20,322 research outputs found

    Shape-resonance-induced non-Franck–Condon effects in (2+1) resonance enhanced multiphoton ionization of the C 3Πg state of O2

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    We show that strong non-Franck–Condon effects observed in (2+1) resonance enhanced multiphoton ionization of the C 3Pig state of O2 are due to the ksigmau shape resonance previously observed in single-photon studies of diatomic molecules. Calculated vibrational branching ratios for the v=2,3 levels of the C 3Πg state are in reasonable agreement with experiment. Certain discrepancies remain in comparing theoretical results with the measured spectra, and possible electron-correlation effects which underly this are discussed

    Critical Temperature and Amplitude Ratios from a Finite-Temperature Renormalization Group

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    We study \l\f^4 theory using an environmentally friendly finite-temperature renormalization group. We derive flow equations, using a fiducial temperature as flow parameter, develop them perturbatively in an expansion free from ultraviolet and infrared divergences, then integrate them numerically from zero to temperatures above the critical temperature. The critical temperature, at which the mass vanishes, is obtained by integrating the flow equations and is determined as a function of the zero-temperature mass and coupling. We calculate the field expectation value and minimum of the effective potential as functions of temperature and derive some universal amplitude ratios which connect the broken and symmetric phases of the theory. The latter are found to be in good agreement with those of the three-dimensional Ising model obtained from high- and low-temperature series expansions.Comment: 14 pages of LaTeX. Postscript figures available upon request form [email protected]

    Recurrence interval analysis of high-frequency financial returns and its application to risk estimation

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    We investigate the probability distributions of the recurrence intervals τ\tau between consecutive 1-min returns above a positive threshold q>0q>0 or below a negative threshold q<0q<0 of two indices and 20 individual stocks in China's stock market. The distributions of recurrence intervals for positive and negative thresholds are symmetric, and display power-law tails tested by three goodness-of-fit measures including the Kolmogorov-Smirnov (KS) statistic, the weighted KS statistic and the Cram\'er-von Mises criterion. Both long-term and shot-term memory effects are observed in the recurrence intervals for positive and negative thresholds qq. We further apply the recurrence interval analysis to the risk estimation for the Chinese stock markets based on the probability Wq(Δt,t)W_q(\Delta{t},t), Value-at-Risk (VaR) analysis and VaR analysis conditioned on preceding recurrence intervals.Comment: 17 pages, 10 figures, 1 tabl

    Long-distance entanglement generation with scalable and robust two-dimensional quantum network

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    We present a protocol for generating entanglement over long distances in a two-dimensional quantum network based on the surface error-correction code. This protocol requires a fixed number of quantum memories at each node of the network and tolerates error rates of up to 1.67% in the quantum channels.Comment: 5 pags, 4 figs. V2: text corrected, discussion on channel losses added. Accepted by PR

    Vibrational state dependence of ionic rotational branching ratios in resonance enhanced multiphoton ionization of CH

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    We show that rapid evolution of a Rydberg orbital with internuclear distance in a resonance enhanced multiphoton ionization (REMPI) process can have a profound influence on the production of molecular ions in alternative rotational states. This is illustrated by calculations of ionic rotational branching ratios for (2+1′) REMPI via the O11 (20.5) branch of the E′ ^2Σ^+(3pσ) Rydberg state of CH. The rotational propensity rule for ionization changes from ΔN=odd (ΔN=N_+−N_i) at lower vibrational excitation, as expected from the ΔN+l=odd selection rule, to ΔN=even at higher vibrational levels. This effect is expected to be quite general and should be most readily observable in diatomic hydrides
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