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Radiative Penguins @ B Factories

Radiative Penguins @ B Factories. V. Erkcan Özcan University College London. l +. g, Z. l -. W+. + BOX. g. b. d. t,c,u. W+. b  sll penguin BF , CPV , A FB , F L ,  / e , q 2 -spectrum. b. s. t,c,u. g. W+. b. d. t,c,u. For B s penguins, see talk by R. V. Kooten.

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Radiative Penguins @ B Factories

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  1. Radiative Penguins@ B Factories V. Erkcan Özcan University College London V. Erkcan Özcan, UCL

  2. l+ g, Z l- W+ + BOX g b d t,c,u W+ bsll penguin BF, CPV, AFB, FL, /e, q2-spectrum b s t,c,u g W+ b d t,c,u For Bs penguins, see talk by R. V. Kooten. Radiative Penguin FamilyFlavor Changing Neutral Currents bsg penguin BF, CPV, E-spectrum bdg penguin BF, CPV, E-spectrum RARE! … V. Erkcan Özcan, UCL

  3. BB Backgrounds Mostly decays of light mesons (π0/η) Problem for inclusive measurements. Experimental Challenge Analyses of all radiative penguins impeded by huge BGs. • Continuum Backgrounds • e+e-qq(g) or ll(g). • Penguins as signal & BG One signal mode is the BG of another. Signal and Backgrounds vs. photon energy for inclusive BXsg. V. Erkcan Özcan, UCL

  4. A Signal Event Isolated high-E* EM deposition in the calorimeter. p0/hs vetoed. B-tagging: High-P* lepton from other B meson. BG suppression not enough: Psedo-reconstruction, event weighting, BG subtraction, peaking BG fits etc. needed! Isotropic BB event topology. V. Erkcan Özcan, UCL

  5. KEKB (KEK) PEP-II (SLAC) B Factories Asymmetric-energy beams Hermetic detectors High-granularity EM CAL Excellent vertex resolution Data @ Y(4S) resonance and off-resonance (~10%) Total ~560fb-1 Total ~330fb-1 Analyses based on 111-386 M BB Analyses based on 88-232 M BB V. Erkcan Özcan, UCL

  6. Exclusive bsgas of Summer 05 First baryonic channel Reconstructing particular exclusive decay. Experimentally cleaner. BF calculations depend on form factors, so theoretically less precise. Other observables, like CP violation parameters, to be compared to those from tree-level B decays. Some surprises of 2005: K1(1270)g / Kpp0g as large as K*(892)g, pLg observed. ~40% of total rate. Resonance structure in Kppg could tell about g polarization Comparable to K*(892) Branching Ratio × 106 V. Erkcan Özcan, UCL

  7. Firstmeasurement First studied by Belle (275 M BB). New BaBar results consistent (232 M BB). BKh(’)g 5.3sobservation TD CP violation can be studied like BK0p0g. First upper limits Expected to be suppressed due to destructive interference hep-ex/0603054, submitted to PRL V. Erkcan Özcan, UCL

  8. Inclusive bsg : Constraints on NP Total branching fraction very sensitive decay to NP. Two techniques: Sum-of-exclusive (K(np)g), fully inclusive (reconst. g only). World average in good agreement with SM theory. => Strong constraints on NP. Exp. world average (HFAG): BaBar sum-of-exclusive value statistically & systematically independent of BaBar fully inclusive value (not in HFAG). BaBar fully inclusive value to be updated very soon. BaBar Physics Reach Study Combined constraint Constraints to H+ mass in 2hdm.(following Hou, PRD 48 2342, 1993; and Gambino-Misiak hep-ph/0104034) bsg constraint btn constraint (pre-FPCP) Eg > 1.6 GeV SM prediction (NLO): Experimental errors already smaller than theory. NNLO calculation expected to significantly reduce error. Hurth et. al., Nucl. Phys. B, 704, 56 (2005) V. Erkcan Özcan, UCL

  9. g g Gluon Radiation b b B Fermi motion s Xs bsg Photon Spectrum 1st Moment: 2nd Moment: (Momentum of b)2 Motion of b inside B, “Fermi motion”, is “universal” so information from B→Xsg can be used in studying other B decays (ex. extracting Vub). preliminary CLEO sum-of-exclusive fully inclusive V. Erkcan Özcan, UCL

  10. Minimum Photon Energy (GeV) Moments of the Photon Spectrum Moments as a function of minimum Eg. Good agreement among experiments and with theory predictions. Theory is Bigi,Benson and Uraltsev (Nucl Phys B 710 371 2005) using BaBar measured B->Xcln moments PRL 93 011803 (2004). (Moments at higher E from Belle – not shown – also consistent.) V. Erkcan Özcan, UCL

  11. Fit to bsg moments Fit to bcln moments Combined fit to moments Fit to bsg spectrum (BaBar) Fits from O. Buchmüller, H. Flächer, hep-ph/0507253. Thanks to H. Flächer for plot. Fits to HQE Parameters • Fits performed to obtain b­quark mass and Fermi momentum in kinetic scheme (Benson, Bigi, Uraltsev) and SF scheme (Lange, Neubert, Paz). • Fits to bcln moments, bsg moments or bsg spectra are consistent. mb error less than 1%! V. Erkcan Özcan, UCL

  12. Belle psedo-reco. technique (152 M BB) BaBar sum-of-exclusive modes (89 M BB) CP Asymmetry measured in many exclusive modes. Even time-dependent asymmetry studied in channels like Ks0p0g (see talk by H. Kakuno). Direct CP AsymmetryInclusive BXg For inclusive bsg : For inclusive “untagged” b(s+d)g : BaBar lepton-tagged fully-inclusive (89 M BB) V. Erkcan Özcan, UCL

  13. 386M BB bdgFirst Observation hep-ex/0506079 • Requires strong BG suppression: • Flavor-tagging, vertex displacement from other B, K* veto, r/w helicity cuts… • Fit for signal, continuum, K*g, other B BGs. • Central values show big isospin violation! • Combined fit, assuming isospin. V. Erkcan Özcan, UCL

  14. 211M BB bdgComparison with BaBar PRL 94 011801 2005 Combined fit, assuming isospin: V. Erkcan Özcan, UCL

  15. Recent Belle result: bdg : |Vtd/Vts| Ratio of form factors 2 = 0.85 ± 0.10 SU(3) breaking R = 0.1 ± 0.1 UTfit to all modes UTfit to r0 data only Earlier BaBar result: Independent constraint on CKM – “ms of B Factories” V. Erkcan Özcan, UCL

  16. bsllC7, C9 & C10 Exclusive Kll and K*ll Inclusive (Sum-of-exclusive) Gambino et.al., PRL 94 061803 (2005) BF (10-6) • Established in all individual modes except K*+ modes & K0ee mode. • Kll smallest B decay measured at 5s. 3s away from exp. Kll preliminary V. Erkcan Özcan, UCL

  17. 386M BB BK*ll @ Belle hep-ex/0603018 • 113.6 ± 13.0 K*ll events (44% purity). • Fix A7=-0.33 (SM) and fit for A9/A7 and A10/A7. • Repeat for A7=+0.33. • Use Kll for null test. A9/A7 = -12.33 A10/A7 = 12.82 SM V. Erkcan Özcan, UCL

  18. 229M BB BKll @ BaBar preliminary • BaBar follows broader approach. • C1-C10 would not account for pseudoscalar/scalar particles that can replace g/Z. • In presence of such scalar contribution, FS, AFB can be non-zero even for BKll. Fits are performed to obtain both AFB & FS. Consistent with zero (SM). V. Erkcan Özcan, UCL

  19. 229M BB • For K*ll decay, in addition to AFB, another quantity of interest : longitudinal polarization FL of K*. • FL sensitive to left-handed currents with complex phases or right-handed currents in g penguin amplitude. BK*ll @ BaBar preliminary SM inconsistent with AFB fit at low-q2 !!! (98% CL) Wrong sign C9C10 excluded! (consistent with Belle) FL fit consistent with SM. With 1 ab-1 could exclude wrong-sign C7. V. Erkcan Özcan, UCL

  20. Summary • Extracted BFs / CPV / AFB almost all in agreement with SM. • BaBar AFB (BK*ll)measurement at low q2 away from SM; would be useful to average BaBar and Belle measurements. • Developed techniques highly scaleable, experimental errors to be reduced significantly as B factories collect more data. • Inclusive modes : • NNLO theoretical calculation to reduce theory errors (as much as a factor of two) in two years. • Measured HQE parameters quantify “universal” motion of b quark in B meson. Useful in extracting Vub and Vcb from semileptonic decays. • Exclusive modes : • bd penguin observed. CKM fits with rare radiative decays… • Wilson coefficients are now experimental observables. With even 1ab-1 data important discoveries are at hand. V. Erkcan Özcan, UCL

  21. Backup Slides

  22. KEKB HER [8 GeV] Detector KEKB LER [3.5 GeV] Cavity e+ source BB threshold ~90% data on-resonance @ 10.58 GeV CM BB pairs almost at rest in e+e– CM frame. PEP-II @ SLAC KEKB @ KEK 1033cm-2s-1 ≈ 1 BB pair / sec Enough energy to create b­quark pairs, but not enough for B-meson pairs. Off-resonance data @ 10.54/10.52 GeV CM; no BB pairs, only continuum BG V. Erkcan Özcan, UCL

  23. Thanks to I. Bizjak. Belle Detector Aerogel Cherenkov cntr. n=1.015~1.030 SC solenoid 1.5T 3.5 GeVe+ CsI(Tl) 16X0 ToF cntr. 8 GeVe- Central Drift Chamber small cell +He/C2H6 m / KL detection 14/15 lyr. RPC+Fe Si vertex det. 3/4 layer DSSD V. Erkcan Özcan, UCL

  24. EMC 6580 CsI(Tl) crystals q = q = - o 15 . 8 , 39 . 2 o 1 2 BABAR Detector Electromagnetic Calorimeter 6580 CsI(Tl) crystals 1.5 T Solenoid e+ (3.1 GeV) Cherenkov Detector (DIRC) 144 fused-silica bars 11000 PMTs e- (9 GeV) Drift Chamber 40 radial layers Instrumented Flux Return steel / RPCs (muon / neutral hadrons) Silicon Vertex Tracker 5 layers, double sided strips • SVT:15 mm z hit resolution (inner layers, perp. tracks) • SVT+DCH: 98% efficiency, (pT)/pT= 0.13 %  pT+0.45 % • DIRC:K- separation 4.2 @ 3.0 GeV/c  >3.0 @ 4.0 GeV/c • EMC:E/E = (2.3  E-1/4 1.9)%,   (3.9  E-1/2) mrad V. Erkcan Özcan, UCL

  25. Box Diagrams & Z-Mediated Penguins V. Erkcan Özcan, UCL

  26. γ (4S) Continuum Backgroundsvs. Lepton Tag ~20% of all B decays are Xlν. • Continuum BGs still dominate over signal after previous cuts! • Requiring a lepton tag strongly suppresses what remains (signal efficiency 5%, but continuum suppressed by 1300!). • Tag:High-momentum lepton, not back to back with photon, missing energy due to neutrino • MC tagging rate corrected from independent measurements of inclusive lepton spectra. • What remains is subtracted with off-resonance data. V. Erkcan Özcan, UCL

  27. Single-bin fit to all events Continuum BG (fixed from MC) Signal BB BG and cross-feed Peaking BG (fixed from MC) BXsg Sum-of-Exclusive • Reconstruct B candidate in one of 38 modes. • Use event shape to reduce continuum BG. • Fit mES (for each mXS bin) to extract signal yield. • Use observed yields in different modes to correct MC fragmentation. V. Erkcan Özcan, UCL

  28. Ci()Ôi Fermi Ô7 : dipole (EM) Ô1-6 : 4-quark Ô8 : dipole (gluonic) Ô9 : vector electroweak Ô10 : axial-vector EW Wilson coefficientsencode hard-gluon exchange info Wilson CoefficientsOperator Product Expansion Common framework – Effective theory. New physics expected to change Ci(). V. Erkcan Özcan, UCL

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