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: 2017-09-17
摘要: Λb matrix element of four-quark operator relevant to its lifetime is reanalyzed by QCD sum rule. The new ingredients introduced are that (1) more vacuum condensates are considered; (2) different quark-hadron duality is adopted; and (3) the possible deviation from the vacuum saturation assumption for the four quark condensates is considered. With κ1 = 4 the related hadronic parameter r is calculated to be (3.6 ± 0.9), and the lifetime ratio τ (Λb)/τ (B0) = (0.83 ± 0.04), which is consistent with the experimental data.
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: 2017-09-17
摘要: The three active light neutrinos are used to explain the neutrino oscillations.The inherently bi-large mixing neutrino mass matrix and the Fritzsch type,bi-small mixing charged lepton mass matrix are assumed. By requiring the maximal #23;μ −#23;#28; mixing for the atmospheric neutrino problem and the mass-squared difference approperiate for the almost maximal mixing solution to the solar neutrino problem, the following quantities are predicted: the #23;e−#23;μ mixing, Ve3, CP violation in neutrino oscillations, and the effective electron-neutrino mass relevant to neutrinoless double beta decays.
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: 2017-09-17
摘要: The muon- and tau-neutrinos with the mass in the keV range, which are allowed in a low reheating temperature cosmology, can compose the warm dark matter of the universe. A model of four light neutrinos including the keV scale #23;μ and #23;#28; is studied, which combines the seesaw mechanism and the Abelian flavor symmetry. The atmospheric neutrino anomaly is due to the #23;μ − oscillation. The solar neutrino problem is answered by the oscillation into the light sterile neutrino, where the SMA, LMA, and LOW-QVO solutions can be accommodated in our scenario.