Y. Srivastava

Radiative corrections to e+e− → μ+μ− around the Z0

Abstract Analytical expressions are presented for e.m. radiative effects in the reaction e − e + → μ − μ + , in the vicinity of the Z 0 mass, in the Weinberg-Salam model. Our formulae contain all finite first-order corrections, as well as soft photon effects resummed to all orders, with no restriction on the relative magnitudes of the energy resolution Δω and the Z 0 width Γ. Hard photon effects, other than the tail effect, are not included. Weak interactions are considered only to lowest order. Radiative corrections are explicitly shown to change the lowest-order results drastically, and must therefore be taken in full account for a realistic description of experiments at LEP energies.

Equivalent circuit and simulations for the Landau-Khalatnikov model of ferroelectric hysteresis

We present the circuit equivalent of the Landau-Khalatnikov dynamical ferroelectric model. The differential equation for hysteretic behavior is subject to numerical computer simulations. The size and shape of the simulated hysteretic loops depend strongly on the frequency and the amplitude of the driving electric field. In previous experiments, this dependence made extraction of the coercive field rather difficult. An alternative experimental method for the determination of the coercive field is here suggested. We also develop in detail the dynamics of bifurcation of a driven Landau-Khalatnikov ferroelectric.

The Response of a Superconducting Weak-Link Ring to External Adiabatic Noise (*).

SummaryWe discuss the response of a superconducting weak-link ring to externally applied adiabatic noise and show that this can be used as a probe of the low-lying energy eigenstates of the ring. We compare the observable consequences of this with new experimental results.

Spatial correlations in two neutral kaon decays

Relativistic propagators, the natural tools in field theory to describe the space-time development of a quantum system, are used to study correlations and interferences present in the neutral kaon system due to time-reversal violations. The method allows for a general wave-packet treatment of the problem. While standard results are obtained for singleK decays, quite different results are derived for the interference phase in two kaon decays such as those at DAΦNE.

Pion electromagnetic structure functions from pion exchange in leptoproduction

Abstract The pion-exchange contribution to e + p → e ′+ n + X is calculated using different models, both for pion exchange and for the pion electromagnetic structure functions. Numerical estimates of this contribution to deep inelastic scattering off protons are given.

Physical Kinetics of Ferroelectric Hysteresis

The physical kinetics of single domain ferroelectric materials are studied employing Landau-Khalatnikov equation. The resulting hysteretic curves are obtained numerically. The effective coercive electric field is found to be theoretically dependent on the driving amplitude and frequency as observed in the experimental hysteretic measurements of ferroelectric materials. The effects of thermal noise on the polarization switching time are analyzed using the Fokker-Planck kinetic equation. It is found that the effect of thermal noise is rather significant in a single domain of small volume. It is also shown that for low temperatures quantum effects dominate classical thermal effects in inducing polarization switching in a single ferroelectric domain.

Regge Trajectories For All Flavors

Based on available data for mesonic resonances of light, medium and heavy flavors, we have performed a global analysis to construct the corresponding linear Regge trajectories. These have been supplemented by results from various phenomenological models presented in the literature. A satisfactory formula is found for the dependence of the intercept and the slope on quark masses. We find reasonable agreement with data on production of charmed hadrons through exchange of our charmed trajectories in the space-like region. When applied to mesons containing the top quark, our results suggest the impossibility of their formation as evidenced by other independent analyses.

Hadronic masses and Regge trajectories

A comprehensive phenomenological analysis of experimental data and some theoretical models is presented here (for mesons) to critically discuss how Regge trajectory parameters depend on flavor. Through analytic continuation of physical trajectories (obtained from resonance data) into the space like region, we derive the suppression factor for heavy flavor production. The case of our D Regge exchange, both for D and

Solutions of the time dependent Schrödinger equation for a SQUID ring

\Lambda_c

Inclusive production at large mass and large transverse momentum

production, is considered in some detail. Good agreement with data is reached confirming that indeed the slopes of heavier flavors decrease. This result suggests that the confinement potential has a substantial dependence on the quark masses. In a simple non-relativistic model, constrained to produce linear Regge trajectories, it is shown that a linear quark mass dependence is required (in the confinement part of the potential) in order for the slope to decrease in the appropriate way.