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CP Violation in the B system at LHCb

Rencontres de Moriond. QCD and High Energy Interactions. La Thuile, March 22-29, 2014. Juan J . Saborido University of Santiago de Compostela (USC) On behalf of the LHCb collaboration. CP Violation in the B system at LHCb. Outline.

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CP Violation in the B system at LHCb

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  1. Rencontres de Moriond. QCD and High Energy Interactions. La Thuile, March 22-29, 2014. Juan J. Saborido University of Santiago de Compostela (USC) Onbehalf of theLHCb collaboration CP Violation in the B system at LHCb

  2. Outline Highlights of LHCb results on CP violation (CPV) in the B system CPV in mixing-decay Direct CPV CPV in mixing

  3. Polarization amplitudes and CP asymmetries in B0→f K* FCNC process. Gluonicpenguin in the SM. Sensitiveto NP contribution in theloop 1 fb-1 of 2011 data at 7 TeV. 1655 ± 42 signal events arXiv:1403.2888v1 P → VV decay: angular analysistostudythehelicity structure Three P-wave contributions: Naivetheorypredicts[Chen, Keum, PRD 66 (2002) 054013] a dominantfL (~ 0.8), but observed Two S-wave contributions:

  4. B0→f K*polarization amplitudes arXiv:1403.2888v1 Non-dominant in agreementwith BaBar[PRD 78(2008)092008]and Belle[PRD 88(2013)072004] P-wave KK S-wave Kp S-wave Significant S-wave contribution.

  5. Direct CP asymmetry in B0→f K* Flavor-specificdecay: Measure the “raw” asymmetry from time-integrated rates: Use the control channel B0 → J/ψK*0tocancel instrumental and production asymmetries through the followingdifference: arXiv:1403.2888v1 Resultconsistentwithzeroasymmetry, in agreementwithBaBar and Belle results, butwithsmaller (factor 2) uncertainties.

  6. Direct CPV in B → Kpdecays 1 fb-1of data PRL 110, 221601, (2013) P T + 1 fb-1 of data First observation of CPV in Bs decays (6.5 s) Test of SM expectation, using U-spin, Lipkin PLB 621 (2005) 126 Using LHCb measurement of branching ratios (JHEP 10 (2012) 037 ) SM agreement

  7. Direct CPV in 3-body charmlessB decays CP asymmetriesmeasured in B± → h’±h+h–decays, withh’ = K, p 1 fb-1of data [PRL 112, 011801 (2014)] [PRL 111, 101801 (2013)] [PRL 112, 011801 (2014)] Firstevidenceof inclusive CP asymmetries in B→ 3h, (3s – 5s)

  8. Phase-space dep. CPV in B+→ h+h−h+ (h=K,p) Large CP asymmetriesobservedin regions of phasespaceoutsideresonances 1 fb-1of data PRL 112, 011801, (2014)

  9. CP-violating chargeasymmetries in B±→fK± is a FCNC penguin process CP-violatingchargeasymmetryverysmallin the SM (1-2%). FCNC process, CKM and OZI suppressed. SM prediction: LHCbanalysis of 1fb-1of data to measure the two observables: [PLB 728 (2014) 85–94] to finally determine and

  10. CPV-violatingchargeasymmetries in B±→fK± [PLB 728 (2014) 85–94] A factor of 2 more precise thanthecurrent worldaverage (0.10 ± 0.04), and consistentboth withthe SM prediction and no CPV.

  11. → direct CP violation • → mixing-induced CP violation 1 fb-1 of data JHEP 10 (2013) 183 Firstmeasurements. 2.7 s from (0,0) Results compatible withprevious Babar and Belle measurements 5.6 sfrom (0,0)

  12. CP-violatingsemileptonicasymmetrymeasured in decays Measures CPV in mixing. is a flavour-specific final state verysmall in the SM: Lenz, Nierste (2012) Measure time-integratedasymmetrywith 1fb-1 of data. Use mostly data drivencorrections.

  13. Data analyzedwithdifferentmagnetpolaritiesseparately. Magnet “up” PLB 728 (2014) 607-615 Consistent with the most precise measurement made up to now and with the SM prediction D0 , [PRL 110 (2013) 011801]

  14. CPV throughtheinterferencebetweenmixing and decay Theinteferencebetweentwo “decaypaths” of a Bsmesonto a CP eigenstate Gives rise to a (final statedependent) weakphase in the SM NP might addlargesphasestothe SM prediction: Forindirectdetermination in the SM via global fits gives (neglectingpenguincontributions): CKMfitter, PRD 84 (2011) 033005 A precise determination of fsis as a sensitive test of NP in the Bs sector.

  15. P → VV decaywith CP-even and CP-oddcomponents. • Fitinvariantmass, decay time and angular distributions of flavour-taggedevents. • 1fb-1 of data at √s=7 TeV. (27617 ± 115 events) Total Fit CP-even S-wave CP-odd [PRD 87, 112010 (2013)] Single most precise measurements (Definition of helicity angles as for the B0→fK*decay in slide 4)

  16. CP-oddcomponent in the final state > 97.7% at 95% CL  no ang. analysisrequired. Fromtheanalysis of 1 fb-1 data [PLB 713 (2012) 378]: • New amplitudeanalysiswith 3 fb-1(full LHCb data) to studyresonant and CP components. • Fiveinterferingp+p-statesrequiredto describe thedecay: f0(980), f0(1500), f0(1790), f2(1270), f2(1525). • CP-oddcomponent > 97.7% confirmed. (arXive:1402.6248)

  17. Combinedmeasurement of fs [PRD 87, 112010 (2013)] • In agreementwiththe SM: fs = -0.0364 ± 0.0016 rad. • Limits NP contributionsto Bs mixingtolessthan 30% at 3s (A. Lentz arXiv:1203.0238v2). • Updatewith 3 fb-1comingsoon.

  18. Conclusions • All results (still) in good agreement with the SM. Many more not shown here. • Most of the measurements based only on 1/3 of the data available. • Results with 3 fb-1 luminosity gradually coming. • Eagerly waiting for LHC run 2. Thanks for your attention

  19. BACKUP

  20. The LHCb detector • Single arm forward spectrometer (2<h<5, 4% of solid angle). • Trigger reduces rate from 40MHz to 5kHz. • 3 fb-1 of data collected in 2011-2012. • High-precision tracking system (Dp/p ~0.5%) • Vertex detector • Silicon-strip detector • Charged hadrons identified using two RICH detectors • Photon, electrons and hadrons identified by calorimeters PV Impact Parameter (IP) resolution ~20 μm for high pT tracks Calorimeters Muon system Collected luminosity RICH detectors Vertex detector • 1.11 fb-1 at √s=7TeV (2011) • 2.08 fb-1 at √s=8TeV (2012) Tracking system

  21. Firstmeasurement of the effective lifetimein decayswith 3 fb-1 CP-even arXiv:1312.1217v1 Untagged decay rate probes , and Assuming negligible direct CPV (fs ≈ 0.01): Normalize to the decay, which has a

  22. Most precise measurement of GL arXiv:1312.1217v1 Measure also the effective lifetime using for normalization

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