Triangle Diagram with Off-Shell Coulomb T-Matrix for (In-)Elastic Atomic and Nuclear Three-Body Processes

The driving terms in three-body theories of elastic and inelastic scattering of a charged particle off a bound state of two other charged particles contain the fully off-shell two-body Coulomb T-matrix describing the intermediate-state Coulomb scattering of the projectile with each of the charged target particles. Up to now the latter is usually replaced by the Coulomb potential, either when using the multiple-scattering approach or when solving three-body integral equations. General properties of the exact and the approximate on-shell driving terms are discussed, and the accuracy of this approximation is investigated numerically, both for atomic and nuclear processes including bound-state excitation, for energies below and above the corresponding three-body dissociation threshold, over the whole range of scattering angles.Comment: 22 pages, 11 figures, figures can be obtained upon request from the Authors, revte

Gluon confinement criterion in QCD

We fix exactly and uniquely the infrared structure of the full gluon propagator in QCD, not solving explicitly the corresponding dynamical equation of motion. By construction, this structure is an infinite sum over all possible severe (i.e., more singular than $1/q^2$) infrared singularities. It reflects the zero momentum modes enhancement effect in the true QCD vacuum, which is due to the self-interaction of massless gluons. It existence automatically exhibits a characteristic mass (the so-called mass gap). It is responsible for the scale of nonperturbative dynamics in the true QCD ground state. The theory of distributions, complemented by the dimensional regularization method, allows one to put the severe infrared singularities under the firm mathematical control. By an infrared renormalization of a mass gap only, the infrared structure of the full gluon propagator is exactly reduced to the simplest severe infrared singularity, the famous $(q^2)^{-2}$. Thus we have exactly established the interaction between quarks (concerning its pure gluon (i.e., nonlinear) contribution) up to its unimportant perturbative part. This also makes it possible for the first time to formulate the gluon confinement criterion and intrinsically nonperturbative phase in QCD in a manifestly gauge-invariant ways.Comment: 10 pages, no figures, no tables. Typos corrected and the clarification is intoduced. Shorten version to appear in Phys. Lett.

Thermodynamic analysis of the thermal and exergetic performance of a mixed gas-steam aero derivative gas turbine engine for power generation

A thermodynamic analysis is performed for an aero derivative gas turbine engine which utilizes steam injection to increase its efficiency. The target was to explore the performance of a high efficiency gas turbine unit for electric power generation without downstream Rankine cycle. A Rankine cycle for exhaust heat recovery is unattractive because of its large response time and cost of investment. The main purpose of this research was to develop a better understanding of how the optimal cycle efficiency is reached, when the steam for injection is generated by use of the turbine exhaust heat. The STIG cycle becomes attractive for grid stabilization because of its low CAPEX and small footprint and response time. A thermodynamic model has been developed to simulate the simple cycle gas turbine, steam generation and effects of steam injection. Reference input parameters for the model are taken for the GE LM6000 turbine as publicly available. The performance of the engine without steam injection as predicted by the model is compared with literature for validation and compares well. The performance of the STIG cycle as a function of operation parameter steam mass flow and design parameters pressure ratio and turbine inlet temperature is investigated and the optimal parameter settings determined. It is found that this type of cycle shows a very specific parameter setting for optimal efficiency. By using steam injection for the chosen turbine and its parameters an efficiency gain of around 11% points and an output power augmentation of 45% can be achieved.</p

Conditional linear-optical measurement schemes generate effective photon nonlinearities

We provide a general approach for the analysis of optical state evolution under conditional measurement schemes, and identify the necessary and sufficient conditions for such schemes to simulate unitary evolution on the freely propagating modes. If such unitary evolution holds, an effective photon nonlinearity can be identified. Our analysis extends to conditional measurement schemes more general than those based solely on linear optics.Comment: 16 pages, 2 figure

Detection of water absorption in the day side atmosphere of HD 189733 b using ground-based high-resolution spectroscopy at 3.2 microns

We report a 4.8 sigma detection of water absorption features in the day side spectrum of the hot Jupiter HD 189733 b. We used high-resolution (R~100,000) spectra taken at 3.2 microns with CRIRES on the VLT to trace the radial-velocity shift of the water features in the planet's day side atmosphere during 5 h of its 2.2 d orbit as it approached secondary eclipse. Despite considerable telluric contamination in this wavelength regime, we detect the signal within our uncertainties at the expected combination of systemic velocity (Vsys=-3 +5-6 km/s) and planet orbital velocity (Kp=154 +14-10 km/s), and determine a H2O line contrast ratio of (1.3+/-0.2)x10^-3 with respect to the stellar continuum. We find no evidence of significant absorption or emission from other carbon-bearing molecules, such as methane, although we do note a marginal increase in the significance of our detection to 5.1 sigma with the inclusion of carbon dioxide in our template spectrum. This result demonstrates that ground-based, high-resolution spectroscopy is suited to finding not just simple molecules like CO, but also to more complex molecules like H2O even in highly telluric contaminated regions of the Earth's transmission spectrum. It is a powerful tool that can be used for conducting an immediate census of the carbon- and oxygen-bearing molecules in the atmospheres of giant planets, and will potentially allow the formation and migration history of these planets to be constrained by the measurement of their atmospheric C/O ratios.Comment: 5 pages, 4 figures, accepted for publication in MNRAS Letter

Electrochemical behaviour of cytochrome c at low potentials

d.c. polarograms of bovine heart cytochrome c show reduction currents at low potentials. This is observed in buffer solutions with pH values between 1 and 10.5. These currents are attributed to catalytic hydrogen formation (pre-sodium currents). After succinylation of the protein, the current in glycine-NaOH buffer of pH 10.5 disappears almost completely, whereas that in acetate buffer of pH 4.5 is affected only slightly. It is concluded that different groups are responsible for the currents observed in these two buffer