arXiv subjects

N. Takeda

Publications and source records attributed to N. Takeda.

4 recordsLinked to original sources

arXiv2006

Heavy fermion fluid in high magnetic fields: an infrared study of CeRu$_4$Sb$_{12}$

We report a comprehensive infrared magneto-spectroscopy study of CeRu$_4$Sb$_{12}$ compound revealing quasiparticles with heavy effective mass m$^*$, with a detailed analysis of optical constants in fields up to 17 T. We find that the applied magnetic field strongly affects the low energy excitations in the system. In particular, the magnitude of m$^*$ $\simeq$ 70 m$_b$ (m$_b$ is the quasiparticle band mass) at 10 K is suppressed by as much as 25 % at 17 T. This effect is in quantitative agreement with the mean-field solution of the periodic Anderson model augmented with a Zeeman term.

cond-mat.str-el↗

arXiv2001

MNS Parameters from Neutrino Oscillations, Single Beta Decay and Double Beta Decay

We examine the constraints on the MNS lepton mixing matrix =66rom the present and future experimental data of the neutrino oscillation, tritium beta decay, and neutrinoless double beta decay for Majorana neutrinos. We show that the small mixing angle solutions for solar neutrino problem are disfavored for small averaged mass ($ $) of neutrinoless double beta decay ($\leq 0.01$ eV) in the inverse neutrino mass hierarchy scenario. This is the case even in the normal mass hierarchy scenario except for very restrictive value of the averaged neutrino mass ($\bar{m_ν}$) of single beta decay. The lower mass bound for $\bar{m_ν}$ is given from the present neutrino oscillation data. We obtain some relations between $ $ and $\bar{m_ν}$. The constraints on the Majorana CP violating phases are also given.

hep-ph↗

arXiv2000

Graphical Representation of CP Violation Effects in Neutrinoless Double Beta Decay

We illustrate the graphical method that gives the constraints on the parameters appearing in the neutrino oscillation experiments and the neutrinoless double beta decay. This method is applicable in three and four generations. Though this method is valid for more general case, we examine explicitly the cases in which the CP violating factors take $\pm 1$ or $\pm i$ in the neutrinoless double beta decay for illustrative clearance. We also discuss some mass matrix models which lead to the above CP violating factors.

hep-ph↗

arXiv2000

CP Violations in Lepton Number Violation Processes and Neutrino Oscillations

We examine the constraints on the MNS lepton mixing matrix from the present and future experimental data of the neutrino oscillation and lepton number violation processes. We introduce a graphical representation of the CP violation phases which appear in the lepton number violation processes such as neutrinoless double beta decay, the $μ^--e^+$ conversion, and the K decay, $K^-\toπ^+μ^-μ^-.$ Using this graphical representation, we derive the constraints on the CP violation phases in the lepton sector.

hep-ph↗