FCNC transition c→uγ in B c → B ∗ u γ decay
Abstract
We propose the
B
c
→
B
∗
u
γ
decay as the most suitable probe for the flavour changing neutral transition
c→uγ
. We estimate the short and long distance contributions to this decay within the standard model and we find them to be comparable; this is in contrast to radiative decays of
D
mesons, that are completely dominated by the long distance contributions. Since the
c→uγ
transition is very sensitive to the physics beyond the standard model, the standard model prediction
Br(
B
c
→
B
∗
u
γ)∼
10
−8
obtained here opens a new window for future experiments. The detection of
B
c
→
B
∗
u
γ
decay at branching ratio well above
10
−8
would signal new physics.