arXiv subjects

He Zhang

Publications and source records attributed to He Zhang.

348 records · Page 20Linked to original sources

arXiv2006

Distinguishable RGE running effects between Dirac neutrinos and Majorana neutrinos with vanishing Majorana CP-violating phases

In a novel parametrization of neutrino mixing and in the approximation of $τ$-lepton dominance, we show that the one-loop renormalization-group equations (RGEs) of Dirac neutrinos are different from those of Majorana neutrinos even if two Majorana CP-violating phases vanish. As the latter can keep vanishing from the electroweak scale to the typical seesaw scale, it makes sense to distinguish between the RGE running effects of neutrino mixing parameters in Dirac and Majorana cases. The differences are found to be quite large in the minimal supersymmetric standard model with sizable $\tanβ$, provided the masses of three neutrinos are nearly degenerate or have an inverted hierarchy.

hep-ph↗

arXiv2005

Reconstruction of the Neutrino Mixing Matrix and Leptonic Unitarity Triangles from Long-baseline Neutrino Oscillations

We derive a new set of sum rules between the neutrino mass and mixing parameters in vacuum and their effective counterparts in matter. The moduli of nine genuine lepton mixing matrix elements can then be calculated in terms of the matter-corrected ones, and the latter can directly be determined from a variety of long-baseline neutrino oscillations. We show that it is possible to reconstruct the leptonic unitarity triangles and CP violation in a similar parametrization-independent way.

hep-ph↗

arXiv2005

Leptonic Unitarity Triangles in Matter

We present a geometric description of lepton flavor mixing and CP violation in matter by using the language of leptonic unitarity triangles. The exact analytical relations for both sides and inner angles are established between every unitarity triangle in vacuum and its effective counterpart in matter. The typical shape evolution of six triangles with the terrestrial matter density is illustrated for a realistic long-baseline neutrino oscillation experiment.

hep-ph↗

arXiv2005

Model-independent Constraints on the Weak Phase $α$ (or $ϕ_2$) and QCD Penguin Pollution in $B \to ππ$ Decays

We present an {\it algebraic} isospin approach towards a more straightforward and model-independent determination of the weak phase $α$ (or $ϕ_2$) and QCD penguin pollution in $B\to ππ$ decays. The world averages of current experimental data allow us to impose some useful constraints on the isospin parameters of $B\to ππ$ transitions. We find that the magnitude of $α$ (or $ϕ_2$) extracted from the indirect CP violation in $π^+π^-$ mode is in agreement with the standard-model expectation from other indirect measurements, but its four-fold discrete ambiguity has to be resolved in the near future.

hep-ph↗

arXiv2003

Complete Parameter Space of Quark Mass Matrices with Four Texture Zeros

The full parameter space of Hermitian quark mass matrices with four texture zeros is explored by using current experimental data. We find that all ten free parameters of the four-zero quark mass matrices can well be constrained. In particular, only one of the two phase parameters plays an important role in CP violation. The structural features of this specific pattern of quark mass matrices are also discussed in detail.

hep-ph↗

arXiv2003

Lepton Mass Matrices with Four Texture Zeros

We propose two ans$\rm\ddot{a}$tze of lepton mass matrices with four texture zeros, and confront them with current experimental data on neutrino oscillations. The parameter space of each ansatz is carefully explored. We find that both ans$\rm\ddot{a}$tze can accommodate the normal hierarchy of neutrino masses and the bi-large pattern of lepton flavor mixing. Their predictions for the effective mass of the tritium beta decay and that of the neutrinoless double beta decay are too small to be detectable, but leptonic CP violation at the percent level is allowed. Some discussions are also given about the seesaw invariance of the four-zero texture of Dirac and Majorana neutrino mass matrices.

hep-ph↗