Two theorems on flat space-time gravitational theories

The first theorem states that all flat space-time gravitational theories must have a Lagrangian with a first term that is an homogeneous (degree-1) function of the 4-velocityu ⁱ , plus a functional of _ij u ⁱ u ^j . The second theorem states that all gravitational theories, that satisfy the strong equivalence principle have a Lagrangian with a first termg _ij (x)u ⁱ u ^j plus an irrelevant term. In both cases the theories must issue from a unique variational principle. Therefore, under this condition it is impossible to find a flat space-time theory that satisfies the strong equivalence principle.     

Beta decay of <Superscript>115</Superscript>In to the first excited level of <Superscript>115</Superscript>Sn: Potential outcome for neutrino mass

Recent observation of β decay of ¹¹⁵In to the first excited level of ¹¹⁵Sn with an extremely low Q _β value (Q _β ≤ O(1) [keV]) could be used to set a limit on neutrino mass. To give a restriction potentially competitive with those extracted from experiments with ³H (≃2 eV) and ¹⁸⁷Re (≃15 eV), the atomic mass difference between ¹¹⁵In and ¹¹⁵Sn and energy of the first ¹¹⁵Sn level should be remeasured with higher accuracy (possibly of the order of ∼1 eV). The text was submitted by the authors in English.     

Differential evaluation of the Hall effect in silicon with oxygen-related donors

Three kinds of samples were used to form Co suicides by thermal annealing: firstly, a Co film of about 370 Å thick, evaporated on a (100) single crystal Si (Si ^c /Co); secondly, an evaporated boron-containing Si (Si ^e (B)) layer on the top of the first sample (Si ^c /Co/Si ^e (B)). The last sample is in the Co film of the first sample we deposited a Si^e(B) layer (Si ^c /Co/Si ^e (B)/Co). A laterally uniform CoSi₂ layer can be formed from the second and the third samples by annealing at 450 °C. In the first sample, the CoSi₂ can be formed only at temperatures above 500 °C and the disilicide is laterally less uniform than in the second and third samples. The Schottky barrier heights of the three samples derived from the forward and reverse I–V characteristics show that the barrier height is 0.01–0.02eV higher in the uniform case than in the nonuniform case.     

Hydration characteristics of Ca2+ and Mg2+: a density functional theory,polarized continuum model and molecular dynamics investigation

In this work, density functional theory, Møller–Plesset second-order perturbation theory, and ab initio molecular dynamics (AIMD) were used to investigate hydrated characteristics of Mg²⁺ and Ca²⁺ as a function of coordination number in the first hydration shell (CN) and cluster size. It is generally accepted that the CNs of Mg²⁺ and Ca²⁺ are both six. Calculations show that the hydration of Mg²⁺ generally prefers six-coordinated structures, whereas the CN value of Ca²⁺ varies from 6 to 8 as the hydration proceeds. Moreover, the first hydration of Ca²⁺ is found to be more flexible than that of Mg²⁺, as indicated by the results of transition state calculations and AIMD simulations. In addition, the constraint of Mg²⁺ on the first hydration shell is obviously stronger than that of Ca²⁺, while the constraint on the inner hydration shells fades slightly faster for Mg²⁺ than Ca²⁺. It is also found that the charge transfer from central cation to water molecules is affected only by the first hydration shell for Mg²⁺, whereas by the first and second hydration shells for Ca²⁺. Based on hydration characteristics, approximatively saturated ion hydration shells for the hydration of Mg²⁺ and Ca²⁺ were proposed.     

Application of Huang-Yang pseudopotential to a few-body system

Huang and Yang replace a hard core of radius c by their pseudopotential (HYPP), which can be used in perturbation theory. I show that HYPP and boundary value perturbation theory give the same energy shift, to first order in c. I model a two-body potential as an oscillator potential (angular frequency ω) and a hard core. For an A-body system, the ratio of the first order energy correction to the unperturbed energy is 0.448 A^3/4 c a, where a = (M ω/2h)^1/2.     

Spectroscopic and structural proprieties of LiAr and LiAr<Subscript>2</Subscript> molecules

We determined and tried to understand the spectroscopic and structural properties of small LiAr and LiAr₂ molecules within a simple model considering LiAr as a result of interaction between a valence electron and a LiAr⁺ molecular ion. Potential energy curves, spectroscopic constants, and vibrational levels corresponding to the Li(2s, 2p, 3s, and 3p)+Ar dissociation are reported for the LiAr molecule. The depth of the potential well for the X ²Σ⁺ ground state is found to be 50 cm⁻¹ (the corresponding experimental value is (42.5±1.2) cm⁻1 [1]). R _e is determined to be 9.36 a.u. (the experimental value is 9.24 a.u.). For the first excited state A, R _e = 4.97 a.u. and D _e = 993cm ⁻¹ (the corresponding experimental values are 4.68 a.u. and (925−40) cm⁻¹, respectively [1]). The spacing between the vibrational levels for the ground and first excited states is in very good agreement with the experiment. For the ground state, the difference between our results and the data of the most recent experiment is about 1 cm⁻¹. The model has been extended to study the LiAr₂ molecule in two forms (linear and triangular). We have determined the potential energy surfaces of the states dissociating to Li(2s, 2p)+Ar₂ and thus found the triangular form to be more stable as compared to the linear one. We have also calculated the transition energy between the ground state and first excited states of this molecule. The emission spectrum of the Li(2s)+Ar₂→Li(2p)+Ar₂ transition in both forms redshifts as compared to the Li(2s)→Li(2p) atomic transition.     

Spectroscopic investigations on NO+(x1∑+,a3∑+,A1Ⅱ) ion using multi-reference configuration interaction method and correlation-consistent sextuple b

Three low-lying electronic states (x¹∑⁺,a³∑⁺,and A¹Ⅱ) of NO⁺ ion are studied using the complete active space self-consistent-field (CASSCF) method followed by highly accurate valence internally contracted multi-reference configuration interaction (MRCI) approach in combination of the correlation-consistent sextuple basis set augmented with diffuse functions, aug-cc-pV6Z. The potential energy curves (PECs) of the NO⁺(x¹∑⁺,a³∑⁺,A¹Ⅱ) are calculated. Based on the PECs, the spectroscopic parameters R_e, D_e, ω_e, ω_eχ_e, α _e, B_e, and D₀ are reproduced, which are in excellent agreement with the available measurements. By numerically solving the radial Schrödinger equation of nuclear motion using the Numerov method, the first 20 vibrational levels, inertial rotation and centrifugal distortion constants of NO⁺(x¹∑⁺,a³∑⁺,A¹Ⅱ) ion are derived when the rotational quantum number J is equal to zero (J = 0) for the first time, which accord well with the available measurements. Finally, the analytical potential energy functions of these states are fitted, which are used to accurately derive the first 20 classical turning points when J = 0. These results are compared in detail with those of previous investigations reported in the literature.     

Associated production of sfermions and gauginos at high-energy ee colliders: The case of selectrons and electronic sneutrinos

We analyze the associated production at future high-energy e ⁺ e ^- colliders, of first generation sleptons with neutralinos and charginos in the modes e ⁺ e ^- and , in the framework of the minimal supersymmetric extension of the standard model. We show that the production rates, in particular for associated production of right-handed selectrons and the lightest neutralino which in general is the first accessible kinematically, can be much larger than the corresponding ones for second and third generation scalar leptons and for scalar quarks. With the high luminosities expected at these colliders, the detection of first generation sleptons with masses significantly above the kinematical two-body threshold, , is thus possible in favorable regions of the parameter space. Received: 27 June 2002 / Published online: 20 September 2002     

The Entropy Production of Diffusion Processes on Manifolds and Its Circulation Decompositions

In non-equilibrium statistical mechanics, the entropy production is used to describe flowing in or pumping out of the entropy of a time-dependent system. Even if a system is in a steady state (invariant in time), Prigogine suggested that there should be a positive entropy production if it is open. In 1979, the first author of this paper and Qian Min-Ping discovered that the entropy production describes the irreversibility of stationary Markov chains, and proved the circulation decomposition formula of the entropy production. They also obtained the entropy production formula for drifted Brownian motions on Euclidean space R ⁿ (see a report without proof in the Proc. 1st World Congr. Bernoulli Soc.). By the topological triviality of R ⁿ , there is no discrete circulation associated to the diffusion processes on $R^n$. In this paper, the entropy production formula for stationary drifted Brownian motions on a compact Riemannian manifold M is proved. Furthermore, the entropy production is decomposed into two parts – in addition to the first part analogous to that of a diffusion process on R ⁿ , some discrete circulations intrinsic to the topology of M appear! The first part is called the hidden circulation and is then explained as the circulation of a lifted process on M×S ¹ around the circle S ¹. The main result of this paper is the circulation decomposition formula which states that the entropy production of a stationary drifted Brownian motion on M is a linear sum of its circulations around the generators of the fundamental group of M and the hidden circulation. Received: 4 November 1998 / Accepted: 7 April 1999     

The 2000 Å absorption system of the benzene single crystal in polarized light

The 2000 Å absorption system in the benzene single crystal is investigated at liquid nitrogen temperature. The analysis of the polarized spectra recorded along b and c in (100) plates appears to be not in favour of the assignment of the π* └π system to an upper state of B _1u symmetry, and it is not in contrast with the hypothesis of a ¹ E _2g upper state.

The first band in the system, located at 46 565 cm^-1, and totally polarized along c, is discussed in terms either of an out-of-plane false origin of the ¹ E _2g └¹ A _1g system, or of a new transition lying between the first two well known π-systems of benzene, possibly of π* └σ type.     

钐原子的两步激发共振光电离光谱

采用两步激发共振光电离技术研究了Sm原子的偶宇称高激发态光谱.实验采用了两条激发路线：1)第一束激光的波长固定在478.44nm以便将Sm原子从4f⁶6s²［⁷F₁］态激发至4f⁶6s6p［⁷D₁］态,再用第二束激光使其波长从480nm扫描至530nm,将Sm原子进一步激发至待测的高激发态;2)第一束激光的波长固定在574.8 关键词： Sm原子 光谱 分步激发 共振电离     

Production of delta isobars on tantalum nuclei in CTa collisions at a projectile momentum of 4.2 GeV/<Emphasis Type="Italic">c</Emphasis> per nucleon

A procedure that relies on analyzing the angle between the momenta of the proton and the pion originating from CTa interaction at a projectile momentum of 4.2 GeV/c per nucleon was used to investigate for the first time the production of Δ⁰ and Δ⁺⁺ resonances in such interactions and to determine their parameters. The criterion of stability in the parameter a characterizing the background contribution was presented for the first time and was used to reconstruct the mass distributions of Δ⁰ and Δ⁺⁺ resonances. The contributions of Δ⁰- and Δ⁺⁺-resonance decays to the production of charged pions were estimated. The results of this study are compared with similar data obtained by using the analogous procedure for Δ⁰ and Δ⁺⁺ resonances produced on carbon nuclei in CC and ⁴HeC collisions at a projectile momentum of 4.2 GeV/c per nucleon and in π ⁻¹²C interactions at a projectile momentum of 40 GeV/c.     

Measurement of π0 and η mesons with PHENIX in ?[`(sNN )]\surd \overline {s_{NN} } 200 GeV Au+Au collisions at RHIC

The π ^o meson has been a crucial probe for observing jet quenching in ultrarelativistic heavy-ion collisions at RHIC. Measurements of the η meson in the same collisions have also shed light on a possible dependence of the observed suppression on the particle species. The preliminary π ⁰ nuclear modification factor R _AA from the 2004 RHIC run allowed a first systematic comparison between a precise measurement with high statistics and theoretical calculations, constraining model parameters such as the initial gluon density dN^g/dy, and the transport coefficient [^(q)]\hat q. The final π ⁰ spectra and R _AA are shown as well as the first η results obtained with both PHENIX electromagnetic calorimeters.     

Physics with heavy neutron-rich RIBs at the HRIBF

The Holifield Radioactive Ion Beam Facility at Oak Ridge National Laboratory has recently produced the world's first post-accelerated beams of heavy neutron-rich nuclei. The first experiments with these beam are described, and the results discussed. B(E2;0⁺ → 2⁺) values for neutron-rich ^126,128Sn and ^132,134,136Te isotopes have been measured by Coulomb excitation in inverse kinematics. The results for ¹³²Te and ¹³⁴Te (N = 80, 82) show excellent agreement with systematics of lighter Te isotopes, but the B(E2) value for ¹³⁶Te (N = 84) is unexpectedly small. Single-neutron transfer reactions with a ¹³⁴Te beam on ^natBe and ¹³C targets at energies just above the Coulomb barrier have also been studied. Received: 21 March 2002 / Accepted: 16 May 2002 / Published online: 31 October 2002 RID="a" ID="a"e-mail: radford@mail.phy.ornl.gov     

Photoionization of Al IV (neon-type) from its ground 2s 22p 6 1 S e and excited 2s 22p 53p 3,1 P 0 3 S e states using the R-matrix method

The R-matrix method is used to calculate the total photoionization cross-sections from the ground 2s ²2p ^{6 1} S ^e and the first three excited 2s ²2p ⁵3p ^3,1 S ^e states of Al IV, for photon energies ranging from the first ionization threshold to just above the second threshold of the residual ion Al V. The two lowest LS terms of Al V − 2s ²2p ^{5 2} P ⁰, 2s2p ^{6 2} S ^e, 2s2p ^{6 2} S ^e, represented by sophisticated configuration interaction wavefunctions, are included in the R-matrix calculation. The resulting cross-sections are affected by Rydberg series of resonances converging to the 2s2p ^{6 2} S ^e excited threshold.     

The gravitational field in the wave zone I. The radiating terms of the metric tensor

We consider an asymptotically flat space-time generated by a perfect fluid source of compact spatial support. Using the de Donder gauge conditions, the Einstein equations are reduced to a new form of Poisson-type equations. A formal iterative scheme is set up to solve these equations by expanding the components of the metric tensor in powers ofc ^–1. The coefficient of each power ofc ^–1 depends on the asymptotically retarded timeu andx, y, z and satisfies a Poisson-type equation. Assuming asymptotic flatness the solution is carried out in the first orders. The results are explicit expressions of the metric up to orderc ^–4 in terms of the source functions. These expressions hold over all space-time. A further expansion in powers ofr ^–1 gives the first terms of the metric that contribute to gravitational radiation.     

The importance of gravitational self-field effects in binary systems with compact objects. I. The “static two-body problem” and the attraction law in a post-Newtonian approximation of general relativity

As a first step toward a proper treatment of compact objects in binary systems the attraction force of two massive bodies connected by a rod is calculated in a post-Newtonian expansion. Contrary to a calculation by Weyl und Bach we start without specializing the internal structure of the bodies. We consider general anisotropic pressures and do not require axial symmetry for the bodies. We calculate the attraction force first in a post-Newtonian approximation and then (in paper II) we shall be concerned with the post-post-Newtonian approximation. In both approximations we obtain Newton's attraction forceM _S1 M _S2/R ² plus terms of order 1/R ³ and higher, whereM _S1,M _S2 are the Schwarzschild masses of the bodies.     

First direct measurement of the total cross-section of 12C(α,γ)16O

The total cross-section of ¹²C(α,γ)¹⁶O was measured for the first time by a direct and ungated detection of the ¹⁶O recoils. This measurement in inverse kinematics using the recoil mass separator ERNA in combination with a windowless He gas target allowed to collect data with high precision in the energy range E = 1.9 to 4.9 MeV. The data represent new information for the determination of the astrophysical S(E) factor.     

Accurate ab initio study of low-lying electronic states of phosphorus nitride radical

This paper employs the highly accurate valence internally contracted multireference configuration interaction method to investigate the potential energy curves (PECs) for the ground state (X 1 Σ +) and two low-lying excited states (A 1 Π and D 1 of phosphorus nitride (PN) radical with the correlation-consistent basis set,aug-cc-pV6Z,in the valence range.Relativistic effects are considered in these calculations.The spectroscopic constants of the X 1 Σ + and A 1 Π states are calculated based on the PECs,and the results are in good accord with the available experimental data.The first 30 vibrational states for the X 1 Σ + state and the first 40 vibrational states for theA 1 Π state are determined when J=0.For each vibrational state,molecular constants G(υ),B(υ) and D(υ) are also attained.