Progress in Particle and Nuclear Physics最新文献

The observed pattern of fermion masses and mixing is an outstanding puzzle in particle physics, generally known as the flavor problem. Over the years, guided by precision neutrino oscillation data, discrete flavor symmetries have often been used to explain the neutrino mixing parameters, which look very different from the quark sector. In this review, we discuss the application of non-Abelian finite groups to the theory of neutrino masses and mixing in the light of current and future neutrino oscillation data. We start with an overview of the neutrino mixing parameters, comparing different global fit results and limits on normal and inverted neutrino mass ordering schemes. Then, we discuss a general framework for implementing discrete family symmetries to explain neutrino masses and mixing. We discuss CP violation effects, giving an update of CP predictions for trimaximal models with nonzero reactor mixing angle and models with partial $\mu -\tau$ reflection symmetry, and constraining models with neutrino mass sum rules. The connection between texture zeros and discrete symmetries is also discussed. We summarize viable higher-order groups, which can explain the observed pattern of lepton mixing where the non-zero ${\theta }_{13}$ plays an important role. We also review the prospects of embedding finite discrete symmetries in the Grand Unified Theories and with extended Higgs fields. Models based on modular symmetry are also briefly discussed. A major part of the review is dedicated to the phenomenology of flavor symmetries and possible signatures in the current and future experiments at the intensity, energy, and cosmic frontiers. In this context, we discuss flavor symmetry implications for neutrinoless double beta decay, collider signals, leptogenesis, dark matter, as well as gravitational waves.

During the past two decades, chiral effective field theory has evolved into a powerful tool to derive nuclear forces from first principles. Nearly all two-nucleon interactions have been worked out up to sixth order of chiral perturbation theory, while, with few exceptions, three-nucleon forces, which play a subtle, but crucial role in microscopic nuclear structure calculations, have been derived up to fifth order. We review the current status of these forces as well as their applications in nuclear many-body systems. While the ab initio description of light nuclei is generally very successful, we point out and analyze problems encountered with medium-mass nuclei. We also survey the construction of equations of state for symmetric nuclear matter and neutron-rich matter based on chiral forces. A focal point is the symmetry energy and its impact on neutron skins and systems of astrophysical relevance. The physics of neutron-rich systems, from nuclei to compact stars, is essentially determined by the density dependence of the symmetry energy. We review the status of predictions in comparison with latest empirical constraints, with particular attention to those extracted from parity-violating electron scattering.

We present a detailed study of the lowest-lying ${\frac{1}{2}}^{-}$ and ${\frac{3}{2}}^{-}$ ${\Lambda }_Q$ resonances both in the heavy quark (bottom and charm) and the strange sectors. We have paid special attention to the interplay between the constituent quark-model and chiral baryon–meson degrees of freedom, which are coupled using a unitarized scheme consistent with leading-order heavy quark symmetries. We show that the ${\Lambda }_b\left(5912\right)$ [$J^P=1/2^{-}$], ${\Lambda }_b\left(5920\right)$ [$J^P=3/2^{-}$] and the ${\Lambda }_c\left(2625\right)$ [$J^P=3/2^{-}$], and the $\Lambda \left(1520\right)$ [$J^P=3/2^{-}$] admitting larger breaking corrections, are heavy-quark spin-flavor siblings. They can be seen as dressed quark-model states with ${\Sigma }_Q^{(\ast )}\pi$ molecular components of the order of 30%. The ${J^P=\frac{1}{2}}^{-}$ ${\Lambda }_c\left(2595\right)$ has, however, a higher molecular probability of at least 50%, and even values greater than 70% can be easily accommodated. This is because it is located almost on top of the threshold of the