V. Q. Phong | Searcharxiv

arXiv2012

Neutral currents in reduced minimal 3-3-1 model

This work is devoted for gauge boson sector of the recently proposed model based on SU(3)_C X SU(3)_L X U(1)_X group with minimal content of leptons and Higgses. The limits on the masses of the bilepton gauge bosons and on the mixing angle among the neutral ones are deduced. Using the Fritzsch anzats on quark mixing, we show that the third family of quarks should be different from the first two. We obtain a lower bound on mass of the new heavy neutral gauge boson as 6.051 TeV. Using data on branching decay rates of the $Z$ boson, we can fix the limit to the Z and Z^prime mixing angle phi as $-0.001\leϕ\le 0.0003$.

hep-ph↗

arXiv2012

Dynamic of the accelerated expansion of the universe in the DGP model

According to experimental data of SNe Ia (Supernovae type Ia), we will discuss in detial dynamics of the DGP model and introduce a simple parametrization of matter $ω$, in order to analyze scenarios of the expanding universe and the evolution of the scale factor. We find that the dimensionless matter density parameter at the present epoch $Ω^0_m=0.3$, the age of the universe $t_0= 12.48$ Gyr, $\frac{a}{a_0}=-2.4e^{\frac{-t}{25.56}}+2.45$. The next we study the linear growth of matter perturbations, and we assume a definition of the growth rate, $f \equiv \frac{dlnδ}{dlna}$. As many authors for many years, we have been using a good approximation to the growth rate $f \approx Ω^{γ(z)}_m$, we also find that the best fit of the growth index, $γ(z)\approx 0.687 - \frac{40.67}{1 + e^{1.7. (4.48 + z)}}$, or $γ(z)= 0.667 + 0.033z$ when $z\ll1$. We also compare the age of the universe and the growth index with other models and experimental data. We can see that the DGP model describes the cosmic acceleration as well as other models that usually refers to dark energy and Cold Dark Matter (CDM).

astro-ph.CO↗