Addition of boundary localised kinetic and Yukawa terms to the action of a 5-dimensional Standard Model would non-trivially modify the Kaluza-Klein spectra and some of the interactions among the Kaluza-Klein excitations compared to the minimal versio
n of this model, in which, these boundary terms are not present. In the minimal version of this framework known as Universal Extra Dimensional model, special assumptions are made about these unknown, beyond the cut-off contributions to restrict the number of unknown parameters of the theory to a minimal. We estimate the contribution of Kaluza-Klein modes to the branching ratios of $B_{s(d)}rightarrowmu^{+}mu^{-}$ in the framework of non-minimal Universal Extra Dimensional, at one loop level. The results have been compared to the experimental data to constrain the parameters of this model. From the measured decay branching ratio of $B_s rightarrow mu^+ mu^-$ (depending on the values of boundary localised parameters) lower limit on $R^{-1}$ can be as high as 800 GeV. We have briefly reviewed the bounds on nmUED parameter space coming from electroweak precision observables. The present analysis ($B_s rightarrow mu^+ mu^-$) has ruled out new regions of parameter space in comparison to the analysis of electroweak data. We have revisited the bound on $R^{-1}$ in Universal Extra Dimensional model, which came out to be 454 GeV. This limit on $R^{-1}$ in Universal Extra Dimensional framework is not as competitive as the limits derived from the consideration of relic density or Standard Model Higgs boson production and decay to $W^+ W^-$. Unfortunately, $B_{d}rightarrowmu^{+}mu^{-}$ decay branching ratio would not set any significant limit on $R^{-1}$ in a minimal or non-minimal Universal Extra Dimensional model.
Electroweak observables are highly sensitive to the loop corrections. Therefore, a proper gauge-fixing mechanism is always needed to define the propagators which are involved in Feynman loop amplitude. With this spirit we compute gauge-fixing mechani
sm in five dimensional (5-D) Universal Extra-Dimensional (UED) model with boundary localised terms (BLTs). These BLTs are not 5-D operators in four-dimensional (4-D) effective theory but some sort of boundary conditions on the respective fields at the fixed points of $S^1/Z_2$ orbifold. Furthermore, these BLTs non-trivially modify the Kaluza-Klein (KK) spectra and some of the interactions among the KK-excitations compared to the minimal UED (mUED), in which, these BLTs are absent. In this note we calculate the gauge-fixing mechanism in the electroweak sector of such non-trivial UED scenario. Moreover, we discuss the composition and masses of Goldstone and any physical scalar that emerge after the symmetry breaking in this set up with different choices of gauge.
We investigate the impact of the latest data on Higgs boson branching ratios on the minimal model with a Universal Extra Dimension (mUED). Combining constraints from vacuum stability requirements with these branching ratio measurements we are able to
make realistic predictions for the signal strengths in this model. We use these to find a lower bound of 1.3 TeV on the size parameter $R^{-1}$ of the model at 95% confidence level, which is far more stringent than any other reliable bound obtained till now.
The exotic physical properties of graphene have led to intense research activities on the synthesis and characterization of graphene composites during the last decade. In this article the methods developed for preparation of such materials and the di
fferent application areas are reviewed. The composites discussed are of two types, viz; graphene/polymer and inorganic/ graphene. The techniques of ex-situ hybridization and in-situ hybridization have been pointed out. Some of the application areas are batteries and ultracapacitor for energy storage and fuel cell and solar cell for energy generation and some of the possible future directions of research have been discussed.
Nickel nanosheets of thickness 0.6 nm were grown within the nanochannels of Na-4 mica template. The specimens show magnetodielectric effect at room temperature with a change of dielectric constant as a function of magnetic field, the electric field f
requency varying from 100 to 700 kHz. A decrease of 5% in the value of dielectric constant was observed up to a field of 1.2 Tesla. This is explained by an inhomogeneous two-component composite model as theoretically proposed recently. The present approach will open up synthesis of various nanocomposites for sensor applications.
Ferromagnetic behaviour has been observed experimentally for the first time in nanostructured Manganese. Ultrathin ($sim$ 0.6 nm) Manganese nanosheets have been synthesized inside the two dimensional channels of sol-gel derived Na-4 mica. The magneti
c properties of the confined system are measured within 2K-300K temperature range. The confined structure is found to show a ferromagnetic behaviour with a nonzero coercivity value. The coercivity value remains positive throughout the entire temperature range of measurement. The experimental variation of susceptibility as a function of temperature has been satisfactorily explained on the basis of a two dimensional system with a Heisenberg Hamiltonian involving direct exchange interaction.
Nanosheets of nickel with thickness equal to 0.6 nm have been grown within the interlayer spaces of Na-4 mica. The sheets are made up of percolative clusters of nanodisks. Magnetization characteristics indicate a superparamagnetic behavior with a blo
cking temperature of 428 K.The magnetic anisotropy constant as extracted from the coercivity data has been found to be higher than that of bulk nickel by two orders of magnitude. This is ascribed to a large aspect ratio of the nickel nanophase. The Bloch exponent is also found to be considerably different from that of bulk nickel because of a size effect. The Bloch Equation is still found to be valid for the two dimensional structures.
