The geometry of open bosonic strings

The coordinate conditions usually used to describe the open string and its boundary conditions are intrinsically singular at the boundary. As a result, the boundary conditions are difficult to understand or interpret geometrically. The physical requirement that the variation of the string at the boundary yield a vanishing contribution to the variation of the action may be accomplished by the requirement that the induced metric, in non-singular coordinates, have signature (0, — 1) at the boundary and that the metric be C¹ on the boundary. These geometrically simple by analytically somewhat complicated requirements are equivalent to the usual boundary conditions. Lastly it is shown that the open string is, in a strict sense, a special case of the closed string. Some of the peculiar behavior of characteristic curves on the open string becomes clear in this context.     

All NSR-models in terms of bosonic strings: An explicit derivation

We construct the open and closed string NSR-models in terms ofD15 bosonic string theories. All anticommuting NSR-operators are obtained after fermionizing 4 bosonic dimensions, and the NSR-Hilbert spaces are embedded as linear subspaces of the bosonic Hilbert spaces. We thus show the existence of various 10D supersymmetric sectors of the state spaces ofD=26 consistent bosonic strings.     

The construction of the sh-Lie-algebra of closed bosonic strings

We present a construction of the closed string algebra in terms of Gaussian processes and crossed products. Also we give a purely functional analytical prove of the sh-Lie-structure.     

The integration ofG-invariant functions and the geometry of the Faddeev-Popov procedure

Various versions of the Fubini theorem on the principal fibre bundle are derived. The formal generalizations of these theorems are used as a basic tool for the investigation of the geometrical setting of the Faddeev-Popov procedure in the cases of pure Yang-Mills theories, spinless particle and Polyakov's bosonic string.     

The extended loop group: An infinite dimensional manifold associated with the loop space

A set of coordinates in the non-parametric loop-space is introduced. We show that these coordinates transform under infinite dimensional linear representations of the diffeomorphism group. An extension of the group of loops in terms of these objects is proposed. The enlarged group behaves locally as an infinite dimensional Lie group. Ordinary loops form a subgroup of this group. The algebraic properties of this new mathematical structure are analyzed in detail. Applications of the formalism to field theory, quantum gravity and knot theory are considered.     

The Nambu–Goto theory of closed bosonic strings moving in 1 + 3–dimensional Minkowski space: the quantum algebra of observables

A relevant part of the quantum algebra of observables for the closed bosonic strings moving in 1 + 3–dimensional Minkowski space is presented in the form of generating relations involving still one, as yet undetermined, real free parameter.     

The Nambu-Goto theory of closed bosonic strings moving in 1 + 3–dimensional Minkowski space: the construction of the quantum algebra of observables up to degree five

The quantum algebra of observables of closed bosonic strings moving in 1 + 3–dimensional Minkowski space is constructed up to degree five. All independent relations of degree four are computed; they involve three as yet undetermined parameters. Definitions and symbols are used as introduced in the above-mentioned article.     

Gauge fixing in fully gauge-invariant field theory of closed bosonic and Neveu-Schwarz strings

The gauge fixing procedure is reanalyzed in our fully gauge-invariant closed bosonic and Neveu-Schwarz string field theory which does not have any constraint on string functionals and gauge parameters. The relations to other formulations are clarified; in particular, it is shown that our theory recovers other formulation with constraints L₊ − L₋ = 0 after partial gauge fixing but without any truncation. Complete gauge fixing is also made and the expected propagator is obtained. The constraint L₊ − L₋ = 0 appears as a field equation in our formulation.     

New 3-mode bosonic operator realization of SU（2） Lie algebra： From the point of view of squeezing

We consider the quantum mechanical SU(2) transformation e2λ JzJ± e-2λJz= e±2λJ± as if the meaning of squeezing with e±2λbeing squeezing parameter. By studying SU(2) operators(J±,Jz) from the point of view of squeezing we find that(J±,Jz) can also be realized in terms of 3-mode bosonic operators. Employing this realization, we find the natural representation(the eigenvectors of J+ or J-) of the 3-mode squeezing operator e2λ Jz. The idea of considering quantum SU(2) transformation as if squeezing is liable for us to obtain the new bosonic operator realization of SU(2) and new squeezing operators.     

CP invariance: A point of view

That the longlived componentL ofK ₀ has bothcp=+1 andcp=−1 modes of decay is often cited as evidence of violation ofcp invariance. The careful ones find the compelling evidence to be the non-dilution of the regeneration interference pattern when the incidentK ₀ beam is mixed even substantially with . However the two phenomena comprehensively imply thatL has acp=+1 componentL ₊ and acp=−1 componentL ₋ and that the longlived component of bothK ₀ and are one and the sameL. This does not demand abandoningcp invariance. It does imply that is not thecp conjugate ofK ₀.     

Sorption systems: The point of view of a gas utility

This paper describes the point of view of a gas utility regarding systems for cooling and heating by solid sorption. Indeed, the context is favorable to the emergence of such systems first, of course, due to the regulatory constraints on certain refrigerant fluids, but also for their specific technical characteristics (the storage capacity, for example). The gas utilities have in fact shown an increasingly keen interest in all types of sorption systems, as a way of diversifying natural gas utilization, particularly in the summer.After a review of that context, this paper highlights the advantages of solid sorption and describes the criteria for choosing an installation in air conditioning and cooling production applications. Finally, it discusses the difficulties likely to be encountered in developing sorption systems, as well as the prospects for the future.     

MITO: a procedure for CBA measurements and a search for cosmic strings

Summary MITO (Millimetric and Infrared Testa Grigia Observatory) is a 3 m telescope dedicated to the study of Cosmic Background Anisotropies. It is located at 3500 m above sea-level at Plateau Rosa, Cervinia. We describe the Observatory and discuss two on-going research programs: a clearning procedure in order to remove galactic dust signals from cosmological data and a search for cosmic strings toward double-lensed quasars. Both the programs will be carried out by means of a He-3 photometer operating at the frequencies of 5, 10, 12, 30 cm⁻¹.     

Numerical renormalization group for bosonic systems and application to the sub-ohmic spin-boson model

We describe the generalization of Wilson's numerical renormalization group method to quantum impurity models with a bosonic bath, providing a general nonperturbative approach to bosonic impurity models which can access exponentially small energies and temperatures. As an application, we consider the spin-boson model, describing a two-level system coupled to a bosonic bath with power-law spectral density, J(omega) proportional to omega(s). We find clear evidence for a line of continuous quantum phase transitions for sub-Ohmic bath exponents 0相似文献   

The exact response of a two-dimensional flat-layered medium to a probing pulse: An application to a layer stripping reconstruction procedure

Abstract

We consider a simple model problem that can be found in many fields of application such as, for example, reflection seismology. That is we consider an initial boundary value problem on a half-plane for a class of two-dimensional wave equations with a piecewise-constant coefficient. This coefficient describes the flat layered medium under consideration. An initial pulse located on the boundary of the half-plane is used to probe the medium. An integral representation of the solution of this problem is obtained by studying the spectral measures of some differential operators in one variable. This integral representation is exploited to obtain an ‘explicit’ formula for the solution of the problem considered evaluated at the location of the probing pulse. This ‘explicit’ formula is exploited to reconstruct the structure of the medium from its response to a probing pulse via a layer stripping procedure. Some numerical results obtained with this procedure on test problems are shown. The ‘explicit’ formula obtained can be used in several other contexts such as, for example, the study of perturbed flat layered media or the study of random flat layered media.     

Objects and their attributes: A physicist's point of view

We treat some puzzling aspects of the notions of objects and attributes by presenting a mathematical model which exhibits these very same, seemingly perplexing, features.     

Master equation approach to conductivity of bosonic and fermionic carriers in one‐ and two‐dimensional lattices

The master equation approach to diffusive current of bosonic or fermionic carriers in one‐ and two‐dimensional lattices is discussed. This approach is shown to reproduce all known results of the linear response theory, including the integer quantum Hall effect for fermionic carriers. The main advantage of the approach is that it allows to calculate the current beyond the linear response regime where new effects are found. In particular, the Hall current can be inverted by changing orientation of the static force (electric field) relative to the primary axes of the lattice.     

The statistical mechanics of topological polymers: a field theorist point of view

This is a self‐contained introduction to polymer physics and to the application of field theoretical techniques to the statistical mechanics of polymer systems. Of course, since polymer physics is a highly interdisciplinary subject, involving different disciplines like knot theory, field theory, statistical mechanics and some notions of bio‐chemistry and chemistry, it is not possible to cover all these topics in a single review. Particular emphasis is given here to the problem of describing the fluctuations of topologically linked polymers in a solution from a microscopical point of view. Some recent advances in this direction are presented. Another purpose of this work is to serve as a guide for whoever would like to apply the methods of field theory to polymers. To ease reading, technical terms have been quoted in boldface characters at the points in which their meaning is explained.     

点声源入射下无限大平板的隔声

利用球面波的平面波展开形式,推导了自由场中点声源入射下无限大平板的隔声公式,研究了其隔声性能。数值模拟结果表明,点声源入射下平板隔声规律不同于通常采用的平面波入射条件下的质量隔声定律。在频率较低或板厚度较薄时,频率或板面密度增加一倍,平板隔声量的增加约为3 dB,而插入损失的增加约为6 dB。