The reaction Kp→Λπ in the c.m. energy range 1915 to 2168 MeV

A formationstudy of the reaction K⁻p→Λπ^o at 13 c.m. energies between 1915 and 2168 MeV is presented. Experimental differential cross sections and polarizations are given as expansions of Legendre polynomials and associated Legendre polynomials respectively. Partial wave analysis confirms the assignment of the Σ(2030) and the assignment of the Σ(1915). The parameters of these resonances are determined. The possible existence of other resonances coupled to this channel is investigated.     

Jet substructure as a new Higgs-search channel at the Large Hadron Collider

It is widely considered that, for Higgs boson searches at the CERN Large Hadron Colider, WH and ZH production where the Higgs boson decays to bb are poor search channels due to large backgrounds. We show that at high transverse momenta, employing state-of-the-art jet reconstruction and decomposition techniques, these processes can be recovered as promising search channels for the standard model Higgs boson around 120 GeV in mass.     

Aryne-Enabled C−N Arylation of Anilines

Anilines are potentially high-value arylating agents, but are limited by the low reactivity of the strong C−N bond. We show that the reactive intermediate benzyne can be used to both activate anilines, and set-up an aryl transfer reaction in a single step. The reaction does not require any transition metal catalysts or stoichiometric organometallics, and establishes a metal-free route to valuable biaryl products by functionalizing the aniline C−N bond.     

A weight-function approach for determining watershed initial conditions for combustion waves

In many generic combustion models, one finds that a combustionwave will develop with a specific wave speed. However, thereare possible initial temperature profiles which do not evolveinto such waves, but rather die out to the ambient temperature.There can exist, in some models, a clear distinction betweenthose initial conditions that do evolve into combustion wavesand those that do not; this is sometimes referred to as thewatershed initial condition. When fuel consumption is consideredto be negligible, analytical methods can be used to obtain theexact watershed. In this paper, we consider the problem of determiningpseudo-watersheds and ascertaining the relationship betweenthese pseudo-watersheds and the exact watersheds. In the processa novel weight-function approach for infinite spatial domainsis developed.     

Reactions within fluorobenzene-ammonia heterocluster ions: experiment and theory

Reactions occurring within gas phase fluorobenenze-ammonia heterocluster cations (FC(6)H(5)-(NH(3))(n=1-4)) have been studied through the use of a triple quadrupole mass spectrometer as well as employing density functional theory (DFT). Collision induced dissociation (CID) experiments were conducted in which mass selected cluster ions are accelerated into a cell containing argon gas and the resulting products then subsequently mass analyzed. Two dominate reaction channels are observed. The first is simple evaporative loss of neutral ammonia from the cluster ion. The second involves a substitution reaction occurring within the cluster ion to form the aniline cation, C(6)H(5)NH(2)(+), where the reactivity was found to vary as a function of cluster size. DFT calculations have been performed to both help analyze the structure and the reactivity of these cluster ions. Pronounced differences in activation energies were found that provide an explanation for the observed variation of reactivity as a function of cluster size. An ad hoc model based upon the Arrhenius equation was developed to fit both the experimental collision energy dependence of the reaction and the observed lowering of the reaction barrier to aniline formation as a function of cluster size.     

Expert Assessment of Examination Grades

This paper investigates the abilities of a group of experts to produce subjective probabilities on the likelihood of their students obtaining various grades in their final-year examinations. We examine the calibration of these experts, and how their ability to forecast depends on experience and assessment procedures. We find that these well-motivated and statistically literate assessors, working in their field of expertise, still suffer from the types of assessment problems noted in previous studies on more naive subjects.     

Picosecond Ti:sapphire-pumped optical parametric oscillator based on periodically poled LiNbO(3)

Periodically poled lithium niobate has been used in a singly resonant optical parametric oscillator pumped by a cw mode-locked Ti:sapphire laser. A tuning range of 1.15 to 2.4 microm was achieved when the pump was tuned, and this range was limited only by the mirror reflection bandwidth. Thresholds as low as 18 mW and an overall slope efficiency of 44% were observed, with average output powers of 130 mW (70 mW) for the signal (idler).     

Tunable single-frequency ultraviolet generation from a continuous-wave Ti : sapphire laser with an intracavity PPLN frequency doubler

We report a single-longitudinal-mode continuous-wave Ti:sapphire ring laser that is intracavity frequency doubled in periodically poled lithium niobate (PPLN). Using a multi-grating PPLN crystal, the second harmonic is tunable from 386 to 403 nm – close to the PPLN ultraviolet absorption edge – with a maximum generated power of 114 mW. The wavelength dependence of the critical operating temperature required to eliminate photorefractive effects in the PPLN crystal is determined. PACS 42.65.Ky; 42.70.Mp; 42.72.Bj