Neutrino Masses from Cosmological Probes in Interacting Neutrino Dark-Energy Models

We investigate whether interaction between massive neutrinos and quintessence scalar field is the origin of the late time accelerated expansion of the universe. We present explicit formulas of the cosmological linear perturbation theory in the neutrinos probes of dark-energy model, and calculate cosmic microwave background anisotropies and matter power spectra. In these models, the evolution of the mass of neutrinos is determined by the quintessence scalar field, which is responsible for a varying effective equation of states: $\omega_{eff}(z)$ goes down -1. We consider several types of scalar field potential and put constraints on the coupling parameter between neutrinos and dark energy. By combining data from cosmic microwave background (CMB) experiments including the WMAP 3-year results, large scale structure with 2dFGRS data sets, we constrain the hypothesis of massive neutrinos in the mass-varying neutrino scenario. Assuming the flatness of the universe, the constraint we can derive from the current observation is $\sum m_{\nu} < 0.45$ eV at 1$\sigma$ (0.87 eV at 2$\sigma$) confidence level for the sum over three species of neutrinos. The dynamics of scalar field and the impact of scalar field perturbations on cosmic microwave background anisotropies are discussed. We also discuss on the instability issue of the our model and confirm that neutrinos are stable against the density fluctuation.Comment: Latex, 34 pages, 11 figures, final version to appear in JHE

Nonleptonic charmless B decays: factorization vs perturbative QCD

We compare the factorization approach, the perturbative QCD approach and the Beneke-Buchalla-Neubert-Sachrajda approach to nonleptonic charmless $B$ meson decays. We discuss their treatments of factorizable, nonfactorizable, and annihilation contributions, infrared-cutoff and scale dependences, and strong phases. It is proposed that measurement of CP asymmetries in two-body $B$ meson decays provides an appropriate test of the these approaches.Comment: 18 pages, revtex, aps.style, 5 figure

Neutrino Oscillation in Magnetized Gamma-Ray Burst Fireball

Neutrinos of energy about 5-20 MeV are produced due to the stellar collapse or merger events that trigger the Gamma-Ray Burst. Also low energy MeV neutrinos are produced within the fireball due to electron positron annihilation and nucleonic bremsstrahlung. Many of these neutrinos will propagate through the dense and relativistic magnetized plasma of the fireball. We have studied the possibility of resonant oscillation of $\nu_e\leftrightarrow \nu_{\mu,\tau}$ by taking into account the neutrino oscillation parameters from SNO, SuperKamiokande and Liquid Scintillator Detector. Using the resonance condition we have calculated the resonance length for these neutrinos and also the fireball observables like lepton asymmetry and the baryon load are estimated based on the assumed fireball radius of 100 Km.Comment: Revtex 11 pages, 3 figures, Added references and revised versio

Probing for Dynamics of Dark-Energy in Mass Varying Neutrinos: Cosmic Microwave Background Radiation and Large Scale Structure

We present cosmological perturbation theory in neutrino probe interacting dark-energy models, and calculate cosmic microwave background anisotropies and matter power spectrum. In these models, the evolution of the mass of neutrinos is determined by the quintessence scalar field, which is responsible for the cosmic acceleration today. We consider several types of scalar field potentials and put constraints on the coupling parameter between neutrinos and dark energy. Assuming the flatness of the universe, the constraint we can derive from the current observation is $\sum m_{\nu} < 0.87 eV$ at the 95 % confidence level for the sum over three species of neutrinos.Comment: 12 pages, 8 figures, Present in conferences COSPA-2006, NEPSE-2007 and Yong-Pyung APCTP-200

SU(4)L×U(1)XSU(4)_L \times U(1)_X models with little Higgs

We discuss the aspects of the fermions and gauge bosons in $SU(4)_L \times U(1)_X$ models with little Higgs. We introduce a set of fermions which ensures the cancellation of gauge anomaly, and explicitly show the cancellation of one-loop quadratic divergence to the Higgs mass from all fermion multiplets and all gauge bosons. We present the interactions of the standard model fermions with the physical gauge bosons. We also discuss some phenomenological implications of the model based on recent experimental results.Comment: Revtex, 13 pages, 2 figure

Determination of weak phases ϕ2\phi_2 and ϕ3\phi_3 from B→ππ,KπB\to \pi\pi,K\pi in the pQCD method

We look at two methods to determine the weak phases $\phi_2$ and $\phi_3$ from $B \to \pi\pi$ and $K\pi$ decays within the perturbative QCD approach. We obtain quite interesting bounds on $\phi_2$ and $\phi_3$ from recent experimental measurements in asymmetric B-factory: $55^o \leq \phi_2 \leq 100^o$ and $51^o \leq \phi_3 \leq 129^o$. Specially we predict the possibility of large direct CP violation effect in $B^0 \to \pi^{+}\pi^{-}$ decay with $A_{cp}^{dir}(B\to \pi^{+} \pi^{-})=(23\pm7)$ %.Comment: 6 pages, Latex, 3 figures, typos corrected. Presented at Workshop on CKM Unitarity Triangle (CERN 2002-2003), Geneva, Switzerland, 13-16 Feb 200

Fat penguins and imaginary penguins in perturbative QCD

We evaluate $B\to K\pi$ decay amplitudes in perturbative QCD picture. It is found that penguin contributions are dynamically enhanced by nearly 50% compared to those assumed in the factorization approximation. It is also shown that annihilation diagrams are not negligible, and give large strong phases. Our results for branching ratios of $B\to K\pi$ decays for a representative parameter set are consistent with data. We evaluate $B\to K\pi$ decay amplitudes in perturbative QCD picture. It is found that penguin contributions are dynamically enhanced by nearly 50% compared to those assumed in the factorization approximation. It is also shown that annihilation diagrams are not negligible, and give large strong phases. Our results for branching ratios of $B\to K\pi$ decays for a representative parameter set are consistent with data.Comment: 11 pages, Latex2e, 3 figures, corrected some typos and reduced no. of figures. Changed the abstract, Submit at PL

Perturbative SO(10) Grand Unification

We consider a phenomenologically viable SO(10) grand unification model of the unification scale $M_G$ around $10^{16}$ GeV which reproduces the MSSM at low energy and allows perturbative calculations up to the Planck scale $M_P$ or the string scale $M_{st}$. Both requirements strongly restrict a choice of Higgs representations in a model. We propose a simple SO(10) model with a set of Higgs representations $\{2 \times {\bf 10} + {\bf \bar{16}} + {\bf 16} + {\bf 45} \}$ and show its phenomenological viability. This model can indeed reproduce the low-energy experimental data relating the charged fermion masses and mixings. Neutrino oscillation data can be consistently incorporated in the model, leading to the right-handed neutrino mass scale $M_R \simeq M_G^2/M_P$. Furthermore, there exists a parameter region which results the proton life time consistent with the experimental results.Comment: 14 pages, no figure, section5 was slightly modifie