Ricerc@Sapienza

We report measurements of the lifetimes of the Λ+c, Ξ+c and Ξ0c charm baryons using proton-proton collision data at center-of-mass energies of 7 and 8 TeV, corresponding to an integrated luminosity of 3.0  fb−1, collected by the LHCb experiment. The charm baryons are reconstructed through the decays Λ+c→pK−π+, Ξ+c→pK−π+ and Ξ0c→pK−K−π+, and originate from semimuonic decays of beauty baryons.

An angular analysis of B0→J/ψK+π- decays is performed, using proton-proton collision data corresponding to an integrated luminosity of 3 fb-1 collected with the LHCb detector. The m(K+π-) spectrum is divided into fine bins. In each m(K+π-) bin, the hypothesis that the three-dimensional angular distribution can be described by structures induced only by K∗ resonances is examined, making minimal assumptions about the K+π- system. The data reject the K∗-only hypothesis with a large significance, implying the observation of exotic contributions in a model-independent fashion.

The radiative decay Λb0→Λγ is observed for the first time using a data sample of proton-proton collisions corresponding to an integrated luminosity of 1.7 fb-1 collected by the LHCb experiment at a center-of-mass energy of 13 TeV. Its branching fraction is measured exploiting the B0→K∗0γ decay as a normalization mode and is found to be B(Λb0→Λγ)=(7.1±1.5±0.6±0.7)×10-6, where the quoted uncertainties are statistical, systematic, and systematic from external inputs, respectively. This is the first observation of a radiative decay of a beauty baryon.