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B physics from the e + e B factories. Paul Dauncey, Imperial College London on behalf of the BaBar Collaboration. 2007 Aspen Winter Conference on Particle Physics "New Physics at the Electroweak Scale and New Signals at Hadron Colliders”. Belle and BaBar. Belle. Both operating at U (4S)
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B physics from the e+e B factories Paul Dauncey, Imperial College London on behalf of the BaBar Collaboration 2007 Aspen Winter Conference on Particle Physics"New Physics at the Electroweak Scale and New Signals at Hadron Colliders” B Physics from the B Factories
Belle and BaBar Belle Both operating at U(4S) Belle: 8 GeV e/3.5 GeV e+ BaBar: 9 GeV e/3.1 GeV e+ Very similar detectors; main difference is in PID: BaBar: Ring-imaging Cherenkov Belle: Threshold Cherenkov and ToF BaBar B Physics from the B Factories
Recorded luminosity Y(4S)BB cross section ~1nb Total > 1ab1 KEKB (Belle) PEP-II (BaBar) Total sample > 109 BB events; allows precision SM measurements B Physics from the B Factories
CKM unitary matrix CKM matrix relates weak and mass eigenstates of quarks Four physical parameters; fundamental constants of the SM Complex elements allow (only source of) CP violation in SM Unitary means Wolfenstein expansion (A~0.82, l~0.23, r, h) in powers of l: Only two complex elements to this order; both small ~l3 B Physics from the B Factories
Unitarity triangle Represent as “Unitarity Triangle” in complex r,h plane To O(l6), use corrected values: , Apex is B Physics from the B Factories
Example of New Physics in loops B0B0 mixing bsg penguin SM SM SUSY: squark, gluino loop with soft term dd13 SUSY: squark, gluino loop with soft breaking term dd23 NP can change phase and/or amplitude of loops compared to expectations from measurements of tree processes inconsistent r, h B Physics from the B Factories
Measurements of b/f1 Phase of Vtd* B Physics from the B Factories
CP violation in bccs Golden mode: B0J/yK; high rate, theoretically clean No Wolfenstein phase Two Vtd vertices Two Vtd vertices ei2b ei0 B0 J/yK ei0 B0 ei2b Measurable = relative phase = ei2b Note: true for any B0 decay with no phase from decay amplitude B Physics from the B Factories
Experimental method Proper time DtDz/bgc Exclusive B meson vertex reconstruction Y(4S) boost bg ~0.5 Tag B meson flavour and vertex reconstruction Time dependent asymmetry = SCPsin(DmDt) CCPcos(DmDt) SCP = fCP sin2b (fCP= ±1), CCP “direct” CP violation = 0 for J/yK B Physics from the B Factories
Dt time-dependence BaBar preliminary, hep-ex/0607107 Belle preliminary, hep-ex/0608039 B0J/yKL B0J/yKS Dt for B0 tag B0J/yK Dt for B0 tag B0J/yK Background Dt asymmetry J/yKLis fCP= +1 J/yKS is fCP= 1 Belle Preliminary Belle Preliminary B0 tags B0 tags B0 tags B0 tags Dt oscillation Period = B mixing Dm Amplitude = D sin2b (Dilution D due to mistags; measured experimentally) B Physics from the B Factories
World average (HFAG) Heavy Flavors Averaging Group E.Barberio et al., hep-ex/0603003 SCP= Statistics limited Consistent with zero: no evidence for NP in tree decay Precision measurement; allows comparison with other b measurements to overconstrain the SM Extracting b from sin2b has ambiguities; removed by J/yK*, D*D*KS and Dp0/h/h'/w analyses B Physics from the B Factories
CP violation in bsss V*ub vertex eig E.g. B0fK + Suppressed ei0 eiD Two Vtd vertices ei2b B0 fK ei0 eiD B0 ei2b Relative phase = ei2b ei2(b+D) Overall sin2beff sin2b B Physics from the B Factories
Theoretical estimates of SM offsets Lazzaro, ICHEP06 QCDF Short distance effect: QCDF: Beneke, PLB 620, 143 (2005) Cheng, Chua, Yang, PRD 73, 014017 (2006) pQCD: Mishima, Sanda, PRD 72, 114005 (2005) SCET: Williamson, Zupan, PRD 74, 014003 (2006) Long distance effect: Cheng, Chua, Soni, PRD 72, 014006 (2005) Mainly positive but large error, sin2beff > sin2b Small value and error, sin2beff ~ sin2b Representative theory estimates 0.0 0.2 0.1 0.1 D(sin2b/f1) sin2b experimental error B Physics from the B Factories
BfKS and Bh'KS BfKS: B.F. = (4.3±0.6)×106 Even with small rates, clear CP violation observed in penguin decays BfKS Belle Preliminary Bh'KS: B.F. = (3.4±0.2)×105 BaBar Preliminary Belle Preliminary Bh'KS Belle preliminary, hep-ex/0608039 BaBar preliminary, hep-ex/0607112 BaBar preliminary, hep-ex/0609052 B Physics from the B Factories
Comparison to bccs sin2b from J/yK NP? More data needed! B Physics from the B Factories
Measurements of a/f2 pbg B Physics from the B Factories
CP violation in charmless modes Vtd vertex eib E.g. B0p+p/r+r + V*ub vertex eig Suppressed eig ei(g+D) Two Vtd vertices ei2b p+p/r+r B0 eig ei(g+D) B0 ei2b ei2(a+D) Relative phase = ei2(b+g) = ei2(pa) =ei2a Overall sin2aeff sin2a B Physics from the B Factories
Penguin corrections SM correction for penguin from first principles difficult Use isospin or SU(3) relations with input from data • Other pp and rr modes; p0p0, p+p0,r0r0, r+r0 Branching fractions (×106) Zupan, hep-ph/0701004 Penguin correction cleaner for rrthan pp; largest penguin contribution is in p0p0 or r0r0 Isospin SU(3) B Physics from the B Factories Amplitude Penguin/Tree
Bp+pdecays BaBar preliminary; hep-ex/0607106 Belle preliminary; hep-ex/0608035 BellePreliminary B0 tags B0 tags B0 tags Direct CP B0 tags CCP 0 SCP = (1CCP2)sin2aeff B Physics from the B Factories
Bpp decay results Including p+p0, p0p0isospin analysis UTFit, M.Bona et al., hep-ph/0606167 Primarily Bayesian CKMFitter, J.Charles et al., Eur.Phys.J.C41, 1 (2005) Belle and BaBar only marginally in agreement Primarily frequentist SCP= (1CCP2)sin2aeff Bayesian and frequentist interpretations give quantitively different conclusions B Physics from the B Factories
Br+rdecays BaBar preliminary; hep-ex/0607098 Belle; Phys.Rev.Lett.96, 171801 (2006) Belle Direct CP consistent with zero B Physics from the B Factories
Brr decay results Including r+r0, r0r0isospin analysis SCP= (1CCP2)sin2aeff Small CP violation: restricts aeff ~ 90 or 0/180 B Physics from the B Factories
Overall result, including rp Other solutions disfavoured CL=0.683 Indirect:a = [100+57] Combined:a = [93+119] B Physics from the B Factories
Measurements of g/f3 Phase of Vub* B Physics from the B Factories
CP violation in DK modes GLW: Gronau, London, Wyler (2001) ADS: Atwood, Dunietz, Soni (1997) GGSZ: Giri, Grossman, Soffer, Zupan (2003) E.g. B+D0 /D0K+ D decays do not involve Vub or Vtd: no contribution to phase ei0 ei0 D0K+ D0/D0 CP state (GLW) D0/D0Kp+/K+p, CA/DCS (ADS) D0/D0KSp+p, Dalitz(GGSZ) B+ V*ub vertex eig D0K+ eig ei0 Relative phase = eig B± no time dependence; extract g from rates and CP asymmetries B Physics from the B Factories
The GGSZ method Look for deviations in B±D0K±plots Map out Dalitz plot from all D0 decays B+ B Belle Belle BaBar preliminary; hep-ex/0607104 Belle; Phys.Rev.D 73, 172009 (2006) B Physics from the B Factories
Results from GGSZ method Express in terms of measurables from B± dBg 2g rB is ratio of D/D amplitudes = 0.16±0.07 dB is D/D relative (strong) phase Different rB, dB for each mode D(*)K(*) dB+g BaBar preliminary; hep-ex/0607104 Belle; PRD 73, 112009 (2006) B Physics from the B Factories
Overall result Indirect:g = [59+94] Combined:g = [62+3824 ] B Physics from the B Factories
Measurements of Ru Error on Ru dominated by error on |Vub| B Physics from the B Factories
Semileptonic bu decays In principle, simple measurement of rate |Vub|2 • But huge rate of semileptonic bc to remove Inclusive BXul+nl • Use high momentum lepton (“endpoint”), Xu mass (or both) • Need to correct for missing parts of spectra Exclusive B0/+p/0l+nl • Correct B+ decays for lifetime difference • Need to include form factor f+(q2=mln2) for Bp transition B Physics from the B Factories
Vub inclusive summary BLNP: Lange, Neubert, Paz (2005) DGE: Anderson, Gardi (2006) LLR: Leibovich, Low, Rothstein (2006) Representative theory example (BLNP) Room for some experimental statistical improvement B Physics from the B Factories
Vub exclusive summary Using theoretical form factors Measured branching fractions (all 2006) Theoretical errors dominate Experiments starting to measure form factor shape from data; allows elimination of some theory models Will still need form factor normalisation from theory B Physics from the B Factories
Vub vs. sin2b/f1 Direct: sin2b/f1 = 0.67±0.03 Indirect: sin2b/f1 = 0.76±0.04 Difference: = 0.09±0.05 Not statistically significant, but… Limits amplitudes to at most ~50% of SM Model independent NP in B mixing Add new amplitude to SM modifies b to b+fdNP B Physics from the B Factories
Measurements of Rt Not covered here • B mixing; new Dms • See talk by P. Gutierrez • bsg and dg rates • See talk by S. Robertson Error on Rt dominated by error on |Vtd| B Physics from the B Factories
Overall CKM agreement Frequentist Bayesian Conclusion is the same: All measurements agree with SM picture of CKM matrix within errors B Physics from the B Factories
Trees versus loops Trees Loops B Physics from the B Factories
Trees versus loops Trees Loops Consistent within errors B Physics from the B Factories
Prospects for the future • BaBar and Belle only half way • Both aiming for around 1ab1each over next two years • Some measurements are clearly statistics limited • Sin2b/f1 bccs vs. bsss comparison • All angle measurements • Vub is mainly theory limited • Some experimental improvements possible • Theory error can be reduced but with substantial work • More data also brings new techniques and decay modes • Improvements better than N can be expected • The Tevatron and LHC may also help us out B Physics from the B Factories
Conclusions • Standard Model is in very good shape • NP must be correction, not alternative, to SM in flavour sector • Little room for any NP in trees; possible in loops • Items to watch… • Vub vs. sin2b/f1 (NP in B0 mixing loop?) • sin2b/f1 in bccs vs. bsss (NP in bsg penguin loop?) • …but neither is significant at this stage • More data will help and will come • More likely to limit NP through loops than discover it • NP in flavor sector is constrained • Flavor physics must be considered in any NP model building B Physics from the B Factories
Backup slides B Physics from the B Factories
Isospin analysis for pp, rr Assuming isospin symmetry between amplitudes Flipping triangles gives four-fold ambiguity in solution B Physics from the B Factories
Results from GLW, ADS methods GLW CP+ No significant CP± differences CP CP+ CP ADS CP+ CP Most rates consistent with zero so few measured asymmetries AADS=0.22±0.63 B Physics from the B Factories
Results from GGSZ method Express in terms of measurables from B± rB is ratio of D/D amplitudes and dB the relative (strong) phases B+ B B± difference due to g B Physics from the B Factories
Angles versus sides Angles Sides Consistent B Physics from the B Factories
sin2b vs. time (BaBar only) 1/N B Physics from the B Factories