A New Interpretation of MOND Based on Mach Principle and Generalized Equivalence Principle

A new interpretation is introduced for MOND based on the Sciama’s interpretation of Mach principle and an Unruh like effect, in the context of a generalized equivalence principle. It is argued that in a locally accelerated frame with acceleration a the appearance of a Rindler horizon may give rise to a constant acceleration a ₀ as the local properties of cosmological horizon or Hubble length. The total gravitational acceleration inside this frame becomes the combination of a with a ₀. For a≫a ₀, the conventional gravitational mass m _g interacts with the dominant acceleration as m _g a and application of Sciama’s interpretation leads to the standard Newtonian dynamics. For a≪a ₀, however, a reduced gravitational mass [`(m)]<sub>g</sub>\bar{m}_{g} interacts with the dominant acceleration as [`(m)]_ga₀\bar{m}_{g}a_{0} and the application of Sciama’s interpretation on this reduced gravitational mass leads to MOND. This introduces a third proposal for MOND: The modification of gravitational mass.     

The Matrix Algebras of Continuous Groups with Antilinear Operations

The corepresentation theory of continuous groups is presented without the assumption that the subgroup G of the group with antilinear operations is unitary. Continuous groups of the form: G+a ₀ G are defined, where G denotes a linear Lie group and a ₀ denotes an antilinear operation which fulfils the condition a²₀=±1a^{2}_{0}=\pm1. The matrix algebras connected with the groups G+a ₀ G are defined. The structural constants of these algebras fulfill the conditions following from the Jacobi identities. Applications are presented to the groups G=SU(d), d=1,2,… , for a ₀=K, the complex conjugation operation, and to the group SL(2,C) for a ₀=K or Θ, the time-reversal operation.     

Analogs in general relativity of Ferraro's law of isorotation

Two relativistic analogs of Ferraro's law of isorotation for a fluid with infinite electrical conductivity are given. In the first case it is assumed that the flow is shear-free withH ^a =0 and it is shown that £(H) ^a =0. In the second case it is assumed that there exists a space-like Killing vector field parallel toH _a , and it is proved that, _a H ^a =0.     

Wide binaries as a critical test of classical gravity

Modified gravity scenarios where a change of regime appears at acceleration scales a<a ₀ have been proposed. Since for 1M _⊙ systems the acceleration drops below a ₀ at scales of around 7000 AU, a statistical survey of wide binaries with relative velocities and separations reaching 10⁴ AU and beyond should prove useful to the above debate. We apply the proposed test to the best currently available data. Results show a constant upper limit to the relative velocities in wide binaries which is independent of separation for over three orders of magnitude, in analogy with galactic flat rotation curves in the same a<a ₀ acceleration regime. Our results are suggestive of a breakdown of Kepler’s third law beyond a≈a ₀ scales, in accordance with generic predictions of modified gravity theories designed not to require any dark matter at galactic scales and beyond.     

Z n-graded differential calculus

We investigate the properties of differential algebras generated by an operator d satisfying the property d ^N = 0 instead of d ² = 0 as in the usual case. The commutation relations for the generalized differentials ensuring the desired property can be put into the cyclic form a ₁ a ₂ a ₃...a _N = q a _N a ₁ a ₂...a _N–1, where q is a primitive N-th root of unity.Examples of realizations of such differential algebras are given, either in the space of Z _N-graded N × N matrix algebras, or as generalized differential calculus on manifolds. A generalization of gauge theories based on such differential calculus is briefly discussed.     

Emergence of order in nanocrystalline SmFe9

Three samples consistent with 1 : 12, 2 : 17 and 1 : 7 stoichiometry, ball-milled and subsequently annealed at temperature T_a between 600 and 1200°C were studied by Rietveld analysis, coupled to Curie temperature T_c measurements and Mössbauer spectroscopy. For all samples, at 600°CT_a<900°C, the detected out-of-equilibrium phase is the hexagonal P6/mmm structure derived from TbCu₇ with the composition SmFe₉. At T_a900°C the ordered phase of Th₂Zn₁₇-type is observed. With increasing T_a the unit cell parameter small variation of the parent SmFe₉ induces a decrease of T_c and H_hf. For T_a=600°C SmFe₉ is defined by a=0.4919 nm, c=0.4162 nm, T_c=207°C and H_hf=232 kOe. The resulting ordered Sm₂Fe₁₇ is characterized by nm, c=3×0.4147 nm, T_c=144°C and H_hf=219 kOe. For T_a=750°C the SmFe₉ T_c is 171°C associated to H_hf=222 kOe.     

Production of a0-mesons in the reactions πN↦a0N and pp↦da0 + at GeV energies

We investigate the reactions πN↦a ₀ N and pp↦da ₀ ⁺ near threshold and at medium energies. An effective Lagragian approach and the Regge pole model are applied to analyze different contributions to the cross-section of the reaction πN↦a ₀ N. These results are used to calculate the differential and total cross-sections of the reaction pp↦da ₀ ⁺ within the framework of the two-step model in which two nucleons produce an a₀-meson via π-meson exchange and fuse to a deuteron. The necessity of new measurements on a₀ production and branching fractions (of its decay to the K and πη channels) is emphasized for clarifying the a₀ structure. Detailed predictions for the reaction pp→da ₀ ⁺ are presented for the energy regime of the proton synchrotron COSY-Jülich. Received: 4 August 2000 / Accepted: 17 September 2000     

The temperature dependence of the spectral width of singlet oxygen dimole emission

In the temperature range of T = 150–400 K, the dependence of spectral widths (cm⁻¹) on temperature, 182 + 0.38(±0.01)T and 217 + 0.48(±0.01)T, respectively, has been obtained for dimole emission of O₂(a, 0) + O₂(a, 0) → O₂(X, 1) + O₂(X, 0) + hν (λ = 703 nm) and O₂(a, 0) + O₂(a, 0) → O₂(X, 0) + O₂(X, 0) + hν (λ = 634 nm). It was shown that the ratio of dimole emission rate constants does not depend on temperature in the range of 150–400 K and is 1.06 ± 0.01.     

交叉色关联噪声驱动的单模激光系统统计性质研究

采用交叉色关联的加性色噪声和乘性色噪声驱动的单模激光立方模型,通过诺维科夫理论和福克斯近似以及斯特拉托诺维奇近似,得到反映激光统计性质的强度关联函数C的表达式;研究关联时间τ、净增益系数a₀和交叉关联强度λ对强度关联函数C的影响.数值模拟发现,在阈值以上（a₀>0）时,关联函数C随关联时间τ的增大而增大;在阈值以下（a₀<0）时,关联函数C随关联时间τ的增大而减小.无论在阈值以上还是阈值以下,关联函数C均随交叉关联强度λ的增大而减小.在C-a₀曲线上存在单峰. 关键词： 单模激光 交叉关联 强度涨落 强度关联函数     

Mass spectral condition for leptons and quarks

Consideration is given to the mass spectral conditiona(a,_m)a =a _m, wherea is the annihilation operator forQ=–1 states in the Hilbert space of leptons and quarks anda _m is the commutator resolvent ofa with respect tom. It is observed that this spectral condition, which simply requires a to be a congruent automorph ofa _m , implies that the third-, fourth-, and fifth-generationQ=-1 leptons have the masses 1788.03 MeV, 42.1649 GeV, and 1.33422 TeV, respectively. With the assumption that the mass spectral condition also holds forQ=0 states in the Hilbert space, one obtains new theoretical upper and lower bounds on the neutrino masses.     

A possible assignment for the ground scalar meson nonet

Based on the main assumption that a₀(980) and D ^* _sJ(2317) belong to the 1³P₀ q¯ multiplet, in the framework of Regge phenomenology and meson-meson mixing, it is suggested that a₀(980), K ^* ₀(1052), f₀(1099) and f₀(530) constitute the ground scalar meson nonet, and that the f₀(1099) is composed mostly of s¯, while the f₀(530) is mainly a u¯ + d¯ system. It is supposed that these states would likely correspond to the observed scalar states a₀(980), κ(900), f₀(980) and f₀(600)/σ, respectively. The agreement between the present findings and those given by other different approaches is satisfactory.     

Near-threshold production of a0(980) mesons in πN and NN collisions and a0-f0 mixing

We consider near-threshold a ₀(980)-meson production in πN and NN collisions. An effective Lagrangian approach with one-pion exchange is applied to analyze different contributions to the cross section for different isospin channels. The Reggeon exchange mechanism is also evaluated for comparison. The results from πN reactions are used to calculate the contribution of the a ₀ meson to the cross sections and invariant mass distributions of the reactions and pp → ppK ⁺ K ⁻. It is found that the experimental observation of a ₀ ⁺ mesons in the reaction is much more promising than the observation of a ₀ ⁰ mesons in the reaction pp → ppK ⁺ K ⁻. Effects of isospin violation in the reactions pN → da ₀, pd → ³He(³H)a ₀, and dd → ⁴Hea ₀, which are induced by a ₀(980)-f ₀(980) mixing, are also analyzed. From Yadernaya Fizika, Vol. 66, No. 1, 2003, pp. 155–174. Original English Text Copyright ? 2003 by Kondratyuk, Bratkovskaya, Grishina, Büscher, Cassing, Str?her. This article was submitted by the authors in English.     

Production of a0 +-mesons in the reaction pp↦da0 +

We investigate the reaction pp↦da ₀ ⁺ at COSY and SIS energies together with accompanying background reactions and inclusive particle yields. The a ₀ ⁺ is considered as a usual u quark model state with two decay channels a ₀ ⁺↦K ⁺ and a ₀ ⁺↦π⁺η. Calculated cross-sections for a ₀ ⁺ production as well as for the corresponding non-resonant channels pp↦dK ⁺ and pp↦dπ⁺η are compared. Especially, in case of the final channel dπ⁺η, high statistics measurements are necessary to extract the a ₀ ⁺ signal from the high non-resonant background. Received: 20 December 2000 / Accepted: 7 May 2001     

Electron spin resonance study of oxygen-17 enriched N,N-dimethyl-4-nitroaniline radical anion

N,N-Dimethyl-d₆-4-nitroaniline enriched to approximately 11 atom. per cent in oxygen-17 has been prepared and the oxygen-17 isotropic hyperfine interaction in the corresponding radical anion has been examined. In dry dimethylformamide solution we find a _O = -8·85 ± 0·02 and a _N = 11·39 ± 0·10 gauss, while in moist acetonitrile solution a _O = -8·82 ± 0·07 and a _N = 12·23 ± 0·11 gauss. These results substantiate the recent suggestion that the isotropic oxygen-17 splittings in π-radicals may be described by a single parameter equation analogous to McConnell's relation for aromatic proton splittings, i.e. a _O = Q _OρO ^π, where Q _O = -41 ± 3 gauss.     

On kaonic hydrogen. Phenomenological quantum field theoretic model revisited

We argue that due to isospin and U-spin invariance of strong low-energy interactions the S-wave scattering lengths a ⁰ ₀ and a ¹ ₀ of ˉN scattering with isospin I = 0 and I = 1 satisfy the low-energy theorem a ⁰ ₀ +3a ¹ ₀ = 0 valid to leading order in chiral expansion. In the model of strong low-energy ˉN interactions at threshold (Eur. Phys. J. A 21, 11 (2004)) we revisit the contribution of the Σ(1750) resonance, which does not saturate the low-energy theorem a ⁰ ₀ +3a ¹ ₀ = 0, and replace it by the baryon background with properties of an SU(3) octet. We calculate the S-wave scattering amplitudes of K^-N and K^-d scattering at threshold. We calculate the energy level displacements of the ground states of kaonic hydrogen and deuterium. The result obtained for kaonic hydrogen agrees well with recent experimental data by the DEAR Collaboration. We analyse the cross-sections for elastic and inelastic K^-p scattering for laboratory momenta 70MeV/c < p _K < 150MeV/c of the incident K^--meson. The theoretical results agree with the available experimental data within two standard deviations.     

Hyperacceleration effects on turbulent combustion in premixed step-stabilized flames

Experimental results are presented from an investigation of the effects of large transverse accelerations on flame propagation and blowout limits in premixed step-stabilized flames. The accelerations, which exceed ±10,000 g in the present study, induce large body forces on the high-density reactants and low-density products. These body forces can substantially alter the flame propagation mechanisms and dramatically increase the flame blowout limits. Sustained centripetal accelerations a_c ≡ U²/R are created by flowing a premixed propane–air reactant stream with equivalence ratios 0.7  Φ  1.9 at various speeds U through a semicircular channel with radius R. A backward-facing step of height h on the radially outer (a_c > 0) or inner (a_c < 0) wall stabilizes the flame. For a_c > 0 the acceleration acts to force high-density reactants into the recirculation zone and low-density products into the reactant stream, while a_c < 0 forces hot products into the recirculation zone and impedes cold reactants from entering this zone. An otherwise identical straight channel provides corresponding baseline (a_c = 0) results for comparison. The flow speed U, equivalence ratio Φ, and step height h are systematically varied for a_c = 0, a_c > 0, and a_c < 0. Shadowgraph and chemiluminescence imaging show that as a_c→ +∞ the propagation of the flame across the channel becomes independent of the flame burning velocity and instead is primarily due to large-scale “centrifugal pumping” driven by the induced body forces. For a_c → −∞ the body forces effectively segregate reactants and products to produce a nearly flat flame. In both cases, for large |a_c| values the resulting blowout limits can be substantially higher than those at a_c = 0.     

The rate constants of singlet oxygen collision-induced emission at 634 and 703 nm wavelengths

Absolute spectral luminosity from an O₂–O₂(a)-H₂O gas flow formed by a chemical singlet oxygen generator was measured at 600–800 and 1230–1310 nm wavelengths. The results were used to determine the rate constants for O₂(a, 0) + O₂(a, 0) → O₂(X, 0) + O₂(X, 0) + hν (λ = 634 nm) and O₂(a, 0) + O₂(a, 0) → O₂(X, 1) + O₂(X, 0) + hν (λ = 703 nm) collision-induced emission ((6.72 ± 0.8) × 10⁻²³ and (7.17 ± 0.8) × 10⁻²³ cm³/s, respectively).     

Running coupling: does the coupling between dark energy and dark matter change sign during the cosmological evolution?

In this paper we put forward a running coupling scenario for describing the interaction between dark energy and dark matter. The dark sector interaction in our scenario is free of the assumption that the interaction term Q is proportional to the Hubble expansion rate and the energy densities of dark sectors. We only use a time-variable coupling b(a) (with a the scale factor of the universe) to characterize the interaction Q. We propose a parametrization form for the running coupling b(a)=b ₀ a+b _e (1−a) in which the early-time coupling is given by a constant b _e , while today the coupling is given by another constant, b ₀. For investigating the feature of the running coupling, we employ three dark energy models, namely, the cosmological constant model (w=−1), the constant w model (w=w ₀), and the time-dependent w model (w(a)=w ₀+w ₁(1−a)). We constrain the models with the current observational data, including the type Ia supernova, the baryon acoustic oscillation, the cosmic microwave background, the Hubble expansion rate, and the X-ray gas mass fraction data. The fitting results indicate that a time-varying vacuum scenario is favored, in which the coupling b(z) crosses the noninteracting line (b=0) during the cosmological evolution and the sign changes from negative to positive. The crossing of the noninteracting line happens at around z=0.2–0.3, and the crossing behavior is favored at about 1σ confidence level. Our work implies that we should pay more attention to the time-varying vacuum model and seriously consider the phenomenological construction of a sign-changeable or oscillatory interaction between dark sectors.     

A particle model for spinodal decomposition

We study a one-dimensional lattice gas where particles jump stochastically obeying an exclusion rule and having a small drift toward regions of higher concentration. We prove convergence in the continuum limit to a nonlinear parabolic equation whenever the initial density profile satisfies suitable conditions which depend on the strengtha of the drift. There is a critical valuea _c ofa. Fora<a _c, the density values are unrestricted, while foraa _c, they should all be to the right or to the left of a given interval (a). The diffusion coefficient of the limiting equation can be continued analytically to (a), and, in the interior of (a), it has negative values which should correspond to particle aggregation phenomena. We also show that the dynamics can be obtained as a limit of a Kawasaki evolution associated to a Kac potential. The coefficienta plays the role of the inverse temperature. The critical value ofa coincides with the critical inverse temperature in the van der Waals limit and (a) with the spinodal region. It is finally seen that in a scaling intermediate between the microscopic and the hydrodynamic, the system evolves according to an integrodifferential equation. The instanton solutions of this equation, as studied by Dal Passo and De Mottoni, are then related to the phase transition region in the thermodynamic phase diagram; analogies with the Cahn-Hilliard equations are also discussed.This paper is dedicated to Jerry Percus with great affection on the occasion of his 65th birthday.     

Nontrivial extensions of a massless representation with definite helicity of the Poincaré group in 3+1 dimensions by the tensor product of two other massless representations with definite helicity

Let U _n (a, ) be a massless, helicity n/2, representation of the Poincaré group in 3+1 dimensions. U _n (a, ) is realized in an adapted nuclear space D _n. We explicitly determine the various classes of cohomology for the extension of U _n (a, ) by U _n1 (a, ) U _n2 (a, ).