Download presentation

Presentation is loading. Please wait.

Published byLauren Dunlap Modified over 4 years ago

1
Stato di Vub e Vcb Concezio Bozzi INFN Ferrara Babar Italia, Trieste 14 Aprile 2005

2
Sommario Decadimenti semileptonici inclusivi –con charm (Vcb) –senza charm (Vub) Decadimenti semileptonici esclusivi – l, l (nuovi risultati, Moriond&CKM05) – D*l NB: ho attinto a piene mani da materiale presentato (da altri ma anche da me!) a CKM2005

3
Misure inclusive

4
Inclusive Decays – the Big Picture

5
Semileptonic B Decays & HQE contains b- and c-quark masses, m b and m c 2 related to kinetic energy of b-quark G 2 related to chromomagnetic operator: B / B * mass splitting Darwin term ( ρ D 3 ) and spin-orbit interaction ( ρ LS 3 ) enter at 1/m b 3 = scale which separates effects from long- and short-distance dynamics r = m c /m b ; z 0 (r), d(r): phase space factors; A EW = EW corrections; A pert = pert. corrections ( s j, s k 0 ) No 1/m b term! Several HQE schemes exist; ops and coeffs are scheme dependent free-quark rate

6
Inclusive b c ν Measure electron momentum spectrum and mass of hadronic system in SL decay Determine moments to allow comparison with parton- level calculations (duality assumed) Calculations exist for the following: Fit for HQE parameters and |V cb | Mass of hadronic system Lepton energy spectrum Gambino & Uraltsev (hep-ph/0401063, 0403166)

7
Fit Results m X moments E moments = used, = unused in the nominal fit Red line: OPE fit Yellow band: theory errors B A B AR 2 /ndf = 20/15 B A B AR PRL 93:011803

8
Fit Results Impressive agreement between data and theory identical results obtained in another renorm. scheme: Bauer, Ligeti, Luke, Manohar, Trott in hep-ph/0408002 kinetic mass scheme with μ=1 GeV Fitted values consistent with external knowledge 2 /ndf = 20/15 Uncalculated corrections to B A B AR PRL 93:011803 precision on m b = 1.5% precision on |V cb | = 2% 2% accuracy!

9
Inclusive |V cb | status BaBar result compared with previous measurements: Agrees with value coming from exclusive B D * ν decays (from HFAG):

10
Inclusive b u Limiting factor in CKM precision tests; known much less well than |V cb | CKM suppressed – therefore harder to measure Challenge for experiment and theory

11
Starting point: HQE Just like b c ν …, and with similar accuracy …until limited exptl acceptance is considered Poor convergence of OPE in region where b c ν decays are kinematically forbidden Non-perturbative Shape Function must be used to calculate partial rates = scale which separates effects from long- and short-distance dynamics A EW = EW corrections; A pert = pert. corrections ( s j, s k 0 )

12
Theory input Reference (ICHEP04, HFAG) results based on triple differential decay rate ( E e, m X, q 2 ) computed to O( s, m b -2 ) over the entire phase space by de Fazio and Neubert (DFN, JHEP 06:17 (1999) ) Use as input the shape function parameters determined by a fit (hep-ex/0407052) to the Belle bs spectrum: Λ = 0.66 GeV, λ 1 = -0.40 GeV 2 + covariance δ Λ ~ δm b 80 MeV q 2 vs m X analysis: take acceptances from Bauer, Ligeti and Luke (BLL, hep-ph/0111387 ), OPE calculation in a region of the phase space where SF effects are small. f(k+)f(k+) Acceptance in b uv E spectrum in b s

13
Inclusive V ub measurements with BaBar methodS/B Pros&Cons V ub (x10 -3 ) Electron spectrum endpoint E e >2.0GeV Total rate using DeFazio-Neubert 0.05 0.2 High statistics Duality valid for tight E e cuts? Bkg subtraction E e vs q 2 and neutrino reconstruction E e >2.0GeV and s h <3.5 GeV 2 /c 4 Total rate using DeFazio-Neubert ~0.5 High statistics Lower syst. on shape functions Bkg subtraction m X analysis (1-D) m X <1.55 GeV/c 2 Total rate using DeFazio-Neubert ~1.7 Low background High resolution Low statistics Shape func. syst. m X vs q 2 analysis m X 8.0 GeV 2 /c 4 V ub using Bauer et al. ~2 Low background Very small syst. on SF param. Small statistics Total rate using Form Factors calc. 1 20 Very small bkg ~no cut on kinem Small statistics Untagged Untagged Partial Tags Breco Tags exclusive Current Vub errors: 10-15% Total experimental syst @250-500 ifb: 3-6% 4.40 ± 0.24 exp ± 0.35 theo 4.99 ± 0.48 exp ± 0.29 theo 5.22 ± 0.43 exp ± 0.33 theo 5.18 ± 0.57 exp ± 0.34 theo

14
V ub measurements

15
A different theory approach Bosch, Lange, Neubert and Paz (BLNP) Nucl. Phys. B 699, 335 (2004) Acceptances computed in BLNP using SF parameters from –Belle bs hep-ex/0407052 –BaBar bc moments (hadronic and leptonic) hep-ex/0404017 Proper translation into shape function scheme of BLNP hep-ph/0412241 Courtesy of Henning Flächer

16
Results with BLNP and BaBar bc moments Using m b = 4.63±0.08 GeV and μ π 2 = 0.15±0.07 GeV 2 (SF scheme) with correlation coefficient -0.4. Errors are: expt ± SF ± theory expt ± (SF+theory) MethodB × 10 4 |V ub | (BLNP) SF params from b c ν |V ub | (BLNP) (Belle SF) |V ub | ICHEP (DFN, Belle SF) Endpoint5.31±0.59 3.93 ± 0.34 ± 0.38 ± 0.18 (8.7 ± 9.7 ± 4.6)% 4.55 4.40 ± 0.24 ± 0.35 ( ± 6.4 ± 8.6) % q 2 -E e 4.46±0.933.89 ± 0.40 ± 0.45 ± 0.21 (10.3 ±11.5 ± 5.4)% 4.53 4.99 ± 0.48 ± 0.29 ( ± 9.6 ± 5.8) % q 2 -m x 8.96±2.044.45 ± 0.49 ± 0.40 ± 0.22 (11.1 ± 9.0 ± 4.9)% 5.00 5.18 ± 0.57 ± 0.34 ( ±11.0 ± 6.5) % Average4.07 ± 0.514.61 ± 0.46 bc moments: significant change in inclusive | V ub | values BLNP: increased sensitivity to SF

17
Misure di Vub esclusive

18
Jochen Dingfelder – CKM Workshop 2005 03/16/05 Exclusive B X u l Decays Goal : Measure Branching Fractions and |V ub | Need FF predictions to describe QCD effects New unquenched LQCD calculations (HPQCD04, FNAL04) Try to measure q 2 dependence of FF with data Breco Tags Semilep.Tags Untagged l-l- Y(4S) X u = +, 0, +, 0,, a 0 0, a 0 + low bkg, low stat.: 27,… (ICHEP04) Balance between efficiency and purity High statistics, high hackground (b cl ) 3 new l results

19
Jochen Dingfelder – CKM Workshop 2005 03/16/05 Semileptonic Tag Analyses Reconstruct B D ( * ) l and study semileptonic recoil use both D and D* tags sizable BF Tagging efficiency measured with Double Tags (two D ( * ) l ) Correct sl. decay |cos BY | < 1 ( tag side: cos BY, signal side: cos B, l ) cos 2 B < 1 for signal, bkg flat D ( * ) l decays

20
Jochen Dingfelder – CKM Workshop 2005 03/16/05 0 l with SL Tag : Signal Extraction Cut-and-count analysis in cos B, l and m D Signal region: -1.1 < cos B l < 1.0 Subtract m D sidebands remove cominatoric background Subtract other background using MC normalized in -10 < cos B l < -1.5 82 fb -1 45 0

21
Jochen Dingfelder – CKM Workshop 2005 03/16/05 + l with SL Tag : Signal Extraction Extract signal yields by binned fit to cos 2 B in 3 bins of q 2 : Fit parameters = signal and background normalizations 211 fb -1 21 + 26 + 14 + 30% l X-feed Mainly B 0 B 0 bkg

22
Jochen Dingfelder – CKM Workshop 2005 03/16/05 + l with SL Tag : Branching Fractions and q SL tag analyses statistically limited. Yields not yet large enough to discriminate between FF models.

23
Jochen Dingfelder – CKM Workshop 2005 03/16/05 Neutrino Reconstruction: Reconstruct from full event & ensure good reco. quality Untagged B l and B l Fit all 4 signal modes simultaneously ( +, 0, +, 0 ) Use isospin relations to reduce number of signal parameters: (B 0 - l + ) = 2 (B + 0 l + ) Max-LH fit of signal and background in E, m ES, and q 2 Harsh suppression of b cl bkg (kinem. cuts, mainly for l ) e + e - qq bkg (topological cuts) Cut on missing mass: |M 2 miss / 2E miss | < 0.4 GeV

24
Jochen Dingfelder – CKM Workshop 2005 03/16/05 Untagged l : Fitted E and m ES 76 fb -1 427, 147 0 5 bins for l 3 bins for l

25
Jochen Dingfelder – CKM Workshop 2005 03/16/05 Untagged l : Fitted E and m ES 5 bins for l 3 bins for l 101, 104 0 76 fb -1

26
Jochen Dingfelder – CKM Workshop 2005 03/16/05 Recent LQCD and LCSR calculations agree well with data ISGW2 shows marginal agreement for l Errors for l still too large to study 3 form factors. Measured q 2 Distributions and Form Factors ll

27
Jochen Dingfelder – CKM Workshop 2005 03/16/05 Systematic Uncertainties (Untagged) Better statistical precision than previous measurements Syst. error dominated by reconstruction. Will decrease with improved track/neutral reconstruction. Results less dependent on theoretical predictions (own FF measurement)

28
Jochen Dingfelder – CKM Workshop 2005 03/16/05 Overview: Branching Fraction Measurements Testing isospin symmetry: Measure + l, 0 l separately (untagged) ll

29
Jochen Dingfelder – CKM Workshop 2005 03/16/05 Extraction of | V ub | Measurement in bins of q 2 allows extraction of |V ub | for various q 2 regimes and FF calculations : LCSR q 2 15 GeV 2 or extrapolation to whole q 2 range Quote LQCD2 as representative

30
Misure di Vcb esclusive

36
Ultimate solution: combined measurement of form factors and Vcb! (work in progress in Trieste)

38
Other ideas? D* 0 l (little/undermanned efforts) Yet another measurement of D* + l –D* partial reconstruction –On the recoil of a fully reconstructed hadronic decay Run1-4 M. Andreotti PhD thesis

39
Conclusioni Mole impressionante di risultati sperimentali e teorici Collaborazione virtuosa tra le due comunità Effetto complessivo: –Vcb inclusivo: ~1.5% Accordo impressionante teoria-esperimenti! –Vub inclusivo: 10% 5% ? Aggiornare misure con tutta la statistica disponibile Ampio consenso teorico sulla validità delle relazioni bcν bs buν Un po meno sulle incertezze relative –Vub esclusivo: Occorre più statistica e migliorare le sistematiche sperimentali calcolo dei fattori di forma non ancora pienamente maturo –Vcb esclusivo: 4% ? Nuove misure (Dl ) per limitare incertezze teoriche e per risolvere laccordo marginale tra le misure esistenti (D*l )

Similar presentations

OK

Charm Form Factors from from B -Factories A. Oyanguren BaBar Collaboration (IFIC –U. Valencia)

Charm Form Factors from from B -Factories A. Oyanguren BaBar Collaboration (IFIC –U. Valencia)

© 2018 SlidePlayer.com Inc.

All rights reserved.

To ensure the functioning of the site, we use **cookies**. We share information about your activities on the site with our partners and Google partners: social networks and companies engaged in advertising and web analytics. For more information, see the Privacy Policy and Google Privacy & Terms.
Your consent to our cookies if you continue to use this website.

Ads by Google

Ppt on fdi in india 2013 Ppt on working of search engines Ppt on social networking dangers Marketing mix ppt on nokia Ppt on zener diode application Ppt online compressor mechanic school Free ppt on mind power Ppt on basel 3 Ppt on traction rolling stock wheels Ppt on computer system for class 9