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*  B--v  signal  1500-     *
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FIG. 1: Distributions of the selection values in the signal re-
gion for the q2-dependent variables used in the analysis of
B0 -> 7r-f+v decays. The vertical axis represents the selec-
tion value for a given q2 value. We reject an event when its
value is in the shaded region.
the B0 -> 7--f+v mode only, in which there are many
events, each of the first two categories is further split
into a background category where the pion and the lep-
ton come from the decay of the same B ("same B" cat-
egory), and a background category where the pion and
the lepton come from the decay of different B mesons
("both B" category).
Given the sufficient number of events for the rfv decay
mode, the data samples can be subdivided in 12 bins of q2
for the signal and two bins for each of the five background
categories. Two bins are used for each background cat-
egory since the background q2 spectra are not that well
known and need to be adjusted in the fit when the num-
ber of events is sufficiently large to permit it. The q2
ranges of the background binning for the B0 - 7--f+v*
decays are: [0,18,26.4] GeV2 for the b --> ulv same B
category, [0,22,26.4] GeV2 for the b --> ulv both B cat-
egory, [0,10,26.4] GeV2 for the other BB same B cate-
gory, [0,14,26.4] GeV2 for the other BB both B category
and [0,22,26.4] GeV2 for the continuum category. In each
case, the q2 ranges of the two bins are chosen to contain a
similar number of events. All the signal and background
events are fitted simultaneously for a total of 22 param-
eters. For the y('){v modes, a smaller number of events
leads us to restrict the signal and each of the three back-
ground categories to a single q2 bin except for the signal
in the nfv mode when y -> yy, which is investigated in
three bins of q2.
We use the AE-mES histograms, obtained from the
MC simulation as two-dimensional probability density
functions (PDFs), in our fit to the data to extract the

FIG. 2: (color online) Distributions in the signal region for the
q2-dependent selections used in the analysis of B0 -> 7r--f+
decays. The arrows indicate the rejected regions. All the
selections have been applied except for the one of interest. In
each panel, the signal area is scaled to the area of the total
background.
yields of the signal and backgrounds as a function of
q2. As an initial estimate, the MC continuum back-
ground yield and q2-dependent shape are first normal-
ized to match the yield and q2-dependent shape of the
off-resonance data control sample. This results in a large
statistical uncertainty due to the small number of events
in the off-peak data. To improve the statistical preci-
sion, the continuum background, initially normalized to
the off-peak data, is allowed to vary in the fit to the data
for the 7rfv and fv(-y-y) modes where we have a large
number of events. The fit result is compatible with the
off-peak prediction within at most 1 standard deviation.
Because of an insufficient number of events, the b --> ufv
background is fixed in the fit for the n(')fv modes, and
the continuum contribution is also fixed for the yfv(3w)
and n'fv modes. Whenever a background is not varied
in the fit, it is fixed to the MC prediction except for
the continuum background which is fixed to its normal-
ized yield and q2-dependent shape using the off-resonanc
data. The background parameters which are free in the
fit require an adjustment of less than 10% with respect
to the MC predictions. For illustration purposes only, we
show in Fig. 3 AE and mES fit projections in the signal-
enhanced region for B0   > 7--f+v decays in two ranges of
q2 corresponding to the sum of eight bins below and four
bins above q2   16 GeV2, respectively. More detailed AE
and mES fit projections in each q2 bin are also shown in
Figs. 8 and 9 of the Appendix for the B0 -> 7--f+v de-
cays. The data and the fit results are in good agreement.
Fit projections for B+ > y('){ v, only available below

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