Neutrino masses, cosmological bound and four zero Yukawa textures

Four zero neutrino Yukawa textures in a specified weak basis, combined with $\mu\tau$ symmetry and type-I seesaw, yield a highly constrained and predictive scheme. Two alternately viable $3\times3$ light neutrino Majorana mass matrices $m_{\nu A}/m_{\nu B}$ result with inverted/normal mass ordering. Neutrino masses, Majorana in character and predicted within definite ranges with laboratory and cosmological inputs, will have their sum probed cosmologically. The rate for $0\nu\beta\beta$ decay, though generally below the reach of planned experiments, could approach it in some parameter region. Departure from $\mu\tau$ symmetry due to RG evolution from a high scale and consequent CP violation, with a Jarlskog invariant whose magnitude could almost reach $6\times 10^{-3}$, are explored.Comment: Published versio

SIZE-DEPENDENT OPTICAL PROPERTIES OF COPPER NANOPARTICLE OVER A WIDE RANGE OF WAVELENGTHS: AN ELECTROMAGNETIC SIMULATION STUDY

In this article, we modulate the optical absorption, scattering, extinction, transmission and field intensities of an ellipsoid copper nanoparticle by tuning its dimension. The finite-difference time-domain (FDTD) method is employed for this electromagnetic simulation study and a comparative investigation has been carried out. In the investigation it is found that Cu nanoparticle with 20 nm size exhibiting the optical absorption at the resonant wavelength ~530 nm. This plasmon peak is shifted to ~550 nm when the particle size is increased to 40 nm. In addition to shifting, the enhancement of the plasmon peak is also observed. This nonlinear enhancement arises due to the size dependent property of the surface plasmon resonance (SPR). For smaller nanoparticle, the scattering is found to be negligible as compared to the larger particle. The scattering becomes dominant as the particle size increases beyond 28 nm. The scattering cross-sections of all the particle decreases at the longer wavelength. All the structures exhibit a strong transmission minimum at a wavelength close to 590 nm in the visible spectrum. However, above 600 nm high transmission is observed. The electric field intensity is also enhanced from 5.15 (V/m)2 to 16.9 (V/m)2 as the particle size increases from 20 nm to 40 nm. We strongly believe that this research could provide an overall idea about the importance of particle size variation while fabricating Cu based solar energy harvesting systems, plasmonics photovoltaic devices etc

Analysis of a model with a common source of CP violation

We work in a model where all CP violating phenomena have a common source. CP is spontaneously broken at a large scale $V$ through the phase of a complex singlet scalar. An additional $SU(2)_L$ singlet vector-like down-type quark relates this high scale CP violation to low energy. We quantitatively analyze this model in the quark sector. We obtain the numerical values of the parameters of the Lagrangian in the quark sector for a specific ansatz of the $4\times4$ down-type quark mass matrix where the weak phase is generated minimally. $Z \bar b b$ vertex will modify in presence of the extra vector-like down-type quark. From the experimental lower bound of the partial decay width $Z\to \bar b b$ we find out the lower bound of the additional down-type quark mass. Tree level flavor changing neutral current appears in this model due to the presence of the extra vector-like down-type quark. We give the range of values of the mass splitting $\Delta m_{B_q}$ in $B^0_q-{\bar B}^0_q$ system using SM box, $Z$ mediating tree level and $Z$ mediating one loop diagrams together for both $q=d, s$. We find out the analytical expression for $\Gamma_{12}^q$ in this model from standard box, $Z$ and Higgs mediated penguin diagrams for $B^0_q-{\bar B}^0_q$ system, $q=d,s$. From this we numerically evaluate the decay width difference $|\Delta\Gamma_{B_q}/\Gamma_{B_q}|$. We also find out the numerical values of the CP asymmetry parameters $a_J$ and $a_\pi$ for the decays $B^0_d\to J/\psi K_s$ and $B^0_d\to \pi^+ \pi^-$ respectively. We get the lower bound of the scale $V$ through the upper bound of the strong CP phase.Comment: 20 pages, no figures New materials and references have been added. Text has been modified. To be appear in J.Phys.