Updates of Semileptonic Results for Winter 2006

The changes of this update with respect to the status of EPS 2005 are described here.
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Exclusive Branching Fraction: B0 -> Dlnu

This is a one-dimensional fit for the average branching fraction.
Experiment BF (rescaled) [%] Parameters Remarks
ALEPH 2.28 +/- 0.20+/- 0.41 input     parameters Phys.Lett.B395:373-,1997
CLEO 2.11+/- 0.13+/- 0.17 input     parameters Phys.Rev.Lett.82:3746-,1999
BELLE 2.12+/- 0.12+/- 0.39 input     parameters Phys.Lett.B526:258-268,2002
Average 2.12+/- 0.20 chi2/dof = 0.14/2 (CL = 0.93) eps pdf
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Exclusive Branching Fraction: B0 -> D*lnu

This is a one-dimensional fit for the average branching fraction.
Experiment BF (rescaled) [%] Parameters Remarks
ALEPH 5.77 +/- 0.26 +/- 0.36 input     parameters Phys.Lett.B395:373-,1997
OPAL (excl) 5.51 +/- 0.19 +/- 0.39 input     parameters Phys.Lett.B482:15-,2000, exclusive reco.
OPAL (partial reco) 6.20 +/- 0.27 +/- 0.58 input     parameters Phys.Lett.B482:15-,2000, partial reco.
DELPHI (partial reco) 5.04 +/- 0.13 +/- 0.36 input     parameters Phys.Lett.B510:55-,2001, partial reco.
CLEO 6.29 +/- 0.19 +/- 0.39 input     parameters Phys.Rev.Lett.89:081803,2002
BELLE 4.74 +/- 0.23 +/- 0.42 input     parameters Phys.Lett.B526:247-,2002
BABAR 4.89 +/- 0.07 +/- 0.34 input     parameters Phys.Rev.D71:051502,2004
DELPHI (exclu) 5.80 +/- 0.22 +/- 0.46 input     parameters Eur.Phys.J.C33:213,2004
Average 5.35 +/- 0.20 chi2/dof = 14.8/7 (CL = 0.038) eps pdf

Inclusive Semileptonic (Partial) Branching Fraction for B+/B0 Admixture: B -> Xlnu

This is a one-dimensional fit for the average partial branching fraction for a cut on the momentum
of the lepton at p* > 0.6 GeV/c as measured in the Upsilon(4S) frame.  Note for the Belle(Breco)
measurement, the cut was placed in the rest frame of the B-meson - the difference between the partial branching
above 0.6 GeV/c as measured in either the Upsilon(4S) and B-meson rest frames is entirely negligible.

Experiment BF (Rescaled) [%] Input Remarks
p(l) > 0.6 GeV/c
ARGUS (e tag) 9.17 +/- 0.50 +/- 0.33 input     parameters Phys.Lett.B318:397-, 1993
BELLE (l tag) 10.32 +/- 0.11 +/- 0.46 input     parameters Phys.Lett.B547:181-, 2002
BABAR (e tag) 10.37 +/- 0.06 +/- 0.23 input     parameters Phys.Rev.D69:111104, 2004
CLEO (e tag) 10.24 +/- 0.08 +/- 0.22 input     parameters Phys.Rev.D70:032003,2004
BELLE (breco) 10.35 +/- 0.20 +/- 0.37 input     parameters Phys.Lett.B614:27-,2005
Average 10.27 +/- 0.17 chi2/dof = 3.9/4 (CL = 0.42) eps pdf
  
Using the results of a global fit (Phys.Rev.D73,073008(2006))
for HQET parameters in the Kinetic Scheme (Eur. Phys. J C 34 (2004) 181)
where none of the measurements listed above have been used as input, one can extract the extrapolation factor necessary to calculate the full branching fraction,  f_c = 1.0495 +/- 0.0005 +/- 0.0010, where the first error is from experiment and theory in the global fit and the second error is assigned as an additional theoretical uncertainty for the ratio Gamma_sl(0.6)/Gamma_sl(0.0) - for Gamma_sl total width this uncertainty is typically 1.5%, on the recommendation of the authors of the fit, for the ratio it is estimated to be 0.1%.
The full branching fraction is extracted as BF( B+/B0 -> X l nu ) = (10.78 +/- 0.18)% .

Inclusive Semileptonic Branching Fraction for B0 -> X-l+nu and B+ -> Xl+nu

An average of the semileptonic branching fraction separated according to B-meson charge is currently being pursued. For now we list the available measurements taken at the Upsilon(4S). In calculating the Belle result we use of the extrapolation factor (1.0495) explained above. The BABAR measurements were made with a requirement on the prompt lepton momentum of greater than 0.5 GeV/c as measured in the Y(4S) frame, they used an extrapolation factor of 1.053 +- 0.002 to get the full branching fraction.

Experiment BF(B0 -> X-l+nu)[%] Remarks
CLEO 10.78 +/- 0.60 +/- 0.69 Phys.Lett.B399:321,1997
ARGUS 9.3 +/- 1.1 +/- 1.5 Phys.Lett.B324:249,1994
CLEO 9.9 +/- 3.0 +/- 0.9 Phys.Rev.D45:2212,1992
BELLE (breco) 10.32 +/- 0.36 +/- 0.35 Phys.Lett.B614:27-,2005
BABAR (breco) 10.4 +/- 0.8 +/- 0.5 Preliminary (hep-ex/0204001)
  

Experiment BF(B+ -> Xl+nu)[%] Remarks
CLEO 10.25 +/- 0.57 +/- 0.65 Phys.Lett.B399:321,1997
BELLE (breco) 11.15 +/- 0.26 +/- 0.41 Phys.Lett.B614:27-,2005
BABAR (breco) 10.3 +/- 0.6 +/- 0.5 Preliminary (hep-ex/0204001)
  


Exclusive |Vcb| F(1)

Our average currently relies on the form factor ratios R_1=(1.18+/-0.30+/-0.12) and R_2=(0.71+/-0.22+/-0.07) as measured by the CLEO collaboration (Phys. Rev. Lett. 76, 3898 (1996)). The BABAR collaboration has reported measurements R_1=(1.396+/-0.060+/-0.035+/-0.027) and R_2=(0.885+/-0.040+/-0.022+/-0.013) (hep-ex/0602023: submitted to PRD). Studies are underway to incorporate this result into our average.

This table and the plots in the last row document the two-dimensional simultaneous fit to |Vcb|*F(1) and rho2. Note: The fit is two-dimensional and systematics limited, no confidence level is given at the moment.
Experiment |Vcb| F(1) (rescaled) [10-3] rho2 (rescaled) Correlation (stat/syst/total) Parameters Remarks
ALEPH 33.7 +/- 2.1 +/- 1.6 0.75 +/- 0.25 +/- 0.37 0.94/0.60/0.72 input     parameters Phys.Lett.B395:373-,1997
OPAL (partial reco) 38.6 +/- 1.2 +/- 2.4 1.25 +/- 0.14 +/- 0.39 0.77/0.70/0.71 input     parameters Phys.Lett.B482:15-,2000
OPAL (excl) 39.3 +/- 1.6 +/- 1.8 1.49 +/- 0.21 +/- 0.26 0.95/0.42/0.61 input     parameters Phys.Lett.B482:15-,2000
DELPHI (partial reco) 37.0 +/- 1.4 +/- 2.5 1.50 +/- 0.14 +/- 0.37 0.94/0.77/0.79 input     parameters Phys.Lett.B510:55-,2001
BELLE 36.0 +/-1.9 +/- 1.8 1.45 +/- 0.16 +/- 0.20 0.91/0.68/0.78 input     parameters Phys.Lett.B526:247-,2002
CLEO 43.8 +/- 1.3 +/- 1.8 1.61 +/- 0.09 +/- 0.21 0.87/0.62/0.67 input     parameters Phys.Rev.Lett.89:081803,2002
BABAR 35.5 +/- 0.3 +/- 1.6 1.29 +/- 0.03 +/- 0.27 0.56/0.73/0.72 input     parameters Phys.Rev.D71:051502,2004
DELPHI (exclu) 38.9 +/- 1.8 +/- 2.1 1.32 +/- 0.15 +/- 0.33 0.89/0.50/0.58 input     parameters Eur.Phys.J.C33:213,2004
Average 37.6 +/- 0.8 1.58 +/- 0.14 0.73/0.58/0.59 chi2/dof = 30.2/14 eps 1  pdf 1  eps 2  pdf 2 
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Exclusive |Vcb|G(1)

This table and the plots in the last row document the two-dimensional simultaneous fit to |Vcb|*G(1) and rho2. Note: The fit is two-dimensional, no confidence level is given at the moment.
Experiment |Vcb| G(1) (rescaled) [10-3] rho2 (rescaled) Correlation (stat/syst/total) Parameters Remarks
ALEPH 39.76+/- 10.00+/- 6.43 1.00+/- 0.98+/- 0.37 0.98/0.99/0.96 input     parameters Phys.Lett.B395:373-,1997
CLEO 45.12 +/- 5.80+/- 3.51 1.27+/- 0.25+/- 0.14 0.95/0.98/0.96 input     parameters Phys.Rev.Lett.82:3746-,1999
BELLE 40.99+/- 4.40 +/- 5.10 1.12+/- 0.22+/- 0.14 0.96/0.96/0.92 input     parameters Phys.Lett.B526:258-268,2002
Average 42.6+/- 4.5 1.17+/- 0.18 0.95/0.95/0.93 chi2/dof = 0.3/4 eps 1  pdf 1  eps 2  pdf 2 

Inclusive Vub average for winter 2006

|Vub| in inclusive semileptonic B decays

The results in this section are determined by comparing the measured partial branching fractions to theoretical calculations of the corresponding rates, which are proportional to |Vub|2. We extract |Vub| using two theoretical frameworks:

The latter, DGE, which stands for Dressed Gluon Exponentiation and is a recent new addition to the phenomenology landscape of inclusive B-meson decays, requires an introduction. In this framework the on-shell b-quark calculation, converted into hadronic variables, can be directly used as an approximation to the meson decay spectrum, without need of a leading-power non-perturbative function i.e no shape function. The on-shell mass of the b-quark within the B-meson is required as an input (m_b). Theoretical uncertainties are assessed by varying the inputs of: m_b, and the strong coupling constant (alpha_s), the number of light fermion flavours (NF), and the method and scale of the matching scheme intrinsic to the approach.


We perform a total of four averages for inclusive V_ub

  1. BLNP with m_b from global fit in the Kinetic scheme to data of B->Xc l nu  and B->Xs g decays
  2. DGE with m_b from global fit in the Kinetic scheme to data of B->Xc l nu  and B->Xs g decays
  3. BLNP with m_b from global fit in the Shape function scheme to data of B->Xs g decays
  4. DGE with m_b from global fit in the DGE framework to data of B->Xs g decays

No attempt is made to average BLNP and DGE derived |Vub|.

The procedure for performing the average is documented in a brief note on averaging

The input files for the average are linked below. To summarize briefly, all theoretical uncertainties are considered to be correlated, as are the uncertainties on the modeling of b -> clnu and b -> ulnu decays. Experimental uncertainties (particle identification, reconstruction efficiencies, etc.) are taken as correlated amongst measurements from the same experiment, but not correlated across experiments. The set of results averaged have negligeable statistical correlations.

The errors in the tables are experimental (statistical and systematic) and external (theoretical and HQ parameter uncertainties). The average B lifetime used was 1.584 ps.

BLNP : Vub with HQ parameters from b -> c l nu and b -> s g moments

BLNP : |Vub| with HQ parameters from b -> c l nu and b -> s g moments

The following values, calculated within the BLNP framework, use HQ parameter input from a global fit (Phys.Rev.D73,073008(2006)) to both b -> c l nu and b -> s g moments in the Kinetic Scheme (Eur. Phys. J C 34 (2004) 181) , which gives parameters, translated into the Shape Function scheme (SF), 

with correlation coefficient -0.26 . 

BLNP Vub (B->Xc l nu & B->Xs g moments)
Experiment Value [10-3] Parameters References Remarks
CLEO (endpoint) 4.09 +/- 0.48 +/- 0.36 input Phys.Rev.Lett.88:231803,2002 (hep-ex/0202019) 2.1 < p < 2.6, Vub redetermined from partial BF
BELLE (endpoint) 4.82 +/- 0.45 +/- 0.30 input Phys.Lett.B621:28-40 (2005) (hep-ex/0504046) 1.9 < p < 2.6
BABAR (endpoint) 4.41 +/- 0.29 +/- 0.31 input Phys.Rev.D73:012006,2006 (hep-ex/0509040) 2.0 < p < 2.6, Vub redetermined from partial BF
BABAR (E_{e}, q^{2}) 4.10 +/- 0.27 +/- 0.36 input Phys.Rev.Lett.95:111801,2005 (hep-ex/0506036) (Ee-q2)
BELLE m_{X} 4.06 +/- 0.27 +/- 0.24 input Phys.Rev.Lett.95:241801,2005 (hep-ex/0505088) mX, BRECO tag; other methods (mX-q2 and P not used)
BELLE sim. ann. (m_{X}, q^{2}) 4.37 +/- 0.46 +/- 0.29 input Phys.Rev.Lett.92:101801,2004 (hep-ex/0311048) mX - Q2, tag with annealing method
BABAR (m_{X}, q^{2}) 4.75 +/- 0.35 +/- 0.32 input preliminary (hep-ex/0507017) mX-q2, BRECO tag
Average +/- exp +/- (mb,theory) 4.45 +/- 0.20 +/- 0.26 chi2/dof = 5.5/6 (CL = 0.49) Plots: eps pdf HQ parameter input from b to c l nu and b to s gamma moments
The full breakdown of the uncertainties on the average |Vub| above is (all errors quoted in percent):

+-2.2stat +-2.7exp +-1.9b2c model +-2.1b2u model +-4.1HQ param +-3.8sub SF +-1.9WA = +-7.4tot

where the errors correspond to statistics, experimental systematics, the modeling of b -> c l nu and b -> u l nu decays, the HQ parameters mb and mupi2, subleading shape functions and Weak Annihilation. No uncertainty is assigned for possible duality violations.

Using the average |Vub| along with the calculated full b -> u l nu rate from BLNP \(70.8/ps-1/|Vub|2) results in a total BF

BF(b -> u l nu) = (2.22 +- 0.33)*10-3

DGE : Vub with HQ parameters from b -> c l nu and b -> s g moments

DGE: |Vub| with b-quark mass from b -> c l nu and b -> s g moments

The following values, calculated within the DGE framework, use HQ parameter input from a global fit (Phys.Rev.D73,073008(2006)) to both b -> c l nu and b -> s g moments in the Kinetic Scheme (Eur. Phys. J C 34 (2004) 181) , which the b-quark mass, translated into the modified minimal subtraction scheme

DGE Vub (B->Xc l nu & B->Xs g moments)
Experiment Value [10-3] Parameters References Remarks
CLEO (endpoint) 3.85 +/- 0.45 +/- 0.22 input Phys.Rev.Lett.88:231803,2002 (hep-ex/0202019) 2.1 < p < 2.6, Vub redetermined from partial BF
BELLE (endpoint) 4.80 +/- 0.45 +/- 0.20 input Phys.Lett.B621:28-40 (2005) (hep-ex/0504046) 1.9 < p < 2.6
BABAR (endpoint) 4.29 +/- 0.29 +/- 0.21 input PRD 73, 012006 (2006) (hep-ex/0509040) 2.0 < p < 2.6, Vub redetermined from partial BF
BABAR (E_{e}, q^{2}) 3.96 +/- 0.26 +/- 0.22 input Phys.Rev.Lett.95:111801,2005 (hep-ex/0506036) (Ee-q2)
BELLE m_{X} 4.30 +/- 0.29 +/- 0.22 input  Phys.Rev.Lett.95:241801,2005 (hep-ex/0505088) mX, BRECO tag; other methods (mX-q2 and P not used)
BELLE sim. ann. (m_{X}, q^{2}) 4.42 +/- 0.47 +/- 0.19 input Phys.Rev.Lett.92:101801,2004 (hep-ex/0311048) mX - Q2, tag with annealing method
BABAR (m_{X}, q^{2}) 4.80 +/- 0.35 +/- 0.21 input preliminary (hep-ex/0507017) mX-q2, BRECO tag
Average +/- exp +/- (mb,theory) 4.41 +/- 0.20 +/- 0.20 chi2/dof = 11.9/6 (CL = 0.063) Plots: eps pdf m_b input from b to c l nu and b to s gamma moments
The full breakdown of the uncertainties on the average |Vub| above is (all errors quoted in percent):

+-1.8stat +-2.5exp +-2.3b2c model +-2.3b2u model +-1.3mb (R_CUT) +-1.0alpha_s (R_CUT) +-3.0 (TOTAL SL WIDTH) +-2.9DGE theory

=+-6.3tot

where the errors correspond to statistics, experimental systematics, the modeling of b -> c l nu and b -> u l nu decays, effect of uncertainty on mb
on the prediction of  the event fraction (R_CUT),  effect  of alpha_s uncertainty on R_CUT, uncertainty on total semileptonic B width, and from the change
and variation of scale of the matching scheme (DGE theory).

Using the average |Vub| along with the calculated full b -> u l nu rate from DGE \(66.5/ps-1/|Vub|2) results in a total BF

BF(b -> u l nu) = (2.12 +- 0.31)*10-3

BLNP: Vub using fit to b to s gamma moments as input for HQ parameters

BLNP: |Vub| using b to s gamma fit as input for HQ parameters

The following values, calculated within the DGE framework, use b-quark mass input  from a fit to the lowest energy moments of the Egamma spectrum in b -> s gamma as measured CLEO, Belle and Babar.  The fit yields

The details of the fit are here.

BLNP Vub (B->Xs g moments)
Experiment Value [10-3] Parameters References Remarks
CLEO (endpoint) 4.37 +/- 0.51 +/- 0.47 input Phys.Rev.Lett.88:231803,2002 (hep-ex/0202019) 2.1 < p < 2.6, Vub redetermined from partial BF
BELLE (endpoint) 5.10 +/- 0.47 +/- 0.43 input Phys.Lett.B621:28-40 (2005) (hep-ex/0504046) 1.9 < p < 2.6
BABAR (endpoint) 4.69 +/- 0.31 +/- 0.43 input Phys.Rev.D73:012006,2006 (hep-ex/0509040) 2.0 < p < 2.6, Vub redetermined from partial BF
BABAR (E_{e}, q^{2}) 4.38 +/- 0.29 +/- 0.51 input Phys.Rev.Lett.95:111801,2005 (hep-ex/0506036) (Ee-q2)
BELLE m_{X} 4.34 +/- 0.29 +/- 0.38 input Phys.Rev.Lett.95:241801,2005 (hep-ex/0505088) mX, BRECO tag; other methods (mX-q2 and P not used)
BELLE sim. ann. (m_{X}, q^{2}) 4.65 +/- 0.49 +/- 0.42 input Phys.Rev.Lett.92:101801,2004 (hep-ex/0311048) mX - Q2, tag with annealing method
BABAR (m_{X}, q^{2}) 5.06 +/- 0.37 +/- 0.46 input preliminary (hep-ex/0507017) mX-q2, BRECO tag
Average +/- exp +/- (mb,theory) 4.75 +/- 0.22 +/- 0.39 chi2/dof = 4.8/6 (CL = 0.57) Plots: eps pdf HQ parameter input from b to s gamma moments fitted in the Shape Function scheme
The full breakdown of the uncertainties on the average |Vub| above is (all errors quoted in percent):

+-2.1stat +-2.8exp +-2.2b2c model +-2.1b2u model +-7.1HQ param +-3.8sub SF +-2.2WA = +-9.5tot

where the errors correspond to statistics, experimental systematics, the modeling of b -> c l nu and b -> u l nu decays, the HQ parameters mb and mupi2, subleading shape functions and Weak Annihilation. No uncertainty is assigned for possible duality violations.

Using the average |Vub| along with the calculated full b -> u l nu rate from BLNP \(70.8/ps-1/|Vub|2) results in a total BF

BF(b -> u l nu) = (2.54 +- 0.48)*10-3

DGE: Vub with input b-quark mass from fit to b to s gamma moments

DGE: |Vub| with input b-quark mass from fit to b to s gamma moments

The following values, calculated within the DGE framework, use b-quark mass input  from a fit to the lowest energy moments of the Egamma spectrum in b -> s gamma as measured CLEO, Belle and Babar.  The fit yields

The details of the fit are here.

DGE Vub (B->Xs g moments)
Experiment Value [10-3] Parameters References Remarks
CLEO (endpoint) 3.93 +/- 0.46 +/- 0.32 input Phys.Rev.Lett.88:231803,2002 (hep-ex/0202019) 2.1 < p < 2.6, Vub redetermined from partial BF
BELLE (endpoint) 4.85 +/- 0.45 +/- 0.25 input Phys.Lett.B621:28-40 (2005) (hep-ex/0504046) 1.9 < p < 2.6
BABAR (endpoint) 4.35 +/- 0.29 +/- 0.27 input Phys.Rev.D73:012006,2006 (hep-ex/0509040) 2.0 < p < 2.6, Vub redetermined from partial BF
BABAR (E_{e}, q^{2}) 4.04 +/- 0.27 +/- 0.25 input Phys.Rev.Lett.95:111801,2005 (hep-ex/0506036) (Ee-q2)
BELLE m_{X} 4.39 +/- 0.29 +/- 0.26 input Phys.Rev.Lett.95:241801,2005 (hep-ex/0505088) mX, BRECO tag; other methods (mX-q2 and P not used)
BELLE sim. ann. (m_{X}, q^{2}) 4.47 +/- 0.47 +/- 0.21 input Phys.Rev.Lett.92:101801,2004 (hep-ex/0311048) mX - Q2, tag with annealing method
BABAR (m_{X}, q^{2}) 4.86 +/- 0.36 +/- 0.22 input preliminary (hep-ex/0507017) mX-q2, BRECO tag
Average +/- exp +/- (mb,theory) 4.49 +/- 0.22 +/- 0.20 chi2/dof = 10.4/6 (CL = 0.11) Plots: eps pdf HQ parameter input from b to s gamma moments fitted in the Shape Function scheme
The full breakdown of the uncertainties on the average |Vub| above is (all errors quoted in percent):

+-1.8stat +-2.4exp +-1.6b2c model +-2.2b2u model +-1.5mb (R_CUT) +-2.4alpha_s (R_CUT) +-3.0TOTAL SL WIDTH +-3.1DGE theory

where the errors correspond to statistics, experimental systematics, the modeling of b -> c l nu and b -> u l nu decays, effect of uncertainty on mb
on the prediction of  the event fraction (R_CUT),  effect  of alpha_s uncertainty on R_CUT, uncertainty on total semileptonic B width, and from the change
and variation of scale of the matching scheme (DGE theory).

Using the average |Vub| along with the calculated full b -> u l nu rate from DGE \(66.5/ps-1/|Vub|2) results in a total BF

BF(b -> u l nu) = (2.05 +- 0.28)*10-3

Vub comparison

Inclusive Vub comparison

The errors on |Vub| are experimental and theoretical, respectively.

Vub (B->Xc l nu & B->Xs g moments)
Theory framework Vub [10-3]
BLNP (Phys. Rev. D72:073006 (2005)) 4.45 +/- 0.20 +/- 0.26
DGE (JHEP 0601:097 (2006)) 4.41 +/- 0.20 +/- 0.20

A plot of this table is available in two formats: eps pdf

The errors on |Vub| are experimental and theoretical, respectively.

Vub (B->Xs g moments)
Theory framework Vub [10-3]
BLNP (Phys. Rev. D72:073006 (2005)) 4.75 +/- 0.22 +/- 0.39
DGE (JHEP 0601:097 (2006)) 4.49 +/- 0.22 +/- 0.20

A plot of this table is available in two formats: eps pdf

Vub comparison_with LLR method

Shape Function Model Independent extraction of Inclusive Vub comparison

Above we have used two theoretical formulations to extract Vub from measurements of inclusive charmless B-meson decays in various kinematic regions of phase space. Recently BABAR measured inclusive Vub using the prescription of Leibovich, Low, and Rothstein (LLR) that extracts Vub with reduced model dependence by combining data of the hadronic mass spectrum from B->Xulnu decays with that of the photon energy spectrum from B->Xs gamma decays (hep-ex/0601046). The LLR approach reduces the dependence on the shape function because no model for the shape function is assumed, in contrast to the BLNP formulation used above. Here we provide a comparison.

The errors on |Vub| are experimental and theoretical, respectively.

Description Vub [10-3] Reference
HFAG Ave. (BLNP) 4.45 +/- 0.20 +/- 0.26
HFAG Ave. (DGE) 4.41 +/- 0.20 +/- 0.20
BABAR (LLR) hep-ph/0601046 4.43 +/- 0.45 +/- 0.29 Preliminary (hep-ph/0601046)

A plot of this table is available in two formats: eps pdf


B -> pi l nu average for Winter 2006

Branching fractions of B -> pi l nu

The measurements quoted here include both B0 and B+ decays; the average assumes equality of the semileptonic decays widths for these isospin-conjugate states, and is quoted for B0 decays.

Experiment / Mode BF [10-4] BF(q2<16 GeV2) [10-4] BF(q2>16 GeV2) [10-4] Reference
BABAR SL tag: B ^{+} \rightarrow \pi^{0} l^{+} \nu \times 2\tau_{0}/\tau_{+} 3.31 +/- 0.68 +/- 0.42 NA NA (1.80+-0.37+-0.23) Preliminary, SL tag (hep-ex/0506065) (input)
BABAR Breco tag: B ^{+} \rightarrow \pi^{0} l^{+} \nu \times 2\tau_{0}/\tau_{+} 1.60 +/- 0.41 +/- 0.21 1.10 +/- 0.35 +/- 0.16 0.50 +/- 0.22 +/- 0.12 (0.79+-0.20+-0.11) preliminary Breco tag (hep-ex/0507085) (input)
BELLE SL tag: B ^{+} \rightarrow \pi^{0} l^{+} \nu \times 2\tau_{0}/\tau_{+} 1.37 +/- 0.24 +/- 0.17 0.97 +/- 0.20 +/- 0.11 0.40 +/- 0.15 +/- 0.05 (0.76+-0.13+-0.09) Preliminary, SL tag (hep-ex/0508018) (input)
BABAR SL tag: B ^{0} \rightarrow \pi^{-} l^{+} \nu 1.02 +/- 0.25 +/- 0.13 0.81 +/- 0.23 +/- 0.11 0.21 +/- 0.14 +/- 0.05 Preliminary, SL tag (hep-ex/0506064) (input)
BELLE SL tag: B ^{0} \rightarrow \pi^{-} l^{+} \nu 1.46 +/- 0.20 +/- 0.16 1.06 +/- 0.16 +/- 0.12 0.39 +/- 0.12 +/- 0.05 Preliminary, SL tag (hep-ex/0508018) (input)
BABAR Breco tag: B ^{0} \rightarrow \pi^{-} l^{+} \nu 1.14 +/- 0.27 +/- 0.17 0.49 +/- 0.19 +/- 0.07 0.65 +/- 0.20 +/- 0.13 Preliminary, Breco tag, (hep-ex/0507085) (input)
CLEO untagged: B \rightarrow \pi l^{+} \nu 1.32 +/- 0.18 +/- 0.13 1.07 +/- 0.16 +/- 0.11 0.25 +/- 0.09 +/- 0.05 Untagged, Phys. Rev. D 68, 072003 (2003) ) (input)
BABAR untagged: B \rightarrow \pi l^{+} \nu 1.38 +/- 0.10 +/- 0.18 0.89 +/- 0.09 +/- 0.12 0.49 +/- 0.05 +/- 0.06 Untagged, Phys .Rev. D72, 051102 (2005) ) (input)
Average: B ^{0} \rightarrow \pi^{-} l^{+} \nu 1.34 +/- 0.08 +/- 0.08 0.94 +/- 0.06 +/- 0.06 0.39 +/- 0.04 +/- 0.04 Plots: eps pdf   chi2/dof = 8.4/7 (CL = 0.30)

Vub from B -> pi l nu average for Winter 2006

Exclusive Vub determination

The partial BF quoted above along with theoretical calculations of the form factor normalization can be used to determine Vub; a few recent calculations are shown below. Note that the FNAL04 and HPQCD unquenched LQCD calculations are not entirely independent, we do not use their quenched results as they are superseded by their unquenched results. We also use the quenched LQCD result of the APE collaboration. The Ball-Zwicky calculation is based on light-cone sum rules.  At this time we do not attempt to average the Vub results or select a best value. We divide the results into two tables: the first table lists extractions of |V_ub| in q^2 regions where the theory formulation is applicable and the second lists results where these same formulations have relied on a model to extrapolate to the uncovered q^2 region.

A determination of |Vub| making use of the experimental input on the q2 dependence is under study but not yet available.

The errors on |Vub| are experimental and theoretical, respectively.

FF calculation Vub [10-3] q2 range FF norm (ps-1) Reference
Ball-Zwicky q2 < 16 3.36 +/- 0.15 +0.55-0.37 <16 GeV2 5.44 +/- 1.43 Phys. Rev. D71:014015 (2005)
HPQCD q2 > 16 4.20 +/- 0.29 +0.63-0.43 >16 GeV2 1.46 +/- 0.35 Phys. Rev. D73:074502 (2006)
FNAL q2 > 16 3.75 +/- 0.26 +0.65-0.43 >16 GeV2 1.83 +/- 0.50 hep-lat/0409116
APE q2 > 16 3.78 +/- 0.26 +1.45-0.67 >16 GeV2 1.80 +/- 0.86 Nucl. Phys. B 619 (2000) 565-587

A plot of this table is available in two formats: eps pdf

FF calculation Vub [10-3] q2 range FF norm (ps-1) Reference
Ball-Zwicky full q2 3.36 +/- 0.15 +0.66-0.41 full 7.74 +/- 2.32 Phys. Rev. D71:014015 (2005)
HPQCD full q2 3.81 +/- 0.16 +0.82-0.50 full 6.03 +/- 1.94 Phys. Rev. D73:074502 (2006)
FNAL full q2 3.74 +/- 0.16 +0.86-0.51 full 6.24 +/- 2.12 hep-lat/0409116
APE full q2 3.53 +/- 0.15 +1.08-0.56 full 7.0 +/- 2.9 Nucl. Phys. B 619 (2000) 565-587

A plot of this table is available in two formats: eps pdf

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Branching fractions of other exclusive charmless semileptonic decays

Experiment Mode BF [10-4] Reference
CLEO B+-> eta l+ nu 0.84 +/-0.31 +0.16 +/-0.09 Phys. Rev. D 68, 072003 (2003)
CLEO B0-> rho- l+ nu 2.69 +/-0.41 +0.35/-0.40 +/-0.50 Phys. Rev. D 61, 052001 (2000)
BABAR B0-> rho- l+ nu 2.57 +/-0.52 +/-0.59 Preliminary, Breco tag (ICHEP conference paper)
BABAR B0-> rho- l+ nu 3.29 +/-0.42 +/-0.47 +/-0.60 Phys. Rev. Lett. 90, 181801 (2003)
CLEO B0-> rho- l+ nu 2.17 +/-0.34 +0.47/-0.54 +/-0.41 +/-0.01 Phys. Rev. D 68, 072003 (2003)
BABAR B0-> rho- l+ nu 2.14 +/-0.21 +/-0.51 +/-0.28 Untagged, Phys .Rev. D72, 051102 (2005) (hep-ex/0507003)
BELLE B0-> rho- l+ nu 2.07 +/-0.47 +/-0.25 +/-0.14 Preliminary, SL tag (hep-ex/0508018)
BELLE B+-> rho0 l+ nu 1.39 +/-0.23 +/-0.17 +/-0.02 Preliminary, SL tag (hep-ex/0508018)
BELLE B+-> omega l+ nu 1.3 +/-0.4 +/-0.2 +/-0.3 Phys. Rev. Lett. 93:131803 (2004)


Last update: 2006/06/19 Antonio Limosani (Bug fix).