A new method for resolving combinatorial ambiguities at hadron colliders

We present a new method for resolving combinatorial ambiguities that arise in multi-particle decay chains at hadron colliders where the assignment of visible particles to the different decay chains has ambiguities. Our method, based on selection cuts favoring high transverse momentum and low invariant mass pairings, is shown to be significantly superior to the more traditional hemisphere method for a large class of decay chains, producing an increase in signal retention of up to a factor of 2. This new method can thus greatly reduce the combinatorial ambiguities of decay chain assignments.     

Parametric characterisation of a chaotic attractor using the two scale Cantor measure

A chaotic attractor is usually characterised by its multifractal spectrum which gives a geometric measure of its complexity. Here we present a characterisation using a minimal set of independent parameters which is uniquely determined by the underlying process that generates the attractor. The method maps the f(α) spectrum of a chaotic attractor on to that of a general two scale Cantor measure. We show that the mapping can be done in practice with reasonable accuracy for many of the standard chaotic attractors. In order to implement this procedure, we also propose a generalisation of the standard equations for the two scale Cantor set in one dimension to that in higher dimensions. Another interesting result we have obtained both theoretically and numerically is that, the f(α) characterisation gives information only up to two scales, even when the underlying process generating the multifractal involves more than two scales.     

Resolution,absolute configuration and antifilarial activity of coumarinyl amino alcohols

The resolution of racemic coumarinyl amino alcohols 5–10 was achieved by using the inexpensive and readily accessible chiral resolving agent N-carbethoxy-l-proline (S)-11. Direct esterification of rac-5–10 with (S)-11 furnished diastereomeric esters, which were easily separated by column chromatography. The obtained diastereomers yielded the desired enantiopure coumarinyl amino alcohols (S)-(+)-5–10 and (R)-(?)-5–10 in good yields with high enantiomeric excess on saponification. The absolute configurations were determined by X-ray crystal analysis and/or by comparison of the specific rotations. Furthermore, in in vitro antifilarial motility inhibition assays, enantiopure coumarins (S)-(+)-9, (R)-(?)-9 and (S)-(+)-10, (R)-(?)-10 were found to be less efficient in affecting the viability of macrofilariae of Brugia malayi than their racemic forms 9 and 10, respectively, indicating the synergistic effect of the enantiomers in evoking antifilarial action.     

Atomic scale imaging and spectroscopy of a CuO(2) plane at the surface of Bi(2)Sr(2)CaCu(2)O(8+delta)

We have used a scanning tunneling microscope to demonstrate that a single CuO2 plane can form a stable and atomically ordered layer at the surface of Bi(2)Sr(2)CaCu(2)O(8+delta). In contrast to previous studies on high-T(c) surfaces, the CuO2-terminated surface exhibits a strongly suppressed tunneling conductance at low voltages. We consider a number of different explanations for this phenomena and propose that it may be caused by how the orbital symmetry of the CuO2 plane's electronic states affects the tunneling process.     

Complexes containing phosphorus lignads—161: New phosphinite,phosphonite and phosphite derivatives of ruthenium,osmium and iridium

The complexes [MHCl(CO)(PPh₃)₃] (M = Ru or Os) readily undergo substitution at the site trans to the hydride ligand to afford phosphinite-, phosphonite-, or phosphite-containing products [MHCI(CO)(PPh₃)₂L] [L = P(OR)Ph₂, P(OR)₂Ph or P(OR)₃ respectively; R = Me or Et]. The ruthenium complexes alone undergo further substitution to afford complex cations [RuH(CO)(PPh₃)_nL_4?n]⁺ [n = 2, L = P(OMe)₃; n = 1, L = P(OR)₃; n = 0, L = P(OR)₂Ph or P(OR)Ph₂] which were isolated and characterised as their tetraphenylborate salts. Synthesis of the cationic complexes [IrHL₅][BPh₄]₂ [L = P(OR)₃, R = Me or Et] is also reported. Stereochemical assignments based on NMR data are given, and second order ³¹P and high field ¹H NMR patterns are analysed.     

Kinematic cuts and backward photoproduction

We present a phenomenological analysis of backward photoproduction in terms of the recently proposed kinematic cut model. The cut fills in the dip at u ≈ −0.15 without having to invoke the N_γ trajectory. Good agreement with the data is obtained in the scattering region; the extrapolation to the nucleon pole is unsatisfactory.     

Electromagnetic solutions of the field equations in presence of zeromass mesons

The field equations of general relativity with electromagnetic stress tensor and zeromass scalar meson field are investigated. The metric coefficients are assumed to be functions of three variables only. It is then shown that, if one assumes a functional relation between some one of the metric coefficients and the electromagnetic potentials, that one can find a solution of the coupled Einstein-Maxwell equations in terms of a solution of the Einstein equations with zeromass scalar meson field as source.