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Moriond EW March 5-12, 2005 Antonio Limosani KEK Slide 1 Mini- Review( Belle & BaBar ) By Antonio Limosani JSPS Fellow (KEK-IPNS JAPAN) XLth Rencontres.

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Presentation on theme: "Moriond EW March 5-12, 2005 Antonio Limosani KEK Slide 1 Mini- Review( Belle & BaBar ) By Antonio Limosani JSPS Fellow (KEK-IPNS JAPAN) XLth Rencontres."— Presentation transcript:

1 Moriond EW March 5-12, 2005 Antonio Limosani KEK Slide 1 Mini- Review( Belle & BaBar ) By Antonio Limosani JSPS Fellow (KEK-IPNS JAPAN) XLth Rencontres de Moriond ELECTROWEAK INTERACTIONS AND UNIFIED THEORIES

2 Moriond EW March 5-12, 2005 Antonio Limosani KEK Slide 2 Motivation Fundamental parameter in SM CKM mixing matrix element Unitarity Triangle Sidelength Directly test the mechanism for CP Violation in SM

3 Moriond EW March 5-12, 2005 Antonio Limosani KEK Slide 3 THEORYTHEORY EXPTEXPT ubWl leptonic Extremely rare, not yet seen e,  helicity suppressed  is challenging Cleanest mode Need B decay constant f B b u W d dl semileptonic Many channels. Not rare. Complicated but manageable Formalisms exist b u W d dcs hadronic Feasible e.g. B  D s  measurements exist Very complicated require factorisation But no gin’n’tonic! PR0SPECTPR0SPECT Super B factory? LHCb? Need a revolution in calc. hadronic matrix elements It is happening now …

4 Moriond EW March 5-12, 2005 Antonio Limosani KEK Slide 4 The B-factories LuminosityKEK-BPEP-II Peak>15x10 33 /cm 2 /s >9x10 33 /cm 2 /s Total Integrated 364/fb254/fb 1/fb  1.1M B-meson pairs

5 Moriond EW March 5-12, 2005 Antonio Limosani KEK Slide 5 The Detectors Large solid angle coverage is crucial~92% Excellent particle-ID e, , , ,K,p e  (9GeV) e  (3.1GeV) Instrumented Flux Return Silicon Vertex Tracker DIRC CsI(Tl) crystals Drift Chamber 1.5T solenoid

6 Moriond EW March 5-12, 2005 Antonio Limosani KEK Slide 6  Use B  X u l  Measurements Types: Inclusive(X u ?) and Exclusive(X u )  Experimentally challenging task  background is large because  Tight selection criteria results  limited phase space  extra theoretical uncertainties

7 Moriond EW March 5-12, 2005 Antonio Limosani KEK Slide 7 Inclusive method MXMX hadrons Charged lepton neutrino q2q2 p lepton 1. Cuts to avoid B  X c l 2. Measure 3. Extrapolate 4. Calculate V ub Shape function Quark level

8 Moriond EW March 5-12, 2005 Antonio Limosani KEK Slide 8 b-quark Shape Function What is it? b-quark “Fermi motion” inside the B-meson How do we get it? Universal at leading order for all b- quark to light-quark transitions. Use photon energy spectrum in B  X s  decays

9 Moriond EW March 5-12, 2005 Antonio Limosani KEK Slide 9 Lepton endpoint Well established method  Endpoint region Suppress continuum background  exploit topology differences Estimate non B background using  off resonance data Estimate B  X c l background  use MC tuned to data Jet-like spherical Off data Equal normalisation

10 Moriond EW March 5-12, 2005 Antonio Limosani KEK Slide 10 CLEO at  (4S) November 1989 Data 0.2/fb 30% Uncertainty First Evidence of non-zero Phys.Rev.Lett.64:16-20,1990

11 Moriond EW March 5-12, 2005 Antonio Limosani KEK Slide 11 BaBar Results 82/fb Widest momentum region yet! Data (continuum sub) MC for BB background Preliminary

12 Moriond EW March 5-12, 2005 Antonio Limosani KEK Slide 12 Other endpoint results Belle 28/fb (2003) CLEO 9/fb (2002) Phys.Rev.Lett.88:231803,2002 Signal Region BaBar 80/fb Preliminary

13 Moriond EW March 5-12, 2005 Antonio Limosani KEK Slide 13 BaBar Results 80/fb Preliminary

14 Moriond EW March 5-12, 2005 Antonio Limosani KEK Slide 14 Tag side Fully reconstruct the B via Full B reconstruction tag- Belle & BABAR Event level  Q=0 N(leptons)=1, no extra -0.5 < M 2 miss < 1.0 GeV 2 (Belle) M 2 miss < 0.5 GeV 2 (BaBar) p miss within acceptance kinematic fit (BaBar only) Signal region: (BLL Phys.Rev.D64:113004,2001) Measure Signal side N(K S +K + )=0 Veto  + slow from D *+ (BaBar only) P lep > 1 GeV/c Reconstruct the neutrino

15 Moriond EW March 5-12, 2005 Antonio Limosani KEK Slide 15 BaBar result 82/fb Data: 82/fb ~1000 B modes ~110K B0 ~190K B+ Purity~ 10-50% M B-tag, P l >1 GeV/c Preliminary M B-tag

16 Moriond EW March 5-12, 2005 Antonio Limosani KEK Slide 16 Belle result 140/fb Data: 140/fb ~180 B modes ~150K B0 ~250K B+ Purity ~ 50% M B-tag, P l >1 GeV/c Preliminary M B-tag

17 Moriond EW March 5-12, 2005 Antonio Limosani KEK Slide 17 Results Unfolded M x spectrum from BaBar OPE HFAG 2004 Summer Preliminary Points - unfolded spectra Lines - Prediction using Belle SF parameters In principle, can get SF parameters directly

18 Moriond EW March 5-12, 2005 Antonio Limosani KEK Slide 18  2 /n.d.f=6.7/7 (CL=46.5%) |V ub |=(4.70  0.44)  10 -3 Do we see discrepancies between different kinematic regions Sub-leading effects? Weak annihilation effects? Quark-hadron duality violations? HFAG |V ub | inclusive averages

19 Moriond EW March 5-12, 2005 Antonio Limosani KEK Slide 19 Many measurements in the past, which all relied on neutrino reconstruction in untagged samples  large detector related systematic uncertainty Tagged samples herald a new era!  Loose cuts, good signal to background  Clean topology (small detector systematic)  Yet lacking lots of statistics To get V ub, use Form Factor(s) predictions from  Lattice QCD  Light Cone Sum Rules  Quark models which describe hadronisation effects. Discriminate against models using a precise measurement of the differential branching ratios Extract Exclusive method CLEO 9/fb

20 Moriond EW March 5-12, 2005 Antonio Limosani KEK Slide 20 Data: 82/fb Same cuts as inclusive analysis focus of exclusive mass regions , , ,  Imposing Isospin relations BaBar (fully reconstructed B) 82/fb Preliminary

21 Moriond EW March 5-12, 2005 Antonio Limosani KEK Slide 21 Belle - semileptonic tag method Kinematics of double semileptonic decay Reconstruction of all particles except neutrinos Determine B direction up to a two-fold ambiguity

22 Moriond EW March 5-12, 2005 Antonio Limosani KEK Slide 22 Belle (semileptonic tag) 140/fb - Fits

23 Moriond EW March 5-12, 2005 Antonio Limosani KEK Slide 23 Belle (semileptonic tag) 140/fb - q 2 Use unquenched lattice QCD to extract |V ub | Preliminary

24 Moriond EW March 5-12, 2005 Antonio Limosani KEK Slide 24 Headlines Broken the 10% error barrier on V ub (30% in 1989!) Much more data to analyse Tagged samples will play a more significant role Our inclusive measurements challenge theorists to predict with greater precision Lattice QCD calculations are coming to the fore  results of unquenched calculations now available

25 Moriond EW March 5-12, 2005 Antonio Limosani KEK Slide 25

26 Moriond EW March 5-12, 2005 Antonio Limosani KEK Slide 26 Measurement types at  (4S) resonance Experimental Efficiency Signal to Background Untagged Partial tags Full tags Luminosity

27 Moriond EW March 5-12, 2005 Antonio Limosani KEK Slide 27 Backup

28 Moriond EW March 5-12, 2005 Antonio Limosani KEK Slide 28 Backup2

29 Moriond EW March 5-12, 2005 Antonio Limosani KEK Slide 29 bu V ub W Quark level  Simple Real world  Complicated

30 Moriond EW March 5-12, 2005 Antonio Limosani KEK Slide 30 Backup3

31 Moriond EW March 5-12, 2005 Antonio Limosani KEK Slide 31


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