Search for CP violation in the decay B0-->D*+/-D-/+

We report a search for CP-violating asymmetry in B0-->D(*+/-)D-/+ decays. The analysis employs two methods of B0 reconstruction: full and partial. In the full reconstruction method all daughter particles of the B0 are required to be detected; the partial reconstruction technique requires a fully reconstructed D- and only a slow pion from the D(*+)-->D0pi(+)(slow) decay. From a fit to the distribution of the time interval corresponding to the distance between two B meson decay points we calculate the CP-violating parameters and find the significance of nonzero CP asymmetry to be 2.7 standard deviations.     

Direct observation of large electronic domains with memory effect in doped manganites

We use a spatially resolved, direct spectroscopic probe for electronic structure with an additional sensitivity to chemical compositions to investigate high-quality single crystal samples of La(1/4)Pr(3/8)Ca(3/8)MnO3, establishing the formation of distinct insulating domains embedded in the metallic host at low temperatures. These domains are found to be at least an order of magnitude larger in size compared to previous estimates and exhibit memory effects on temperature cycling in the absence of any perceptible chemical inhomogeneity, suggesting long-range strains as the probable origin.     

Observation of radiative B-->phi K gamma decays

The radiative decay B-->phi K gamma is observed for the first time. The branching fraction for the charged B--->phi K- gamma decay mode is measured to be B(B--->phi K- gamma)=(3.4+/-0.9+/-0.4)x10(-6). The photon energy distribution for the B--->phi K- gamma decay is presented. The signal for the neutral B(0)-->phi K(0)gamma decay mode is not statistically significant and an upper limit, B(B(0)-->phi K(0)gamma)<8.3x10(-6) at 90% C.L., is set. The analysis is based on a data set of 90 fb(-1) collected by the Belle experiment at the e(+)e(-) asymmetric collider KEKB.     

Interpretation of anomalous normal state optical conductivity of La-Sr-CuO cuprates

The observed frequency dependent optical response of hole doped cuprate La_1.85Sr_0.15CuO₄ superconductors, has been theoretically analysed. Starting from an effective two-dimensional (2D) interaction potential for superlattice of hole doped cuprates treated as a layered electron gas, the spectral function is formulated. Calculations of the optical conductivity σ(ω) have been made within the two-component scheme: one is the coherent Drude carriers responsible for superconductivity and the other is incoherent motion of carriers from one site to other leads to a pairing between Drude carriers. The approach accounts for the anomalies reported (frequency dependence of optical conductivity) in the optical measurements for the normal state. Estimating the effective mass from specific heat measurement and ε_∞ from band structure calculations for the low-energy charge density waves, the model has only one free parameter, the relaxation rate. The frequency dependent relaxation rates are expressed in terms of memory functions, and the coherent Drude carriers from the effective interaction potential lead to a sharp peak at zero frequency and a long tail at higher frequencies, i.e. in the infrared (IR) region. However, the hopping of carriers from one site to other (incoherent motion of doped carriers) yields a peak value in the optical conductivity centred at mid-IR (MIR) region. We find that both the Drude and hopping carriers in the superlattice of cuprates will contribute to the optical process of conduction in the CuO₂ planes and shows similar results on optical conductivity in the MIR as well as IR frequency regions as those revealed from experiments.     

Net baryon density in Au+Au collisions at the relativistic heavy ion collider

We calculate the net-baryon rapidity distribution in Au+Au collisions at the Relativistic Heavy Ion Collider (RHIC) in the framework of the parton cascade model (PCM). Parton rescattering and fragmentation leads to a substantial increase in the net-baryon density at midrapidity over the density produced by initial primary parton-parton scatterings. The PCM is able to describe the measured net-baryon density at RHIC.     

Dicationic Ionic Liquid Mediated Synthesis of 5-Arylidine-2,4-thiazolidinediones

An efficient synthesis of 5‐arylidine‐2,4‐thiazolidinediones has been developed using dicationic ionic liquid as green medium and catalyst. This method performed well for the condensation of both aryl as well as heteryl aldehydes with 2,4‐thiazolidinedione and gave 5‐arylidine‐2,4‐thiazolidinediones with excellent yields.     

Quantum theory of stimulated raman scattering in an inhomogeneously broadened three-level gaseous system

A quantum-statistical treatment of stimulated Raman scattering in a gaseous system is presented using a density-matrix formalism. The molecular (atomic) system is described by three energy levels. Both atomic system and the radiation fields are quantized. The effects of atomic motion and detuning are incorporated in the analysis. Higher order nonlinearities and loss terms are included to render the problem more realistic. The equations of motion describing the photonstatistics of pump and Stokes fields are obtained. The equation, without detailed balance, is solved in the steady-state by a slowly varying function technique in the case of two variables. The steady state characteristics of the Stokes field are studied. The coherence properties, occurrence of antibunching phenomena are studied for different initial distributions.     

Stochastic analysis and maintenance planning of the ash handling system in the thermal power plant

This paper discusses stochastic analysis of the ash handling system in a thermal power plant. The system consists of four subsystems A_i, B_j, C and D_k in series, with three possible states: good, reduced and failed. Failure and repair rates for each subsystem are taken to be constants. Using a probabilistic approach, the differential equations are generated and the expression for steady state availability is computed. Taking data from the thermal power plant, situated in North India, the behaviour of each working unit is analysed. Problems and remedies with appropriate maintenance schedules have been discussed. The results are discussed with the plant personnel and are helpful to the management in predicting the behaviour of each operating unit, so that timely decisions can be taken for maintaining the system in upstate for a long duration.