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Prospects for rare and forbidden hyperon decays at BESIII

Hai-Bo LiSubjects: Physics >> General Physics: Statistical and Quantum Mechanics, Quantum Information, etc.

The study of hyperon decays at the Beijing Electron Spectrometer III (BESIII) is proposed to investigate the events of J/ψ decay into hyperon pairs, which provide a pristine experimental environment at the Beijing Electron–Positron Collider II. About 106–108 hyperons, i.e., Λ, Σ, Ξ, and ?, will be produced in the J/ψ and ψ(2S) decays with the proposed data samples at BESIII. Based on these samples, the measurement sensitivity of the branching fractions of the hyperon decays is in the range of 10?5–10?8. In addition, with the known center-of-mass energy and “tag technique,” rare decays and decays with invisible ?nal states can be probed. |

Subjects: Physics >> Nuclear Physics

Within the factorization-assisted topological-amplitude approach, we study the two-body charmed?B?meson decays?Bu,d,s→D(?)M, with?M?denoting a light pseudoscalar (or vector) meson. The meson decay constants and transition form factors are factorized out from the hadronic matrix element of topological diagrams. Therefore the effect of SU(3) symmetry breaking is retained, which is different from the conventional topological diagram approach. The number of free nonperturbative parameters to be fitted from experimental data is also much less. Only four universal nonperturbative parameters?χC,??C,?χE?and??E?are introduced to describe the contribution of the color suppressed tree and?W-exchanged diagrams for all the decay channels. With the fitted parameters from 31 decay modes induced by?b→c?transition, we then predict the branching fractions of 120 decay modes induced by both?b→c?and?b→u?transitions. Our results are well consistent with the measured data or to be tested in the LHCb and Belle-II experiments in the future. Besides, the SU(3) symmetry breaking, isospin violation and?CP?asymmetry are also investigated. |

Electromagnetic $N-\Delta(1232)$ transitions within the point-form of relativistic quantum mechanics

Yubing Dong; Mauro Giannini; Elena Santopinto; Andrea VassalloSubjects: Physics >> Nuclear Physics

The electromagnetic?N?Δ(1232)?transition amplitudes are calculated using the point-form of relativistic quantum mechanics. The relativistic effects incorporated in the electromagnetic matrix elements give a good description of the transition amplitudes to the?Δ(1232)?resonance, reproducing well the?Q2?behaviour of the data, apart from the low?Q2?one. |

Two-body Charmed $B$ Meson Decays In Factorization Assisted Topological Amplitude Approach

CAI-DIAN LU; SI-HONG ZHOUSubjects: Physics >> Nuclear Physics

We analyze the two-body charmed?B?meson decays?Bu,d,s→D(?)P(V)?in the factorization assisted topological amplitude approach, where?P(V)?denoting a light pseudoscalar (vector) meson. Different from the conventional topological diagram approach, flavor?SU(3)?symmetry breaking effects are taken into account. Therefore only four universal nonperturbative parameters are introduced to describe the contribution from non-factorization diagrams for all the decay channels. The number of free parameters and the?χ2?per degree of freedom are both significantly reduced comparing with the conventional topological diagram approach. With the 4 fitted parameters, we predict the branching fractions of 120 decay modes induced by both?b→c?and?b→u?transitions, which are well consistent with the measured data or to be tested on the future experiments. We also investigated the relative size of different topological diagrams, isospin violation, flavor?SU(3)?symmetry breaking effects, compared with previous approaches. |

Spectra of heavy-light mesons in a relativistic model

Jing-Bin Liu; Cai-Dian LuSubjects: Physics >> Nuclear Physics

The spectra and wave functions of heavy-light mesons are calculated within a relativistic quark model, which is derived from the instantaneous Bethe-Salpeter equation by applying the Foldy-Wouthuysen transformation on the heavy quark. The kernel we choose is based on scalar confining and vector Coulomb potentials. The Hamiltonian for heavy-light quark-antiquark system is calculated up to order?1/m2Q. The results are in good agreement with available experimental data except for the masses of the anomalous?D?s0(2317)?and?Ds1(2460)?states. The newly observed charmed meson states can be accommodated successfully in the relativistic model and their assignments are presented, the?D?sJ(2860)?can be interpreted as the?|13/2D1??and?|15/2D3??states being the?JP=1??and?3??members of the 1D family in our model. |

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