Description of self-synchronization effects in distributed Josephson junction arrays using harmonic analysis and power balance

Power generation and synchronisation in Josephson junction arrays have attracted attention for a long time. This stems from fundamental interest in nonlinear coupled systems as well as from potential in practical applications. In this paper we study the case of an array of junctions coupled to a distributed transmission line either driven by an external microwave or in a self-oscillating mode. We simplify the theoretical treatment in terms of harmonic analysis and power balance. We apply the model to explain the large operation margins of SNS- and SINIS-junction arrays. We show the validity of the approach by comparing with experiments and simulations with self-oscillating es-SIS junction arrays.Comment: 5 pages, 3 figure

η−η′\eta-\eta^\prime mixing and the next-to-leading-order power correction

The next-to-leading-order $O(1/Q^4)$ power correction for $\eta\gamma$ and $\eta^\prime\gamma$ form factors are evaluated and employed to explore the $\eta-\eta^\prime$ mixing. The parameters of the two mixing angle scheme are extracted from the data for form factors, two photon decay widths and radiative $J/\psi$ decays. The $\chi^2$ analysis gives the result: $f_{\eta_1}=(1.16\pm0.06)f_\pi, f_{\eta_8}=(1.33\pm0.23)f_\pi, \theta_1=-9^\circ\pm 3^\circ, \theta_8=-21.3^\circ\pm 2.3^\circ$, where $f_{\eta_{1(8)}}$ and $\theta_{1(8)}$ are the decay constants and the mixing angles for the singlet (octet) state. In addition, we arrive at a stringent range for $f_{\eta^\prime}^c:-10$ MeV$\le f_{\eta^\prime}^c\le -4$ MeV.Comment: 23 pages, 9 figures, To be publshied in Phys. Rev.

Beam-Dynamics Studies and Advanced Accelerator Research at CTF-3: Compact Final Focus, Laser Compton Scattering, Plasmas, etc.

Preliminary investigations are summarized on the possible use of the CTF3 facility for extended beam-dynamics studies and advanced accelerator R&D, which would exploit its unique properties and beam availability. The key element of these considerations is the possible addition of a test beam-delivery system comprising a compact final focus and advanced collimation concepts, scaled from 3 TeV down to low energy and having a short total length. Operational experience, verification of critical questions (octupole tail folding, beam halo transport, etc.), diagnostics (e.g., rf BPMs) and stabilization could all be explored in such a facility, which would benefit not only the CLIC study, but all linear collider projects. Another interesting application would be the study of plasma-beam interaction, which may include plasma focusing, plasma acceleration, ion-channel radiation, and plasma wigglers

Two photon decay of the pseudoscalars, the chiral symmetry breaking corrections

The extrapolation of the decay amplitudes of the pseudoscalar mesons into two photons from the soft meson limit where it is obtained from the axial-anomaly to the mass shell involves the contribution of the 0^ - continuum. These chiral symmetry breaking corrections turn out to be large. The effects of these corrections on the calculated pi ^0 decay rate, on the values of the singlet-octet mixing angle and on the ratios f_8 / f_pi and f_0 / f_pi are discussed. The implications for the transition form factors gamma gamma* --> pseudoscalars are also evaluated and confronted with the available experimental data.Comment: Computational errors straightened and study of the implications on the form factors of the transitions gamma gamma* --> pseudoscalars adde

Determination of the η\eta and η′\eta' Mixing Angle from the Pseudoscalar Transition Form Factors

The possible range of $\eta-\eta'$ mixing angle is determined from the transition form factors $F_{\eta \gamma}(Q^2)$ and $F_{\eta' \gamma}(Q^2)$ with the help of the present experimental data. For such purpose, the quark-flavor mixing scheme is adopted and the pseudoscalar transition form factors are calculated under the light-cone pQCD framework, where the transverse momentum corrections and the contributions beyond the leading Fock state have been carefully taken into consideration. We construct a phenomenological expression to estimate the contributions to the form factors beyond the leading Fock state based on their asymptotic behavior at $Q^2\to 0$ and $Q^2\to\infty$. By taking the quark-flavor mixing scheme, our results lead to $\phi= 38.0^{\circ}\pm 1.0^{\circ}\pm 2.0^{\circ}$, where the first error coming from experimental uncertainty and the second error coming from the uncertainties of the wavefunction parameters. The possible intrinsic charm component in $\eta$ and $\eta'$ is discussed and our present analysis also disfavors a large portion of intrinsic charm component in $\eta$ and $\eta'$, e.g. $|f^c_{\eta'}|\le 50 {\rm MeV}$.Comment: 18 Pages, 3 figures. Several references added. To be published in EPJ

Instanton Contribution to the Pion Electro-Magnetic Formfactor at Q^2 > 1 GeV^2

We study the effects of instantons on the charged pion electro-magnetic formfactor at intermediate momenta. In the Single Instanton Approximation (SIA), we predict the pion formfactor in the kinematic region Q^2=2-15 GeV^2. By developing the calculation in a mixed time-momentum representation, it is possible to maximally reduce the model dependence and to calculate the formfactor directly. We find the intriguing result that the SIA calculation coincides with the vector dominance monopole form, up to surprisingly high momentum transfer Q^2~10 GeV^2. This suggests that vector dominance for the pion holds beyond low energy nuclear physics.Comment: 8 pages, 5 figures, minor revision

Higgs Physics with a gamma gamma Collider Based on CLIC 1

We present the machine parameters and physics capabilities of the CLIC Higgs Experiment (CLICHE), a low-energy $\gamma\gamma$ collider based on CLIC 1, the demonstration project for the higher-energy two-beam accelerator CLIC. CLICHE is conceived as a factory capable of producing around 20,000 light Higgs bosons per year. We discuss the requirements for the CLIC 1 beams and a laser backscattering system capable of producing a $\gamma\gamma$ total (peak) luminosity of $2.0 (0.36) \times 10^{34}$ cm$^{-2}$s$^{-1}$ with $E_{CM}(\gamma \gamma) \sim 115$ GeV. We show how CLICHE could be used to measure accurately the mass, $\bar b b$, $WW$ and $\gamma \gamma$ decays of a light Higgs boson. We illustrate how these measurements may distinguish between the Standard Model Higgs boson and those in supersymmetric and more general two-Higgs-doublet models, complementing the measurements to be made with other accelerators. We also comment on other prospects in $\gamma\gamma$ and $e^- \gamma$ physics with CLICHE.Comment: 34 pages, 20 figures, Latex. submitted to Eur. Phys. Jou

Primakoff effect in eta-photoproduction off protons

We analyse data on forward eta-meson photoproduction off a proton target and extract the eta to gamma gamma decay width utilizing the Primakoff effect. The hadronic amplitude that enters into our analysis is strongly constrained because it is fixed from a global fit to available gamma p to p eta data for differential cross sections and polarizations. We compare our results with present information on the two-photon eta-decay from the literature. We provide predictions for future PrimEx experiments at Jefferson Laboratory in order to motivate further studies.Comment: 5 pages, 6 figures, gamma-gamma*-eta form factor included, version to appear in Eur. Phys. J. A

Power corrections to the π0γ\pi^0\gamma transition form factor and pion distribution amplitudes

Employing the standard hard-scattering approach and the running coupling method we calculate a class of power-suppressed corrections $\sim 1/Q^{2n},n=1,2,3,...$ to the electromagnetic $\pi^0\gamma$ transition form factor (FF) $Q^2F_{\pi\gamma}(Q^2)$ arising from the end-point $x \to 0,1$ integration regions. In the investigations we use a hard-scattering amplitude of the subprocess $\gamma+\gamma^{*} \to q +\bar{q}$, symmetrized under exchange $\mu_R^2 \leftrightarrow \bar{\mu}_R^2$ important for exclusive processes containing two external photons. In the computations the pion model distribution amplitudes (DA's) with one and two non-asymptotic terms are employed. The obtained predictions are compared with the CLEO data and constraints on the DA parameters $b_2(\mu_0^2)$ and $b_4(\mu_0^2)$ at the normalization point $\mu_0^2=1 GeV^2$ are extracted. Further restrictions on the pion DA's are deduced from the experimental data on the electromagnetic FF $F_{\pi}(Q^2)$.Comment: 23 pages, 6 figures; the version published in Phys. Rev. D69, 094010 (2004

Incidence trends of prostate cancer in East Anglia, before and during the era of PSA diagnostic testing

We investigated prostate cancer incidence in East Anglia from 1971 to 2000. Using age-period-cohort modelling, the number of cases expected in 1991–2000, based on pre-PSA trends, 1971–1990, was compared with that observed. Based on pre-1991 trends, 9203 new cases were expected in 1991–2000, but 9788 cases were observed, an excess of 6%