Conformal space-times—The arenas of physics and cosmology

The mathematical and physical aspects of the conformal symmetry of space-time and of physical laws are analyzed. In particular, the group classification of conformally flat space-times, the conformal compactifications of space-time, and the problem of imbedding of the flat space-time in global four-dimensional curved spaces with non-trivial topological and geometrical structure are discussed in detail. The wave equations on the compactified space-times are analyzed also, and the set of their elementary solutions constructed. Finally, the implications of global compactified space-times for cosmology are discussed. It is argued that the recent discovery of periodic structure of matter distribution on large distances strongly suggests that the global cosmological space-time should be close. Next we analyze the inflation scalar field in the inflationary model of universe evolution considered on the spatially compact Robertson-Walker space-time. It is shown that the energy distribution in this model is periodic and the periods and density decrease with increasing distance, in striking agreement with experimental data. Our model of the universe also provides a definite predictions for the energy distribution, polar and azimuthal, considered as a function of angles and . These predictions should be tested with the new astronomical data.Dedicated to Professor Constantin Piron on the occasion of his sixtieth birthday, June 11, 1992.This publication is based on work sponsored by the US-Czechoslovakia Science and Technological Joint Fund under Project Number 92067 and by Grant ASCR under Project Number 19085.Partially supported by the Stiftung Für Deutsch-Polnische Zusammenarbeit Grant No. 984/94/LN.     

Accelerator neutrino physics—Current status and future prospects

This review article describes the current status and future prospects of accelerator neutrino physics. The emphasis is on recent developments in the oscillation physics area but there is also a limited discussion about the status of neutrino cross sections. The approach taken is pedagogical and an effort is made to explain the basic techniques used in the accelerator studies of neutrino physics.     

World spinors—Construction and some applications

The existence of a topological double-covering for the GL(n, R) and diffeomorphism groups is reviewed. These groups do not have finite-dimensional faithful representations. An explicit construction and the classification of all (n, R), n=3,4 unitary irreducible representations is presented. Infinite-component spinorial and tensorial fields, “manifields”, are introduced. Particle content of the ladder manifields, as given by the (3, R) “little” group, is determined. The manifields are lifted to the corresponding world spinorial and tensorial manifields by making use of generalized infinite-component frame fields. World manifields transform w.r.t. corresponding representations, which are constructed explicitly. Supported in part by the Science Foundation (Belgrade).     

μ +SR in solids — trends and expectations

Conventional ⁺SR studies are classified according to their relation with Solid State Physics, and an attempt is made to identify current trends in the field of ⁺SR in solids. Desirable trends and development in ⁺SR techniques are also discussed shortly. Rather than risk attempts at predicting the future [1] of ⁺SR in solids, it is perhaps prudent merely to identify trends in the field and let individual readers to extrapolate. We shall start with trends in the main stream conventional ⁺SR and then discuss some desirable technical development.     

Charm physics — A field full of challenges and opportunities

In this review, we discuss some interesting issues in charm physics, which is full of puzzles and challenges. So far in this field, there exist many problems which have not obtained satisfactory answers yet as more unexpected phenomena Continue to be observed at the current facilities of high energy physics. Charm physics may become an ideal place for searching new resonances and studying non-perturbative QCD effects, moreover it is probably an area for exploring new physics beyond the Standard Model. More data will be available at the BE-SIII, B-factories, LHC and even the future ILC, which may open a wide window to a better understanding of its nature.      

Laser physics—20-year jubilee

From the Editorial Board

Laser physics—20-year jubilee     

Electroweak symmetry breaking and beyond the Standard Model physics — A review

In this talk, I shall first discuss the Standard Model Higgs mechanism and then highlight some of its deficiencies making a case for the need to go beyond the Standard Model (BSM). The BSM tour will be guided by symmetry arguments. I shall pick up four specific BSM scenarios, namely, supersymmetry, little Higgs, gauge-Higgs unification, and the Higgsless approach. The discussion will be confined mainly on their electroweak symmetry breaking aspects.      

Mass distribution in n—polymer stochastic aggregation and large—mass behaviour

The exact solutions of the rate equations of the n-polymer stochastic aggregation involving two types of clusters, active and passive for the kernel \dprⁿ_k=1s_(ik)(s_(ik)=i_k) and \dsumⁿ_k=1s_(ik)(s_(ik)=i_k), are obtained. The large-mass behaviours of the final mass distribution of the active and passive clusters have scaling-like forms, although the models exhibit different properties. Respectively, they have different decay exponents γ=\dfrac{2n+1}{2(n-1)} and γ=q+\dfrac{2n+1}{2(n-1)} for \dprⁿ_{k=1}s(ik)(s(ik)=ik) and γ=\dfrac 3{2(n-1)} and γ=q+\dfrac 3{2(n-1)} for \dsumⁿk=1}s(ik)(s(ik)=ik), which include exponents of two-polymer stochastic aggregation. We also find that gelation is suppressed for kernel \dprⁿk=1s(ik)(s(ik)=ik) which is different from the deterministic aggregation.}     

Worldwide activities and fiber optic market trends: Part I—markets

Abstract

This paper reviews the recent progress of fiber optics applications worldwide and assesses the potential market growth. Market growth will occur at the expense of existing or planned technologies, such as the circular waveguide, and hence, the potential market growth must be considered in light of these existing markets.

Although the application of fiber optics technology is developing rapidly, there are certain countries which are progressing more rapidly than others. Each of the major countries or groups will be discussed, and the reasons for the activity or lack thereof will be given. The impact of fiber optics on the third world is yet to be felt; however, this may be one of the areas of future potential growth.

In order to give the reader an indication of the extent of applications that have occurred in the telephone, data, power, CATV, and military sectors, a complete listing and review of over 100 experimental systems is provided in Part II of this paper.     

Cosmic-coincidence problem and variable constants of physics

The standard model of cosmology is investigated using a time-dependent cosmological constant Λ and Newton gravitational constant G. The total energy content is described by the modified Chaplygin gas equation of state. It is found that the time-dependent constants coupled with the modified Chaplygin gas interpolate between the earlier matter to the later dark-energy dominated phase of the universe. We also achieve a convergence of the parameter ω→−1, almost at the present time. Thus our model fairly alleviates the cosmic-coincidence problem, which demands ω=−1 at the present time.     

Universal Teichmüller space in geometry and physics

Lipman Bers' universal Teichmüller space, classically denoted by T(1), plays a significant role in Teichmüller theory, because all the Teichmüller spaces T(G) of Fuchsian groups G can be embedded into it as complex submanifolds. Recently, T(1) has also become an object of intensive study in physics, because it is a promising geometric environment for a non-perturbative version of bosonic string theory. We provide a non-technical survey of what is currently known about the geometry of T(1) and what is conjectured about its physical meaning. Our bibliography should be rather comprehensive, but we apologize for any unjustified omissions.     

Study of η and η＇ physics at BES-III

Decays of both η and η＇ provide very useful information in our understanding of low-energy QCD, and experimental signatures for these decays would be extremely helpful at BES-III. The rare decays of the η and η＇ mesons could serve as a low-energy test of the Standard Model and its beyond. The sensitivities of the measurements of η and η＇ decays are discussed at BES-III, in which the η and η＇ mesons are produced in the ψ decays.     

Recent research process on perovskite photodetectors:A review for photodetector——materials,physics,and applications

The perovskite photodetectors can be used for image sensing, environmental monitoring, optical communication, and chemical/biological detection. In the recent five years, the perovskite photoelectric detectors with various devices are welldesigned and have made unprecedented progress of light detection. It is necessary to emphasize the most interesting works and summarize them to provide researchers with systematic information. In this review, we report the recent progress in perovskite photodetectors, including highly sensitive, ultrafast response speed, high gain, low noise, flexibility, and narrowband, concentrating on the photodetection performance of versatile halide perovskites(organic–inorganic hybrid and all inorganic compositions). Currently, organic–inorganic hybrid and all-inorganic halide microcrystals with polycrystalline film, nanoparticle/wire/chip, and block monocrystalline morphology control show important performance in response rate,decomposition rate, noise equivalent power, linear dynamic range, and response speed. It is expected that a comprehensive compendium of the research status of perovskite photodetectors will contribute to the development of this area.