Radiative and leptonic decays of B-mesons represent an excellent laboratory for the search for New Physics. I present here recent results on radiative and leptonic decays from the Belle and BABAR collaborations.
We present measurements on penguin dominated B decays which are sensitive to new physics, such as CP-violation parameters and branching fractions in $b to s qbar{q}$ and $b to d qbar{q}$ gluonic and radiative decays using a large sample of $Bbar{B}$ pairs recorded at the $Upsilon(4S)$ resonance with the Belle detector at the KEKB asymmetric energy $e^+e^-$ collider.
Penguin transitions play a key role in the search of New Physics hints in the heavy flavor sector. During the last decade CDF has been exploring this opportunity with a rich study of two--body charmless decays of neutral B mesons into charged final--state particles. After briefly introducing the aspects of this physics peculiar to the hadron collision environment, I report on two interesting results: the first polarization measurement of the B^0_s --> phi phi decay and the update of the B^0(_s) --> h^+h^- decays analysis.
We have searched for the baryon-containing radiative penguin decays B^- -> Lambda p-bar gamma and B^- -> Sigma^0 p-bar gamma, using a sample of 9.7 million BBbar events collected at the Upsilon(4S) with the CLEO detector. We find no evidence for either, and set 90% confidence level upper limits for photons with B rest frame energy greater than 2.0 GeV of [Br(B^- -> Lambda p-bar gamma) + 0.3 Br(B^- -> Sigma^0 p-bar gamma)] < 3.3 x 10^-6, [Br(B^- -> Sigma^0 p-bar gamma) + 0.4 Br(B^- -> Lambda p-bar gamma)] < 6.4 x 10^-6. From the latter, we estimate (for photons with B rest frame energy greater than 2.0 GeV) Br(B -> X_s gamma, X_s containing baryons) < 3.8 x 10^-5. This limit implies upper limits on corrections to CLEOs recent measurement of branching fraction, mean photon energy, and variance in photon energy from b -> s gamma that are less than half the combined statistical and systematic errors quoted on these quantities.