9 Symmetry Violations and Quark Flavour Physics
591
candidates and 0.829 × 10 6 B 0 → D ∗− μ + ν μ X candidates (charge conjugated
decays included) are used [88] and yield
d = (0.5050 ± 0.0021 ± 0.0010) ps
−1 .
Dominated by the LHCb result, the current world average of the existing d
measurements yields
d = (0.5064 ± 0.0019] ps
−1 [130].
Using the B 0 lifetime average of 1.520 ± 0.004 ps [130] one obtains the mixing
parameter,
x d =
d
d
= 0.770 ± 0.004 [130],
which is of similar magnitude as the value of the neutral K system, x K = 0.945 ±
0.002 (see Sect. 9.5). As predicted, the decay width difference of the B 0 turns out to
be very small. The world average [130] of y d is,
y d =
d
2 d
= −0.001 ± 0.005
compared to y K = −0.9965 for the K meson.
9.6.3.2 Measurement of the B 0
s −B
0
s Oscillation Frequency
Inserting the corresponding CKM elements in Eq. (9.187) one expects that the
oscillation of the neutral B 0
s meson is by a factor |V ts | 2 / |V td | 2 faster than the
oscillation of the B 0 . To resolve the fast oscillation pattern represented a challenge
and the first measurement of s was achieved only in 2006 by the CDF
experiment [85].
The by far most precise determination of s was performed by LHCb [86]
using about 34,000 B 0
s → D −
s π + decays (charge conjugated decays are included).
Figure 9.28 shows the decay time distribution dependent number of observed B 0
s
meson decays which decay with the same (unmixed) or the different flavor (mixed)
with respect to their production. One can nicely observe the rather fast oscillation
pattern. A fit accounting for the tagging dilution and for the finite time resolution
results into
s = (17.768 ± 0.023 ± 0.006) ps
−1 [86] .
This value agrees well with the theoretical prediction s = (18.3 ± 2.5) ps −1
which however, exhibits large errors due to the uncertainties of the hadronic
591
candidates and 0.829 × 10 6 B 0 → D ∗− μ + ν μ X candidates (charge conjugated
decays included) are used [88] and yield
d = (0.5050 ± 0.0021 ± 0.0010) ps
−1 .
Dominated by the LHCb result, the current world average of the existing d
measurements yields
d = (0.5064 ± 0.0019] ps
−1 [130].
Using the B 0 lifetime average of 1.520 ± 0.004 ps [130] one obtains the mixing
parameter,
x d =
d
d
= 0.770 ± 0.004 [130],
which is of similar magnitude as the value of the neutral K system, x K = 0.945 ±
0.002 (see Sect. 9.5). As predicted, the decay width difference of the B 0 turns out to
be very small. The world average [130] of y d is,
y d =
d
2 d
= −0.001 ± 0.005
compared to y K = −0.9965 for the K meson.
9.6.3.2 Measurement of the B 0
s −B
0
s Oscillation Frequency
Inserting the corresponding CKM elements in Eq. (9.187) one expects that the
oscillation of the neutral B 0
s meson is by a factor |V ts | 2 / |V td | 2 faster than the
oscillation of the B 0 . To resolve the fast oscillation pattern represented a challenge
and the first measurement of s was achieved only in 2006 by the CDF
experiment [85].
The by far most precise determination of s was performed by LHCb [86]
using about 34,000 B 0
s → D −
s π + decays (charge conjugated decays are included).
Figure 9.28 shows the decay time distribution dependent number of observed B 0
s
meson decays which decay with the same (unmixed) or the different flavor (mixed)
with respect to their production. One can nicely observe the rather fast oscillation
pattern. A fit accounting for the tagging dilution and for the finite time resolution
results into
s = (17.768 ± 0.023 ± 0.006) ps
−1 [86] .
This value agrees well with the theoretical prediction s = (18.3 ± 2.5) ps −1
which however, exhibits large errors due to the uncertainties of the hadronic