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Using the BaBar Detector At Stanford Linear Accelerator Center (SLAC)

Using the BaBar Detector At Stanford Linear Accelerator Center (SLAC) Giampiero Mancinelli UC based at SLAC Kalanand Mishra UC based at SLAC Rolf Andreasson UC Peter Moomaw UC M. Sokoloff, B. Meadows UC. Main Activities. Measurement of CP violation parameter g .

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Using the BaBar Detector At Stanford Linear Accelerator Center (SLAC)

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  1. Using the BaBar Detector At Stanford Linear Accelerator Center (SLAC) Giampiero Mancinelli UC based at SLAC Kalanand Mishra UC based at SLAC Rolf Andreasson UC Peter Moomaw UC M. Sokoloff, B. Meadows UC Brian Meadows, U. Cincinnati.

  2. Main Activities • Measurement of CP violation parameter g. • D0 Mixing using D tagged events. • Charm spectroscopy • Various Dalitz plot analyses of >= 3- body decays of D and B mesons. Brian Meadows, U. Cincinnati

  3. Angle g of the Unitarity Triangle Measure relative phase between Vub and Vcb • Process mediated by both b  c and b u amplitudes g from direct CP asymmetry sin(2b+g) time dependent CP asymmetry Brian Meadows, U. Cincinnati Updated and newresults

  4. Interference when D final state common to both D0and D0 g from direct CP violation Relative size (rB) of B decay amplitudes Not well constrained by theory. Larger rB, larger interference, betterg experimental precision BaBar hep-ex/0402024 Belle hep-ex/0406067 Relative strong phase (dB) unknown Different incarnations… Brian Meadows, U. Cincinnati

  5. Gronau London Wyler method Theoretically clean, but with 8-fold ambiguity D decays into CP eigenstate • CP modes:small D0branching ratio Select CP-even and CP-odd final states 3 observables, 3 unknowns • Normalize to D0decay into flavour state (K-p+) Experimentally Brian Meadows, U. Cincinnati

  6. From DCPK* Loose bound on rB GLW B-D(*)0CPK(*)- results D0CP K - D0CP K* - (K*- KSp -) NBB=227 106 NBB=214 106 Additional systematic error on ACP- ( CP even background) D*0 (D0CPp0)K - NBB=123 106 More CP eigenstate final states still to be added… More statistics needed to constrain g Brian Meadows, U. Cincinnati

  7. Atwood Dunietz Soni method D decay into flavor state dB dD Count B candidates with opposite sign kaons Input: Phys.Rev.Lett.91:171801,2003 Brian Meadows, U. Cincinnati D decay strong phase dDunknown

  8. ADS results D*0(D0g)K D0K D*0(D0p0)K NBB=227 106 No signal in current dataset Brian Meadows, U. Cincinnati

  9. rB from ADS method Sensitive to rB (RADS~r2B) D*0(D0p0)K D*0(D0g)K D0K RADS R*ADS No AADS measurement Brian Meadows, U. Cincinnati Not easy to determine g

  10. If we knew the charm phase shift dD? B-D(*)0K- D0(KSpp) Dalitz analysis Amplitude for B-/B+ “D0”K-/K+ g=75,d=180,rB=0.125 Sensitivity to g Isobar model for f(m2+ ,m2- ) can fix phase variationdD across Dalitz plot. Only two-fold ambiguity in g extraction r(770) DCS K*(892) Brian Meadows, U. Cincinnati

  11. D0(KSp+p-) Dalitz model Determined on D* D0p sample CA K*(892) Plot of mpipi r(770) DCS K*(892) Brian Meadows, U. Cincinnati No D-mixing, No CP violation in D decays

  12. Measurement of g • We are repeating this work using events where D0!p-p+p0 • The Dalitz plot for a small subset is shown here: Brian Meadows, U. Cincinnati

  13. The BaBar Detector at SLAC (PEP2) • Asymmetric e+e- collisions at (4S). •  = 0.56 (3.1 GeV e+, 9.0 GeV e-) • Principal purpose – study CPV in B decays 1.5 T superconducting field. Instrumented Flux Return (IFR) Resistive Plate Chambers (RPC’s): Barrel: 19 layers in 65 cm steel Endcap: 18 “ “ 60 cm “ Brian Meadows, U. Cincinnati

  14. Electromagnetic Calorimeter • CsI (doped with Tl) crystals • Arranged in 48()£120() • » 2.5% gaps in . • Forward endcap with 8 more  rings (820 crystals). g g  BABAR  0!gg 0!gg Brian Meadows, U. Cincinnati

  15. 144 quartz bars Particle ID - DIRC • Measures Cherenkov angle in 144 quartz bars arranged as a “barrel”. • Photons transported by internal reflection • Along the bars themselves. • Detected at end by ~ 10,000 PMT’s Detector of Internally Reflected Cherenkov light PMT’s Brian Meadows, U. Cincinnati

  16. Particle ID - DIRC It Works Beautifully! 10 8 6 4 2 0 BABAR K/ separation () Provides excellent K/ separation over the whole kinematic range • 2.5 3 3.5 4 • Momentum (GeV/c) Brian Meadows, U. Cincinnati

  17. Drift Chamber 40 layer small cell design 7104 cells He-Isobutane for low multiple scattering dE/dx Resolution »7.5% Mean position Resolution 125 m Brian Meadows, U. Cincinnati

  18. Silicon Vertex Tracker (SVT) • 5 Layers double sided AC-coupled Silicon • Rad-hard readout IC (2 MRad – replace ~2005) • Low mass design • Stand alone tracking for slow particles • Point resolution z» 20 m • Radius 32-140 mm Brian Meadows, U. Cincinnati

  19. “A Typical Event”  clusters Brian Meadows, U. Cincinnati

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