Status and perspectives of measurements of Vub and g BaBar (pictures) and title Gianluca Cavoto INFN and Università Roma ‘La Sapienza’ BaBar Collaboration LHC Flavour Workshop CERN – 7-10 nov 2005 G.Cavoto

The reference Unitarity Triangle L.Silvestrini, LP’05 g and Vub from pure tree level processes! Assumptions: 3 generations only No new physics at tree level Any new physics must satisfy this constraint Mainly results from BaBar (Summer 2005) G.Cavoto

Vub, inclusive and exclusive large signal rate, large Xcl background Select limited region of phase space Total rate evaluates from OPE Non-perturbative contribution: Shape Function determined experimentally from bsg, bcl BNLP S.W. Bosch, B.O. Lange, M. Neubert, G. Paz, Nucl. Phys. B 669, 355 (2004) B.O. Lange, M. Neubert, G. Paz, hep-ph/0504071 BLL C.W. Bauer, Z. Ligeti, M. Luke, hep-ph/0111387 Form Factor 1: 2: Exclusive Low signal rate, background rejection (kin. constraint) FormFactors normalization (Vub) : theory error FF shape (acceptance) affects exp’l uncert. G.Cavoto

Measuring Vub, experimental methods Tagging methods G.Cavoto

Vub: inclusive analyses Endpoint spectrum 2.0 < Ee < 2.6 GeV |Vub| = (4.44 ± 0.25exp ± 0.22th-BLNP) x 10-3 +0.42 – 0.38SF s ~ 12% b →sg, b →clv moments (BaBar) [O.Buchmuller and H.Flacher, hep-ph/0507253 ] MX vs q2 : hadronic tag Neutrino reconst.: El vs q2 b→cln and other bkg signal region signal region sideband region non-signal b→uln signal b→uln q2 cut |Vub|BLL = (4.82 ±0.26stat ± 0.25syst±0.46SF+theo) x 10-3 s ~ 12% +0.46 – 0.36 SF |Vub|BLNP(BaBar b→cln) = (4.65 ±0.24stat ± 0.24syst ±0.23th) x 10-3 s ~ 13% hep-ex/0507017 211 fb-1 G.Cavoto

Results (and current limitations) HFAG results are rescaled to common HQE inputs: mb=4.60±0.04 GeV, μπ2=0.20±0.04 GeV2 Results (and current limitations) Eℓ endpoint Limited by uncertainties on SF paramaters (mb) Improve inputs from bcln and b sg Improve SF evaluation Weak annihilation Should be small (2%) Can be checked with B0/B+ comparison Eℓ vs. q2 mX mX vs. q2 expt mb, theory G.Cavoto

Vub: exclusive, Bpln,rln Untagged Binning in q2 Semileptonic tag No phase space cut Coarse q2 binning Hadronic tag Low background, no phase space cut!!! Low signal rate More channels in progress: G.Cavoto

Vub: exclusive results Full q2 range FNAL LQCD Projection to 1 ab-1 (data taken to be on BK fit curve from present measurement). In the high q2 region alone, branching fraction at (6-7)% , or (3-3.5)% on |Vub |. Lattice expect to reach 6% G.Cavoto

experimental systematics MX spectrum Vub: outlook 250 fb-1 500 fb-1 technique D|Vub| / |Vub | (%) Statistical experimental systematics El > 2.0 GeV 2 → 1 3 El vs. q2 3 → 2 4 MX vs. q2 5 → 3 5 Projection to 1 ab-1 Inclusive Combination of larger dataset and confidence in theory (subleading SF ): 5-7% 210 fb-1 sexp(%) 1000 fb-1 sexp(%) hadronic tag 17 9 semileptonic tag 13 n reconstruction 8 Exclusive Need help from theory: Uncertainty on |Vub| dominated by theory error! (~15%) Reliable error estimate for rln FF  needed for p and r BF and |Vub| Progress in LQCD for pln : theory error 6-7% ? (Lubicz, Lattice04; Bernard CKMWS 05) Big improvements possible total error ~ 9% G.Cavoto

g from direct CP violation Interference when D final state common to both D0 and D0 Relative size (rB) of B decay amplitudes Larger rB, larger interference, better g experimental precision (degrees) 0.1 0.2 G.Cavoto

Gronau London Wyler method Gronau & London, PLB 253, 483 (1991), Gronau & Wyler, PLB 265, 172 (1991)]. Gronau London Wyler method D decays into CP eigenstate Theoretically clean, but with 8-fold ambiguity Select CP-even and CP-odd final states 3 observables, 3 unknowns Experimentally Normalize to D0 decay into flavour state (K-p+) CP modes: small D0 branching ratio G.Cavoto

Systematic uncertainties hardly visible ! GLW results Systematic uncertainties hardly visible ! PRD71,031102(2005) ACP RCP DCP+ DCP- ! Large value  (rB)² (D0K- ) = -0.17±0.16  (rsB)² (D0K*-) = 0.30±0.25 G.Cavoto

Atwood Dunietz Soni method Atwood, Dunietz, & Soni, PRL 78, 3257 (1997), PRD 63, 036005 (2001) 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 D decay strong phase dD unknown G.Cavoto

(Bayesian r*B²>0 & uniform,  g and dD*) hep-ex/0504047 232×106 BB ADS: results 0<dD<2p rD±1s 51°<g<66° g[0,p] rB<0.23 @ 90% CL B-→D0K- * B-→D*0[D0p0]K- No DCS signal … D*0→D0p0/D0g ≠ in dD* by p (r*B)²< (0.16)² @ 90% CL (Bayesian r*B²>0 & uniform,  g and dD*) Bondar & Gershon PRD70,091503(2004) B-→D*0[D0g]K- G.Cavoto

B- D(*)0 K- D0(KSpp) Dalitz analysis Giri, Grossman, Soffer, & Zupan, PRD 68, 054018 (2003), Bondar (Belle), PRD 70, 072003 (2004) If we knew the charm phase shift dD? B- D(*)0 K- D0(KSpp) Dalitz analysis Amplitude for B-/B+  “D0”K-/K+ Sensitivity to g Isobar model for f(m2+ ,m2- ) can fix phase variation dD across Dalitz plot. Only two-fold ambiguity in g extraction r(770) DCS K*(892) g=75,d=180,rB=0.125 G.Cavoto

D0(KSp+p-) Dalitz model Determined on D* D0p sample D0(KSp+p-) Dalitz model D0 decay model  coherent sum of Breit-Wigner (BW) amplitudes (quasi 2 body terms). CA K*(892) 13 distinct resonances (3 WS DCS) + 1 NR term. This isobar model is not so good for pp S waves  need controversial s(500) / s’(1000) to describe reasonably well the data. Plot of mpipi r(770) Better description of quasi 2-body terms: BW + pp S-waves with K-matrix formalism Anisovich & Saratev Eur. Phys. J A16, 229 (2003) DCS K*(892) No D-mixing, No CP violation in D decays G.Cavoto

g=[67°±28°(stat.) ±13°(syst. exp.) ± 11°(Dalitz model*) ] g from Dalitz 2 s CL 1 s CL (stat. only) 2D y± ~ y*± ~ D0K- D*0K- B- B+ B- d  2 rB|sing|≠0  size of direct CPV d B+ d* x± x*± X and y def g=[67°±28°(stat.) ±13°(syst. exp.) ± 11°(Dalitz model*) ] *evaluated removing pp S-wave 3° for K-matrix / BW difference G.Cavoto

Projected g uncertainty Model independent approach A.Bondar and A.Poluetkov, hep-ph/0510246 rb =0.2 rb =0.1 Projected sys error due to D0 Dalitz plot Charm and (super)B-factory interplay G.Cavoto

Summary By 2008 1 ab-1/B-factory 2005 Many different and independent techniques to constrain Vub and g By 2008 1 ab-1/B-factory Vub inclusive: 5-6% Vub exclusive : dominated by theoretical error total error 8% (?) g Dalitz technique most promising rb critical parameter for sensitivity Dalitz model limit at 5° ? More stat for model indep. Including more modes/techniques adds to 1/N improvements 2008 G.Cavoto

Backup slides G.Cavoto

UT in 2008 2005 2008 G.Cavoto