Global Fit in the Kinetic Scheme to the Moments in B -> Xclnu and B -> Xsgamma

This fit includes the measurements of moments in B -> Xclnu and B -> Xsgamma available by the end of the year 2009. All measurements are published. We use only moment measurements where correlation matrices are available. The fit follows closely the approach of Phys.Rev. D78 (2008) 032016.

Theoretical inputs are the calculations in Eur.Phys.J. C34 (2004) 181-189 and Nucl.Phys. B710 (2005) 371-401. Errors concerning the accuracy in the expression for a given moment have been assigned following the recipes given by the authors of the above publications. The calculation of |Vcb| uses the expression from Nucl.Phys. B665 (2003) 367-401.

Fit Results in the Kinetic Scheme

Input |Vcb| (10-3) mbkin (GeV) mu2pi (GeV2) chi2/ndf.
all moments (Xclnu and Xsgamma) 41.85 +/- 0.42(fit) +/- 0.09(tauB) +/- 0.59(th) 4.591 +/- 0.031 0.454 +/- 0.038 details 29.7 / (66-7)
Xclnu only 41.68 +/- 0.44(fit) +/- 0.09(tauB) +/- 0.58(th) 4.646 +/- 0.047 0.439 +/- 0.042 details 24.2 / (55-7)

Figures of the Delta chi2=1 ellipses can be found here:

Fit input

We consider two data samples for the fit (Table 1), using:

  1. the full set of input data currently available
  2. only the semileptonic moments, i.e., hadron and lepton moments only
Table 1. The list of the moment measurements that form the basis for the combined fit. The symbol 'n' indicates the order of the moment while 'c' indicates the value of the minimum lepton or photon energy (in GeV) with which the moments are measured.
Experiment Hadron moments <MnX> Lepton moments <Enl> Photon moments <Engamma> References
BaBar n=2 c=0.9,1.1,1.3,1.5
n=4 c=0.8,1.0,1.2,1.4
n=6 c=0.9,1.3 [1]		 n=0 c=0.6,1.2,1.5
n=1 c=0.6,0.8,1.0,1.2,1.5
n=2 c=0.6,1.0,1.5
n=3 c=0.8,1.2 [1,2]		 n=1 c=1.9,2.0
n=2 c=1.9 [3,4]		 [1] Phys.Rev. D81 (2010) 032003
[2] Phys.Rev. D69 (2004) 111104
[3] Phys.Rev. D72 (2005) 052004
[4] Phys. Rev. Lett. 97, 171803 (2006)
Belle n=2 c=0.7,1.1,1.3,1.5
n=4 c=0.7,0.9,1.3 [5]		 n=0 c=0.6,1.0,1.4
n=1 c=0.6,0.8,1.0,1.2,1.4
n=2 c=0.6,1.0,1.4
n=3 c=0.8,1.0, 1.2 [6]		 n=1 c=1.8,1.9
n=2 c=1.8,2.0 [7]		 [5] Phys.Rev. D75 (2007) 032005
[6] Phys.Rev. D75 (2007) 032001
[7] Phys.Rev.Lett. 103 (2009) 241801
CDF n=2 c=0.7
n=4 c=0.7 [8]		 . . [8] Phys.Rev. D71 (2005) 051103
CLEO n=2 c=1.0,1.5
n=4 c=1.0,1.5 [9]		 . n=1 c=2.0 [10] [9] Phys.Rev. D70 (2004) 032002
[10] Phys.Rev.Lett. 87 (2001) 251807
DELPHI n=2 c=0.0
n=4 c=0.0 [11]		 n=1 c=0.0
n=2 c=0.0
n=3 c=0.0 [11]		 . [11] Eur.Phys.J. C45 (2006) 35-59

The only external input used is the average B lifetime taken to be (1.582 +/- 0.007) ps.

last update: Apr 7, 2010 by C.Schwanda