arXiv subjects

Shao-Long Chen

Publications and source records attributed to Shao-Long Chen.

42 records · Page 3Linked to original sources

arXiv2005

Smallness of Leptonic $θ_{13}$ and Discrete Symmetry

The leptonic mixing angle $θ_{13}$ is known to be small. If it is indeed tiny, the simplest explanation is that charged leptons mix only in the $μ-τ$ sector and neutrinos only in the 1-2 sector. We show that this pattern may be explained by the discrete symmetry $Z_2 \times Z_2$ of a complete Lagrangian, which has 2 Higgs doublets and 2 Higgs triplets (or 2 heavy right-handed singlet neutrinos). In the case of Higgs triplets, the Majorana neutrino masses are arbitrary, whereas in the case of heavy singlet neutrinos, an inverted hierarchy is predicted. Lepton-Flavor-Violation effects, present only in the $μ-τ$ sector, are analyzed in detail: the LFV $τ$-decay rates are predicted below the present bounds by a few orders of magnitude, whereas LFV Higgs decays could allow for a direct test of the model.

hep-ph↗

arXiv2004

Large neutrino mixing and normal mass hierarchy: a discrete understanding

We discuss the possibility of flavor symmetries to explain the pattern of charged lepton and neutrino masses and mixing angles. We emphasize what are the obstacles for the generation of an almost maximal atmospheric mixing and what are the minimal ingredients to obtain it. A model based on the discrete symmetry $S_3$ is constructed, which leads to the dominant $μτ$-block in the neutrino mass matrix, thus predicting normal hierarchy. This symmetry makes it possible to reproduce current data and predicts $0.01\lesssimθ_{13}\lesssim 0.03$ and strongly suppressed neutrinoless $2β$-decay. Moreover, it implies a relation between lepton and quark mixing angles: $θ_{23}^q \approx 2(π/4-θ_{23})$. The Cabibbo mixing can also be reproduced and $θ_{13}^q\sim θ_{12}^qθ_{23}^q$. $S_3$ is thus a candidate to describe all the basic features of Standard Model fermion masses and mixing.

hep-ph↗

arXiv2004

Exotic Fermions and Bosons in the Quartification Model

Exotic fermions of half-integral charges at the TeV energy scale are predicted by the quartification model of Babu, Ma, and Willenbrock. We add to these one copy of their scalar analogs and discuss the ensuing phenomenological implications, i.e. radiative contributions to lepton masses and flavor-changing leptonic decays.

hep-ph↗

arXiv2002

Cabibbo-suppressed non-leptonic decays of Lambda_c and final state interaction

With the diquark structure of Lambda_c, we investigate the branching ratios of Lambda_c -> n pi^+ and p pi^0. The results show that without considering the final state interaction (FSI), the branching ration of Lambda_c -> p pi^+ is only of order 10^{-6} whereas taking into account the FSI effects, this ratio could reach 10^{-4} and is at the same order as Lambda_c -> n pi^0. Concrete values depend on phenomenological parameters adopted in the calculations. These branching ratios can be measured in the experiments to come.

hep-ph↗

arXiv2001

Study of the $B_c$-meson lifetime

We in terms of optical theorem estimate the lifetime of $B_c-$meson with the parameters which are deturmined by fitting the data for the lifetimes and inclusive semilepton-decays of various $B$ and $D$ mesons. In the estimate, we find that the bound-state effects are important, and take them into account carefully in the framework which attributes the effects to the effective masses of the decay heavy quarks in the inclusive processes. We also find that to $B_c$ lifetime the penguin contribution is enhanced due to possible interference between the penguin and the `tree part' $c_1O_1+c_2O_2$.

hep-ph↗

arXiv2000

The lifetime of B_c-meson and some relevant problems

The lifetime of the B_c-meson is estimated with consistent considerations on all of the heavy mesons ($B^0, B^\pm, B_s, D^0, D^\pm D_s$) and the double heavy meson B_c. In the estimate, the framework, where the non-spectator effects for nonleptonic decays are taken into account properly, is adopted, and the parameters needed to be fixed are treated carefully and determined by fitting the available data. The bound-state effects in it are also considered. We find that in decays of the meson B_c, the QCD correction terms of the penguin diagrams and the main component terms c_1O_1, c_2O_2 of the effective interaction Lagrangian have direct interference that causes an enhancement about 3 ~ 4% in the total width of the B_c meson.

hep-ph↗