分类: 物理学 >> 普通物理:统计和量子力学,量子信息等 提交时间: 2017-11-10
摘要: 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 Ω, 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 final states can be probed.
分类: 物理学 >> 核物理学 提交时间: 2016-09-14
摘要: 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, ϕC, χE and ϕE 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.
分类: 物理学 >> 核物理学 提交时间: 2016-09-13
摘要: 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.
分类: 物理学 >> 核物理学 提交时间: 2016-09-05
摘要: 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.
分类: 物理学 >> 核物理学 提交时间: 2016-09-05
摘要: 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.