Is the weak interaction constant really constant?

A comparison is made of the probability of the process of two-neutrino double beta decay for ⁸²Se and ⁹⁶Zr in direct (counter) and geochemical experiments. The experimental data for ¹³⁰Te are also analyzed. It is shown that the probability is systematically lower in geochemical experiments, which characterize the probability of (2) decay 10⁹ y ago. It is proposed that this could be due to a change in the weak interaction constant with time. It is proposed that a series of new, precise measurements be performed with the aid of counters and geochemical experiments.     

Thermoelastic constant or thermoelastic parameter?

Recently, some evidence has been reported in the literature which indicates that the thermoelastic ‘constant’ of a material is significantly dependent on the mean stress applied. This paper presents the theory which supports the possibility of such a phenomenon. It is shown that the stress dependence of the thermoelastic constant can be explained by the temperature dependence of the elastic properties of the material. Excellent agreement between the theoretical predictions and experimental data is achieved.     

Cosmologies with variable Newton's “constant”

We discuss cosmologies where the Planck length is not a fundamental constant but rather evolves with time. The dynamics which should be responsible for today's tiny value of this length scale are governed by the effective potential of a Brans-Dicke type theory. Qualitative properties of this potential depend on the short distance behaviour of the unifying fundamental theory. We discuss criteria for the asymptotic behaviour of realistic cosmologies and show that the role of a possible cosmological constant is quite different from the case of standard cosmology.     

The Cosmological constant and the coincidence problem in a new cosmological interpretation of the universal constant “c”

In a recent paper (Vigoureux et al. in Int. J. Theor. Phys. 47:928, 2007) it has been suggested that the velocity of light and the expansion of the universe are two aspects of one single concept connecting space and time in the expanding universe. It has then be shown that solving Friedmann’s equations with that interpretation (and keeping c=constant) can explain number of unnatural features of the standard cosmology (for example: the flatness problem, the problem of the observed uniformity in term of temperature and density of the cosmological background radiation, the small-scale inhomogeneity problem…) and leads to reconsider the Hubble diagram of distance moduli and redshifts as obtained from recent observations of type Ia supernovae without having to need an accelerating universe. In the present work we examine the problem of the cosmological constant. We show that our model can exactly generate Λ (equation of state P _φ =−ρ _φ c ² with Λ∝ R ⁻²) contrarily to the standard model which cannot generate it exactly. We also show how it can solve the so-called cosmic coincidence problem.     

A broad-band constant beam-width array with four elements

This paper describes in detail an acoustical array structure with fourelements that have cosine directivity function over a certain frequency range.The acoustical axis directions of these elements are orthogonal to each other,sotheir beams cover all bearing angles within 360°.By use of the amplitude bear-ing method,it is easy to detect the bearing of incident acoustic signal.A specialsound reflection foam rubber is designed as a back baffle of the array.It hasbeen shown,in practice,that the constant beam-width has been obtained for amultiple frequency band of the ratio of 8:1.The paper also gives a mathematicalmodel for the array structure.The theoretical values are consistent with themeasured results.     

Large-scale–small-scale duality and the cosmological constant

We study a model of quantum cosmology originating from a classical model of gravitation where a self-interacting scalar field is coupled to gravity with the metric undergoing a signature transition. We show that there are dual classical signature changing solutions, one at large scales and the other at small scales. It is possible to fine-tune the physics in both scales with an infinitesimal effective cosmological constant.     

Fine structure constant variation or spacetime anisotropy?

The European Physical Journal C - We try to understand the recently observed anomalous behavior of the photon-to-pion transition form factor in the holographic QCD approach. First the holographic...     

Time evolution of the cosmological “constant”

We discuss cosmologies where the cosmological constant λ depends on time. The requirements of realistic cosmology impose restrictions on the functional dependence of λ on the Hubble parameter H. We show that for a wide class of functions with λ of the order H³ the system of field equations leads to a stable fix-point behaviour with λ naturally very small today. The age of the universe, critical matter density and deceleration parameter may be modified.     

Fine structure constant variation or spacetime anisotropy?

Recent observations on the quasar absorption spectra supply evidence for the variation of the fine structure constant α. In this paper, we propose another interpretation of the observational data on the quasar absorption spectra: a scenario with spacetime inhomogeneity and anisotropy. Maybe the spacetime is characterized by the Finsler geometry instead of the Riemann one. The Finsler geometry admits fewer symmetries than the Riemann geometry does. We investigate the Finslerian geodesic equations in the Randers spacetime (a special Finsler spacetime). It is found that the cosmological redshift in this spacetime deviates from the one in general relativity. The modification term to the redshift could be generally revealed as a monopole plus dipole function of spacetime locations and directions. We suggest that this modification corresponds to the spatial monopole and dipole of α variation in the quasar absorption spectra.     

A weighting orthogonal method for constant beamwidth beamforming matrices

A weighting orthogonal method for constant beamwidth beamforming matrices is proposed. This method multiplies weighting factors to each orthogonal beamforming matrix corresponding to different frequency bins. The method proposed doesn't cause waveform aberration, and doesn't cause additional loss of array signal-to-noise ratio when the sources have uniform spectrum. The waveform aberration and additional loss of array signal-to-noise ratio can not be avoided simultaneously by ordinary orthogonal method. So we can get good detection and estimation performances at the same time by the weightmg method. Simulation results and water tank experiments are presented to confirm the conclusion above.     

The coupling constant averaged exchange–correlation energy density

ABSTRACT

The exchange–correlation energy, central to density-functional theory, may be represented in terms of the coupling constant averaged (CCA) exchange–correlation energy density. We present an approach to calculate the CCA energy density using accurate ab initio methods and its application to simple atomic systems. This function provides a link between intrinsically non-local, many-body electronic structure methods and simple local and semi-local density-functional approximations (DFAs). The CCA energy density is resolved into separate exchange and correlation terms and the features of each compared with those of quantities commonly used to construct DFAs. In particular, the more complex structure of the correlation energy density is found to exhibit features that align well with those present in the Laplacian of the density, suggesting its role as a key variable to be used in the construction of improved semi-local correlation functionals. The accurate results presented in this work are also compared with those provided by the Laplacian-dependent Becke–Roussel model for the exchange energy.     

Effects of cosmological constant on motion of UHECR particles

Recent astronomical observations manifest that about two-thirds of the whole energy in the Universe is contributed by a small positive cosmological constant A (> 0). Then, an asymptotically de Sitter spacetime is premised naturally. However, physics in the de Sitter spacetime is very different from that in the Minkowski spacetime. As the first step, a covariant formalism of the kinematics in the de Sitter spacetime is presented here. By solving exactly the equations of motion for a field, we obtain the dispersion relation of a free particle. It is noticed that the dispersion relation is dependent on the degree of freedom of angular momentum of the particle. We show the threshold anomaly of the ultra high energy cosmic ray disappears naturally in the framework of the de Sitter kinematics.     

Small cosmological constant from the QCD trace anomaly?

According to recent astrophysical observations the large scale mean pressure of our present Universe is negative suggesting a positive cosmological constant-like term. The issue of whether nonperturbative effects of self-interacting quantum fields in curved space-times may yield a significant contribution is addressed. Focusing on the trace anomaly of quantum chromodynamics, a preliminary estimate of the expected order of magnitude yields a remarkable coincidence with the empirical data, indicating the potential relevance of this effect.     

Hyperfine coupling constant in manganese-doped Cd1−xZnxTe

An E.P.R. study was made on Mn-doped Cd_1−xZn_xTe using an X-band spectrometer. Hyperfine coupling constant of the material was measured both at ambient and liquid nitrogen temperature. The results obtained were correlated to the ionicity of the constituent compounds. A comparison of the present results is also made with a theoretical model proposed by Huang.     

QCD sum rule analysis of the coupling constant g ωσγ

We employ QCD sum rules to calculate the coupling constant g by studying the three point -correlation function. Our result complements the analysis of this coupling constant utilizing the experimental value of the ⁰⁰ decay rate studied within the framework of chiral perturbation theory including vector meson and meson intermediate states.     

ζ-Regularized Lagrangians for massive quarks in constant background mean-fields

Hawking's ζ-function regularization method is used in order to obtain the effective QCD Lagrangian for ordinary quarks moving in some constant background field. The general context is Adler's mean-field approximation to QCD, and an extension of his results is obtained for three particular models. Namely, at one loop order, massive quarks in a constant self-dual, pure colormagnetic, or pure colorelectric field are confined, and this is true for any number of quark flavors. Also, a criterion is established in order to calculate the values and signs of the imaginary parts for E- and B-fields. The final results for these imaginary parts are in agreement with those of Nielsen and Olesen and of Yildiz and Cox.     

Beamforming for broadband constant beamwidth based on FIR and DSP

1IntroductionInbroadbandsighalprocessing,thespectralcharacteristicsofthetargetechoareusedmostlyintargetdetectionandtargetclassification.Toguaranteetheaccuracysitisrequiredthatthedifferentfrequencyelementsofthetransmittingbroadbandsignalincidentonthetargetevenlyaswellasthebroadbandechosignalundistortedbereceived.AtthispointthebeamformershouldbeaBroadb.a.ndConstantBeamwidthone(BCBB),soitisnecessarytostudyanddesignBCBBs.Conventionally,broadbandbeamformerscanbeclassifiedtotwotypes.Oneisimplem…     

Is the electron radiation length constant at high energies?

Experimental results for the radiative energy loss of 149, 207, and 287 GeV electrons in a thin Ir target are presented. From the data we conclude that at high energies the radiation length increases in accordance with the Landau-Pomeranchuk-Migdal (LPM) theory and thus electrons become more penetrating the higher the energy. The increase of the radiation length as a result of the LPM effect has a significant impact on the behavior of high-energy electromagnetic showers.     

Cosmic strings in a space–time with positive cosmological constant

We study Abelian strings in a fixed de Sitter background. We find that the gauge and Higgs fields extend smoothly across the cosmological horizon and that the string solutions have oscillating scalar fields outside the cosmological horizon for all currently accepted values of the cosmological constant. If the gauge to Higgs boson mass ratio is small enough, the gauge field function has a power-like behaviour, while it is oscillating outside the cosmological horizon if Higgs and gauge boson mass are comparable. Moreover, we observe that Abelian strings exist only up to a maximal value of the cosmological constant and that two branches of solutions exist that meet at this maximal value. We also construct radially excited solutions that only exist for non-vanishing values of the cosmological constant and are thus a novel feature as compared to flat space–time. Considering the effect of the de Sitter string on the space–time, we observe that the deficit angle increases with increasing cosmological constant. Lensed objects would thus be separated by a larger angle as compared to asymptotically flat space–time.