

  17. Charmless B decays • Many such decays are dominated by bs penguins • Tree amplitudes subdominant in SM • Time-dependence and FSI (intermediate states) allow to measure the CKM angles • NP can change CP asymmetries, branching fractions and polarizations in BVV decays • Use kinematic constraints from beam energies • Event shape variables combined into a linear (Fisher) or non linear (NN) combination. Tagging (other “B”) information often used Tree Penguin • Apply selection to reject continuum • As variable in ML fit 16 SUSY 2011, FNAL Recent CP violation results from BaBar F. Martínez-Vidal, IFIC-Valencia

  18. B+r0K*+ and B+f0K*+ 467x106 BB pairs • B+r0K*+ is a VV decay. QCDF • Predicts longitudinal polarization fL~0.9 • Works for Brr, not for other VV decays where fL~0.5 (“polarization puzzle”) • Reconstruct r0/f0p+p- , K*+ Ksp+,K+p0 • ML fit with 7 variables: mES, DE, NN, invariant masses, cosq • Measure simultaneously BFs, ACPs, fLs • First observation of B+r0K*+ with 5.3s • Consistent with QCDF, BF  (5±1)10-6 • fL compatible with other bs decays NPB 774, 64 (2007) PRD 79, 039903 (2009) ρ0K*+ signal f0K*+ signal PRD 83, 051101 (2011) 17 SUSY 2011, FNAL Recent CP violation results from BaBar F. Martínez-Vidal, IFIC-Valencia

  19. B0r0/f0K*0 and B0r-K*+ Preliminary 471x106 BB pairs • Very similar to previous analysis • f2(1270)K*0 events extrapolated from mpp sideband • First 5s observations of B0r-K*+ and B0f0K*0 • BF consistent with QCDF, BF  510-6 • fLinconsistent with QCDF, but consistent with experimental results from other bs decays • Experiment: • QCDF: • Also measure scalar (Kp)*0 and tensor K*2(1430) states in a (Kp) “high-mass” region (not shown here) 18 SUSY 2011, FNAL Recent CP violation results from BaBar F. Martínez-Vidal, IFIC-Valencia

  20. B0K+p-p0 and B+K+p0p0 • We expect ACP(B0K+p-)  ACP(B+K+p0) • Experimentally • ACP(B+K+p0) = +0.050 ± 0.025 • ACP(B0K+p-) = -0.098 ± 0.012 • Is there a similar K*p puzzle? • Have to measure B0K*+p- and B+K*+p0 • P/T predicted to be 2-3 larger than in Kp • Many resonances interfere  full amplitude (Dalitz plot) analysis • Large backgrounds • qq + many different BB categories + large amount of signal misreconstructed (especially for K+p0p0), all accounted for 5s difference SM or NP? “Kp puzzle” Mod.Phys.Lett.A 24, 1983 (2009) 19 SUSY 2011, FNAL Recent CP violation results from BaBar F. Martínez-Vidal, IFIC-Valencia

  21. B0K+p-p0 and B+K+p0p0: results PRD 83, 112010 (2011) 454x106 BB pairs • Perform ML fit with mES and NN, and for K+p-p0 only, also DE and DP • For B0K+p-p0 • BF(B0K+p-p0) = (38.5 ± 1.0 ± 3.9)10-6 • ACP(K*+p-) = -0.29 ± 0.11 ± 0.02 • When combined with B0Ksp+p- : • For B+K+p0p0 • First inclusive measurement • Measure resonances in a two-body fashion • More statistics is needed to better test ACP(K*+p-) ACP(K*+p0) 3.1s evidence for direct CPV • ACP(K*+p-) = -0.24 ± 0.07 ± 0.02 471x106 BB pairs 10s significance • To be compared to • -0.24 ± 0.07 ± 0.02 Preliminary 20 SUSY 2011, FNAL Recent CP violation results from BaBar F. Martínez-Vidal, IFIC-Valencia

  22. Conclusions • ended data-taking in 2008 but continues to produce many new physics results on CP violation in D, t and B decays • Only the most recent new results shown in this talk • Most results agree with SM predictions but some puzzles remain • Charmless BVV “polarization” puzzle • “Kp” puzzle • …and a 3s effect has just appeared • Direct CP violation int-p-K0snt • A larger data sample is required to perform stringent tests and searches • We look forward for many interesting flavor results from present and future flavor facilities 21 SUSY 2011, FNAL Recent CP violation results from BaBar F. Martínez-Vidal, IFIC-Valencia

  23. Bonus slides 22 SUSY 2011, FNAL Recent CP violation results from BaBar F. Martínez-Vidal, IFIC-Valencia

  24. BffK • Interference at mff ~mhc • SM tree and penguin have  the same weak phase • NP in the penguin could induce large direct CPV BffK (Penguin) Bhc(ff)K (Tree) PLB 583, 285 (2004) • ML fit in mES, DE, Fisher (and 2 f masses for BF) • Use (mf1,mf2) sidebands to extractpeaking backgrounds from BfKKK, 5K, f0fK, f0KKK decays mff<2.85 GeV region 464x106 BB pairs First 5s observation of B0ffK0 ACP consistent with 0 (SM expectation) PRD 84, 012001 (2011) 23 SUSY 2011, FNAL Recent CP violation results from BaBar F. Martínez-Vidal, IFIC-Valencia

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