Internal down quark's flavour changing contribution to the effective tcZ vertex

The effective vertex may be influenced by tree vertex formed by a mixing with heavy exotic isosinglet down type quarks. To study that the electroweak penguin diagrams involving one insertion of the vertex have been considered and we have calculated the contribution arising out of those diagrams using the Fourth Generation CKM matrix elements; also the applicability of the generalized GIM mechanism is considered. The additional effects of the heavy isosinglets are compared with the effects of exotic heavy isodoublets appearing in multi-generational models. We see that in the effective vertex amplitude, the down flavour changing contribution interferes constructively with the one loop penguin diagrams and experimental data may put constraint on the fourth generation down quark mass. Received: 21 March 1997 / Revised version: 19 August 1997 / Published online: 20 February 1998     

Stability and largeness of core for symmetric games

Largeness of the core is sufficient for stability of the core. In general the necessity is not known. In this paper we answer affirmatively the necessity for symmetric games. We also prove its equivalence to n specified vectors being imputations and also to the convexity of the lower boundary of the set of all acceptable pay-off vectors of the game. In this paper we establish the equivalence of a condition given by Shapley to the newly evolved condition, thereby give an alternate proof to Shapley’s condition. Received: January 1997/final version: March 1999     

Gevrey regularity for a class of dissipative equations with applications to decay

In this paper, following the techniques of Foias and Temam, we establish Gevrey class regularity of solutions to a class of dissipative equations with a general quadratic nonlinearity and a general dissipation including fractional Laplacian. The initial data is taken to be in Besov type spaces defined via “caloric extension”. We apply our result to the Navier–Stokes equations, the surface quasi-geostrophic equations, the Kuramoto–Sivashinsky equation and the barotropic quasi-geostrophic equation. Consideration of initial data in critical regularity spaces allow us to obtain generalizations of existing results on the higher order temporal decay of solutions to the Navier–Stokes equations. In the 3D case, we extend the class of initial data where such decay holds while in 2D we provide a new class for such decay. Similar decay result, and uniform analyticity band on the attractor, is also proven for the sub-critical 2D surface quasi-geostrophic equation.     

Constraint on three-Higgs-doublet model parameters by b → sγ decay considering possibility of the fourth generation in quark sector

Weak radiative B-meson decay has been studied to find plausible constraints on the complex coupling constants that arise from the diagonalization of the charged scalar mixing matrix in Weinberg three-Higgs-doublet model considering possibility of the fourth generation in quark sector. We examined the range of these complex coupling constants taking in to account corrections up to leading QCD logarithms, using evolution of fourth-generation CKM matrix with CP violation phase approximately equal to zero. Range of the mass of fourth generation down-type quark b′ and that of fourth-generation uptype quark t′ have been taken with due consideration of the constraint imposed by the present experimental value of theρ parameter keeping in view the mass difference of the fourth-generation quark doublet.     

1-Soliton solution of the generalized Camassa–Holm Kadomtsev–Petviashvili equation

An exact 1-soliton solution of the generalized Camassa–Holm Kadomtsev–Petviashvili equation is obtained in this paper by the solitary wave ansatze. This solution is a generalized form of the solution that is obtained in earlier works.     

The Jacobian of a nonorientable Klein surface, II

The aim here is to continue the investigation in [1] of Jacobians of a Klein surface and also to correct an error in [1].     

Numerically effectiveness and principal bundles on Kähler manifolds

Let E _G be a holomorphic principal G-bundle over a compact connected Kähler manifold, where G is a connected complex reductive linear algebraic group. Consider a line bundle over E _G /P corresponding to a character of P, where P is a parabolic subgroup of G. We give conditions for this holomorphic line bundle to be numerically effective.     

Mechanism of film growth of pulsed electrodeposition of nanocrystalline copper in presence of thiourea

This article reports the effect of addition of small amount of thiourea on mechanism of film growth, levelling and grain refinement of pulsed electrodeposition of nanocrystalline copper on stainless steel substrate using simple aqueous acidic copper sulphate solution prepared from 0.25 M CuSO₄·5H₂O and 0.5 M H₂SO₄. The amount of thiourea used in the electrolyte is 0 and 36 mg/l. The results indicate the change in morphology of the deposits with addition of thiourea leading to dendrite free copper deposits. The growth mechanism of the copper deposition is found to change from Volmer–Weber type to Frank-Vander Merwe type making the deposits smoother when deposited with thiourea addition. A small amount (36 mg/l) of thiourea addition leads to decrease in the average grain size of copper from 1160 nm to 14 nm. The results clearly reveal the formation of nanocrystalline copper by addition of thiourea with three orders of magnitude reduction in grain size as compared to the sample deposited without thiourea. Preferential segregation of sulphur (present in thiourea) along the grain boundaries of nanocrystalline copper is shown by energy filter imaging using ultra high resolution transmission electron microscope (TEM), thereby restricting the growth of copper grains during pulsed electrodeposition.     

Emergent Scenario and Different Anisotropic Models

In this work, Emergent Universe scenario has been developed in general homogeneous anisotropic model and for the inhomogeneous LTB model. In the first case, it is assumed that the matter in the universe has two components—one is perfect fluid with barotropic equation of state p=ωρ (ω, a constant) and the other component is a real or phantom (or tachyonic) scalar field. In the second case, the universe is only filled with a perfect fluid and possibilities for the existence of emergent scenario has been examined.     

On the operation of switch-less transversely excited atmosphere CO<Subscript>2</Subscript> lasers in the oscillator and amplifier configurations

The work presented in this paper deals with the triggering aspect of a switchless laser. Many methods were utilized to affect the operation of two switch-less lasers in the oscillator-amplifier configuration. Most satisfactory performance in terms of the range and reliability of the delay was obtained with the LC inversion-based triggering option.