分类: 物理学 >> 核物理学 提交时间: 2016-09-18
摘要: Two empirical formulae for the lepton and quark masses (i.e. Kartavtsev's extended Koide formulae), Kl=(∑lml)/(∑lml−−√)2=2/3 and Kq=(∑qmq)/(∑qmq−−−√)2=2/3, are explored in this paper. For the lepton sector, we show that Kl=2/3, only if the uncertainty of the tauon mass is relaxed to about 2σ confidence level, and the neutrino masses can consequently be extracted with the current experimental data. For the quark sector, the extended Koide formula should only be applied to the running quark masses, and Kq is found to be rather insensitive to the renormalization effects in a large range of energy scales from GeV to 1012 GeV. However, Kq is always slightly larger than 2/3, but the discrepancy is merely about 5%.
分类: 物理学 >> 核物理学 提交时间: 2016-09-18
摘要: Considering the mass splitting between three active neutrinos, we represent the new constraints on the sum of neutrino mass ∑mν by updating the anisotropic analysis of Baryon Acoustic Oscillation (BAO) scale in the CMASS and LOWZ galaxy samples from Data Release 12 of the SDSS-III Baryon Oscillation Spectroscopic Survey (BOSS DR12). Combining the BAO data of 6dFGS, MGS, LOWZ and CMASS with Planck~2015 data of temperature anisotropy and polarizations of Cosmic Microwave Background (CMB), we find that the 95% C.L. upper bounds on ∑mν refer to ∑mν,NH<0.18 eV for normal hierarchy (NH), ∑mν,IH<0.20 eV for inverted hierarchy (IH) and ∑mν,DH<0.15 eV for degenerate hierarchy (DH) respectively, and the normal hierarchy is slightly preferred than the inverted one (Δχ2≡χ2NH−χ2IH≃−3.4). In addition, the additional relativistic degrees of freedom and massive sterile neutrinos are neither favored at present.
分类: 物理学 >> 核物理学 提交时间: 2016-09-18
摘要: Behind the observed pattern of lepton flavor mixing is a partial or approximate mu-tau flavor symmetry --- a milestone on our road to the true origin of neutrino masses and flavor structures. In this review article we first describe the features of mu-tau permutation and reflection symmetries, and then explore their various consequences on model building and neutrino phenomenology. We pay particular attention to soft mu-tau symmetry breaking, which is crucial for our deeper understanding of the fine effects of flavor mixing and CP violation.
分类: 物理学 >> 核物理学 提交时间: 2016-09-18
摘要: Hadron spectroscopy is one of the most important physics goals of BESIII. BESIII brings great opportunities to study the XYZ states of charmonium by directly producing the Y states up to 4.6 GeV. High statistics of charmonium decays collected at BESIII provide an excellent place for hunting gluonic excitations and studying the excited baryons. Recent results of light hadron spectroscopy and charmonium spectroscopy from BESIII will be reported.
分类: 物理学 >> 核物理学 提交时间: 2016-09-18
摘要: Within the framework of dispersion theory, we analyze the dipion transitions between the lightest Υ states, Υ(nS)→Υ(mS)ππ with m
分类: 物理学 >> 核物理学 提交时间: 2016-09-18
摘要: A foremost task in understanding the nature of the X(3872) involves the discrimination of the two-quark and multiquark configurations. In this work, we propose a method to probe the short-distance component of the X(3872) by measuring the ratio between the Bc semileptonic and nonleptonic decays into the X(3872). We demonstrate that if the X(3872) production mechanism is through the c¯c component, the ratios would be universal and could be reliably predicted in theory. Measurements of these ratios at LHC and the next-generation electron-positron colliders are capable of validating/invalidating this production mechanism and providing deeper insights into the nature of the X(3872).
分类: 物理学 >> 核物理学 提交时间: 2016-09-18
摘要: Proton spin is investigated in chiral effective field theory through an examination of the singlet axial charge, a0, and the two non-singlet axial charges, a3 and a8. Finite-range regularization is considered as it provides an effective model for estimating the role of disconnected sea-quark loop contributions to baryon observables. Baryon octet and decuplet intermediate states are included to enrich the spin and flavour structure of the nucleon, redistributing spin under the constraints of chiral symmetry. In this context, the proton spin puzzle is well understood with the calculation describing all three of the axial charges reasonably well. The strange quark contribution to the proton spin is negative with magnitude 0.01. With appropriate Q2 evolution, we find the singlet axial charge at the experimental scale to be a^0=0.31+0.04−0.05, consistent with the range of current experimental values.
分类: 物理学 >> 核物理学 提交时间: 2016-09-18
摘要: Anomalies in recent observational data indicate that there might be some "anisotropic hair" generated in an inflation period. To obtain general information about the effects of this anisotropic hair to inflation models, we studied anisotropic inflation models that involve one vector and one scalar using several types of potentials. We determined the general relationship between the degree of anisotropy and the fraction of the vector and scalar fields, and concluded that the anisotropies behave independently of the potentials. We also generalized our study to the case of multi-directional anisotropies.