Noncommutative gauge fields coupled to noncommutative gravity
Aschieri, Paolo; Castellani, Leonardo
2013-03-01
We present a noncommutative (NC) version of the action for vielbein gravity coupled to gauge fields. Noncommutativity is encoded in a twisted star -product between forms, with a set of commuting background vector fields defining the (abelian) twist. A first order action for the gauge fields avoids the use of the Hodge dual. The NC action is invariant under diffeomorphisms and star -gauge transformations. The Seiberg-Witten map, adapted to our geometric setting and generalized for an arbitrary abelian twist, allows to re-express the NC action in terms of classical fields: the result is a deformed action, invariant under diffeomorphisms and usual gauge transformations. This deformed action is a particular higher derivative extension of the Einstein-Hilbert action coupled to Yang-Mills fields, and to the background vector fields defining the twist. Here noncommutativity of the original NC action dictates the precise form of this extension. We explicitly compute the first order correction in the NC parameter of the deformed action, and find that it is proportional to cubic products of the gauge field strength and to the symmetric anomaly tensor D_{IJK}.
Noncommutative Field Theory and the Dynamics of Quantum Hall Fluids
Barbón, José L F
2002-01-01
We study the spectrum of density fluctuations of Fractional Hall Fluids in the context of the noncommutative hidrodynamical model of Susskind. We show that, within the weak-field expansion, the leading correction to the noncommutative Chern--Simons Lagrangian (a Maxwell term in the effective action,) destroys the incompressibility of the Hall fluid due to strong UV/IR effects at one loop. We speculate on possible relations of this instability with the transition to the Wigner crystal, and conclude that calculations within the weak-field expansion must be carried out with an explicit ultraviolet cutoff at the noncommutativity scale. We point out that the noncommutative dipoles exactly match the spatial structure of the Halperin--Kallin quasiexcitons. Therefore, we propose that the noncommutative formalism must describe accurately the spectrum at very large momenta, provided no weak-field approximations are made. We further conjecture that the noncommutative open Wilson lines are `vertex operators' for the quas...
Gravitational fields on a noncommutative space
International Nuclear Information System (INIS)
Nair, V.P.
2003-01-01
Noncommutative three-dimensional gravity can be described in terms of a noncommutative Chern-Simons theory. We extend this structure and also propose an action for gravitational fields on an even-dimensional noncommutative space. The action is worked out in some detail for fields on a noncommutative CP 2 and on S 4
Emergent Abelian Gauge Fields from Noncommutative Gravity
Directory of Open Access Journals (Sweden)
Allen Stern
2010-02-01
Full Text Available We construct exact solutions to noncommutative gravity following the formulation of Chamseddine and show that they are in general accompanied by Abelian gauge fields which are first order in the noncommutative scale. This provides a mechanism for generating cosmological electromagnetic fields in an expanding space-time background, and also leads to multipole-like fields surrounding black holes. Exact solutions to noncommutative Einstein-Maxwell theory can give rise to first order corrections to the metric tensor, as well as to the electromagnetic fields. This leads to first order shifts in the horizons of charged black holes.
Interacting open Wilson lines from noncommutative field theories
International Nuclear Information System (INIS)
Kiem, Youngjai; Lee, Sangmin; Rey, Soo-Jong; Sato, Haru-Tada
2002-01-01
In noncommutative field theories, it is known that the one-loop effective action describes the propagation of noninteracting open Wilson lines, obeying the flying dipole's relation. We show that the two-loop effective action describes the cubic interaction among 'closed string' states created by open Wilson line operators. Taking d-dimensional λ[Φ 3 ] * theory as the simplest setup, we compute the nonplanar contribution at a low-energy and large noncommutativity limit. We find that the contribution is expressible in a remarkably simple cubic interaction involving scalar open Wilson lines only and nothing else. We show that the interaction is purely geometrical and noncommutative in nature, depending only on the size of each open Wilson line
Open Wilson lines and generalized star product in noncommutative scalar field theories
International Nuclear Information System (INIS)
Kiem, Youngjai; Sato, Haru-Tada; Rey, Soo-Jong; Yee, Jung-Tay
2002-01-01
Open Wilson line operators and a generalized star product have been studied extensively in noncommutative gauge theories. We show that they also show up in noncommutative scalar field theories as universal structures. We first point out that the dipole picture of noncommutative geometry provides an intuitive argument for the robustness of the open Wilson lines and generalized star products therein. We calculate the one-loop effective action of noncommutative scalar field theory with a cubic self-interaction and show explicitly that the generalized star products arise in the nonplanar part. It is shown that, at the low-energy, large noncommutativity limit, the nonplanar part is expressible solely in terms of the scalar open Wilson line operator and descendants
Pair production by a constant external field in noncommutative QED
International Nuclear Information System (INIS)
Chair, N.; Sheikh-Jabbari, M.M.
2000-09-01
In this paper we study QED on the noncommutative space in the constant electro-magnetic field background. Using the explicit solutions of the noncommutative version of Dirac equation in such background, we show that there are well-defined in and out-going asymptotic states and also there is a causal Green's function. We calculate the pair production rate in this case. We show that at tree level noncommutativity will not change the pair production and the threshold electric field. We also calculate the pair production rate considering the first loop corrections. In this case we show that the threshold electric field is decreased by the noncommutativity effects. (author)
Noncommutative gravity and quantum field theory on noncummutative curved spacetimes
International Nuclear Information System (INIS)
Schenkel, Alexander
2011-01-01
The purpose of the first part of this thesis is to understand symmetry reduction in noncommutative gravity, which then allows us to find exact solutions of the noncommutative Einstein equations. We propose an extension of the usual symmetry reduction procedure, which is frequently applied to the construction of exact solutions of Einstein's field equations, to noncommutative gravity and show that this leads to preferred choices of noncommutative deformations of a given symmetric system. We classify in the case of abelian Drinfel'd twists all consistent deformations of spatially flat Friedmann-Robertson-Walker cosmologies and of the Schwarzschild black hole. The deformed symmetry structure allows us to obtain exact solutions of the noncommutative Einstein equations in many of our models, for which the noncommutative metric field coincides with the classical one. In the second part we focus on quantum field theory on noncommutative curved spacetimes. We develop a new formalism by combining methods from the algebraic approach to quantum field theory with noncommutative differential geometry. The result is an algebra of observables for scalar quantum field theories on a large class of noncommutative curved spacetimes. A precise relation to the algebra of observables of the corresponding undeformed quantum field theory is established. We focus on explicit examples of deformed wave operators and find that there can be noncommutative corrections even on the level of free field theories, which is not the case in the simplest example of the Moyal-Weyl deformed Minkowski spacetime. The convergent deformation of simple toy-models is investigated and it is shown that these quantum field theories have many new features compared to formal deformation quantization. In addition to the expected nonlocality, we obtain that the relation between the deformed and the undeformed quantum field theory is affected in a nontrivial way, leading to an improved behavior of the noncommutative
Noncommutative gravity and quantum field theory on noncummutative curved spacetimes
Energy Technology Data Exchange (ETDEWEB)
Schenkel, Alexander
2011-10-24
The purpose of the first part of this thesis is to understand symmetry reduction in noncommutative gravity, which then allows us to find exact solutions of the noncommutative Einstein equations. We propose an extension of the usual symmetry reduction procedure, which is frequently applied to the construction of exact solutions of Einstein's field equations, to noncommutative gravity and show that this leads to preferred choices of noncommutative deformations of a given symmetric system. We classify in the case of abelian Drinfel'd twists all consistent deformations of spatially flat Friedmann-Robertson-Walker cosmologies and of the Schwarzschild black hole. The deformed symmetry structure allows us to obtain exact solutions of the noncommutative Einstein equations in many of our models, for which the noncommutative metric field coincides with the classical one. In the second part we focus on quantum field theory on noncommutative curved spacetimes. We develop a new formalism by combining methods from the algebraic approach to quantum field theory with noncommutative differential geometry. The result is an algebra of observables for scalar quantum field theories on a large class of noncommutative curved spacetimes. A precise relation to the algebra of observables of the corresponding undeformed quantum field theory is established. We focus on explicit examples of deformed wave operators and find that there can be noncommutative corrections even on the level of free field theories, which is not the case in the simplest example of the Moyal-Weyl deformed Minkowski spacetime. The convergent deformation of simple toy-models is investigated and it is shown that these quantum field theories have many new features compared to formal deformation quantization. In addition to the expected nonlocality, we obtain that the relation between the deformed and the undeformed quantum field theory is affected in a nontrivial way, leading to an improved behavior of the
Discrete symmetries (C,P,T) in noncommutative field theories
International Nuclear Information System (INIS)
Sheikh-Jabbari, M.M.
2000-01-01
In this paper we study the invariance of the noncommutative gauge theories tinder C, P and T transformations. For the noncommutative space (when only the spatial part of θ is non-zero) we show that NCQED is Parity invariant. In addition, we show that under charge conjugation the theory on noncommutative R θ 4 is transformed to the theory on R -θ 4 , so NCQED is a CP violating theory. The theory remains invariant under time reversal if, together with proper changes in fields, we also change θ by -θ. Hence altogether NCQED is CPT invariant. Moreover we show that the CPT invariance holds for general noncommutative space-time. (author)
Noncommutative Geometry, Quantum Fields and Motives
Connes, Alain
2007-01-01
The unifying theme of this book is the interplay among noncommutative geometry, physics, and number theory. The two main objects of investigation are spaces where both the noncommutative and the motivic aspects come to play a role: space-time, where the guiding principle is the problem of developing a quantum theory of gravity, and the space of primes, where one can regard the Riemann Hypothesis as a long-standing problem motivating the development of new geometric tools. The book stresses the relevance of noncommutative geometry in dealing with these two spaces. The first part of the book dea
Naka, S.; Toyoda, H.; Takanashi, T.; Umezawa, E.
2014-04-01
In kappa -Minkowski spacetime, the coordinates are Lie algebraic elements such that time and space coordinates do not commute, whereas space coordinates commute with each other. The noncommutativity is proportional to a Planck-length-scale constant kappa ^{-1}, which is a universal constant other than the velocity of light, under the kappa -Poincaré transformation. In this sense, the spacetime has a structure called "doubly special relativity." Such a noncommutative structure is known to be realized by SO(1,4) generators in 4-dimensional de Sitter space. In this paper, we try to construct a noncommutative spacetime having a commutative n-dimensional Minkowski spacetime based on AdS_{n+1} space with SO(2,n) symmetry. We also study an invariant wave equation corresponding to the first Casimir invariant of this symmetry as a nonlocal field equation expected to yield finite loop amplitudes.
Nonperturbative studies of quantum field theories on noncommutative spaces
International Nuclear Information System (INIS)
Volkholz, J.
2007-01-01
This work deals with three quantum field theories on spaces with noncommuting position operators. Noncommutative models occur in the study of string theories and quantum gravity. They usually elude treatment beyond the perturbative level. Due to the technique of dimensional reduction, however, we are able to investigate these theories nonperturbatively. This entails translating the action functionals into a matrix language, which is suitable for numerical simulations. First we explore the λφ 4 model on a noncommutative plane. We investigate the continuum limit at fixed noncommutativity, which is known as the double scaling limit. Here we focus especially on the fate of the striped phase, a phase peculiar to the noncommutative version of the regularized λφ 4 model. We find no evidence for its existence in the double scaling limit. Next we examine the U(1) gauge theory on a four-dimensional spacetime, where two spatial directions are noncommutative. We examine the phase structure and find a new phase with a spontaneously broken translation symmetry. In addition we demonstrate the existence of a finite double scaling limit which confirms the renormalizability of the theory. Furthermore we investigate the dispersion relation of the photon. In the weak coupling phase our results are consistent with an infrared instability predicted by perturbation theory. If the translational symmetry is broken, however, we find a dispersion relation corresponding to a massless particle. Finally, we investigate a supersymmetric theory on the fuzzy sphere, which features scalar neutral bosons and Majorana fermions. The supersymmetry is exact in the limit of infinitely large matrices. We investigate the phase structure of the model and find three distinct phases. Summarizing, we study noncommutative field theories beyond perturbation theory. Moreover, we simulate a supersymmetric theory on the fuzzy sphere, which might provide an alternative to attempted lattice formulations. (orig.)
Nonperturbative studies of quantum field theories on noncommutative spaces
Energy Technology Data Exchange (ETDEWEB)
Volkholz, J.
2007-11-16
This work deals with three quantum field theories on spaces with noncommuting position operators. Noncommutative models occur in the study of string theories and quantum gravity. They usually elude treatment beyond the perturbative level. Due to the technique of dimensional reduction, however, we are able to investigate these theories nonperturbatively. This entails translating the action functionals into a matrix language, which is suitable for numerical simulations. First we explore the {lambda}{phi}{sup 4} model on a noncommutative plane. We investigate the continuum limit at fixed noncommutativity, which is known as the double scaling limit. Here we focus especially on the fate of the striped phase, a phase peculiar to the noncommutative version of the regularized {lambda}{phi}{sup 4} model. We find no evidence for its existence in the double scaling limit. Next we examine the U(1) gauge theory on a four-dimensional spacetime, where two spatial directions are noncommutative. We examine the phase structure and find a new phase with a spontaneously broken translation symmetry. In addition we demonstrate the existence of a finite double scaling limit which confirms the renormalizability of the theory. Furthermore we investigate the dispersion relation of the photon. In the weak coupling phase our results are consistent with an infrared instability predicted by perturbation theory. If the translational symmetry is broken, however, we find a dispersion relation corresponding to a massless particle. Finally, we investigate a supersymmetric theory on the fuzzy sphere, which features scalar neutral bosons and Majorana fermions. The supersymmetry is exact in the limit of infinitely large matrices. We investigate the phase structure of the model and find three distinct phases. Summarizing, we study noncommutative field theories beyond perturbation theory. Moreover, we simulate a supersymmetric theory on the fuzzy sphere, which might provide an alternative to attempted
Noncommutative complex scalar fields in a D=10 operatorial space
Energy Technology Data Exchange (ETDEWEB)
Amorim, Ricardo [Universidade Federal do Rio de Janeiro (UFRJ), RJ (Brazil); Abreu, Everton M.C. [Universidade Federal Rural do Rio de Janeiro (UFRRJ), Seropedica, RJ (Brazil)
2009-07-01
Full text. Through the last years the space-time noncommutativity has been a target of intense analysis. After the first published work by Snyder a huge amount of papers has appeared in the literature. The connection with strings, gravity and noncommutative field theories brought attention to the subject. The main objective with this construction is to introduce a natural cutoff for quantum field theories. Unfortunately, it fails. The fundamental issue brings the idea that the standard space-time may be not a continuous manifold. Instead, it may be a quantized object. Therefore, the proper tool to manipulate this object would be the noncommutativity of coordinate operators, although both related theories are yet in construction. Other approaches to noncom- mutativity can also be given in a global way, generalizing some of the celebrated Connes ideas. In this work we analyze complex scalar fields using a new framework where the object of noncommutativity theta{sub m}u{sub n}u represents independent degrees of freedom. Namely, theta{sub m}u{sub n}u is an operator as well as its canonical momentum pi{sub m}u{sub n}u and both live in an augmented D = 10 Hilbert space. This structure comprises the minimal canonical extension of the Doplicher-Fredenhagen-Roberts (DFR) algebra and consequently a modified Poincare group of symmetry. In this D = 4+6 (x +theta) space we construct the noncommutative Klein-Gordon equation for the charged field and the elements of its modified algebra and symmetry group. (author)
Non-commutative field theory with twistor-like coordinates
International Nuclear Information System (INIS)
Taylor, Tomasz R.
2007-01-01
We consider quantum field theory in four-dimensional Minkowski spacetime, with the position coordinates represented by twistors instead of the usual world-vectors. Upon imposing canonical commutation relations between twistors and dual twistors, quantum theory of fields described by non-holomorphic functions of twistor variables becomes manifestly non-commutative, with Lorentz symmetry broken by a time-like vector. We discuss the free field propagation and its impact on the short- and long-distance behavior of physical amplitudes in perturbation theory. In the ultraviolet limit, quantum field theories in twistor space are generically less divergent than their commutative counterparts. Furthermore, there is no infrared-ultraviolet mixing problem
Structural aspects of quantum field theory and noncommutative geometry
Grensing, Gerhard
2013-01-01
This book is devoted to the subject of quantum field theory. It is divided into two volumes. The first can serve as a textbook on the main techniques and results of quantum field theory, while the second treats more recent developments, in particular the subject of quantum groups and noncommutative geometry, and their interrelation. The first volume is directed at graduate students who want to learn the basic facts about quantum field theory. It begins with a gentle introduction to classical field theory, including the standard model of particle physics, general relativity, and also supergravity. The transition to quantized fields is performed with path integral techniques, by means of which the one-loop renormalization of a self-interacting scalar quantum field, of quantum electrodynamics, and the asymptotic freedom of quantum chromodynamics is treated. In the last part of the first volume, the application of path integral methods to systems of quantum statistical mechanics is covered. The book ends with a r...
Quantum Field Theory with a Minimal Length Induced from Noncommutative Space
International Nuclear Information System (INIS)
Lin Bing-Sheng; Chen Wei; Heng Tai-Hua
2014-01-01
From the inspection of noncommutative quantum mechanics, we obtain an approximate equivalent relation for the energy dependence of the Planck constant in the noncommutative space, which means a minimal length of the space. We find that this relation is reasonable and it can inherit the main properties of the noncommutative space. Based on this relation, we derive the modified Klein—Gordon equation and Dirac equation. We investigate the scalar field and ϕ 4 model and then quantum electrodynamics in our theory, and derive the corresponding Feynman rules. These results may be considered as reasonable approximations to those of noncommutative quantum field theory. Our theory also shows a connection between the space with a minimal length and the noncommutative space. (physics of elementary particles and fields)
Loop calculations for the non-commutative U*(1) gauge field model with oscillator term
International Nuclear Information System (INIS)
Blaschke, Daniel N.; Grosse, Harald; Kronberger, Erwin; Schweda, Manfred; Wohlgenannt, Michael
2010-01-01
Motivated by the success of the non-commutative scalar Grosse-Wulkenhaar model, a non-commutative U * (1) gauge field theory including an oscillator-like term in the action has been put forward in (Blaschke et al. in Europhys. Lett. 79:61002, 2007). The aim of the current work is to analyze whether that action can lead to a fully renormalizable gauge model on non-commutative Euclidean space. In a first step, explicit one-loop graph computations are hence presented, and their results as well as necessary modifications of the action are successively discussed. (orig.)
High-field dipoles for future accelerators
Energy Technology Data Exchange (ETDEWEB)
Wipf, S.L.
1984-09-01
This report presents the concept for building superconducting accelerator dipoles with record high fields. Economic considerations favor the highest possible current density in the windings. Further discussion indicates that there is an optimal range of pinning strength for a superconducting material and that it is not likely for multifilamentary conductors to ever equal the potential performance of tape conductors. A dipole design with a tape-wound, inner high-field winding is suggested. Methods are detailed to avoid degradation caused by flux jumps and to overcome problems with the dipole ends. Concerns for force support structure and field precision are also addressed. An R and D program leading to a prototype 11-T dipole is outlined. Past and future importance of superconductivity to high-energy physics is evident from a short historical survey. Successful dipoles in the 10- to 20-T range will allow interesting options for upgrading present largest accelerators.
Noncommutative field theory and violation of translation invariance
International Nuclear Information System (INIS)
Bertolami, Orfeu; Guisado, Luis
2003-01-01
Noncommutative field theories with commutator of the coordinates of the form [x μ , x ν ] = i Λ μν ω x ω with nilpotent structure constants are studied and shown that a free quantum field theory is not affected. Invariance under translations is broken and the conservation of energy-momentum is violated, obeying a new law which is expressed by a Poincare-invariant equation. The resulting new kinematics is studied and applied to simple examples and to astrophysical puzzles, such as the observed violation of the GZK cutoff. The λΦ 4 quantum field theory is also considered in this context. In particular, self interaction terms violate the usual conservation of energy-momentum and, hence, the radiative correction to the propagator is altered. The correction to first order in λ is calculated. The usual UV divergent terms are still present, but a new type of term also emerges, which is IR divergent, violates momentum conservation and implies a correction to the dispersion relation. (author)
Noncommutative field theory and violation of translation invariance
Energy Technology Data Exchange (ETDEWEB)
Bertolami, Orfeu [Departamento de Fisica, Instituto Superior Tecnico, Lisbon (Portugal)]. E-mail: orfeu@cosmos.ist.utl.pt; Guisado, Luis [Departamento de Fisica, Instituto Superior Tecnico, Lisbon (Portugal)
2003-12-01
Noncommutative field theories with commutator of the coordinates of the form [x{sup {mu}}, x{sup {nu}}] = i {lambda}{sup {mu}}{sup {nu}}{sub {omega}}x{sup {omega}} with nilpotent structure constants are studied and shown that a free quantum field theory is not affected. Invariance under translations is broken and the conservation of energy-momentum is violated, obeying a new law which is expressed by a Poincare-invariant equation. The resulting new kinematics is studied and applied to simple examples and to astrophysical puzzles, such as the observed violation of the GZK cutoff. The {lambda}{phi}{sup 4} quantum field theory is also considered in this context. In particular, self interaction terms violate the usual conservation of energy-momentum and, hence, the radiative correction to the propagator is altered. The correction to first order in {lambda} is calculated. The usual UV divergent terms are still present, but a new type of term also emerges, which is IR divergent, violates momentum conservation and implies a correction to the dispersion relation. (author)
Unusual high-energy phenomenology of Lorentz-invariant noncommutative field theories
International Nuclear Information System (INIS)
Carone, Christopher D.; Kwee, Herry J.
2006-01-01
It has been suggested that one may construct a Lorentz-invariant noncommutative field theory by extending the coordinate algebra to additional, fictitious coordinates that transform nontrivially under the Lorentz group. Integration over these coordinates in the action produces a four-dimensional effective theory with Lorentz invariance intact. Previous applications of this approach, in particular, to a specific construction of noncommutative QED, have been studied only in a low-momentum approximation. Here we discuss Lorentz-invariant field theories in which the relevant physics can be studied without requiring an expansion in the inverse scale of noncommutativity. Qualitatively, we find that tree-level scattering cross sections are dramatically suppressed as the center-of-mass energy exceeds the scale of noncommutativity, that cross sections that are isotropic in the commutative limit can develop a pronounced angular dependence, and that nonrelativistic potentials (for example, the Coloumb potential) become nonsingular at the origin. We consider a number of processes in noncommutative QED that may be studied at a future linear collider. We also give an example of scattering via a four-fermion operator in which the noncommutative modifications of the interaction can unitarize the tree-level amplitude, without requiring any other new physics in the ultraviolet
Models with oscillator terms in noncommutative quantum field theory
International Nuclear Information System (INIS)
Kronberger, E.
2010-01-01
The main focus of this Ph.D. thesis is on noncommutative models involving oscillator terms in the action. The first one historically is the successful Grosse-Wulkenhaar (G.W.) model which has already been proven to be renormalizable to all orders of perturbation theory. Remarkably it is furthermore capable of solving the Landau ghost problem. In a first step, we have generalized the G.W. model to gauge theories in a very straightforward way, where the action is BRS invariant and exhibits the good damping properties of the scalar theory by using the same propagator, the so-called Mehler kernel. To be able to handle some more involved one-loop graphs we have programmed a powerful Mathematica package, which is capable of analytically computing Feynman graphs with many terms. The result of those investigations is that new terms originally not present in the action arise, which led us to the conclusion that we should better start from a theory where those terms are already built in. Fortunately there is an action containing this complete set of terms. It can be obtained by coupling a gauge field to the scalar field of the G.W. model, integrating out the latter, and thus 'inducing' a gauge theory. Hence the model is called Induced Gauge Theory. Despite the advantage that it is by construction completely gauge invariant, it contains also some unphysical terms linear in the gauge field. Advantageously we could get rid of these terms using a special gauge dedicated to this purpose. Within this gauge we could again establish the Mehler kernel as gauge field propagator. Furthermore we where able to calculate the ghost propagator, which turned out to be very involved. Thus we were able to start with the first few loop computations showing the expected behavior. The next step is to show renormalizability of the model, where some hints towards this direction will also be given. (author) [de
Fringing field measurement of dipole magnet
International Nuclear Information System (INIS)
Lu Hongyou; Jiang Weisheng; Mao Naifeng; Mao Xingwang
1985-01-01
The fringing field of a dipole magnet with a C-type circuit and homogeneous field in the gap has been measured including the distributions of fringing fields with and without magnetic shield. The measured data was analyzed by using the concept of virtual field boundary
String states, loops and effective actions in noncommutative field theory and matrix models
Energy Technology Data Exchange (ETDEWEB)
Steinacker, Harold C., E-mail: harold.steinacker@univie.ac.at
2016-09-15
Refining previous work by Iso, Kawai and Kitazawa, we discuss bi-local string states as a tool for loop computations in noncommutative field theory and matrix models. Defined in terms of coherent states, they exhibit the stringy features of noncommutative field theory. This leads to a closed form for the 1-loop effective action in position space, capturing the long-range non-local UV/IR mixing for scalar fields. The formalism applies to generic fuzzy spaces. The non-locality is tamed in the maximally supersymmetric IKKT or IIB model, where it gives rise to supergravity. The linearized supergravity interactions are obtained directly in position space at one loop using string states on generic noncommutative branes.
String states, loops and effective actions in noncommutative field theory and matrix models
Directory of Open Access Journals (Sweden)
Harold C. Steinacker
2016-09-01
Full Text Available Refining previous work by Iso, Kawai and Kitazawa, we discuss bi-local string states as a tool for loop computations in noncommutative field theory and matrix models. Defined in terms of coherent states, they exhibit the stringy features of noncommutative field theory. This leads to a closed form for the 1-loop effective action in position space, capturing the long-range non-local UV/IR mixing for scalar fields. The formalism applies to generic fuzzy spaces. The non-locality is tamed in the maximally supersymmetric IKKT or IIB model, where it gives rise to supergravity. The linearized supergravity interactions are obtained directly in position space at one loop using string states on generic noncommutative branes.
The Riesz-Clifford Functional Calculus for Non-Commuting Operators and Quantum Field Theory
Kisil, Vladimir V.; de Arellano, Enrique Ramírez
1995-01-01
We present a Riesz-like hyperholomorphic functional calculus for a set of non-commuting operators based on the Clifford analysis. Applications to the quantum field theory are described. Keywords: Functional calculus, Weyl calculus, Riesz calculus, Clifford analysis, quantization, quantum field theory. AMSMSC Primary:47A60, Secondary: 81T10
Perturbed nonlinear models from noncommutativity
International Nuclear Information System (INIS)
Cabrera-Carnero, I.; Correa-Borbonet, Luis Alejandro; Valadares, G.C.S.
2007-01-01
By means of the Ehrenfest's Theorem inside the context of a noncommutative Quantum Mechanics it is obtained the Newton's Second Law in noncommutative space. Considering discrete systems with infinite degrees of freedom whose dynamical evolutions are governed by the noncommutative Newton's Second Law we have constructed some alternative noncommutative generalizations of two-dimensional field theories. (author)
Domain wall solitons and Hopf algebraic translational symmetries in noncommutative field theories
International Nuclear Information System (INIS)
Sasai, Yuya; Sasakura, Naoki
2008-01-01
Domain wall solitons are the simplest topological objects in field theories. The conventional translational symmetry in a field theory is the generator of a one-parameter family of domain wall solutions, and induces a massless moduli field which propagates along a domain wall. We study similar issues in braided noncommutative field theories possessing Hopf algebraic translational symmetries. As a concrete example, we discuss a domain wall soliton in the scalar φ 4 braided noncommutative field theory in Lie-algebraic noncommutative space-time, [x i ,x j ]=2iκε ijk x k (i,j,k=1,2,3), which has a Hopf algebraic translational symmetry. We first discuss the existence of a domain wall soliton in view of Derrick's theorem, and construct explicitly a one-parameter family of solutions in perturbation of the noncommutativity parameter κ. We then find the massless moduli field which propagates on the domain wall soliton. We further extend our analysis to the general Hopf algebraic translational symmetry
Anatomy of One-Loop Effective Action in Noncommutative Scalar Field Theories
Kiem, Youngjai; Sato, Haru-Tada; Yee, Jung-Tay; Kiem, Youngjai; Rey, Soo-Jong; Sato, Haru-Tada; Yee, Jung-Tay
2002-01-01
One-loop effective action of noncommutative scalar field theory with cubic self-interaction is studied. Utilizing worldline formulation, both planar and nonplanar part of the effective action are computed explicitly. We find complete agreement of the result with Seiberg-Witten limit of string worldsheet computation and standard Feynman diagrammatics. We prove that, at low-energy and large noncommutativity limit, nonplanar part of the effective action is simplified enormously and is resummable into a quadratic action of scalar open Wilson line operators.
THE SNS RING DIPOLE MAGNETIC FIELD QUALITY.
Energy Technology Data Exchange (ETDEWEB)
WANDERER,P.; JACKSON,J.; JAIN,A.; LEE,Y.Y.; MENG,W.; PAPAPHILIPPOU,I.; SPATARO,C.; TEPIKIAN,S.; TSOUPAS,N.; WEI,J.
2002-06-03
The large acceptance and compact size of the Spallation Neutron Source (SNS) ring implies the use of short, large aperture dipole magnets, with significant end field errors. The SNS will contain 32 such dipoles. We report magnetic field measurements of the first 16 magnets. The end field errors have been successfully compensated by the use of iron bumps. For 1.0 GeV protons, the magnets have been shimmed to meet the 0.01% specification for rms variation of the integral field. At 1.3 GeV, the rms variation is 0.036%. The load on the corrector system at 1.3 GeV will be reduced by the use of sorting.
Bent Solenoids with Superimposed Dipole Fields
Energy Technology Data Exchange (ETDEWEB)
Meinke, Rainer, B.; Goodzeit, Carl, L.
2000-03-21
A conceptual design and manufacturing technique were developed for a superconducting bent solenoid magnet with a superimposed dipole field that would be used as a dispersion device in the cooling channel of a future Muon Collider. The considered bent solenoid is equivalent to a 180° section of a toroid with a major radius of ~610 mm and a coil aperture of ~416 mm. The required field components of this magnet are 4 tesla for the solenoid field and 1 tesla for the superimposed dipole field. A magnet of this size and shape, operating at these field levels, has to sustain large Lorentz forces resulting in a maximum magnetic pressure of about 2,000 psi. A flexible round mini-cable with 37 strands of Cu-NbTi was selected as the superconductor. Detailed magnetic analysis showed that it is possible to obtain the required superimposed dipole field by tilting the winding planes of the solenoid by ~25°. A complete structural analysis of the coil support system and the helium containment vessel under thermal, pressure, and Lorentz force loads was carried out using 3D finite element models of the structures. The main technical issues were studied and solutions were worked out so that a highly reliable magnet of this type can be produced at an affordable cost.
Trapped field internal dipole superconducting motor generator
Energy Technology Data Exchange (ETDEWEB)
Hull, John R. (Downers Grove, IL)
2001-01-01
A motor generator including a high temperature superconductor rotor and an internally disposed coil assembly. The motor generator superconductor rotor is constructed of a plurality of superconductor elements magnetized to produce a dipole field. The coil assembly can be either a conventional conductor or a high temperature superconductor. The superconductor rotor elements include a magnetization direction and c-axis for the crystals of the elements and which is oriented along the magnetization direction.
Self quartic interaction for a scalar field in a non-commutative space with Lorentz invariance
Energy Technology Data Exchange (ETDEWEB)
Neves, M.J.; Abreu, Everton M.C. [UFRRJ, Seropedica, RJ (Brazil)
2013-07-01
Full text: The framework Doplicher-Fredenhagen-Roberts (DFR) of a noncommutative (NC) space-time is considered as alternative approach to study the NC space-time of the early Universe. In this formalism, the parameter of noncommutative θ{sup μν} is promoted to a coordinate of the space-time. The consequence of this statement is that we are describing a NC field theory with Lorentz invariance in a space-time with extra-dimension. The addition of a canonical momentum associated to θ-coordinate is a extension of the NC DFR, in which the effects of a new physics can emerge in the propagation of the fields along the extra-dimension. This extension is called Doplicher-Fredenhagen-Roberts-Amorim (DFRA) NC space-time. The main concept that we would like to emphasize from the outset is that the formalism demonstrated here will not be constructed introducing a NC parameter in the system, as usual. It will be generated naturally from an already NC space. We study a scalar field with self-quartic interaction ϕ{sup 4} ∗ in the approach of non-commutative space with Lorentz invariance. We compare the two frameworks, DFR and DFRA NC space-time. We obtain the Feynman rules in the Fourier space for the scalar propagator and vertex. The divergences are analyzed at the one loop approximation, in which the non-commutativity scale can improve the ultraviolet behavior for the mass correction in the propagator. (author)
International Nuclear Information System (INIS)
Gopakumar, R.
2002-01-01
Though noncommutative field theories have been explored for several years, a resurgence of interest in it was sparked off after it was realised that they arise very naturally as limits of string theory in certain background fields. It became more plausible (at least to string theorists) that these nonlocal deformations of usual quantum field theories are consistent theories in themselves. This led to a detailed exploration of many of their classical and quantum properties. I will elaborate further on the string theory context in the next section. One of the consequences of this exploration was the discovery of novel classical solutions in noncommutative field theories. Since then much work has been done in exploring many of their novel properties. My lectures focussed on some specific aspects of these noncommutative solitons. They primarily reflect the topics that I have worked on and are not intended to be a survey of the large amount of work on this topic. We have tried to give a flavour of the physics that can be captured by the relatively elementary classical solutions of noncommutative field theories. We have seen in different contexts how these solitons are really simple manifestations of D-branes, possessing many of their important features. Though they have been primarily studied in the context of tachyon condensation, we saw that they can also shed some light on the resolution of singularities in spacetime by D-brane probes. In addition to other applications in string theory it is important at this stage to explore their presence in other systems with a strong magnetic field like the quantum hall effect
Neutral dipole-dipole dimers: A new field in science
Kosower, Edward M.; Borz, Galina
2018-03-01
Dimer formation with dipole neutralization produces species such as low polarity water (LPW) compatible with hydrophobic surfaces (Phys. Chem. Chem. Phys. 2015, 17, 24895-24900) Dimerization and dipole neutralization occurs for N-methylacetamide on polyethylene, a behavior drastically different from its contortions in acetonitrile on AgBr:AgCl planar crystals (AgX) (ChemPhysChem 2014, 15, 3598-3607). The weak infrared absorption of the amide dimer on polyethylene is shown experimentally. Dimerization of palmitic acid is shown along with some of the many ramifications for intracellular systems. Polyoligomers of water are present on polyethylene surfaces. Some high resolution spectra of three of the polyoligomers of water are shown along with a mechanistic scheme for polyoligomer formation and dissolution. The structures of some of the oligomers are known from spectroscopic studies of water on AgX. The scope of the article begins with PE, generally accepted as hydrophobic. The IR of PE revealed not only that water was present but that it appeared in two forms, oligomers (O) and polyoligomers (PO). How did we recognize what they were? These species had been observed as especially strong "marker" peaks in the spectra1 of water placed on planar AgX, a platform developed by Katzir and his coworkers [6]. But there was a problem: the proximity to PE of oligomers with substantial (calculated) dipole moments and thus polarity, including cyclic hexamers of water (chair and boat forms), the cyclic pentamer, the books I and II, and the cyclic trimer [7a]. Another link was needed, a role perfectly fit by the already cited low polarity water (LPW). The choice was experimentally supported by the detection of low intensity absorption in the bending region.Some important generalities flow from these results. What other dimers might be present in the biological or chemical world? Palmitic acid dimer (PAD) would be a candidate for decreasing the polarity of the acid (PA). Another
Holographic thermalization in noncommutative geometry
Directory of Open Access Journals (Sweden)
Xiao-Xiong Zeng
2015-05-01
Full Text Available Gravitational collapse of a shell of dust in noncommutative geometry is probed by the renormalized geodesic length, which is dual to probe the thermalization by the two-point correlation function in the dual conformal field theory. We find that the larger the noncommutative parameter is, the longer the thermalization time is, which implies that the large noncommutative parameter delays the thermalization process. We also investigate how the noncommutative parameter affects the thermalization velocity and thermalization acceleration.
From quantum gravity to quantum field theory via noncommutative geometry
International Nuclear Information System (INIS)
Aastrup, Johannes; Grimstrup, Jesper Møller
2014-01-01
A link between canonical quantum gravity and fermionic quantum field theory is established in this paper. From a spectral triple construction, which encodes the kinematics of quantum gravity, we construct semi-classical states which, in a semi-classical limit, give a system of interacting fermions in an ambient gravitational field. The emergent interaction involves flux tubes of the gravitational field. In the additional limit, where all gravitational degrees of freedom are turned off, a free fermionic quantum field theory emerges. (paper)
A summary of SSC dipole magnet field quality measurements
International Nuclear Information System (INIS)
Wanderer, P.; Anerella, M.; Cottingham, J.; Ganetis, G.; Garber, M.; Ghosh, A.; Greene, A.; Gupta, R.; Jain, A.; Kahn, S.; Kelly, E.; Morgan, G.; Muratore, J.; Prodell, A.; Rehak, M.; Rohrer, E.P.; Sampson, W.; Shutt, R.; Thomas, R.; Thompson, P.; Willen, E.; Devred, A.; Bush, T.; Coombes, R.; DiMarco, J.; Goodzeit, C.; Kuzminski, J.; Nah, W.; Ogitsu, T.; Puglisi, M.; Radusewicz, P.; Sanger, P.; Schermer, R.; Tompkins, J.; Turner, J.; Yu, Y.; Zhao, Y.; Zheng, H.; Bleadon, M.; Bossert, R.; Carson, J.; Delchamps, S.; Gourlay, S.; Hanft, R.; Koska, W.; Kuchnir, M.; Lamm, M.; Mantsch, P.; Mazur, P.O.; Orris, D.; Peterson, T.; Strait, J.; Wake, M.; Royet, J.; Scanlan, R.; Taylor, C.
1992-01-01
This paper reports results of field quality measurements of the initial 15 m-long, 50 mm- aperture SSC Collider dipoles tested at Brookhaven National Laboratory and Fermi National Laboratory. These data include multipole coefficients and the dipole angle at room temperature and 4.35 K, 4.35 K integral field measurements, and time-dependent effects. Systematic uncertainties are also discussed
Towards Noncommutative Topological Quantum Field Theory: Tangential Hodge-Witten cohomology
International Nuclear Information System (INIS)
Zois, I P
2014-01-01
Some years ago we initiated a program to define Noncommutative Topological Quantum Field Theory (see [1]). The motivation came both from physics and mathematics: On the one hand, as far as physics is concerned, following the well-known holography principle of 't Hooft (which in turn appears essentially as a generalisation of the Hawking formula for black hole entropy), quantum gravity should be a topological quantum field theory. On the other hand as far as mathematics is concerned, the motivation came from the idea to replace the moduli space of flat connections with the Gabai moduli space of codim-1 taut foliations for 3 dim manifolds. In most cases the later is finite and much better behaved and one might use it to define some version of Donaldson-Floer homology which, hopefully, would be easier to compute. The use of foliations brings noncommutative geometry techniques immediately into the game. The basic tools are two: Cyclic cohomology of the corresponding foliation C*-algebra and the so called ''tangential cohomology'' of the foliation. A necessary step towards this goal is to develop some sort of Hodge theory both for cyclic (and Hochschild) cohomology and for tangential cohomology. Here we present a method to develop a Hodge theory for tangential cohomology of foliations by mimicing Witten's approach to ordinary Morse theory by perturbations of the Laplacian
Towards Noncommutative Topological Quantum Field Theory – Hodge theory for cyclic cohomology
International Nuclear Information System (INIS)
Zois, I P
2014-01-01
Some years ago we initiated a program to define Noncommutative Topological Quantum Field Theory (see [1]). The motivation came both from physics and mathematics: On the one hand, as far as physics is concerned, following the well-known holography principle of 't Hooft (which in turn appears essentially as a generalisation of the Hawking formula for black hole entropy), quantum gravity should be a topological quantum field theory. On the other hand as far as mathematics is concerned, the motivation came from the idea to replace the moduli space of flat connections with the Gabai moduli space of codim-1 taut foliations for 3 dim manifolds. In most cases the later is finite and much better behaved and one might use it to define some version of Donaldson-Floer homology which, hopefully, would be easier to compute. The use of foliations brings noncommutative geometry techniques immediately into the game. The basic tools are two: Cyclic cohomology of the corresponding foliation C*-algebra and the so called ''tangential cohomology'' of the foliation. A necessary step towards this goal is to develop some sort of Hodge theory both for cyclic (and Hochschild) cohomology and for tangential cohomology. Here we present a method to develop a Hodge theory for cyclic and Hochschild cohomology for the corresponding C*-algebra of a foliation
Design, construction, and field mapping of the HISTRAP prototype dipole
International Nuclear Information System (INIS)
Tatum, B.A.; Dowling, D.T.; Lord, R.S.; Mosko, S.W.; Olsen, D.K.
1989-01-01
HISTRAP is a proposed 2.67 T-m synchrotron-cooler-storage ring having eight 45/degree/, C-design dipole magnets. A prototype dipole has been designed, fabricated, and mapped. The magnet design utilizes curved and angled coil ends to compensate for end effects in the field. Construction of the prototype dipole has been completed by the FNAL magnet factory. The magnetic field has been mapped using a Hall-effect probe afixed to a newly constructed, PC-based, horizontal positioning system. Results of the field mapping are presented. 6 refs., 7 figs., 1 tabs
Interaction between two magnetic dipoles in a uniform magnetic field
Ku, J. G.; Liu, X. Y.; Chen, H. H.; Deng, R. D.; Yan, Q. X.
2016-02-01
A new formula for the interaction force between two magnetic dipoles in a uniform magnetic field is derived taking their mutual magnetic interaction into consideration and used to simulate their relative motion. Results show that when the angle β between the direction of external magnetic field and the centerline of two magnetic dipoles is 0 ° or 90 °, magnetic dipoles approach each other or move away from each other in a straight line, respectively. And the time required for them to contact each other from the initial position is related to the specific susceptibility and the diameter of magnetic particles, medium viscosity and magnetic field strength. When β is between 0 ° and 90 °, magnetic dipole pair performs approximate elliptical motion, and the motion trajectory is affected by the specific susceptibility, diameter and medium viscosity but not magnetic field strength. However, time required for magnetic dipoles to complete the same motion trajectory is shorter when adopting stronger magnetic field. Moreover, the subsequent motion trajectory of magnetic dipoles is ascertained once the initial position is set in a predetermined motion trajectory. Additionally, magnetic potential energy of magnetic dipole pairs is transformed into kinetic energy and friction energy during the motion.
Interaction between two magnetic dipoles in a uniform magnetic field
Directory of Open Access Journals (Sweden)
J. G. Ku
2016-02-01
Full Text Available A new formula for the interaction force between two magnetic dipoles in a uniform magnetic field is derived taking their mutual magnetic interaction into consideration and used to simulate their relative motion. Results show that when the angle β between the direction of external magnetic field and the centerline of two magnetic dipoles is 0 ° or 90 °, magnetic dipoles approach each other or move away from each other in a straight line, respectively. And the time required for them to contact each other from the initial position is related to the specific susceptibility and the diameter of magnetic particles, medium viscosity and magnetic field strength. When β is between 0 ° and 90 °, magnetic dipole pair performs approximate elliptical motion, and the motion trajectory is affected by the specific susceptibility, diameter and medium viscosity but not magnetic field strength. However, time required for magnetic dipoles to complete the same motion trajectory is shorter when adopting stronger magnetic field. Moreover, the subsequent motion trajectory of magnetic dipoles is ascertained once the initial position is set in a predetermined motion trajectory. Additionally, magnetic potential energy of magnetic dipole pairs is transformed into kinetic energy and friction energy during the motion.
A summary of SSC dipole magnet field quality measurements
Energy Technology Data Exchange (ETDEWEB)
Wanderer, P.; Anerella, M.; Cottingham, J.; Ganetis, G.; Garber, M.; Ghosh, A.; Greene, A.; Gupta, R.; Jain, A.; Kahn, S.; Kelly, E.; Morgan, G.; Muratore, J.; Prodell, A.; Rehak, M.; Rohrer, E.P.; Sampson, W.; Shutt, R.; Thomas, R.; Thompson, P.; Willen, E. [Brookhaven National Lab., Upton, NY (United States); Devred, A.; Bush, T.; Coombes, R.; DiMarco, J.; Goodzeit, C.; Kuzminski, J.; Nah, W.; Ogitsu, T.; Puglisi, M.; Radusewicz, P.; Sanger, P.; Schermer, R.; Tompkins, J.; Turner, J.; Yu, Y.; Zhao, Y.; Zheng, H. [Superconducting Super Collider Lab., Dallas, TX (United States); Bleadon, M.; Bossert, R.; Carson, J.; Delchamps, S.; Gourlay, S.; Hanft, R.; Koska, W.; Kuchnir, M.; Lamm, M.; Mantsch, P.; Mazur, P.O.; Orris, D.; Peterson, T.; Strait, J.; Wake, M. [Fermi National Accelerator Lab., Batavia, IL (United States); Royet, J.; Scanlan, R.; Taylor, C. [Lawrence Berkeley Lab., CA (United States)
1992-03-01
This paper reports results of field quality measurements of the initial 15 m-long, 50 mm-aperture SSC Collider dipoles tested at Brookhaven National Laboratory and Fermi National Laboratory. These data include multipole coefficients and the dipole angle at room temperature and 4.35 K, 4.35 K integral field measurements, and time-dependent effects. Systematic uncertainties are also discussed.
Magnetic field measurements of model SSC [Superconducting Super Collider] dipoles
International Nuclear Information System (INIS)
Hassenzahl, W.V.; Gilbert, W.S.; Green, M.I.; Barale, P.J.
1986-10-01
To qualify for use in the Superconducting Super Collider, the 8000 or so 16 m long dipole magnets must pass a series of tests. One of these will be a set of warm measurements of field quality, which must be precise to about 0.001% of the 100 G field produced by 10 A, the maximum current the coils are allowed to carry for an extended period at room temperature. Field measurements of better than this accuracy have already been carried out on 1 m long model dipoles. These measurements have included determinations of the dipole fields and the higher harmonics in the central or two dimensional region and in the total magnet. In addition, axial scans of the dipole and higher harmonic magnetic fields have been made to determine the local variations, which might reflect fabrication and assembly tolerances. This paper describes the equipment developed for these measurements, the results of a representative set of measurements of the central and integral fields and axial scans, and a comparison between warm and cold measurements. Reproducibility, accuracy and precision will be described for some of the measurements. The significance of the warm measurements as a part of the certification process for the SSC dipoles will be discussed
Field quality issues in iron-dominated dipoles at low fields
International Nuclear Information System (INIS)
Brown, B.C.
1996-10-01
In order to help assess the usable dynamic range of iron-dominated dipoles, field shape data at low field on several Fermi-lab accelerator dipole designs are presented. Emphasis is placed on the systematic and random values of the low field sextupole since it is the first ''allowed'' field error. The Main Injector dipoles provide four times smaller sextupole and more than 20 times less sextupole hysteresis than earlier designs for the Main Ring
Stability of high field superconducting dipole magnets
International Nuclear Information System (INIS)
Allinger, J.; Danby, G.; Foelsche, H.; Jackson, J.; Prodell, A.; Stevens, A.
1977-01-01
Superconducting dipole magnets of the window-frame type were constructed and operated successfully at Brookhaven National Laboratory. Examples of this type of magnet are the 6 T ''Model T'' magnet, and the 4 T 8 0 superconducting bending magnet. The latter magnet operated reliably since October 1973 as part of the proton beam transport to the north experimental area at the BNL AGS with intensities of typically 8 x 10 12 protons at 28.5 GeV/c passing through the magnet in a curved trajectory with the proton beam center only 2.0 cm from the beam pipe at both ends and the middle of each of the two units comprising the magnet. The energy in the beam is approximately 40 kJ per 3 μsec pulse. Targets were inserted in the beam at locations 2 m and 5.6 m upstream of the first magnet unit to observe the effects of radiation heating. The 8 0 magnet demonstrated ultrastability, surviving 3 μsec thermal pulses delivering up to 1 kJ into the cold magnet at repetition periods as short as 1.3 sec
Long-term dipole-dipole resistivity monitoring at the Cerro Prieto geothermal field
Energy Technology Data Exchange (ETDEWEB)
Wilt, M.; Goldstein, N.E.; Sasaki, Y.
1984-04-01
Dipole-dipole resistivity measurements for the combined purposes of reservoir delineation and reservoir monitoring were first made at Cerro Prieto in 1978 and have continued on approximately an annual basis since then. Two 20 km-long dipole-dipole lines with permanently emplaced electrodes at 1-km spacings were established over the field area. Resistivity remeasurements have been made on one line at 6- to 18-month intervals using a 25 kW generator capable of up to 80A output and a microprocessor-controlled signal-averaging receiver. This high-power, low-noise system provides highly accurate measurements even at large transmitter receiver separations. Standard error calculations for collected data indicate errors less than 5% for all points. Results from four years of monitoring (1979-1983) indicate a 5% average annual increase in apparent resistivity over the present production area, and larger decreases in apparent resistivity in the region to the east. The increase in resistivity in the production zone is most likely due to dilution of reservoir fluids with fresher water, as evidenced by a drop in chloride content of produced waters. The area of decreasing resistivity east of the reservoir is associated with a steeply dipping conductive body, a zone of higher thermal gradients and an increase in shale thickness in the section. Decreasing resistivity in this area may be caused by an influx of high temperature, saline water from depths of 3/sup +/ km through a sandy gap in the shales.
Energy Technology Data Exchange (ETDEWEB)
Fischer, Andre
2011-02-10
In this thesis we construct a class of noncommutative quantum field theories on Minkowski spacetime via an analytical continuation of the Euclidean Grosse-Wulkenhaar and LSZ models, which are defined by a perturbative setting based on modified Feynman diagrams. Characteristic of these theories is the presence of a constant, external electromagnetic field, which renders their ultraviolet and infrared regimes indistinguishable. This feature is known as LS-duality and is believed to be responsible for the renormalizability and vanishing of the {beta}-functions in the Euclidean case. We introduce an alternative to the i{epsilon}-prescription of these Minkowskian models, which is shown to lead to causal propagators. This regularization allows us to map the LS-covariant theories onto matrix models via a generalization of the Landau basis, and to impose a simultaneous UV und IR-regularization of the Feynmann diagrams, while keeping the LS-duality manifestly. A new quality on Minkowski spacetime is the instability of the vacuum with respect to pair production, which is due to the lack of translation invariance caused by the electromagnetic field. We discuss its implication on the perturbative expansion and the unitarity of the scattering matrix. As a first step towards a renormalization of these theories, we derive the corresponding propagators in Minkowski spacetime in position and matrix representation and discuss their asymptotics. (orig.)
Energy Technology Data Exchange (ETDEWEB)
Huang, Wung-Hong; Du, Yi-Hsien [Department of Physics, National Cheng Kung University,No. 1, University Road, Tainan City 701, Taiwan (China)
2017-02-07
We apply the transformation of mixing azimuthal and internal coordinate or mixing time and internal coordinate to a stack of N black M-branes to find the Melvin spacetime of a stack of N black D-branes with magnetic or electric flux in string theory, after the Kaluza-Klein reduction. We slightly extend previous formulas to investigate the external magnetic and electric effects on the butterfly effect and holographic mutual information. It shows that the Melvin fields do not modify the scrambling time and will enhance the mutual information. In addition, we also T-dualize and twist a stack of N black D-branes to find a Melvin Universe supported by the flux of the NSNS b-field, which describes a non-comutative spacetime. It also shows that the spatial noncommutativity does not modify the scrambling time and will enhance the mutual information. We also study the corrected mutual information in the backreaction geometry due to the shock wave in our three model spacetimes.
Space/time noncommutativity in string theories without background electric field
International Nuclear Information System (INIS)
De Risi, Giuseppe; Grignani, Gianluca; Orselli, Marta
2002-01-01
The appearance of space/time non-commutativity in theories of open strings with a constant non-diagonal background metric is considered. We show that, even if the space-time coordinates commute, when there is a metric with a time-space component, no electric field and the boundary condition along the spatial direction is Dirichlet, a Moyal phase still arises in products of vertex operators. The theory is in fact dual to the non-commutatitive open string (NCOS) theory. The correct definition of the vertex operators for this theory is provided. We study the system also in the presence of a B field. We consider the case in which the Dirichlet spatial direction is compactified and analyze the effect of these backgrounds on the closed string spectrum. We then heat up the system. We find that the Hagedorn temperature depends in a non-extensive way on the parameters of the background and it is the same for the closed and the open string sectors. (author)
Electromagnetic fields of ionospheric point dipoles in the earthionosphere waveguide
International Nuclear Information System (INIS)
Rybachek, S.T.
1985-01-01
This paper addresses the problem of excitation of the spherical earth-anisotropic ionosphere waveguide by ionospheric dipole sources. The solution obtained is based on a generalized reciprocity theorem which provides a relationship to the problem of finding electromagnetic fields in the ionosphere created by sources located in the waveguide. Some results of the calculations are presented
The Electromagnetic Dipole Radiation Field through the Hamiltonian Approach
Likar, A.; Razpet, N.
2009-01-01
The dipole radiation from an oscillating charge is treated using the Hamiltonian approach to electrodynamics where the concept of cavity modes plays a central role. We show that the calculation of the radiation field can be obtained in a closed form within this approach by emphasizing the role of coherence between the cavity modes, which is…
Space-time symmetries of noncommutative spaces
International Nuclear Information System (INIS)
Calmet, Xavier
2005-01-01
We define a noncommutative Lorentz symmetry for canonical noncommutative spaces. The noncommutative vector fields and the derivatives transform under a deformed Lorentz transformation. We show that the star product is invariant under noncommutative Lorentz transformations. We then apply our idea to the case of actions obtained by expanding the star product and the fields taken in the enveloping algebra via the Seiberg-Witten maps and verify that these actions are invariant under these new noncommutative Lorentz transformations. We finally consider general coordinate transformations and show that the metric is undeformed
A design proposal for high field dipole magnet
International Nuclear Information System (INIS)
Hirabayashi, H.; Kobayashi, M.; Shintomi, T.; Tsuchiya, K.; Wake, M.
1981-06-01
A design of the high field dipole magnet which is going to be constructed in the KEK-Fermilab collaboration program is proposed. The central field of the magnet is meant to achieve 10 T by the use of ternary alloy conductor in the 1.8 K superfluid environment under atmospheric pressure. Since the electro-magnetic force in such a high field region is strong enough to give a fatal problem, a careful calculation is necessary for the magnet design. The program POISSON and LINDA were used for the magnetic field calculation. The computer code ISAS which is originated from NASTRAN developed at NASA was applied to calculate the stress and the deformation. A horizontal cryostat desigh for the operation of the 10 T dipole magnet is also proposed. (author)
On field line resonances of hydromagnetic Alfven waves in dipole magnetic field
International Nuclear Information System (INIS)
Chen, Liu; Cowley, S.C.
1989-07-01
Using the dipole magnetic field model, we have developed the theory of field line resonances of hydromagnetic Alfven waves in general magnetic field geometries. In this model, the Alfven speed thus varies both perpendicular and parallel to the magnetic field. Specifically, it is found that field line resonances do persist in the dipole model. The corresponding singular solutions near the resonant field lines as well as the natural definition of standing shear Alfven eigenfunctions have also been systematically derived. 11 refs
A finite element field solver for dipole modes
International Nuclear Information System (INIS)
Nelson, E.M.
1992-01-01
A finite element field solver for dipole modes in axisymmetric structures has been written. The second-order elements used in this formulation yield accurate mode frequencies with no spurious modes. Quasi-periodic boundaries are included to allow travelling waves in periodic structures. The solver is useful in applications requiring precise frequency calculations such as detuned accelerator structures for linear colliders. Comparisons are made with measurements and with the popular but less accurate field solver URMEL. (author). 7 refs., 4 figs
Interaction of counter-streaming plasma flows in dipole magnetic field
Shaikhislamov, I F; Posukh, V G; Melekhov, A V; Prokopov, P A; Boyarintsev, E L; Zakharov, Yu P; Ponomarenko, A G
2017-01-01
Transient interaction of counter-streaming super-sonic plasma flows in dipole magnetic dipole is studied in laboratory experiment. First quasi-stationary flow is produced by teta-pinch and forms a magnetosphere around the magnetic dipole while laser beams focused at the surface of the dipole cover launch second explosive plasma expanding from inner dipole region outward. Laser plasma is energetic enough to disrupt magnetic field and to sweep through the background plasma for large distances. ...
Design considerations for a large aperture high field superconducting dipole
Energy Technology Data Exchange (ETDEWEB)
Harfoush, F.; Ankenbrandt, C.; Harrison, M.; Kerby, J.; Koepke, K.; Mantsch, P.; Nicol, T.; Riddiford, A.; Theilacker, J.
1989-03-01
The final phase of the Fermilab upgrade proposal calls for a new ring of superconducting magnets to be placed in the existing Main Accelerator tunnel. The goal of this design study is to specify a high field dipole (HFD) that is capable of supporting fixed target operation (ramping, resonant extraction) at a field of 6.6T (1.5 Tev) and colliding beam physics at 8.0T (1.8 Tev). The magnetic field quality at high field is set by the large amplitude orbits associated with resonant extraction. The field quality must therefore be at least as good as the existing Tevatron magnets which fulfill these criteria. The high fields and large aperture of this magnet result in large forces on the coil and collar assemblies. Therefore, the cold mass design must be able to sustain these forces while providing sufficient cooling to the coils during 4.2 K fixed target operation, and a minimum heat load during 1.8 K collider operation. The design work is still in progress but a cosine-theta, cold-iron dipole with a 70mm inner diameter coil has been tentatively adopted. This report presents details on the conductor and cable parameters, coil cross-section, projected manufacturing tolerances, iron yoke design, and cold mass assembly. 4 refs., 5 figs., 1 tab.
Design considerations for a large aperture high field superconducting dipole
International Nuclear Information System (INIS)
Harfoush, F.; Ankenbrandt, C.; Harrison, M.; Kerby, J.; Koepke, K.; Mantsch, P.; Nicol, T.; Riddiford, A.; Theilacker, J.
1989-03-01
The final phase of the Fermilab upgrade proposal calls for a new ring of superconducting magnets to be placed in the existing Main Accelerator tunnel. The goal of this design study is to specify a high field dipole (HFD) that is capable of supporting fixed target operation (ramping, resonant extraction) at a field of 6.6T (1.5 Tev) and colliding beam physics at 8.0T (1.8 Tev). The magnetic field quality at high field is set by the large amplitude orbits associated with resonant extraction. The field quality must therefore be at least as good as the existing Tevatron magnets which fulfill these criteria. The high fields and large aperture of this magnet result in large forces on the coil and collar assemblies. Therefore, the cold mass design must be able to sustain these forces while providing sufficient cooling to the coils during 4.2 K fixed target operation, and a minimum heat load during 1.8 K collider operation. The design work is still in progress but a cosine-theta, cold-iron dipole with a 70mm inner diameter coil has been tentatively adopted. This report presents details on the conductor and cable parameters, coil cross-section, projected manufacturing tolerances, iron yoke design, and cold mass assembly. 4 refs., 5 figs., 1 tab
Visualizing Special Relativity: The Field of An Electric Dipole Moving at Relativistic Speed
Smith, Glenn S.
2011-01-01
The electromagnetic field is determined for a time-varying electric dipole moving with a constant velocity that is parallel to its moment. Graphics are used to visualize this field in the rest frame of the dipole and in the laboratory frame when the dipole is moving at relativistic speed. Various phenomena from special relativity are clearly…
Kwaadgras, Bas W.; Van Roij, René; Dijkstra, Marjolein
2014-01-01
When calculating the interaction between electric field-induced dipoles, the dipole moments are often taken to be equal to their polarizability multiplied by the external electric field. However, this approach is not exact, since it does not take into account the fact that particles with a dipole
Scattering theory of space-time non-commutative abelian gauge field theory
International Nuclear Information System (INIS)
Rim, Chaiho; Yee, Jaehyung
2005-01-01
The unitary S-matrix for space-time non-commutative quantum electrodynamics is constructed using the *-time ordering which is needed in the presence of derivative interactions. Based on this S-matrix, we formulate the perturbation theory and present the Feynman rule. We then apply this perturbation analysis to the Compton scattering process to the lowest order and check the gauge invariance of the scattering amplitude at this order.
Young's moduli of cables for high field superconductive dipole magnet
International Nuclear Information System (INIS)
Yamada, Shunji; Shintomi, Takakazu.
1983-01-01
Superconductive dipole magnets for big accelerators are subjected to enormous electro-magnetic force, when they are operated with high field such as 10 Tesla. They should be constructed by means of superconductive cables, which have high Young's modulus, to obtain good performance. To develop such cables we measured the Young's moduli of cables for practical use of accelerator magnets. They are monolithic and compacted strand cables. We measured also Young's moduli of monolithic copper and brass cables for comparison. The obtained data showed the Young's moduli of 35 and 15 GPa for the monolithic and compacted strand cables, respectively. (author)
Electromagnetic fields due to dipole antennas over stratified anisotropic media.
Kong, J. A.
1972-01-01
Solutions to the problem of radiation of dipole antennas in the presence of a stratified anisotropic media are facilitated by decomposing a general wave field into transverse magnetic (TM) and transverse electric (TE) modes. Employing the propagation matrices, wave amplitudes in any region are related to those in any other regions. The reflection coefficients, which embed all the information about the geometrical configuration and the physical constituents of the medium, are obtained in closed form. In view of the general formulation, various special cases are discussed.
Bonezzi, Roberto; Boulanger, Nicolas; De Filippi, David; Sundell, Per
2017-11-01
We first prove that, in Vasiliev’s theory, the zero-form charges studied in Sezgin E and Sundell P 2011 (arXiv:1103.2360 [hep-th]) and Colombo N and Sundell P 20 (arXiv:1208.3880 [hep-th]) are twisted open Wilson lines in the noncommutative Z space. This is shown by mapping Vasiliev’s higher-spin model on noncommutative Yang–Mills theory. We then prove that, prior to Bose-symmetrising, the cyclically-symmetric higher-spin invariants given by the leading order of these n-point zero-form charges are equal to corresponding cyclically-invariant building blocks of n-point correlation functions of bilinear operators in free conformal field theories (CFT) in three dimensions. On the higher spin gravity side, our computation reproduces the results of Didenko V and Skvortsov E 2013 J. High Energy Phys. JHEP04(2013)158 using an alternative method amenable to the computation of subleading corrections obtained by perturbation theory in normal order. On the free CFT side, our proof involves the explicit computation of the separate cyclic building blocks of the correlation functions of n conserved currents in arbitrary dimension d>2 using polarization vectors, which is an original result. It is shown to agree, for d=3 , with the results obtained in Gelfond O A and Vasiliev M A 2013 Nucl. Phys. B 876 871–917 in various dimensions and where polarization spinors were used.
Dipole-magnet field models based on a conformal map
Directory of Open Access Journals (Sweden)
P. L. Walstrom
2012-10-01
Full Text Available In general, generation of charged-particle transfer maps for conventional iron-pole-piece dipole magnets to third and higher order requires a model for the midplane field profile and its transverse derivatives (soft-edge model to high order and numerical integration of map coefficients. An exact treatment of the problem for a particular magnet requires use of measured magnetic data. However, in initial design of beam transport systems, users of charged-particle optics codes generally rely on magnet models built into the codes. Indeed, if maps to third order are adequate for the problem, an approximate analytic field model together with numerical map coefficient integration can capture the important features of the transfer map. The model described in this paper is based on the fact that, except at very large distances from the magnet, the magnetic field for parallel pole-face magnets with constant pole gap height and wide pole faces is basically two dimensional (2D. The field for all space outside of the pole pieces is given by a single (complex analytic expression and includes a parameter that controls the rate of falloff of the fringe field. Since the field function is analytic in the complex plane outside of the pole pieces, it satisfies two basic requirements of a field model for higher-order map codes: it is infinitely differentiable at the midplane and also a solution of the Laplace equation. It is apparently the only simple model available that combines an exponential approach to the central field with an inverse cubic falloff of field at large distances from the magnet in a single expression. The model is not intended for detailed fitting of magnetic field data, but for use in numerical map-generating codes for studying the effect of extended fringe fields on higher-order transfer maps. It is based on conformally mapping the area between the pole pieces to the upper half plane, and placing current filaments on the pole faces. An
Anatomy of Two-Loop Effective Action in Noncommutative Field Theories
Kiem, Young-jai; Rey, Soo-Jong; Sato, Haru-Tada
2002-01-01
We compute, at two-loop order, one-particle-irreducible Green functions and effective action in noncommutative $\\lambda[\\Phi^3]_\\star$-theory for both planar (g=0, h=3) and nonplanar (g=1, h=1) contributions. We adopt worldline formulation of the Feynman diagrammatics so that relation to string theory diagrammatics is made transparent in the Seiberg-Witten limit. We argue that the resulting two-loop effective action is expressible via open Wilson lines: one-particle-irreducible effective action is generating functional of connected diagrams for interacting open Wilson lines.
Quantum Phase Shift of a Moving Dipole under a Magnetic Field at a Distance
Lee, Kang-Ho; Kim, Young-Wan; Kang, Kicheon
2018-03-01
We predict a quantum phase shift of a moving electric dipole in the presence of an external magnetic field at a distance. On the basis of the Lorentz-covariant field interaction approach, we show that a phase shift appears in the internal dipole state under the condition that the dipole is moving in the field-free region, which is distinct from the topological He-McKellar-Wilkens phase generated by a direct overlap of the dipole and the field. We discuss the experimental feasibility of detecting this phase with atomic interferometry and argue that detection of this phase will resolve the question of the locality in quantum electromagnetic interaction.
Electric dipole moments of light nuclei in effective field theory
Energy Technology Data Exchange (ETDEWEB)
Bsaisou, Jan; Liebig, Susanna; Minossi, David [Institut fuer Kernphysik, Forschungszentrum Juelich (Germany); Juelich Center for Hadron Physics, Forschungszentrum Juelich (Germany); Hanhart, Christoph; Nogga, Andreas; Vries, Jordy de; Wirzba, Andreas [Institut fuer Kernphysik, Forschungszentrum Juelich (Germany); Juelich Center for Hadron Physics, Forschungszentrum Juelich (Germany); Institute for Advanced Simulation, Forschungszentrum Juelich (Germany); JARA - Forces and Matter Experiments, Forschungszentrum Juelich (Germany); Meissner, UlfG. [Institut fuer Kernphysik, Forschungszentrum Juelich (Germany); Juelich Center for Hadron Physics, Forschungszentrum Juelich (Germany); Institute for Advanced Simulation, Forschungszentrum Juelich (Germany); JARA - Forces and Matter Experiments, Forschungszentrum Juelich (Germany); Helmholtz-Institut fuer Strahlen und Kernphysik, Universitaet Bonn (Germany)
2014-07-01
Electric dipole moments (EDMs) break parity (P) and time-reversal (T) symmetry and thus, by the CPT-theorem, CP-symmetry. Once measured, they will be unambiguous signs of new physics since CP-violation from the standard mechanism predicts EDMs that are experimentally inaccessible in the foreseeable future. We calculate within the framework of effective field theory the two-nucleon contributions to the EDMs of the deuteron, helion, and triton induced by P- and T-violating terms that arise from the QCD θ-term or dimension-6 sources of physics beyond the Standard Model (SM). We demonstrate what insights into physics beyond the SM can be gained from a suitable combination of measurements and, if needed, supplementary lattice QCD calculations.
Some remarks on K_0 of noncommutative tori
Chakraborty, Sayan
2017-01-01
Using Rieffel's construction of projective modules over higher dimensional noncommutative tori, we construct projective modules over some continuous field of C*-algebras whose fibers are noncommutative tori. Using a result of Echterhoff et al., our construction gives generators of K_0 of all noncommutative tori.
Jorgensen, Palle
2017-01-01
The book features new directions in analysis, with an emphasis on Hilbert space, mathematical physics, and stochastic processes. We interpret 'non-commutative analysis' broadly to include representations of non-Abelian groups, and non-Abelian algebras; emphasis on Lie groups and operator algebras (C* algebras and von Neumann algebras.)A second theme is commutative and non-commutative harmonic analysis, spectral theory, operator theory and their applications. The list of topics includes shift invariant spaces, group action in differential geometry, and frame theory (over-complete bases) and their applications to engineering (signal processing and multiplexing), projective multi-resolutions, and free probability algebras.The book serves as an accessible introduction, offering a timeless presentation, attractive and accessible to students, both in mathematics and in neighboring fields.
Noncommutative induced gauge theories on Moyal spaces
International Nuclear Information System (INIS)
Wallet, J-C
2008-01-01
Noncommutative field theories on Moyal spaces can be conveniently handled within a framework of noncommutative geometry. Several renormalisable matter field theories that are now identified are briefly reviewed. The construction of renormalisable gauge theories on these noncommutative Moyal spaces, which remains so far a challenging problem, is then closely examined. The computation in 4-D of the one-loop effective gauge theory generated from the integration over a scalar field appearing in a renormalisable theory minimally coupled to an external gauge potential is presented. The gauge invariant effective action is found to involve, beyond the expected noncommutative version of the pure Yang-Mills action, additional terms that may be interpreted as the gauge theory counterpart of the harmonic term, which for the noncommutative ψ 4 -theory on Moyal space ensures renormalisability. A class of possible candidates for renormalisable gauge theory actions defined on Moyal space is presented and discussed
Cardy-Verlinde Formula of Noncommutative Schwarzschild Black Hole
Directory of Open Access Journals (Sweden)
G. Abbas
2014-01-01
Full Text Available Few years ago, Setare (2006 has investigated the Cardy-Verlinde formula of noncommutative black hole obtained by noncommutativity of coordinates. In this paper, we apply the same procedure to a noncommutative black hole obtained by the coordinate coherent approach. The Cardy-Verlinde formula is entropy formula of conformal field theory in an arbitrary dimension. It relates the entropy of conformal field theory to its total energy and Casimir energy. In this paper, we have calculated the total energy and Casimir energy of noncommutative Schwarzschild black hole and have shown that entropy of noncommutative Schwarzschild black hole horizon can be expressed in terms of Cardy-Verlinde formula.
On noncommutative open string theories
International Nuclear Information System (INIS)
Russo, J.G.; Sheikh-Jabbari, M.M.
2000-08-01
We investigate new compactifications of OM theory giving rise to a 3+1 dimensional open string theory with noncommutative x 0 -x 1 and x 2 -x 3 coordinates. The theory can be directly obtained by starting with a D3 brane with parallel (near critical) electric and magnetic field components, in the presence of a RR scalar field. The magnetic parameter permits to interpolate continuously between the x 0 -x 1 noncommutative open string theory and the x 2 -x 3 spatial noncommutative U(N) super Yang-Mills theory. We discuss SL(2, Z) transformations of this theory. Using the supergravity description of the large N limit, we also compute corrections to the quark-antiquark Coulomb potential arising in the NCOS theory. (author)
Electromagnetic Ion Cyclotron Wavefields in a Realistic Dipole Field
Denton, R. E.
2018-02-01
The latitudinal distribution and properties of electromagnetic ion cyclotron (EMIC) waves determine the total effect of those waves on relativistic electrons. Here we describe the latitudinal variation of EMIC waves simulated self-consistently in a dipole magnetic field for a plasmasphere or plume-like plasma at geostationary orbit with cold H+, He+, and O+ and hot protons with temperature anisotropy. The waves grow as they propagate away from the magnetic equator to higher latitude, while the wave vector turns outward radially and the polarization becomes linear. We calculate the detailed wave spectrum in four latitudinal ranges varying from magnetic latitude (MLAT) close to 0° (magnetic equator) up to 21°. The strongest waves are propagating away from the magnetic equator, but some wave power propagating toward the magnetic equator is observed due to local generation (especially close to the magnetic equator) or reflection. The He band waves, which are generated relatively high up on their dispersion surface, are able to propagate all the way to MLAT = 21°, but the H band waves experience frequency filtering, with no equatorial waves propagating to MLAT = 21° and only the higher-frequency waves propagating to MLAT = 14°. The result is that the wave power averaged k∥, which determines the relativistic electron minimum resonance energy, scales like the inverse of the local magnetic field for the He mode, whereas it is almost constant for the H mode. While the perpendicular wave vector turns outward, it broadens. These wavefields should be useful for simulations of radiation belt particle dynamics.
Dipole and quadrupole synthesis of electric potential fields. M.S. Thesis
Tilley, D. G.
1979-01-01
A general technique for expanding an unknown potential field in terms of a linear summation of weighted dipole or quadrupole fields is described. Computational methods were developed for the iterative addition of dipole fields. Various solution potentials were compared inside the boundary with a more precise calculation of the potential to derive optimal schemes for locating the singularities of the dipole fields. Then, the problem of determining solutions to Laplace's equation on an unbounded domain as constrained by pertinent electron trajectory data was considered.
International Nuclear Information System (INIS)
Delchamps, S.; Bleadon, M.; Bossert, R.; Carson, J.; Gourlay, S.; Hanft, R.; Koska, W.; Kuchnir, M.; Lamm, M.J.; Mazur, P.O.; Mokhtarani, A.; Orris, D.; Strait, J.; Wake, M.; Devred, A.; DiMarco, J.; Kuzminski, J.; Ogitsu, T.; Puglisi, M.; Tompkins, J.C.; Yu, Y.; Zhao, Y.; Zheng, H.
1992-01-01
This paper presents preliminary results of magnetic field measurements made on a series of 50 mm aperture 15 m long SSC collider dipole magnets designed and manufactured at Fermi National Accelerator Laboratory (Fermilab) for use in the Superconducting Super Collider Laboratory (SSCL) Accelerator System String Test. The magnets were assembled by Fermilab and General Dynamics personnel, and were tested at the Magnet Test Facility (MTF) at Fermilab. Measurements of the dipole field angle, dipole field strength, and field shape parameters at various stages in magnet construction and testing are described
Magnetic dipole field in a Schwarzschild metric with non-minimal coupling
International Nuclear Information System (INIS)
Souza, J.G.; Bedran, M.L.; Lesche, B.
1984-01-01
The influence of a non-minimal coupling term of electromagnetism and gravity is studied for a magnetic dipole field in the Schwarzschild metric. It is found that the new coupling term changes the magnetic dipole moment even for small masses. (Author) [pt
Self-Interaction of an electric dipole in the gravitational field
International Nuclear Information System (INIS)
Leaute, B.; Linet, B.
1983-01-01
We consider an electric dipole at rest in a weak gravitational field. We determine the electric self-force and the electric self-torque on the dipole, using a lagrangian method at the post-Newtonian approximation of general relativity [fr
Fuzzy Objects and Noncommutative Solitons
Kobayashi, Shinpei; Asakawa, Tsuguhiko
2015-01-01
The fuzzy disc is a disc-shaped region in a noncommutative plane, and is a fuzzy approximation of a commutative disc. We showed that one can introduce a concept of angles to the fuzzy disc, by using the phase operator and phase states known in quantum optics. We also constructed fan-shaped soliton solutions, which would be identified with D-branes, of a scalar field theory on the fuzzy disc and applied this concept to a theory of noncommutative gravity. This proceeding is based on our previous work.
A second-order approximation of particle motion in the fringing field of a dipole magnet
International Nuclear Information System (INIS)
Tarantin, N.I.
1980-01-01
The radial and axial motion of charged particles in the fringing field of an arbitrary dipole magnet has been considered with accuracy to the second-order of small quantities. The dipole magnet has an inhomogeneous field and oblique entrance and exit boundaries in the form of second-order curves. The region of the fringing field has a variable extension. A new definition of the effective boundary of the real fringing field has a variable extension. A new definition of the effective boundary of the real fringing field of the dipole magnet is used. A better understanding of the influence of the fringing magnetic field on the motion of charged particles in the pole gap of the dipole magnet has been obtained. In particular, it is shown that it is important to take into account, in the second approximation, some terms related formally to the next approximations. The results are presented in a form convenient for practical calculations. (orig.)
Green, M A
1999-01-01
The Ultra Compact Synchrotron (UCS), proposed for UCLA, is a compact 1.5 GeV electron light source with superconducting magnets to produce X-rays with a critical energy of about 10 keV. The design physical length (cold length) for $9 the dipole is 418 mm. The synchrotron requires that a uniform field be produced in a region that is 180 mm wide by 40 mm high by about 380 mm long. The end regions of the dipole should be short compared to the overall length of the $9 dipole field region. A Vobly H type of dipole was selected for the synchrotron bending magnets. In order for each dipole to bend a 1.5 GeV electron beam 30 degrees, the central induction must be in the range of 6.4 to 6.9 T $9 (depending on the dipole magnetic length). The pole width for the dipole was set so that over 90 percent of the X- rays generated by the magnet can be extracted. The three dimensional field calculations were done using TOSCA. This $9 report shows that Vobly type of dipole will behave magnetically as a conventional water cooled...
A method to assess the loss of a dipole antenna for ultra-high-field MRI.
Chen, Gang; Collins, Christopher M; Sodickson, Daniel K; Wiggins, Graham C
2018-03-01
To describe a new bench measurement based on quality (Q) factors to estimate the coil noise relative to the sample noise of dipole antennas at 7 T. Placing a dipole antenna close to a highly conductive sample surrogate (HCSS) greatly reduces radiation loss, and using Q HCSS gives a more accurate estimate of coil resistance than Q unloaded . Instead of using the ratio of unloaded and sample-loaded Q factors, the ratio of HCSS-loaded and sample-loaded Q factors should be used at ultra-high fields. A series of simulations were carried out to analyze the power budget of sample-loaded or HCSS-loaded dipole antennas. Two prototype dipole antennas were also constructed for bench measurements to validate the simulations. Simulations showed that radiation loss was suppressed when the dipole antenna was HCSS-loaded, and coil loss was largely the same as when the dipole was loaded by the sample. Bench measurements also showed good alignment with simulations. Using the ratio Q HCSS /Q loaded gives a good estimate of the coil loss for dipole antennas at 7 T, and provides a convenient bench measurement to predict the body noise dominance of dipole antenna designs. The new approach also applies to conventional surface loop coils at ultra-high fields. Magn Reson Med 79:1773-1780, 2018. © 2017 International Society for Magnetic Resonance in Medicine. © 2017 International Society for Magnetic Resonance in Medicine.
Sakai, Heisuke; Takahashi, Yoshikazu; Murata, Hideyuki
2007-01-01
The authors demonstrate organic field effect transistors (OFETs) with a dipole-polarized polyurea for the gate dielectrics. In the dielectrics, the internal electric field induces the mobile charge carrier in the semiconductor layer to the semiconductor-dielectric interface. OFETs with dipole-polarized gate dielectrics exhibit lower threshold voltage. With nonpolarized gate dielectrics, the threshold voltage was -11.4 V, whereas that decreased to -5.3 V with polarized gate dielectrics. In a...
Spin Hall effect on a noncommutative space
International Nuclear Information System (INIS)
Ma Kai; Dulat, Sayipjamal
2011-01-01
We study the spin-orbital interaction and the spin Hall effect of an electron moving on a noncommutative space under the influence of a vector potential A(vector sign). On a noncommutative space, we find that the commutator between the vector potential A(vector sign) and the electric potential V 1 (r(vector sign)) of the lattice induces a new term, which can be treated as an effective electric field, and the spin Hall conductivity obtains some correction. On a noncommutative space, the spin current and spin Hall conductivity have distinct values in different directions, and depend explicitly on the noncommutative parameter. Once this spin Hall conductivity in different directions can be measured experimentally with a high level of accuracy, the data can then be used to impose bounds on the value of the space noncommutativity parameter. We have also defined a new parameter, σ=ρθ (ρ is the electron concentration, θ is the noncommutativity parameter), which can be measured experimentally. Our approach is based on the Foldy-Wouthuysen transformation, which gives a general Hamiltonian of a nonrelativistic electron moving on a noncommutative space.
Analytical Considerations for Reducing the Effective Emittance with Variable Dipole Field Strengths
Papaphilippou, Yannis
2005-01-01
The basic optics design scope in lepton rings is to match the sections in either side of the bending magnets in order to minimise the equilibrium emittance. A further important emittance reduction can be achieved by incorporating dipoles for which the deflecting field varies along the electron beam path in the magnet. The figure of merit for such lattices when used in a synchrotron light source is the minimization of the so-called effective emittance. The effective emittance is computed in the middle of the undulator straight section as the product of the rms size and divergence and therefore includes contributions from the betatron emittance and from the electron energy spread. In this paper, analytical formulas are obtained for the minimum betatron and effective emittance in arbitrary dipole fields and the associated optics function at the dipole entrance. Examples are given for specific dipole field functions and their properties with respect to the effective emittance minimisation. Finally, the effective ...
International Nuclear Information System (INIS)
Bellesia, B.
2006-12-01
The 1234 superconducting dipoles of the Large Hadron Collider, working at a cryogenic temperature of 1.9 K, must guarantee a high quality magnetic field to steer the particles inside the beam pipe. Magnetic field measurements are a powerful way to detect assembly faults that could limit magnet performances. The aim of the thesis is the analysis of these measurements performed at room temperature during the production of the dipoles. In a large scale production the ideal situation is that all the magnets produced were identical. However all the components constituting a magnet are produced with certain tolerance and the assembly procedures are optimized during the production; due to these the reality drifts away from the ideal situation. We recollected geometrical data of the main components (superconducting cables, coil copper wedges and austenitic steel coil collars) and coupling them with adequate electro-magnetic models we reconstructed a multipolar field representation of the LHC dipoles defining their critical components and assembling procedures. This thesis is composed of 3 main parts: 1) influence of the geometry and of the assembling procedures of the dipoles on the quality of the magnetic field, 2) the use of measurement performed on the dipoles in the assembling step in order to solve production issues and to understand the behaviour of coils during the assembling step, and 3) a theoretical study of the uncertain harmonic components of the magnetic field in order to assess the dipole production
Bochicchio, Marco
2015-03-01
We review a number of old and new concepts in quantum gauge theories, some of which are well-established but not widely appreciated, some are most recent, that may have analogs in gauge formulations of quantum gravity, loop quantum gravity, and their topological versions, and may be of general interest. Such concepts involve noncommutative gauge theories and their relation to the large-N limit, loop equations and the change to the anti-selfdual (ASD) variables also known as Nicolai map, topological field theory (TFT) and its relation to localization and Morse-Smale-Floer homology, with an emphasis both on the mathematical aspects and the physical meaning. These concepts, assembled in a new way, enter a line of attack to the problem of the mass gap in large-NSU(N) Yang-Mills (YM), that is reviewed as well. Algebraic considerations furnish a measure of the mathematical complexity of a complete solution of large-NSU(N) YM: In the large-N limit of pure SU(N) YM the ambient algebra of Wilson loops is known to be a type II1 nonhyperfinite factor. Nevertheless, for the mass gap problem at the leading 1/N order, only the subalgebra of local gauge-invariant single-trace operators matters. The connected two-point correlators in this subalgebra must be an infinite sum of propagators of free massive fields, since the interaction is subleading in (1)/(N), a vast simplification. It is an open problem, determined by the growth of the degeneracy of the spectrum, whether the aforementioned local subalgebra is in fact hyperfinite. Moreover, the sum of free propagators that occurs in the two-point correlators in the aforementioned local subalgebra must be asymptotic for large momentum to the result implied by the asymptotic freedom and the renormalization group: This fundamental constraint fixes asymptotically the residues of the poles of the propagators in terms of the mass spectrum and of the anomalous dimensions of the local operators. For the mass gap problem, in the search of a
International Nuclear Information System (INIS)
Sako, Akifumi; Suzuki, Toshiya
2006-01-01
We investigate the Seiberg-Witten monopole equations on noncommutative (N.C.) R 4 at the large N.C. parameter limit, in terms of the equivariant cohomology. In other words, N=2 supersymmetric U(1) gauge theories with a hypermultiplet on N.C.R 4 are studied. It is known that after topological twisting partition functions of N>1 supersymmetric theories on N.C. R 2D are invariant under the N.C. parameter shift; then the partition functions can be calculated by its dimensional reduction. At the large N.C. parameter limit, the Seiberg-Witten monopole equations are reduced to ADHM equations with the Dirac equation reduced to the 0 dimension. The equations are equivalent to the dimensional reduction of non-Abelian U(N) Seiberg-Witten monopole equations in N→∞. The solutions of the equations are also interpreted as a configuration of a brane antibrane system. The theory has global symmetries under torus actions originated in space rotations and gauge symmetries. We investigate the Seiberg-Witten monopole equations reduced to the 0 dimension and the fixed point equations of the torus actions. We show that the Dirac equation reduced to the 0 dimension is automatically satisfied when the fixed point equations and the ADHM equations are satisfied. Then, we find that the Seiberg-Witten equations reduced to the 0 dimension and fixed point equations of the torus action are equivalent to just the ADHM equations with the fixed point equations. For finite N, it is known that the fixed points of the ADHM data are isolated and are classified by the Young diagrams. We also give a new proof of this statement by solving the ADHM equations and the fixed point equations concretely and by giving graphical interpretations of the field components and these equations
Sako, Akifumi; Suzuki, Toshiya
2006-11-01
We investigate the Seiberg-Witten monopole equations on noncommutative (N.C.) R4 at the large N.C. parameter limit, in terms of the equivariant cohomology. In other words, N =2 supersymmetric U(1) gauge theories with a hypermultiplet on N.C.R4 are studied. It is known that after topological twisting partition functions of N >1 supersymmetric theories on N.C. R2D are invariant under the N.C. parameter shift; then the partition functions can be calculated by its dimensional reduction. At the large N.C. parameter limit, the Seiberg-Witten monopole equations are reduced to ADHM equations with the Dirac equation reduced to the 0 dimension. The equations are equivalent to the dimensional reduction of non-Abelian U(N) Seiberg-Witten monopole equations in N →∞. The solutions of the equations are also interpreted as a configuration of a brane antibrane system. The theory has global symmetries under torus actions originated in space rotations and gauge symmetries. We investigate the Seiberg-Witten monopole equations reduced to the 0 dimension and the fixed point equations of the torus actions. We show that the Dirac equation reduced to the 0 dimension is automatically satisfied when the fixed point equations and the ADHM equations are satisfied. Then, we find that the Seiberg-Witten equations reduced to the 0 dimension and fixed point equations of the torus action are equivalent to just the ADHM equations with the fixed point equations. For finite N, it is known that the fixed points of the ADHM data are isolated and are classified by the Young diagrams. We also give a new proof of this statement by solving the ADHM equations and the fixed point equations concretely and by giving graphical interpretations of the field components and these equations.
High-Field Nb3Sn Cos-theta Dipole with Stress Management
Energy Technology Data Exchange (ETDEWEB)
Novitski, Igor [Fermilab; Carmichael, Justin [Fermilab; Kashikhin, Vadim V. [Fermilab; Zlobin, Alexander V. [Fermilab
2017-01-01
Cost-effective superconducting dipole magnets with operating fields up to 16 T are being considered for the LHC en-ergy upgrade (HE-LHC) and a Future Circular Collider (FCC). To demonstrate feasibility of 15 T accelerator quality dipole mag-nets, FNAL as a part of the US-MDP is developing a single-aper-ture Nb3Sn dipole demonstrator based on a 4-layer graded cos-theta coil with 60 mm aperture and cold iron yoke. In parallel, to explore the limit of the Nb3Sn accelerator magnet technology, op-timize magnet design and performance parameters, and reduce magnet cost, magnet design studies are also being performed to push the nominal bore field to 16 T in a 60-mm aperture cos-theta dipole. Results of these studies are reported and discussed in this paper.
Field Quality Measurements in the FNAL Twin-Aperture 11 T Dipole for LHC Upgrades
Strauss, T; Barzi, E; Chlachidze, G; Di Marco, J; Nobrega, F; Novitski, I; Stoynev, S; Turrioni, D; Velev, G; Zlobin, A V; Auchmann, B; Izquierdo Bermudez, S; Karppinen, M; Rossi, L; Savary, F; Smekens, D
2017-01-01
FNAL and CERN are developing an 11 T Nb3Sn dipole suitable for installation in the LHC to provide room for additional collimators. Two 1 m long collared coils previously tested at FNAL in single-aperture dipole configuration were assembled into the twin-aperture configuration and tested including magnet quench performance and field quality. The results of magnetic measurements are reported and discussed in this paper.
Field Quality Measurements in the FNAL Twin-Aperture 11 T Dipole for LHC Upgrades
Energy Technology Data Exchange (ETDEWEB)
Strauss, T. [Fermilab; Apollinari, G. [Fermilab; Apollinari, G. [Fermilab; Barzi, E. [Fermilab; Chlachidze, G. [Fermilab; Di Marco, J. [Fermilab; Nobrega, F. [Fermilab; Novitski, I. [Fermilab; Stoynev, S. [Fermilab; Turrioni, D. [Fermilab; Velev, G. [Fermilab; Zlobin, A. V. [Fermilab; Auchmann, B. [CERN; Izquierdo Bermudez, S, [CERN; Karppinen, M. [CERN; Rossi, L. [CERN; Savary, F. [CERN; Smekens, D. [CERN
2016-11-08
FNAL and CERN are developing an 11 T Nb3Sn dipole suitable for installation in the LHC to provide room for additional collimators. Two 1 m long collared coils previously tested at FNAL in single-aperture dipole configuration were assembled into the twin-aperture configuration and tested including magnet quench performance and field quality. The results of magnetic measurements are reported and discussed in this paper.
Noncommutative Valuation of Options
Herscovich, Estanislao
2016-12-01
The aim of this note is to show that the classical results in finance theory for pricing of derivatives, given by making use of the replication principle, can be extended to the noncommutative world. We believe that this could be of interest in quantum probability. The main result called the First fundamental theorem of asset pricing, states that a noncommutative stock market admits no-arbitrage if and only if it admits a noncommutative equivalent martingale probability.
Covariant non-commutative space–time
Directory of Open Access Journals (Sweden)
Jonathan J. Heckman
2015-05-01
Full Text Available We introduce a covariant non-commutative deformation of 3+1-dimensional conformal field theory. The deformation introduces a short-distance scale ℓp, and thus breaks scale invariance, but preserves all space–time isometries. The non-commutative algebra is defined on space–times with non-zero constant curvature, i.e. dS4 or AdS4. The construction makes essential use of the representation of CFT tensor operators as polynomials in an auxiliary polarization tensor. The polarization tensor takes active part in the non-commutative algebra, which for dS4 takes the form of so(5,1, while for AdS4 it assembles into so(4,2. The structure of the non-commutative correlation functions hints that the deformed theory contains gravitational interactions and a Regge-like trajectory of higher spin excitations.
Study and realization of a power circuit of a superconducting dipole generator of a magnetic field
International Nuclear Information System (INIS)
Rouanet, E.
1993-01-01
The project of experimental reactor building on controlled fusion (I.T.E.R) needed the development of a superconducting cable made of niobium-tin. Tested with a current of fifty kilo amperes under a twelve tesla constant field, this cable has to be tested under a variable field. The installation of the power circuit of the dipole field generator, consisted to the study and realization of the four following points: an important power cable; a tension protection organ of the dipole, under a seventeen milli Henrys inductance and four kilo amperes; a current regulating system given by the generator; a complete pilot system of the test station
Closed Strings Tachyons and Non-Commutative Instabilities
Armoni, Adi; Uranga, Angel M; Armoni, Adi; Lopez, Esperanza; Uranga, Angel M.
2003-01-01
We observe a relation between closed strings tachyons and one-loop instabilities in non-supersymmetric non-commutative gauge theories. In particular we analyze the spectra of type IIB string theory on C^3/Z_N orbifold singularities and the non-commutative field theory that lives on D3 branes located at the singularity. We find a surprising correspondence between the existence or not of one-loop low-momentum instabilities in the non-commutative field theory and the existence or not of tachyons in the closed string twisted sectors. Moreover, the relevant piece of the non-commutative field theory effective action is suggestive of an exchange of closed string modes. This suggests that non-commutative field theories retain some information about the dynamics of the underlying string configuration. Finally, we also comment on a possible relation between closed string tachyon condensation and field theory tachyon condensation.
Measurement of the zero-field magnetic dipole moment of magnetizable colloidal silica spheres
Claesson, E.M.; Erne, B.H.; Bakelaar, I.A.; Kuipers, B.W.M.; Philipse, A.P.
2007-01-01
The magnetic properties of dispersions of magnetic silica microspheres have been investigated by measuring the magnetization curves and the complex magnetic susceptibility as a function of frequency and field amplitude. The silica spheres appear to have a net permanent magnetic dipole moment, even
Rathjen, C
2002-01-01
A method based on analytical formulas is described to calculate bending moments, stresses, and deformations of vacuum chambers and beam screens in dipole and in quadrupole fields during a magnet quench. Solutions are given for circular and racetrack shaped structures. Without the need of time consuming calculations the solutions enable a quick design and verification of vacuum chambers and beam screens.
Quantum phases for a charged particle and electric/magnetic dipole in an electromagnetic field
Kholmetskii, Alexander; Yarman, Tolga
2017-11-01
We point out that the known quantum phases for an electric/magnetic dipole moving in an electromagnetic field must be composed from more fundamental quantum phases emerging for moving elementary charges. Using this idea, we have found two new fundamental quantum phases, next to the known magnetic and electric Aharonov-Bohm phases, and discuss their general properties and physical meaning.
Electric dipole moments of light nuclei from chiral effective field theory
de Vries, J.; Higa, R.; Liu, C. -P.; Mereghetti, E.; Stetcu, I.; Timmermans, R. G. E.; van Kolck, U.
2011-01-01
We set up the framework for the calculation of electric dipole moments (EDMs) of light nuclei using the systematic expansion provided by chiral effective field theory (EFT). We take into account parity (P) and timer-reversal (T) violation which, at the quark-gluon level, originates from the QCD
Dipole and quadrupole forces exerted on atoms in laser fields: The nonperturbative approach
International Nuclear Information System (INIS)
Sindelka, Milan; Moiseyev, Nimrod; Cederbaum, Lorenz S.
2006-01-01
Manipulation of cold atoms by lasers has so far been studied solely within the framework of the conventional dipole approximation, and the atom-light interaction has been treated using low order perturbation theory. Laser control of atomic motions has been ascribed exclusively to the corresponding light-induced dipole forces. In this work, we present a general theory to derive the potential experienced by an atom in a monochromatic laser field in a context analogous to the Born-Oppenheimer approximation for molecules in the field-free case. The formulation goes beyond the dipole approximation and gives rise to the field-atom coupling potential terms which so far have not been taken into consideration in theoretical or experimental studies. Contrary to conventional approaches, our method is based upon the many electron Floquet theory and remains valid also for high intensity laser fields (i.e., for a strongly nonperturbative atom-light interaction). As an illustration of the developed theory, we investigate the trapping of cold atoms in optical lattices. We find that for some atoms for specific laser parameters, despite the absence of the dipole force, the laser trapping is still possible due to the electric quadrupole forces. Namely, we show that by using realistic laser parameters one can form a quadrupole optical lattice which is sufficiently strong to trap Ca and Na atoms
International Nuclear Information System (INIS)
Kauffman, Louis H
2004-01-01
This paper presents a mathematical view of aspects of physics, showing how the forms of gauge theory, Hamiltonian mechanics and quantum mechanics arise from a non-commutative framework for calculus and differential geometry. This work is motivated by discrete calculus, as it is shown that classical discrete calculus embeds in a non-commutative context. It is shown how various processes are modeled by non-commutative discrete calculus, and how aspects of differential geometry, such as the Levi-Civita connection, arise naturally from commutator equations and the Jacobi identity. A new and generalized version of the Feynman-Dyson derivation of electromagnetic equations is given, with corresponding discrete models
The Röntgen interaction and forces on dipoles in time-modulated optical fields
Sonnleitner, Matthias; Barnett, Stephen M.
2017-12-01
The Röntgen term is an often neglected contribution to the interaction between an atom and an electromagnetic field in the electric dipole approximation. In this work we discuss how this interaction term leads to a difference between the kinetic and canonical momentum of an atom which, in turn, leads to surprising radiation forces acting on the atom. We use a number of examples to explore the main features of this interaction, namely forces acting against the expected dipole force or accelerations perpendicular to the beam propagation axis.
Causality in noncommutative space-time
Energy Technology Data Exchange (ETDEWEB)
Neves, M.J.; Abreu, E.M.C. [Universidade Federal Rural do Rio de Janeiro (UFRRJ), Seropedica, RJ (Brazil)
2011-07-01
Full text: Space-time noncommutativity has been investigated in the last years as a real possibility to describe physics at fundamental scale. This subject is associated with many tough issues in physics, i.e., strings, gravity, noncommutative field theories and others. The first formulation for a noncommutative spacetime was proposed by Snyder in 1947, where the object of noncommutativity is considered as a constant matrix that breaks the Lorentz symmetry. His objective was to get rid of the infinities that intoxicate quantum field theory. Unfortunately it was demonstrated not a success. Here we consider an alternative recent formulation known as Doplicher-Fredenhagen-Roberts-Amorim (DFRA) algebra in which the object of noncommutativity is treated as an ordinary coordinate by constructing an extended space-time with 4 + 6 dimensions (x + {phi}) - spacetime. In this way, the Lorentz symmetry is preserved in DFRA algebra. A quantum field theory is constructed in accordance with DFRA Poincare algebra, as well as a Lagrangian density formulation. By means of the Klein-Gordon equation in this (x + {phi}) - spacetime. We analyze the aspects of causality by studying the advanced and retarded Green functions. (author)
The ramp rate dependence of the sextupole field in superconducting dipoles
International Nuclear Information System (INIS)
Ghosh, A.K.; Robins, K.E.; Sampson, W.B.
1993-01-01
Sextupole components are induced in the magnetic field of superconducting dipoles when the current is changed. The magnitude of this effect depends on the rate of change of field, the strand-to-strand resistance in the superconducting cable, and the twist pitch of the wire. Ramp rate measurements have been made on a number of SSC dipoles wound from conductors with different interstrand resistances. The technique employed uses an array of Hall probes sensitive to the sextupole field and can measure the difference for field increasing or decreasing as a function of axial position. Magnets with very low interstrand resistance exhibit a large axial oscillation in the sextupole field between up and down ramps which is rate dependent When the strand resistance is high the amplitude of this oscillation is almost independent of ramp rate
Directory of Open Access Journals (Sweden)
Vernon Cooray
2016-11-01
Full Text Available The paper describes the net momentum transported by the transient electromagnetic radiation field of a long transient dipole in free space. In the dipole a current is initiated at one end and propagates towards the other end where it is absorbed. The results show that the net momentum transported by the radiation is directed along the axis of the dipole where the currents are propagating. In general, the net momentum P transported by the electromagnetic radiation of the dipole is less than the quantity U / c , where U is the total energy radiated by the dipole and c is the speed of light in free space. In the case of a Hertzian dipole, the net momentum transported by the radiation field is zero because of the spatial symmetry of the radiation field. As the effective wavelength of the current decreases with respect to the length of the dipole (or the duration of the current decreases with respect to the travel time of the current along the dipole, the net momentum transported by the radiation field becomes closer and closer to U / c , and for effective wavelengths which are much shorter than the length of the dipole, P ≈ U / c . The results show that when the condition P ≈ U / c is satisfied, the radiated fields satisfy the condition Δ t Δ U ≥ h / 4 π where Δ t is the duration of the radiation, Δ U is the uncertainty in the dissipated energy and h is the Plank constant.
Results of magnetic field measurements of 40 mm aperture 17-m long SSC model collider dipole magnets
Energy Technology Data Exchange (ETDEWEB)
Wanderer, P.; Anerella, M.; Cottingham, J.; Ganetis, G.; Garber, M.; Ghosh, A.; Greene, A.; Gupta, R.; Herrera, J.; Kahn, S.; Kelly, E.; Meade, A.; Morgan, G.; Muratore, J.; Prodell, A.; Rehak, M.; Rohrer, E.P.; Sampson, W.; Shutt, R.; Thompson, P.; Willen, E. (Brookhaven National Lab., Upton, NY (United States)); Bleadon, M.; Hanft, R.; Kuchnir, M.; Mantsch, P.; Mazur, P.O.; Orris, D.; Peterson, T.; Strait, J. (Fermi Nati
1991-01-01
Magnetic field measurements have been made on twelve 17 m-long, 40 mm-aperture R D superconducting dipoles. Data on dipole field strength, multipole coefficients, and alignment have been obtained. The data indicate that the magnets as built are generally within the expectations for this design. 7 refs., 5 figs.
Results of magnetic field measurements of 40 mm aperture 17-m long SSC model collider dipole magnets
International Nuclear Information System (INIS)
Wanderer, P.; Anerella, M.; Cottingham, J.; Ganetis, G.; Garber, M.; Ghosh, A.; Greene, A.; Gupta, R.; Herrera, J.; Kahn, S.; Kelly, E.; Meade, A.; Morgan, G.; Muratore, J.; Prodell, A.; Rehak, M.; Rohrer, E.P.; Sampson, W.; Shutt, R.; Thompson, P.; Willen, E.; Bleadon, M.; Hanft, R.; Kuchnir, M.; Mantsch, P.; Mazur, P.O.; Orris, D.; Peterson, T.; Strait, J.; Royet, J.; Scanlan, R.; Taylor, C.; Bush, T.; Coombes, R.; Devred, A.; DiMarco, J.; Goodzeit, C.; Kuzminski, J.; Ogitsu, T.; Puglisi, M.; Radusewicz, P.; Sanger, P.; Schermer, R.; Tompkins, J.; Turner, J.; Wolf, Z.; Yu, Y.; Zheng, H.
1991-01-01
Magnetic field measurements have been made on twelve 17 m-long, 40 mm-aperture R ampersand D superconducting dipoles. Data on dipole field strength, multipole coefficients, and alignment have been obtained. The data indicate that the magnets as built are generally within the expectations for this design. 7 refs., 5 figs
Energy Technology Data Exchange (ETDEWEB)
Voitylov, V.V.; Spartakov, A.A.; Tolstoi, N.A.; Trusov, A.A.; Boitsova, I.N. [St. Petersburg State Univ. (Russian Federation)
1995-04-01
An electro-optical method of crossed electric fields is proposed for determining constant dipole colloidal particles moments of colloidal particles. Fields of this type make it possible to study the motion of colloidal particles determined exclusively by their constant moments, which substantially improves the measurement accuracy of these moments. This is of particular importance for the investigation of colloidal particles with constant dipole moments less than or comparable to induced dipole moments. For a number of disperse systems, the constant dipole moments per unit area of particles are determined. It is shown that the values of these specific moments are close to each other.
Noncommutative calculi of probabilty
Directory of Open Access Journals (Sweden)
Michał Heller
2010-12-01
Full Text Available The paper can be regarded as a short and informal introduction to noncommutative calculi of probability. The standard theory of probability is reformulated in the algebraic language. In this form it is readily generalized to that its version which is virtually present in quantum mechanics, and then generalized to the so-called free theory of probability. Noncommutative theory of probability is a pair (M, φ where M is a von Neumann algebra, and φ a normal state on M which plays the role of a noncommutative probability measure. In the standard (commutative theory of probability, there is, in principle, one mathematically interesting probability measure, namely the Lebesgue measure, whereas in the noncommutative theories there are many nonequivalent probability measures. Philosophical implications of this fact are briefly discussed.
Quasi-adiabatic motion of energetic particles in a dipole magnetic field
International Nuclear Information System (INIS)
Il'in, V.D.; Kuznetsov, S.N.; Yushkov, B.Yu.
1992-01-01
A moving coordinate system for a dipole magnetic field, in which reversible variations of magnetic moment for the range of obvious violations of adiabatic conditions are absent, and the description of magnetic moment violations is relatively simple, is considered. Constructing of a coordinate system, features of the central trajectory, determining its motion, the application range, the main application field and consequences are discussed. 11 refs.; 3 figs
Noncommutative Lagrange Mechanics
Directory of Open Access Journals (Sweden)
Denis Kochan
2008-02-01
Full Text Available It is proposed how to impose a general type of ''noncommutativity'' within classical mechanics from first principles. Formulation is performed in completely alternative way, i.e. without any resort to fuzzy and/or star product philosophy, which are extensively applied within noncommutative quantum theories. Newton-Lagrange noncommutative equations of motion are formulated and their properties are analyzed from the pure geometrical point of view. It is argued that the dynamical quintessence of the system consists in its kinetic energy (Riemannian metric specifying Riemann-Levi-Civita connection and thus the inertia geodesics of the free motion. Throughout the paper, ''noncommutativity'' is considered as an internal geometric structure of the configuration space, which can not be ''observed'' per se. Manifestation of the noncommutative phenomena is mediated by the interaction of the system with noncommutative background under the consideration. The simplest model of the interaction (minimal coupling is proposed and it is shown that guiding affine connection is modified by the quadratic analog of the Lorentz electromagnetic force (contortion term.
Non-Dipole Features of the Geomagnetic Field May Persist for Millions of Years
Biasi, J.; Kirschvink, J. L.
2017-12-01
Here we present paleointensity results from within the South Atlantic Anomaly (SAA), which is a large non-dipole feature of the geomagnetic field. Within the area of the SAA, anomalous declinations, inclinations, and intensities are observed. Our results suggest that the SAA has been present for at least 5 Ma. This is orders-of-magnitude greater than any previous estimate, and suggests that some non-dipole features do not `average out' over geologic time, which is a fundamental assumption in all paleodirectional studies. The SAA has been steadily growing in size since the first magnetic measurements were made in the South Atlantic, and it is widely believed to have appeared 400 years ago. Recent studies from South Africa (Tarduno et al. (2015)) and Tristan da Cunha (Shah et al. (2016)) have suggested that the SAA has persisted for 1 ka and 96 ka respectively. We conducted paleointensity (PI) experiments on basaltic lavas from James Ross Island, on the Antarctic Peninsula. This large shield volcano has been erupting regularly over the last 6+ Ma (dated via Ar/Ar geochronology), and therefore contains the most complete volcanostratigraphic record in the south Atlantic. Our PI experiments used the Thellier-Thellier method, the IZZI protocol, and the same selection criteria as the Lawrence et al. (2009) study of Ross Island lavas (near McMurdo Station), which is the only comparable PI study on the Antarctic continent. We determined an average paleointensity at JRI of 13.8±5.2 μT, which is far lower than what we would expect from a dipole field (55 μT). In addition, this is far lower than the current value over James Ross Island of 36 μT. These results support the following conclusions: The time-averaged field model of Juarez et al. (1998) and Tauxe et al. (2013) is strongly favored by our PI data. The SAA has persisted over James Ross Island for at least 5 Ma, and has not drifted significantly over that time. The strength of non-dipole features such as the SAA
Noncommutative QFT and renormalization
International Nuclear Information System (INIS)
Grosse, H.; Wulkenhaar, R.
2006-01-01
It was a great pleasure for me (Harald Grosse) to be invited to talk at the meeting celebrating the 70th birthday of Prof. Julius Wess. I remember various interactions with Julius during the last years: At the time of my studies at Vienna with Walter Thirring, Julius left already Vienna, I learned from his work on effective chiral Lagrangians. Next we met at various conferences and places like CERN (were I worked with Andre Martin, an old friend of Julius), and we all learned from Julius' and Bruno's creation of supersymmetry, next we realized our common interests in noncommutative quantum field theory and did have an intensive exchange. Julius influenced our perturbative approach to gauge field theories were we used the Seiberg-Witten map after his advice. And finally I lively remember the sad days when during my invitation to Vienna Julius did have the serious heart attack. So we are very happy, that you recovered so well, and we wish you all the best for the forthcoming years. Many happy recurrences. (Abstract Copyright [2006], Wiley Periodicals, Inc.)
Non-commutative and commutative vacua effects in a scalar torsion scenario
Energy Technology Data Exchange (ETDEWEB)
Sheikhahmadi, Haidar, E-mail: h.sh.ahmadi@gmail.com [Department of Physics, Faculty of Science, University of Kurdistan, Sanandaj (Iran, Islamic Republic of); Aghamohammadi, Ali, E-mail: a.aghamohamadi@iausdj.ac.ir [Sanandaj Branch, Islamic Azad University, Sanandaj (Iran, Islamic Republic of); Saaidi, Khaled, E-mail: ksaaidi@uok.ac.ir [Department of Physics, Faculty of Science, University of Kurdistan, Sanandaj (Iran, Islamic Republic of)
2015-10-07
In this work, the effects of non-commutative and commutative vacua on the phase space generated by a scalar field in a scalar torsion scenario are investigated. For both classical and quantum regimes, the commutative and non-commutative cases are compared. To take account the effects of non-commutativity, two well known non-commutative parameters, θ and β, are introduced. It should be emphasized, the effects of β which is related to momentum sector has more key role in comparison to θ which is related to space sector. Also the different boundary conditions and mathematical interpretations of non-commutativity are explored.
Non-commutative and commutative vacua effects in a scalar torsion scenario
International Nuclear Information System (INIS)
Sheikhahmadi, Haidar; Aghamohammadi, Ali; Saaidi, Khaled
2015-01-01
In this work, the effects of non-commutative and commutative vacua on the phase space generated by a scalar field in a scalar torsion scenario are investigated. For both classical and quantum regimes, the commutative and non-commutative cases are compared. To take account the effects of non-commutativity, two well known non-commutative parameters, θ and β, are introduced. It should be emphasized, the effects of β which is related to momentum sector has more key role in comparison to θ which is related to space sector. Also the different boundary conditions and mathematical interpretations of non-commutativity are explored.
Non-commutative and commutative vacua effects in a scalar torsion scenario
Directory of Open Access Journals (Sweden)
Haidar Sheikhahmadi
2015-10-01
Full Text Available In this work, the effects of non-commutative and commutative vacua on the phase space generated by a scalar field in a scalar torsion scenario are investigated. For both classical and quantum regimes, the commutative and non-commutative cases are compared. To take account the effects of non-commutativity, two well known non-commutative parameters, θ and β, are introduced. It should be emphasized, the effects of β which is related to momentum sector has more key role in comparison to θ which is related to space sector. Also the different boundary conditions and mathematical interpretations of non-commutativity are explored.
Theta-expanded noncommutative Yang-Mills theory
International Nuclear Information System (INIS)
Grimstrup, J.
2002-07-01
This thesis concerns noncommutative gauge theories characterized through a constant noncommutativity parameter theta. Studying conformal transformations we relate the Seiberg-Witten map - which maps noncommutative gauge fields to commutative ones - to the existence of (broken) conformal transformations compatible with the gauge symmetry. In fact, this leads to a derivation of the Seiberg-Witten map more general as hitherto known in the literature. Further, we address the question of renormalizing theta-expanded gauge theories using the Seiberg-Witten map. The photon self-energy in noncommutative Maxwell theory is proven renormalizable to all orders. In noncommutative QED we prove that the Seiberg-Witten map represent a mere change of variables at first order in theta. This means that theta-expanded theories must entail additional terms linear in theta to be stable. Finally we show that a re-summation in $/q$ cannot improve the renormalizability of these models. (author)
Magnetic field quality in the pilot industrial batch's SC dipoles for the UNK
International Nuclear Information System (INIS)
Bal'bekov, V.I.; Gertsev, K.F.; Zlobin, A.V.
1992-01-01
Now the pilot industrial batch of superconducting magnets is being manufactured at IHEP. The magnetic measurements of 25 dipoles have been performed. This paper contains the measured characteristics of the field quality: systematic and r.m.s. values of nonlinearities and field integral as functions of the supply current. The defects of these field errors on betatron tune spread and an increase of beam emittances are determined. The features of the UNK correction systems for this magnetic field quality are analyzed. 13 refs.; 5 tabs
Electromagnetic core-mantle coupling associated with changes in the geomagnetic dipole field
International Nuclear Information System (INIS)
Watanabe, Hidehumi; Yukutake, Takesi.
1975-01-01
On a shelluar earth model electromagnetic coupling between the mantle and the core is investigated when the geomagnetic dipole field changes its intensity. Besides electromagnetic interaction between the dipole change and the relative slip of the mantle to the core, coupling of the dipole change with shear motions within the core is considered. If, in the core, the dipole change is limited within a surface layer shallower than a few hundred kilometers, the electromagnetic interaction gives the same order of magnitudes and phases of mantle oscillation as suggested from observation for three different periods, 8000, 400 and 65 years, provided that the electrical conductivity of the bottom part of the mantle is 10 -9 to 10 -8 emu. It is shown that mean motion of the surface shells of the core thus calculated is compatible with the observed variations in the drift velocity of the geomagnetic secular change. Except for surface shells, those in the deep interior is confirmed to oscillate almost with the same angular velocity, like a rigid rotation, for all the periods. (auth.)
Studies of time dependence of fields in TEVATRON superconducting dipole magnets
International Nuclear Information System (INIS)
Hanft, R.W.; Brown, B.C.; Herrup, D.A.; Lamm, M.J.; McInturff, A.D.; Syphers, M.J.
1988-01-01
The time variation in the magnetic field of a model Tevatron dipole magnet at constant excitation current has been studied. Variations in symmetry allowed harmonic components over long time ranges show a log t behavior indicative of ''flux creep.'' Both short time range and long time range behavior depend in a detailed way on the excitation history. Similar effects are seen in the remnant fields present in full-scale Tevatron dipoles following current ramping. Both magnitudes and time dependences are observed to depend on details for the ramps, such as ramp rate, flattop duration, and number of ramps. In a few magnets, variations are also seen in symmetry unallowed harmonics. 9 refs., 10 figs
Field quality in the twin aperture D2 dipoles for LHC under asymmetric excitation
Jain, A; Willen, E
1999-01-01
Twin aperture D2 magnets are one of the several types of dipoles to be built by BNL for the interaction regions of LHC. To minimize the number of dipole correctors required in the interaction regions, D2 will also be used as part of the steering system. Consequently, the operating fields in the two apertures may differ by up to ~10at 7 TeV operation and ~33at injection in order to compensate for the strengths of the correctors that would otherwise be required. Such asymmetric excitation of the two apertures may induce undesirable field harmonics. The saturation behavior of various harmonics is studied using POISSON and OPERA-2D. It is shown that the changes in harmonics resulting from the anticipated asymmetry are within tolerable limits. (2 refs).
The Influence of Train Leakage Currents on the LEP Dipole Field
Bravin, Enrico; Dehning, Bernd; Drees, A; Galbraith, Peter; Geitz, M A; Henrichsen, K N; Koratzinos, M; Mugnai, G
1998-01-01
The determination of the mass and the width of the Z boson at CERN's LEP accelerator, an e+e- storage ring with a circumference of approximately 27 kilometres, imposes heavy demands on the knowledge of the LEP counter-rotating electron and positron beam energies. The precision required is of the order of 1 MeV or »20 ppm frequency. Due to its size the LEP collider is influenced by various macroscopic and regional factors such as the position of the moon or seasonal changes of the rainfall in the area, as reported earlier. A new and not less surprising effect of the LEP energy was observed in 1995: railroad trains in the Geneva region perturb the dipole field. A parasitic flow of electricity, originating from the trains, travels along the LEP ground cable and the vacuum chamber, interacting with the dipole field. An account of the phenomenon with its explanation substantiated by dedicated measurements is presented.
Noncommutative gauge theory without Lorentz violation
International Nuclear Information System (INIS)
Carlson, Carl E.; Carone, Christopher D.; Zobin, Nahum
2002-01-01
The most popular noncommutative field theories are characterized by a matrix parameter θ μν that violates Lorentz invariance. We consider the simplest algebra in which the θ parameter is promoted to an operator and Lorentz invariance is preserved. This algebra arises through the contraction of a larger one for which explicit representations are already known. We formulate a star product and construct the gauge-invariant Lagrangian for Lorentz-conserving noncommutative QED. Three-photon vertices are absent in the theory, while a four-photon coupling exists and leads to a distinctive phenomenology
Time-space noncommutative Abelian solitons
International Nuclear Information System (INIS)
Chu, C.-S.; Lechtenfeld, Olaf
2005-01-01
We demonstrate the construction of solitons for a time-space Moyal-deformed integrable U(n) sigma model (the Ward model) in 2+1 dimensions. These solitons cannot travel parallel to the noncommutative spatial direction. For the U(1) case, the rank-one single-soliton configuration is constructed explicitly and is singular in the commutative limit. The projection to 1+1 dimensions transforms it to a noncommutative instanton-like configuration. The latter is governed by a new integrable equation, which describes a Moyal-deformed sigma model with a particular Euclidean metric and a magnetic field
Field Quality and Mechanical Analysis of the Beam Separation Dipole for HL-LHC Upgrade
AUTHOR|(CDS)2086334; Nakamoto, Tatsushi; Xu, Q; Kawamata, H; Todesco, Ezio
2015-01-01
High luminosity upgrade of the Large Hadron Collider (HL-LHC) project has been launched to attain a ten times higher integrated luminosity than the current LHC that has been in operation for over ten years. For this goal, the quadruple and dipole magnets around two interaction points, the ATLAS and the CMS, will be upgraded. High Energy Accelerator Research Organization (KEK) is in charge of developing the new superconducting beam separation dipole magnet (D1). The main dipole field of 5.6 T in a large aperture of 150 mm is generated using a cos-theta coil wound with Nb-Ti cables at nominal operating current of 12.0 kA at 1.9 K corresponding to 75% of the load line ratio. The main challenges for the D1 are larger aperture, a high level of iron saturation, radiation resistance, and tight constraints on field quality. This article summarizes the results of a detailed analysis on field error. Electromagnetic simulation with ROXIE was carried out for the 2-D model of the new D1. As possible design changes, a diam...
Dipole magnetic field of neutron stars in f(R) gravity
Bakirova, Elizat; Folomeev, Vladimir
2016-10-01
The structure of an interior dipole magnetic field of neutron stars in f( R) gravity is considered. For this purpose, the perturbative approaches are used when both the deviations from general relativity and the deformations of spherically symmetric configurations associated with the presence of the magnetic field are assumed to be small. Solutions are constructed which describe relativistic, spherically symmetric configurations consisting of a gravitating magnetized perfect fluid modeled by a realistic equation of state. Comparing configurations from general relativity and modified gravity, we reveal possible differences in the structure of the magnetic field which occur in considering neutron stars in modified gravity.
A D-He3 fusion reactor based on a dipole magnetic field
International Nuclear Information System (INIS)
Hasegawa, Akira; Chen, Liu; Princeton Univ., NJ
1989-07-01
An innovative fusion reactor suitable for D-He 3 fuel is proposed, based on a dipole magnetic field produced by a simple one-turn coil with approx lt 16 T near-field intensity. The equilibrium plasma, phase-space density satisfies ∂ cflx f 0 (μ, J, ψ)/∂ψ = O, where ψ is the flux function, has a steep enough pressure profile for an efficient fusion reaction yet is stable for low frequency instabilities to local beta exceeding unity. The semi-open field configuration is particularly suitable for D-He 3 reactions. 8 refs., 1 fig
Steering field quality in the main dipole magnets of the Large Hadron Collider
Todesco, Ezio; Bottura, L; Devred, Arnaud; Remondino, Vittorio; Pauletta, S; Sanfilippo, S; Scandale, Walter; Völlinger, C; Wildner, E
2004-01-01
More than 10% of the collared coils of the main LHC dipoles have been produced. In this paper we compare the measured field quality to beam dynamics targets using correlations to measurements at 1.9 K. The present status of field quality is given and corrective actions carried out to center field quality on optimal values are presented. Differences among the three manufacturers are analysed, and the main results that concern correlation between cold and warm measurements are outlined. Present trends in the production and open points are discussed.
Galopeau, P. H. M.
2017-12-01
Since the insertion of Cassini in the Saturnian system in July 2004, the radio and plasma wave science (RPWS) experiment on board the spacecraft revealed the presence of two distinct and variable rotation periods in the Saturnian kilometric radiation (SKR) which were attributed to the northern and southern hemispheres respectively. The present study is based on the hypothesis that the periodic time modulations present in the SKR are mainly due to the rotation of Saturn's inner magnetic field. The existence of a double period implies that the inner field is not only limited to a simple rotation dipole but displays more complex structures having the same time periodicities than the radio emission. In order to build a model of this complex magnetic field, it is absolutely necessary to know the accurate phases of rotation linked with the two periods. The radio observations from the RPWS experiment allow a continuous and accurate follow-up of these rotation phases, since the SKR emission is permanently observable and produced very close to the planetary surface. A continuous wavelet transform analysis of the intensity of the SKR signal received at 290 kHz between July 2004 and June 2012 was performed in order to calculate in the same time the different periodicities and phases. The rotation phases associated to the main two periods allow us to define a North and South longitude system essential for such a study. In this context, a dipole model ("birotor dipole") was proposed for Saturn's inner magnetic field: this dipole presents the particularity to have North and South poles rotating around Saturn's axis at two different angular velocities; this dipole is tilted and not centered. 57 Cassini's revolutions, the periapsis of which is less than 5 Saturnian radii, have been selected for this study. For each of these chosen orbits, it is possible to fit with high precision the measurements of the MAG data experiment given by the magnetometers embarked on board Cassini. A
Non-commutative arithmetic circuits with division
Czech Academy of Sciences Publication Activity Database
Hrubeš, Pavel; Wigderson, A.
2015-01-01
Roč. 11, Article 14 (2015), s. 357-393 ISSN 1557-2862 EU Projects: European Commission(XE) 339691 - FEALORA Institutional support: RVO:67985840 Keywords : arithmetic circuits * non-commutative rational function * skew field Subject RIV: BA - General Mathematics http://theoryofcomputing.org/articles/v011a014/
The application of *-products to noncommutative geometry and gauge theory
International Nuclear Information System (INIS)
Sykora, A.
2004-06-01
Due to the singularities arising in quantum field theory and the difficulties in quantizing gravity it is often believed that the description of spacetime by a smooth manifold should be given up at small length scales or high energies. In this work we will replace spacetime by noncommutative structures arising within the framework of deformation quantization. The ordinary product between functions will be replaced by a *-product, an associative product for the space of functions on a manifold. We develop a formalism to realize algebras defined by relations on function spaces. For this purpose we construct the Weyl-ordered *-product and present a method how to calculate *-products with the help of commuting vector fields. Concepts developed in noncommutative differential geometry will be applied to this type of algebras and we construct actions for noncommutative field theories. In the classical limit these noncommutative theories become field theories on manifolds with nonvanishing curvature. It becomes clear that the application of *-products is very fruitful to the solution of noncommutative problems. In the semiclassical limit every *-product is related to a Poisson structure, every derivation of the algebra to a vector field on the manifold. Since in this limit many problems are reduced to a couple of differential equations the *-product representation makes it possible to construct noncommutative spaces corresponding to interesting Riemannian manifolds. Derivations of *-products makes it further possible to extend noncommutative gauge theory in the Seiberg-Witten formalism with covariant derivatives. The resulting noncommutative gauge fields may be interpreted as one forms of a generalization of the exterior algebra of a manifold. For the Formality *-product we prove the existence of the abelian Seiberg-Witten map for derivations of these *-products. We calculate the enveloping algebra valued non abelian Seiberg-Witten map pertubatively up to second order for
Minimal length uncertainty and generalized non-commutative geometry
International Nuclear Information System (INIS)
Farmany, A.; Abbasi, S.; Darvishi, M.T.; Khani, F.; Naghipour, A.
2009-01-01
A generalized formulation of non-commutative geometry for the Bargmann-Fock space of quantum field theory is presented. The analysis is related to the symmetry of the simplistic space and a minimal length uncertainty.
Scalar-graviton interaction in the noncommutative space
International Nuclear Information System (INIS)
Brandt, F. T.; Elias-Filho, M. R.
2006-01-01
We obtain the leading order interaction between the graviton and the neutral scalar boson in the context of noncommutative field theory. Our approach makes use of the Ward identity associated with the invariance under a subgroup of symplectic diffeomorphisms
The Noncommutative Ward Metric
Directory of Open Access Journals (Sweden)
Marco Maceda
2010-06-01
Full Text Available We analyze the moduli-space metric in the static nonabelian charge-two sector of the Moyal-deformed CP^1 sigma model in 1+2 dimensions. After carefully reviewing the commutative results of Ward and Ruback, the noncommutative Kähler potential is expanded in powers of dimensionless moduli. In two special cases we sum the perturbative series to analytic expressions. For any nonzero value of the noncommutativity parameter, the logarithmic singularity of the commutative metric is expelled from the origin of the moduli space and possibly altogether.
Renormalization on noncommutative torus
Energy Technology Data Exchange (ETDEWEB)
D' Ascanio, D.; Pisani, P. [Universidad Nacional de La Plata, Instituto de Fisica La Plata-CONICET, La Plata (Argentina); Vassilevich, D.V. [Universidade Federal do ABC, CMCC, Santo Andre, SP (Brazil); Tomsk State University, Department of Physics, Tomsk (Russian Federation)
2016-04-15
We study a self-interacting scalar φ{sup 4} theory on the d-dimensional noncommutative torus. We determine, for the particular cases d = 2 and d = 4, the counterterms required by one-loop renormalization. We discuss higher loops in two dimensions and two-loop contributions to the self-energy in four dimensions. Our analysis points toward the absence of any problems related to the ultraviolet/infrared mixing and thus to renormalizability of the theory. However, we find another potentially troubling phenomenon which is a wild behavior of the two-point amplitude as a function of the noncommutativity matrix θ. (orig.)
Arnlind, Joakim; Holm, Christoffer
2018-01-01
A noncommutative algebra corresponding to the classical catenoid is introduced together with a differential calculus of derivations. We prove that there exists a unique metric and torsion-free connection that is compatible with the complex structure, and the curvature is explicitly calculated. A noncommutative analogue of the fact that the catenoid is a minimal surface is studied by constructing a Laplace operator from the connection and showing that the embedding coordinates are harmonic. Furthermore, an integral is defined and the total curvature is computed. Finally, classes of left and right modules are introduced together with constant curvature connections, and bimodule compatibility conditions are discussed in detail.
Holographic complexity and noncommutative gauge theory
Couch, Josiah; Eccles, Stefan; Fischler, Willy; Xiao, Ming-Lei
2018-03-01
We study the holographic complexity of noncommutative field theories. The four-dimensional N=4 noncommutative super Yang-Mills theory with Moyal algebra along two of the spatial directions has a well known holographic dual as a type IIB supergravity theory with a stack of D3 branes and non-trivial NS-NS B fields. We start from this example and find that the late time holographic complexity growth rate, based on the "complexity equals action" conjecture, experiences an enhancement when the non-commutativity is turned on. This enhancement saturates a new limit which is exactly 1/4 larger than the commutative value. We then attempt to give a quantum mechanics explanation of the enhancement. Finite time behavior of the complexity growth rate is also studied. Inspired by the non-trivial result, we move on to more general setup in string theory where we have a stack of D p branes and also turn on the B field. Multiple noncommutative directions are considered in higher p cases.
International Nuclear Information System (INIS)
Denisov, V.I.; Krivchenkov, I.V.; Denisov, I.P.
2002-01-01
The study on the electromagnetic waves propagation in the neutron star magnetic dipole and gravitation fields, taking place according to the vacuum nonlinear electrodynamics laws, is carried out. It is shown that depending on the polarization the electromagnetic signals in this field propagate by different beams and with various velocities. The law on these signals motion by beams is established. The calculation of differences in the times of the electromagnetic signals propagation, having the same source up to the detector, is presented. It is shown that this difference in some cases may reach enough measurable value of 1 μs [ru
Remarks on the canonical quantization of noncommutative theories
Energy Technology Data Exchange (ETDEWEB)
Amorim, R.; Barcelos-Neto, J. [Instituto de Fisica, Universidade Federal do Rio de Janeiro, Rio de Janeiro (Brazil)]. E-mails: amorim@if.ufrj.br; barcelos@if.ufrj.br
2001-10-26
Free noncommutative fields constitute a natural and interesting example of constrained theories with higher derivatives. The quantization methods involving constraints in the higher derivative formalism can be nicely applied to these systems. We study real and complex free noncommutative scalar fields where momenta have an infinite number of terms. We show that these expressions can be summed in a closed way and lead to a set of Dirac brackets which matches the usual corresponding brackets of the commutative case. (author)
Pair production of Dirac particles in a d + 1-dimensional noncommutative space-time
Energy Technology Data Exchange (ETDEWEB)
Ousmane Samary, Dine [Perimeter Institute for Theoretical Physics, Waterloo, ON (Canada); University of Abomey-Calavi, International Chair in Mathematical Physics and Applications (ICMPA-UNESCO Chair), Cotonou (Benin); N' Dolo, Emanonfi Elias; Hounkonnou, Mahouton Norbert [University of Abomey-Calavi, International Chair in Mathematical Physics and Applications (ICMPA-UNESCO Chair), Cotonou (Benin)
2014-11-15
This work addresses the computation of the probability of fermionic particle pair production in d + 1-dimensional noncommutative Moyal space. Using Seiberg-Witten maps, which establish relations between noncommutative and commutative field variables, up to the first order in the noncommutative parameter θ, we derive the probability density of vacuum-vacuum pair production of Dirac particles. The cases of constant electromagnetic, alternating time-dependent, and space-dependent electric fields are considered and discussed. (orig.)
Fractional and noncommutative spacetimes
Arzano, M.|info:eu-repo/dai/nl/32616443X; Calcagni, M.; Oriti, D.; Scalisi, M.
2011-01-01
We establish a mapping between fractional and noncommutative spacetimes in configuration space. Depending on the scale at which the relation is considered, there arise two possibilities. For a fractional spacetime with log-oscillatory measure, the effective measure near the fundamental scale
van den Berg, B.|info:eu-repo/dai/nl/314499172; Heunen, C.
2012-01-01
We give substance to the motto “every partial algebra is the colimit of its total subalgebras” by proving it for partial Boolean algebras (including orthomodular lattices), the new notion of partial C*-algebras (including noncommutative C*-algebras), and variations such as partial complete Boolean
Dipole-exchange spin waves in perpendicularly magnetized discs: Role of the Oersted field
Arias, R. E.; Mills, D. L.
2007-06-01
We develop the theory of the exchange dipole spin waves in thin circular discs for the case where the magnetization is nominally perpendicular to the plane. Our interest is in the circumstance where a transport current is injected into the disc, with current also perpendicular to the plane of the disc. Such a current creates an azimuthal magnetic field, referred to often as the Oersted field. We develop the theory of the influence of the Oersted field on the spin-wave spectrum of the disc. This field produces a vortex state. We suggest that this vortex state is stable down to zero applied field. If the external applied field H0 is in the +z direction, perpendicular to the plane of the disc, the vortex state has magnetization at the center of the disc also parallel to +z always. This is the case even when H0<4πMS , where the magnetization at the center of the disc is antiparallel to the local field H0-4πMS there. We present calculations of the current dependence of spin-wave frequencies of several modes as a function of applied magnetic field. We also address an issue overlooked in previous studies of spin waves in thin discs. This is that for quantitative purposes, it is not sufficient to describe internal dipole fields generated by the spin motions simply by adding an effective internal field -4πmzẑ to the equations of motion, with mz the component of dynamic magnetization normal to the surface. For samples of present interest, we derive terms we call gradient corrections, and these play a role quantitatively comparable to exchange itself in the analysis of the spin-wave frequencies. Quantitative studies of spin dynamics in such samples thus must include the gradient corrections.
Hare, V. J.; Gallet, Y.; Genevey, A.
2015-12-01
Current global geomagnetic field models suffer from strong bias towards Northern Hemisphere data. Absolute intensity measurements from the Southern Hemisphere are key to understanding the evolution of the field over the historical era, especially recent strengthening of non-dipole contributions, and the appearance of the South Atlantic Magnetic Anomaly (SAMA). I present the first archaeointensity data for locally-fired historical bricks from several well-dated sites (1660-2009 AD) in Cape Town, South Africa. These data constitute the first archaeomagnetic intensity variation curve for southern Africa for the past few centuries. The ages of the sites are tightly constrained by historical and archaeological considerations. Archaeointensity data obtained by the Thellier and Thellier method (modified by Coe), are corrected for both TRM anisotropy and cooling rate dependence of TRM acquisition. Analysis of magnetic mineralogy was performed to aid selection of fragments. Reliable archaeointensity determinations were obtained for 48 of 80 specimens, and 45 were retained in the final analysis. Intensity results vary from 24.3 ± 0.6 μT (modern brick) to 40.7 ± 0.8 μT (1660 AD), corresponding to Virtual Axial Dipole Moments (VADMs) between 6.1 ± 0.2 and 10.2 ± 0.2 נ1022 Am2. Results are generally not in agreement with current field models, but are coherent with other archaeomagnetic datasets from the Southern Hemisphere. The possible reasons for this are discussed, as well as implications for the historical evolution of the field.
Influence of Austenitic Steel Collar Dimensions on Magnetic Field Harmonics in the LHC Main Dipole
Bellesia, B; Todesco, Ezio
2005-01-01
The influence of the geometry of the collars in the main LHC dipole on the magnetic field harmonics is analyzed. The study aims at finding if the collar geometry is the driving mechanism of field quality for some harmonics and if the two different collar suppliers give a special signature on the magnetic field. Data of more than 700 magnets of the LHC series dipoles are analyzed and discussed. The main result of the analysis is that the collar shape is the driving mechanism of the magnetic field harmonics only for b2 and a3 in one of the three Cold Mass Assemblers (Firm3), where only collars of the supplier S2 are used. Two independent observations support this fact: firstly, strong correlations between apertures of the same magnet as expected from the assembly procedure have been found. Secondly, the expected values based on the measured dimensions of the collars and on a magneto-static model agree with magnetic measurements both for the average and for the standard deviation.
Non-commutative gauge gravity: second-order correction and scalar particle creation
Energy Technology Data Exchange (ETDEWEB)
Zaim, Slimane [Departement de Physique, Faculte des Sciences, Universite de Batna (Algeria); Khodja, Lamine, E-mail: zaimslimane@yahoo.f [Departement de Physique, Faculte des Sciences Exactes, Universite Mentouri, Constantine (Algeria)
2010-05-01
We construct a non-commutative gauge theory for a charged scalar field and verify its invariance under local Poincare and general coordinate transformations. We derive a general Klein-Gordon equation up to the second order of the non-commutativity parameter using the general modified field equation. As an application, we choose the Bianchi I universe and use the Seiberg-Witten maps to obtain the deformed non-commutative metric and study a particle production process. We show that non-commutativity plays the same role as an electric field, gravity and chemical potential.
Dispersion relations in quantum electrodynamics on the noncommutative Minkowski space
International Nuclear Information System (INIS)
Zahn, J.W.
2006-12-01
We study field theories on the noncommutative Minkowski space with noncommuting time. The focus lies on dispersion relations in quantized interacting models in the Yang-Feldman formalism. In particular, we compute the two-point correlation function of the field strength in noncommutative quantum electrodynamics to second order. At this, we take into account the covariant coordinates that allow the construction of local gauge invariant quantities (observables). It turns out that this does not remove the well-known severe infrared problem, as one might have hoped. Instead, things become worse, since nonlocal divergences appear. We also show that these cancel in a supersymmetric version of the theory if the covariant coordinates are adjusted accordingly. Furthermore, we study the Φ 3 and the Wess-Zumino model and show that the distortion of the dispersion relations is moderate for parameters typical for the Higgs field. We also discuss the formulation of gauge theories on noncommutative spaces and study classical electrodynamics on the noncommutative Minkowski space using covariant coordinates. In particular, we compute the change of the speed of light due to nonlinear effects in the presence of a background field. Finally, we examine the so-called twist approach to quantum field theory on the noncommutative Minkowski space and point out some conceptual problems of this approach. (orig.)
Dispersion relations in quantum electrodynamics on the noncommutative Minkowski space
Energy Technology Data Exchange (ETDEWEB)
Zahn, J.W.
2006-12-15
We study field theories on the noncommutative Minkowski space with noncommuting time. The focus lies on dispersion relations in quantized interacting models in the Yang-Feldman formalism. In particular, we compute the two-point correlation function of the field strength in noncommutative quantum electrodynamics to second order. At this, we take into account the covariant coordinates that allow the construction of local gauge invariant quantities (observables). It turns out that this does not remove the well-known severe infrared problem, as one might have hoped. Instead, things become worse, since nonlocal divergences appear. We also show that these cancel in a supersymmetric version of the theory if the covariant coordinates are adjusted accordingly. Furthermore, we study the {phi}{sup 3} and the Wess-Zumino model and show that the distortion of the dispersion relations is moderate for parameters typical for the Higgs field. We also discuss the formulation of gauge theories on noncommutative spaces and study classical electrodynamics on the noncommutative Minkowski space using covariant coordinates. In particular, we compute the change of the speed of light due to nonlinear effects in the presence of a background field. Finally, we examine the so-called twist approach to quantum field theory on the noncommutative Minkowski space and point out some conceptual problems of this approach. (orig.)
Extending the radial diffusion model of Falthammar to non-dipole background field
Energy Technology Data Exchange (ETDEWEB)
Cunningham, Gregory Scott [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
2015-05-26
A model for radial diffusion caused by electromagnetic disturbances was published by Falthammar (1965) using a two-parameter model of the disturbance perturbing a background dipole magnetic field. Schulz and Lanzerotti (1974) extended this model by recognizing the two parameter perturbation as the leading (non--dipole) terms of the Mead Williams magnetic field model. They emphasized that the magnetic perturbation in such a model induces an electric ield that can be calculated from the motion of field lines on which the particles are ‘frozen’. Roederer and Zhang (2014) describe how the field lines on which the particles are frozen can be calculated by tracing the unperturbed field lines from the minimum-B location to the ionospheric footpoint, and then tracing the perturbed field (which shares the same ionospheric footpoint due to the frozen -in condition) from the ionospheric footpoint back to a perturbed minimum B location. The instantaneous change n Roederer L*, dL*/dt, can then be computed as the product (dL*/dphi)*(dphi/dt). dL*/Dphi is linearly dependent on the perturbation parameters (to first order) and is obtained by computing the drift across L*-labeled perturbed field lines, while dphi/dt is related to the bounce-averaged gradient-curvature drift velocity. The advantage of assuming a dipole background magnetic field, as in these previous studies, is that the instantaneous dL*/dt can be computed analytically (with some approximations), as can the DLL that results from integrating dL*/dt over time and computing the expected value of (dL*)^2. The approach can also be applied to complex background magnetic field models like T89 or TS04, on top of which the small perturbations are added, but an analytical solution is not possible and so a numerical solution must be implemented. In this talk, I discuss our progress in implementing a numerical solution to the calculation of DL*L* using arbitrary background field models with simple electromagnetic
Pugnat, P; Siemko, A
2000-01-01
The windings of high-field accelerator magnets are usually made of Rutherford-type superconducting cables. The magnetic field distribution along the axis of such magnets exhibits a pronounced periodic modulation with a wavelength equal to the twist pitch length of the cable used in the winding. Such an effect, resulting from quasi-persistent currents, was investigated with a Hall probe array inserted inside the aperture of 1-metre long LHC superconducting dipole models. The amplitude and the time dependence of this periodic field oscillation have been studied as a function of the transport current history. The impact on the magnet stability of the non-uniform current redistribution producing such a field modulation is discussed.
Measurements of Field Decay and Snapback Effect on Tevatron Dipole and Quadrupole Magnets
Velev, Gueorgui; Annala, Gerald; Bauer, Pierre; Carcagno, Ruben H; Di Marco, Joseph; Glass, Henry; Hanft, Ray; Kephart, Robert; Lamm, Michael J; Martens, Michael A; Schlabach, Philip; Sylvester, C D; Tartaglia, M; Tompkins, John
2005-01-01
Since the beginning of 2002 an intensive measurement program has been performed at the Fermilab Magnet Test Facility to understand dynamic effects in the Tevatron magnets. Based on the results of this program a new correction algorithm was proposed to compensate for the decay of the sextupole field during the dwell at injection and for the subsequent field "snapback" during the first few seconds of the energy ramp. Beam studies showed that the new correction algorithm works better than the original one, and improves the Tevatron efficiency by at least 3%. The beam studies also indicated insufficient correction during the first 20 s of the injection plateau where an unexpected discrepancy of 0.15 sextupole units of extra drift was observed. This paper reports on the most recent measurements of the Tevatron dipoles field at the beginning of the injection plateau. Results on the field decay and snapback in the Tevatron quadrupoles are also presented.
Noncommutative SO(n) and Sp(n) gauge theories
International Nuclear Information System (INIS)
Bonora, L.; INFN, Sezione di Trieste, Trieste; Schnabl, M.; INFN, Sezione di Trieste, Trieste; Sheikh-Jabbari, M.M.; Tomasiello, A.
2000-08-01
We study the generalization of noncommutative gauge theories to the case of orthogonal and symplectic groups. We find out that this is possible, since we are allowed to define orthogonal and symplectic subgroups of noncommutative unitary gauge transformations even though the gauge potentials and gauge transformations are not valued in the orthogonal and symplectic subalgebras of the Lie algebra of antihermitean matrices. Our construction relies on an antiautomorphism of the basic noncommutative algebra of functions which generalizes the charge conjugation operator of ordinary field theory. We show that the corresponding noncommutative picture from low energy string theory is obtained via orientifold projection in the presence of a non-trivial NSNS B-field. (author)
Multiple coil pulsed magnetic resonance method for measuring cold SSC dipole magnet field quality
International Nuclear Information System (INIS)
Clark, W.G.; Moore, J.M.; Wong, W.H.
1990-01-01
The operating principles and system architecture for a method to measure the magnetic field multipole expansion coefficients are described in the context of the needs of SSC dipole magnets. The operation of an 8-coil prototype system is discussed. Several of the most important technological issues that influence the design are identified and the basis of their resolution is explained. The new features of a 32-coil system presently under construction are described, along with estimates of its requirements for measurement time and data storage capacity
Design of the EuCARD high field model dipole magnet FRESCA2
Milanese, A; Durante, M; Manil, P; Perez, J-C; Rifflet, J-M; de Rijk, G; Rondeaux, F
2011-01-01
This paper reports on the design of FRESCA2, a dipole magnet model wound with Nb3Sn Rutherford cable. This magnet is one of the deliverables of the High Field Magnets work package of the European FP7-EuCARD project. The nominal magnetic flux density of 13 Tesla in a 100 mm bore will make it suitable for upgrading the FRESCA cable test facility at CERN. The magnetic layout is based on a block coil, with four layers per pole. The mechanical structure is designed to provide adequate pre-stress, through the use of bladders, keys and an aluminum alloy shrinking cylinder.
Quench Performance and Field Quality of the LHC Preseries Superconducting Dipoles
Siemko, A; Bottura, L; Buzio, M; Chohan, V; Le Floc'h, E; Granata, V; Pojer, M; Pugnat, P; Rossi, L; Sanfilippo, S; Smirnov, N; Vlogaert, J; Walckiers, L
2004-01-01
The preseries production of the LHC main superconducting dipoles is presently being tested at CERN. The foremost features of these magnets are: twin structure, six block two layer coils wound from 15.1 mm wide graded NbTi cables, 56 mm aperture, polyimide insulation and stainless steel collars. This paper reviews the main test results of magnets tested to day in both normal and superfluid helium. The results of the training performance, magnet protection, electrical integrity and the field quality are presented in terms of the specifications and expected performance of these magnets in the future accelerator.
Noncommutative via closed star product
Kupriyanov, V. G.; Vitale, P.
2015-08-01
We consider linear star products on of Lie algebra type. First we derive the closed formula for the polydifferential representation of the corresponding Lie algebra generators. Using this representation we define the Weyl star product on the dual of the Lie algebra. Then we construct a gauge operator relating the Weyl star product with the one which is closed with respect to some trace functional, Tr ( f ⋆ g) = Tr ( f · g). We introduce the derivative operator on the algebra of the closed star product and show that the corresponding Leibniz rule holds true up to a total derivative. As a particular example we study the space R {/θ 3} with type noncommutativity and show that in this case the closed star product is the one obtained from the Duflo quantization map. As a result a Laplacian can be defined such that its commutative limit reproduces the ordinary commutative one. The deformed Leibniz rule is applied to scalar field theory to derive conservation laws and the corresponding noncommutative currents.
Noncommutative geometry and fluid dynamics
International Nuclear Information System (INIS)
Das, Praloy; Ghosh, Subir
2016-01-01
In the present paper we have developed a Non-Commutative (NC) generalization of perfect fluid model from first principles, in a Hamiltonian framework. The noncommutativity is introduced at the Lagrangian (particle) coordinate space brackets and the induced NC fluid bracket algebra for the Eulerian (fluid) field variables is derived. Together with a Hamiltonian this NC algebra generates the generalized fluid dynamics that satisfies exact local conservation laws for mass and energy, thereby maintaining mass and energy conservation. However, nontrivial NC correction terms appear in the charge and energy fluxes. Other non-relativistic spacetime symmetries of the NC fluid are also discussed in detail. This constitutes the study of kinematics and dynamics of NC fluid. In the second part we construct an extension of the Friedmann-Robertson-Walker (FRW) cosmological model based on the NC fluid dynamics presented here. We outline the way in which NC effects generate cosmological perturbations bringing about anisotropy and inhomogeneity in the model. We also derive a NC extended Friedmann equation. (orig.)
Estimation of the Required Amount of Superconductors for High-field Accelerator Dipole Magnets
Schwerg, N
2007-01-01
The coil size and the corresponding amount of superconducting material that is used during the design process of a magnet cross-section have direct impacts on the overall magnet cost. It is therefore of interest to estimate the minimum amount of conductors needed to reach the defined field strength before a detailed design process starts. Equally, it is useful to evaluate the efficiency of a given design by calculating the amount of superconducting cables that are used to reach the envisaged main field by simple rule. To this purpose, the minimum amount of conductors for the construction of a dipole of given main field strength and aperture size is estimated taking the actual critical current density of the used strands into account. Characteristic curves applicable for the NED Nb3Sn strand specification are given and some of the recently studied different dipole configurations are compared. Based on these results, it is shown how the required amount of conductors changes due to the iron yoke contribution and...
Energy Technology Data Exchange (ETDEWEB)
Borland, M.; Lindberg, R.
2017-06-01
The proposed upgrade of the Advanced Photon Source (APS) to a multibend-achromat lattice requires shorter and much stronger quadrupole magnets than are present in the existing ring. This results in longitudinal gradient profiles that differ significantly from a hard-edge model. Additionally, the lattice assumes the use of five-segment longitudinal gradient dipoles. Under these circumstances, the effects of fringe fields and detailed field distributions are of interest. We evaluated the effect of soft-edge fringe fields on the linear optics and chromaticity, finding that compensation for these effects is readily accomplished. In addition, we evaluated the reliability of standard methods of simulating hardedge nonlinear fringe effects in quadrupoles.
Dependence of Magnetic Field Quality on Collar Supplier and Dimensions in the Main LHC Dipole
Bellesia, B; Santoni, C; Todesco, E
2006-01-01
In order to keep the electro-magnetic forces and to minimize conductor movements, the superconducting coils of the main Large Hadron Collider dipoles are held in place by means of austenitic steel collars. Two suppliers provide the collars necessary for the whole LHC production, which has now reached more than 800 collared coils. In this paper we first assess if the different collar suppliers origin a noticeable difference in the magnetic field quality measured at room temperature. We then analyze the measurements of the collar dimensions carried out at the manufacturers, comparing them to the geometrical tolerances. Finally we use a magneto-static model to evaluate the expected spread in the field components induced by the actual collar dimensions. These spreads are compared to the magnetic measurements at room temperature over the magnet production in order to identify if the collars, rather than other components or assembly process, can account for the measured magnetic field effects. It has been found tha...
Tang, Cheng; Zhang, Teng; Weiss, David S.
2018-03-01
We explore ways to use the ability to measure the populations of individual magnetic sublevels to improve the sensitivity of magnetic field measurements and measurements of atomic electric dipole moments (EDMs). When atoms are initialized in the m =0 magnetic sublevel, the shot-noise-limited uncertainty of these measurements is 1 /√{2 F (F +1 ) } smaller than that of a Larmor precession measurement. When the populations in the even (or odd) magnetic sublevels are combined, we show that these measurements are independent of the tensor Stark shift and the second order Zeeman shift. We discuss the complicating effect of a transverse magnetic field and show that when the ratio of the tensor Stark shift to the transverse magnetic field is sufficiently large, an EDM measurement with atoms initialized in the superposition of the stretched states can reach the optimal sensitivity.
Considerations on a Cost Model for High-Field Dipole Arc Magnets for FCC
AUTHOR|(CDS)2078700; Durante, Maria; Lorin, Clement; Martinez, Teresa; Ruuskanen, Janne; Salmi, Tiina; Sorbi, Massimo; Tommasini, Davide; Toral, Fernando
2017-01-01
In the frame of the European Circular Collider (EuroCirCol), a conceptual design study for a post-Large Hadron Collider (LHC) research infrastructure based on an energy-frontier 100 TeV circular hadron collider [1]–[3], a cost model for the high-field dipole arc magnets is being developed. The aim of the cost model in the initial design phase is to provide the basis for sound strategic decisions towards cost effective designs, in particular: (A) the technological choice of superconducting material and its cost, (B) the target performance of Nb3Sn superconductor, (C) the choice of operating temperature (D) the relevant design margins and their importance for cost, (E) the nature and extent of grading, and (F) the aperture’s influence on cost. Within the EuroCirCol study three design options for the high field dipole arc magnets are under study: cos − θ [4], block [5], and common-coil [6]. Here, in the advanced design phase, a cost model helps to (1) identify the cost drivers and feed-back this informati...
Gravity and the structure of noncommutative algebras
International Nuclear Information System (INIS)
Buric, Maja; Madore, John; Grammatikopoulos, Theodoros; Zoupanos, George
2006-01-01
A gravitational field can be defined in terms of a moving frame, which when made noncommutative yields a preferred basis for a differential calculus. It is conjectured that to a linear perturbation of the commutation relations which define the algebra there corresponds a linear perturbation of the gravitational field. This is shown to be true in the case of a perturbation of Minkowski space-time
Noncommutative Phase Spaces by Coadjoint Orbits Method
Directory of Open Access Journals (Sweden)
Ancille Ngendakumana
2011-12-01
Full Text Available We introduce noncommutative phase spaces by minimal couplings (usual one, dual one and their mixing. We then realize some of them as coadjoint orbits of the anisotropic Newton-Hooke groups in two- and three-dimensional spaces. Through these constructions the positions and the momenta of the phase spaces do not commute due to the presence of a magnetic field and a dual magnetic field.
One-loop beta functions for the orientable non-commutative Gross Neveu model TH1"-->
Lakhoua, A.; Vignes-Tourneret, F.; Wallet, J.-C.
2007-11-01
We compute at the one-loop order the β-functions for a renormalisable non-commutative analog of the Gross Neveu model defined on the Moyal plane. The calculation is performed within the so called x-space formalism. We find that this non-commutative field theory exhibits asymptotic freedom for any number of colors. The β-function for the non-commutative counterpart of the Thirring model is found to be non vanishing.
PURE STATE ENTANGLEMENT ENTROPY IN NONCOMMUTATIVE 2D DE SITTER SPACE TIME
Directory of Open Access Journals (Sweden)
M.F Ghiti
2014-12-01
Full Text Available Using the general modified field equation, a general noncommutative Klein-Gordon equation up to the second order of the noncommutativity parameter is derived in the context of noncommutative 2D De Sitter space-time. Using Bogoliubov coefficients and a special technics called conformal time; the boson-antiboson pair creation density is determined. The Von Neumann boson-antiboson pair creation quantum entanglement entropy is presented to compute the entanglement between the modes created presented.
Non-commutative geometry on quantum phase-space
International Nuclear Information System (INIS)
Reuter, M.
1995-06-01
A non-commutative analogue of the classical differential forms is constructed on the phase-space of an arbitrary quantum system. The non-commutative forms are universal and are related to the quantum mechanical dynamics in the same way as the classical forms are related to classical dynamics. They are constructed by applying the Weyl-Wigner symbol map to the differential envelope of the linear operators on the quantum mechanical Hilbert space. This leads to a representation of the non-commutative forms considered by A. Connes in terms of multiscalar functions on the classical phase-space. In an appropriate coincidence limit they define a quantum deformation of the classical tensor fields and both commutative and non-commutative forms can be studied in a unified framework. We interprete the quantum differential forms in physical terms and comment on possible applications. (orig.)
Kulkarni, Anita; Filippone, Bradley; Slutsky, Simon; Swank, Christopher; Carr, Robert; Osthelder, Charles; Biswas, Aritra; Molina, Daniel
2016-09-01
Over the last several decades, physicists have been measuring the neutron electric dipole moment (nEDM) with greater and greater sensitivity. The latest experiment we are developing will have 100 times more sensitivity than the previous leading experiment. A nonzero nEDM could, among other consequences, explain the presence of more matter than antimatter in the universe. To measure the nEDM with high accuracy, it is necessary to have a very uniform magnetic field inside the detector since non-uniformities can create false signals via the geometric phase effect. One way to improve field uniformity is to add superconducting lead endcaps to the detector, which constrain the fields at their surfaces to be parallel to them. Here, we test how the endcaps improve field uniformity by measuring the magnetic field at various points in a 1/3-scale experimental volume, inferring what the field must be at all other points, and calculating gradients in the field. This knowledge could help guide further steps needed to improve field uniformity and characterize limitations to the sensitivity of nEDM measurements for the full-scale experiment. Rose Hills Foundation, National Science Foundation Grant 1506459, and Department of Energy.
Solvents level dipole moments.
Liang, Wenkel; Li, Xiaosong; Dalton, Larry R; Robinson, Bruce H; Eichinger, Bruce E
2011-11-03
The dipole moments of highly polar molecules measured in solution are usually smaller than the molecular dipole moments that are calculated with reaction field methods, whereas vacuum values are routinely calculated in good agreement with available vapor phase data. Whether from Onsager's theory (or variations thereof) or from quantum mechanical methods, the calculated molecular dipoles in solution are found to be larger than those measured. The reason, of course, is that experiments measure the net dipole moment of solute together with the polarized (perturbed) solvent "cloud" surrounding it. Here we show that the reaction field charges that are generated in the quantum mechanical self-consistent reaction field (SCRF) method give a good estimate of the net dipole moment of the solute molecule together with the moment arising from the reaction field charges. This net dipole is a better description of experimental data than the vacuum dipole moment and certainly better than the bare dipole moment of the polarized solute molecule.
Noncommutative topological dynamics
International Nuclear Information System (INIS)
Ramos, C. Correia; Martins, Nuno; Severino, Ricardo; Ramos, J. Sousa
2006-01-01
We study noncommutative dynamical systems associated to unimodal and bimodal maps of the interval. To these maps we associate subshifts and the correspondent AF-algebras and Cuntz-Krieger algebras. As an example we consider systems having equal topological entropy log(1 + φ), where φ is the golden number, but distinct chaotic behavior and we show how a new numerical invariant allows to distinguish that complexity. Finally, we give a statistical interpretation to the topological numerical invariants associated to bimodal maps
Absorption of electromagnetic field energy by superfluid system of atoms with electric dipole moment
International Nuclear Information System (INIS)
Poluektov, Yu.M.
2014-01-01
The modified Gross-Pitaevskii equation which takes into account relaxation and interaction with alternating electromagnetic field is used to consider the absorption of electromagnetic field energy by a superfluid system on the assumption that the atoms has intrinsic dipole moment. It is shown that the absorption may be of a resonant behavior only if the dispersion curves of the electromagnetic wave and the excitations of the superfluid system intersect. It is remarkable that such a situation is possible if the superfluid system has a branch of excitations with the energy gap at low momenta. The experiments on absorption of microwaves in superfluid helium are interpreted as evidence of existence of such gap excitations. A possible modification of the excitation spectrum of superfluid helium in the presence of excitation branch with energy gap is dis-cussed qualitatively
Compensation of Third-Harmonic Field Error in the Main Dipole Magnets
Arpaia, P; Fiscarelli, L; Montenero, G; Garcia Perez, J; Walckiers, L
2010-01-01
One of the main requirements for the operations of the Large Hadron Collider (LHC) at the European Organization for Nuclear Research (CERN) is a suitable correction of multipole errors in magnetic field. The feed-forward control of the LHC is based on the Field Description for the LHC (FiDel), capable of forecasting the magnet’s behavior in order to generate adequate current ramps for main and corrector magnets. Magnetic measurements campaigns aimed at validating the model underlying FiDel highlighted the need for improving the harmonic compensation of the third-harmonic (b3) component of the main LHC dipoles. In this paper, the results of a new measurement campaign for b3 harmonic compensation, carried out through the new Fast Acquisition Measurement Equipment (FAME), are reported. In particular, the mechanism and the measurement procedure of the compensation, as well as the new perspectives opened by preliminary experimental results, are illustrated.
Dudarev, S. L.; Ma, Pui-Wai
2018-03-01
Density functional theory (DFT) calculations show that self-interstitial atom (SIA) defects in nonmagnetic body-centered-cubic (bcc) metals adopt strongly anisotropic configurations, elongated in the direction [S. Han et al., Phys. Rev. B 66, 220101 (2002), 10.1103/PhysRevB.66.220101; D. Nguyen-Manh et al., Phys. Rev. B 73, 020101 (2006), 10.1103/PhysRevB.73.020101; P. M. Derlet et al., Phys. Rev. B 76, 054107 (2007), 10.1103/PhysRevB.76.054107; S. L. Dudarev, Annu. Rev. Mater. Res. 43, 35 (2013), 10.1146/annurev-matsci-071312-121626]. Elastic distortions, associated with such anisotropic atomic structures, appear similar to distortions around small prismatic dislocation loops, although the extent of this similarity has never been quantified. We derive analytical formulas for the dipole tensors of SIA defects, which show that, in addition to the prismatic dislocation looplike character, the elastic field of a SIA defect also has a significant isotropic dilatation component. Using empirical potentials and DFT calculations, we parametrize dipole tensors of defects for all the nonmagnetic bcc transition metals. This enables a quantitative evaluation of the energy of elastic interaction between the defects, which also shows that in a periodic three-dimensional simple cubic arrangement of crowdions, long-range elastic interactions between a defect and all its images favor a orientation of the defect.
Nuclear dipole polarizability from mean-field modeling constrained by chiral effective field theory
Zhang, Zhen; Lim, Yeunhwan; Holt, Jeremy W.; Ko, Che Ming
2018-02-01
We construct a new Skyrme interaction Skχm* by fitting the equation of state and nucleon effective masses in asymmetric nuclear matter from chiral two- and three-body forces as well as the binding energies of finite nuclei. Employing this interaction to study the electric dipole polarizabilities of 48Ca, 68Ni, 120Sn, and 208Pb in the random-phase approximation, we find that the theoretical predictions are in good agreement with experimentally measured values without additional fine tuning of the Skyrme interaction, thus confirming the usefulness of the new Skyrme interaction in studying the properties of nuclei. We further use this interaction to study the neutron skin thicknesses of 48Ca and 208Pb, and they are found to be consistent with the experimental data.
Directory of Open Access Journals (Sweden)
D. Llanwyn Jones
Full Text Available Formulas for computing the Cartesian components of the static (DC fields of horizontal electric dipoles ( HEDs and vertical electric dipoles ( VEDs located in the central zone of a three-layer horizontally stratified medium are derived and presented in a summary form suitable for immediate computation. Formulas are given for the electric and magnetic field components in the upper and central regions. In the general case the computation involves the summation of a convergent infinite series. For the particular case of an infinitely thick central region (corresponding to the two-layer problem, the analysis produces relatively simple closed-form equations for the field components which are suitable for a 'hand calculation'. Specimen calculations for dipoles in seawaters are included and the derived results are compared with computations made using an ac model.
Directory of Open Access Journals (Sweden)
D. Llanwyn Jones
1997-04-01
Full Text Available Formulas for computing the Cartesian components of the static (DC fields of horizontal electric dipoles ( HEDs and vertical electric dipoles ( VEDs located in the central zone of a three-layer horizontally stratified medium are derived and presented in a summary form suitable for immediate computation. Formulas are given for the electric and magnetic field components in the upper and central regions. In the general case the computation involves the summation of a convergent infinite series. For the particular case of an infinitely thick central region (corresponding to the two-layer problem, the analysis produces relatively simple closed-form equations for the field components which are suitable for a 'hand calculation'. Specimen calculations for dipoles in seawaters are included and the derived results are compared with computations made using an ac model.
International Nuclear Information System (INIS)
Wang, J.G.
2013-01-01
The SNS accumulator ring employs 32 electro-magnetic dipoles to bend proton beams. The dipoles are typical sector magnets with relatively large aperture and short length. Thus, how to correctly treat magnetic fringe fields in the devices remains as a question. We have performed 3D computer simulations to study magnetic field distributions in the dipoles. Further, we have analyzed particle optics based on the space-dependent curvature and focusing functions in the magnets. The effect of magnetic fringe fields on the particle motion, especially the focusing/defocusing and dispersion, is investigated. The lens parameters, including the second-order aberrations, are derived and compared with the design hard-edge parameters used in the ring lattice calculations
AUTHOR|(CDS)2107593; Ferracin, P; Fessia, P; Todesco, Ezio
1998-01-01
The stability of the geometry of the superconducting coils is essential to the field homogeneity of the LHC dipole magnets. Mechanical stresses during coil assembly, thermal stresses during cool-down and electromagnetic stresses during operation are the source of deformations of the coil geometry. Additional sources of field-shape errors are the dimensional tolerances of the magnet components and of the manufacturing and assembly tooling. To provide a realistic evaluation of the field-shape imperfections of the LHC dipoles arising from the above effects, appropriate finite-element computations were carried out to model the dipole cross-section in presence of stresses and a first statistical simulation of the effect of the manufacturing tolerances was performed as well.
Particle Physics and Symmetries in Noncommutative Geometry
Devastato, Agostino
2015-01-01
In the context of the spectral action and the noncommutative geometry approach to the physical fundamental interactions, we extend the standard model of particle physics introducing a model based on a larger symmetry in the attempt to obtain a new scalar field, bringing the Higgs mass in the vicinity of 126~GeV and to cure the instability problem of the electroweak vacuum. We also investigate whether inclusion of dimension six terms in the Standard Model Lagrangian or gravitational contributi...
Finite dipole model for extreme near-field thermal radiation between a tip and planar SiC substrate
Jarzembski, Amun; Park, Keunhan
2017-04-01
Recent experimental studies have measured the infrared (IR) spectrum of tip-scattered near-field thermal radiation for a SiC substrate and observed up to a 50cm-1 redshift of the surface phonon polariton (SPhP) resonance peak [1,2]. However, the observed spectral redshift cannot be explained by the conventional near-field thermal radiation model based on the point dipole approximation. In the present work, a heated tip is modeled as randomly fluctuating point charges (or fluctuating finite dipoles) aligned along the primary axis of a prolate spheroid, and quasistatic tip-substrate charge interactions are considered to formulate the effective polarizability and self-interaction Green's function. The finite dipole model (FDM), combined with fluctuational electrodynamics, allows the computation of tip-plane thermal radiation in the extreme near-field (i.e., H / R ≲ 1 , where H is the tip-substrate gap distance and R is the tip radius), which cannot be calculated with the point dipole approximation. The FDM provides the underlying physics on the spectral redshift of tip-scattered near-field thermal radiation as observed in experiments. In addition, the SPhP peak in the near-field thermal radiation spectrum may split into two peaks as the gap distance decreases into the extreme near-field regime. This observation suggests that scattering-type spectroscopic measurements may not convey the full spectral features of tip-plane extreme near-field thermal radiation.
Current-voltage characteristics in organic field-effect transistors. Effect of interface dipoles
Sworakowski, Juliusz
2015-07-01
The role of polar molecules present at dielectric/semiconductor interfaces of organic field-effect transistors (OFETs) has been assessed employing the electrostatic model put forward in a recently published paper (Sworakowski et al., 2014). The interface dipoles create dipolar traps in the surface region of the semiconductor, their depths decreasing with the distance from the interface. This feature results in appearance of mobility gradients in the direction perpendicular to the dielectric/semiconductor interface, manifesting themselves in modification of the shapes of current-voltage characteristics. The effect may account for differences in carrier mobilities determined from the same experimental data using methods scanning different ranges of channel thicknesses (e.g., transconductances vs. transfer characteristics), differences between turn-on voltages and threshold voltages, and gate voltage dependence of mobility.
International Nuclear Information System (INIS)
Kozlov, A.N.; Nikitenko, Yu.V.; Taran, Yu.V.
1980-01-01
A two-cascade magnetic field stabilizer of installation for the measurement of neutron electrjcal dipole moment (EDM) using ultracold neutrons has been constructed and tested. Quantum cesium magnetometers (QCM) with optical pumping placed inside a ferromagnetic screen were used as primary convertors of the magnetic field. A stabilization coefficient of 4x10 5 in a bandwidth of 10 -3 -3x10 -3 Hz in the presence of magnetic noise of an amplitude up to 50 nT was obtained using QCM with Ssub(Z)-signal in the inner and outer cascades having transfer ratios of 300 and 600, respectively. Mean square amplitude of magnetic field fluctuations was below 0.O5 pT. Stabilization in a wider frequency band was performed using QCM with Ssub(Z)-signal in the inner cascade and QCM with Ssub(X)-signal in the outer cascade. In particular, the mean square amplitude of magnetic field fluctuations within a bandwidth of 0.1-1 Hz and 1-10 Hz was below 1 nT and 15 nT respectively
Effects of MHD slow shocks propagating along magnetic flux tubes in a dipole magnetic field
Directory of Open Access Journals (Sweden)
N. V. Erkaev
2002-01-01
Full Text Available Variations of the plasma pressure in a magnetic flux tube can produce MHD waves evolving into shocks. In the case of a low plasma beta, plasma pressure pulses in the magnetic flux tube generate MHD slow shocks propagating along the tube. For converging magnetic field lines, such as in a dipole magnetic field, the cross section of the magnetic flux tube decreases enormously with increasing magnetic field strength. In such a case, the propagation of MHD waves along magnetic flux tubes is rather different from that in the case of uniform magnetic fields. In this paper, the propagation of MHD slow shocks is studied numerically using the ideal MHD equations in an approximation suitable for a thin magnetic flux tube with a low plasma beta. The results obtained in the numerical study show that the jumps in the plasma parameters at the MHD slow shock increase greatly while the shock is propagating in the narrowing magnetic flux tube. The results are applied to the case of the interaction between Jupiter and its satellite Io, the latter being considered as a source of plasma pressure pulses.
Paired quantum Hall states on noncommutative two-tori
Energy Technology Data Exchange (ETDEWEB)
Marotta, Vincenzo [Dipartimento di Scienze Fisiche, Universita di Napoli ' Federico II' and INFN, Sezione di Napoli, Compl. universitario M. Sant' Angelo, Via Cinthia, 80126 Napoli (Italy); Naddeo, Adele, E-mail: naddeo@sa.infn.i [CNISM, Unita di Ricerca di Salerno and Dipartimento di Fisica ' E. R. Caianiello' , Universita degli Studi di Salerno, Via Salvador Allende, 84081 Baronissi (Italy)
2010-08-01
By exploiting the notion of Morita equivalence for field theories on noncommutative tori and choosing rational values of the noncommutativity parameter theta (in appropriate units), a one-to-one correspondence between an Abelian noncommutative field theory (NCFT) and a non-Abelian theory of twisted fields on ordinary space can be established. Starting from this general result, we focus on the conformal field theory (CFT) describing a quantum Hall fluid (QHF) at paired states fillings nu=m/(pm+2) Cristofano et al. (2000) , recently obtained by means of m-reduction procedure, and show that it is the Morita equivalent of a NCFT. In this way we extend the construction proposed in Marotta and Naddeo (2008) for the Jain series nu=m/(2pm+1) . The case m=2 is explicitly discussed and the role of noncommutativity in the physics of quantum Hall bilayers is emphasized. Our results represent a step forward the construction of a new effective low energy description of certain condensed matter phenomena and help to clarify the relationship between noncommutativity and quantum Hall fluids.
Fully-automated field mapping of a dipole magnet of a multi-passage spectrometer (MPS)
Energy Technology Data Exchange (ETDEWEB)
Meissner, Robert; Thirolf, Peter; Weber, Christine [Fakultaet fuer Physik, LMU - Muenchen (Germany)
2013-07-01
MLLTRAP is a Penning-trap mass-spectrometer facility, which is currently being commissioned at the Maier-Leibnitz Laboratory in Garching. Here, atomic mass values are determined by measuring cyclotron frequencies of stored ions in a strong magnetic field. In the future, highly-charged ions should be utilized for an improvement in the achievable mass accuracy. For this purpose, singly-charged ions will have to be injected into a charge-breeding device, such as an EBIT, and transferred back towards the Penning traps, while being q/A selected. To fulfill these tasks a multi-passage-spectrometer (MPS) is being built. It consists of a fast-ramping, round-pole dipole magnet with an electrostatic mirror system. A basic requirement for building the MPS is a detailed knowledge on the magnetic field produced by the magnet. It is necessary to simulate the trajectories of the ions and gain knowledge on the design and geometry of the electrostatic mirror system and the vacuum chamber. For this purpose, a robot was designed, which - powered by three step motors - measures the magnetic field fully automated. The robot moves a Hall probe within three dimensions with a resolution of 1 mm and an uncertainty of 0.5 mm. In this presentation, the development of the robot, its control and data acquisition via LabView and the results are presented.
Evaluating Force-Field London Dispersion Coefficients Using the Exchange-Hole Dipole Moment Model.
Mohebifar, Mohamad; Johnson, Erin R; Rowley, Christopher N
2017-12-12
London dispersion interactions play an integral role in materials science and biophysics. Force fields for atomistic molecular simulations typically represent dispersion interactions by the 12-6 Lennard-Jones potential using empirically determined parameters. These parameters are generally underdetermined, and there is no straightforward way to test if they are physically realistic. Alternatively, the exchange-hole dipole moment (XDM) model from density-functional theory predicts atomic and molecular London dispersion coefficients from first principles, providing an innovative strategy to validate the dispersion terms of molecular-mechanical force fields. In this work, the XDM model was used to obtain the London dispersion coefficients of 88 organic molecules relevant to biochemistry and pharmaceutical chemistry and the values compared with those derived from the Lennard-Jones parameters of the CGenFF, GAFF, OPLS, and Drude polarizable force fields. The molecular dispersion coefficients for the CGenFF, GAFF, and OPLS models are systematically higher than the XDM-calculated values by a factor of roughly 1.5, likely due to neglect of higher order dispersion terms and premature truncation of the dispersion-energy summation. The XDM dispersion coefficients span a large range for some molecular-mechanical atom types, suggesting an unrecognized source of error in force-field models, which assume that atoms of the same type have the same dispersion interactions. Agreement with the XDM dispersion coefficients is even poorer for the Drude polarizable force field. Popular water models were also examined, and TIP3P was found to have dispersion coefficients similar to the experimental and XDM references, although other models employ anomalously high values. Finally, XDM-derived dispersion coefficients were used to parametrize molecular-mechanical force fields for five liquids-benzene, toluene, cyclohexane, n-pentane, and n-hexane-which resulted in improved accuracy in the
Tsang, L.; Kong, J. A.
1974-01-01
With applications to geophysical subsurface probings, electromagnetic fields due to a horizontal electric dipole laid on the surface of a two-layer medium are solved by a combination of analytic and numerical methods. Interference patterns are calculated for various layer thickness. The results are interpreted in terms of normal modes, and the accuracies of the methods are discussed.
Plane waves in noncommutative fluids
Energy Technology Data Exchange (ETDEWEB)
Abdalla, M.C.B., E-mail: mabdalla@ift.unesp.br [Instituto de Física Teórica, UNESP, Universidade Estadual Paulista, Rua Dr. Bento Teobaldo Ferraz 271, Bloco 2, Barra-Funda, Caixa Postal 70532-2, 01156-970, São Paulo, SP (Brazil); Holender, L., E-mail: holender@ufrrj.br [Grupo de Física Teórica e Matemática Física, Departamento de Física, Universidade Federal Rural do Rio de Janeiro (UFRRJ), Cx. Postal 23851, BR 465 Km 7, 23890-000 Seropédica, RJ (Brazil); Santos, M.A., E-mail: masantos@cce.ufes.br [Departamento de Física e Química, Universidade Federal do Espírito Santo (UFES), Avenida Fernando Ferarri S/N, Goiabeiras, 29060-900 Vitória, ES (Brazil); Vancea, I.V., E-mail: ionvancea@ufrrj.br [Grupo de Física Teórica e Matemática Física, Departamento de Física, Universidade Federal Rural do Rio de Janeiro (UFRRJ), Cx. Postal 23851, BR 465 Km 7, 23890-000 Seropédica, RJ (Brazil)
2013-08-01
We study the dynamics of the noncommutative fluid in the Snyder space perturbatively at the first order in powers of the noncommutative parameter. The linearized noncommutative fluid dynamics is described by a system of coupled linear partial differential equations in which the variables are the fluid density and the fluid potentials. We show that these equations admit a set of solutions that are monochromatic plane waves for the fluid density and two of the potentials and a linear function for the third potential. The energy–momentum tensor of the plane waves is calculated.
Sainath, Kamalesh; Teixeira, Fernando L; Donderici, Burkay
2014-01-01
We develop a general-purpose formulation, based on two-dimensional spectral integrals, for computing electromagnetic fields produced by arbitrarily oriented dipoles in planar-stratified environments, where each layer may exhibit arbitrary and independent anisotropy in both its (complex) permittivity and permeability tensors. Among the salient features of our formulation are (i) computation of eigenmodes (characteristic plane waves) supported in arbitrarily anisotropic media in a numerically robust fashion, (ii) implementation of an hp-adaptive refinement for the numerical integration to evaluate the radiation and weakly evanescent spectra contributions, and (iii) development of an adaptive extension of an integral convergence acceleration technique to compute the strongly evanescent spectrum contribution. While other semianalytic techniques exist to solve this problem, none have full applicability to media exhibiting arbitrary double anisotropies in each layer, where one must account for the whole range of possible phenomena (e.g., mode coupling at interfaces and nonreciprocal mode propagation). Brute-force numerical methods can tackle this problem but only at a much higher computational cost. The present formulation provides an efficient and robust technique for field computation in arbitrary planar-stratified environments. We demonstrate the formulation for a number of problems related to geophysical exploration.
Phase singularities and energy fluxes of a noncanonical vortex dipole Airy beam in the far field
Cheng, Ke; You, Yunqi; Zhong, Xianqiong
2015-10-01
Based on the vector angular spectrum representation and stationary phase method, analytical far-field vectorial expressions of a noncanonical vortex dipole Airy beam, namely, a pair of noncanonical vortices with opposite charges embedded in an Airy beam are derived and used to investigate the phase singularities and energy flux distributions of the corresponding beam in the far-field regime, where the noncanonical characteristic of vortex is stressed. It is shown that the noncanonical strength, off-axis distance, and aperture coefficient affect the position and number of phase singularities, and the motion, creation, and annihilation of phase singularities are found by adjusting these parameters. For a low aperture coefficient, the energy flux distributions exhibit different numbers and orientations of lobes by varying the noncanonical strength. With increasing aperture coefficient, the symmetries of lobes are broken, and the energy flux distributions gradually become ellipses and the directions of their major axes vary with different noncanonical strengths. Finally, the energy flux distributions of an Airy beam carrying a single noncanonical vortex are discussed and compared.
Determination of the bending field integral of the LEP spectrometer dipole
Chritin, R; Dehning, Bernd; Hidalgo, A; Hildreth, M; Kalbreier, Willi; Leclère, P; Mugnai, G; Palacios, J; Roncarolo, F; Torrence, E; Wilkinson, G
2005-01-01
The LEP spectrometer performed calibrations of the beam energy in the 2000 LEP run, in order to provide a kinematical constraint for the W boson mass measurement. The beam was deflected in the spectrometer by a steel core dipole, and the bending angle was measured by Beam-Position Monitors on either side of the magnet. The energy determination relies on measuring the change in bending angle when ramping the beam from a reference point at 50 GeV to an energy within the LEP W physics regime, typically 93 GeV. The ratio of integrated bending fields at these settings (approximately 1.18 Tm/0:64 Tm) must be known with a precision of a few 10-5. The paper reports on the field mapping measurements which were conducted to determine the bending integral under a range of excitation currents and coil temperatures. These were made in the laboratory before and after spectrometer operation, using a test-bench equipped with a moving arm, carrying an NMR probe and Hall probes, and in the LEP tunnel itself, with a mapping tro...
Teleparallel gravity and dimensional reductions of noncommutative gauge theory
Langmann, Edwin; Szabo, Richard J.
2001-11-01
We study dimensional reductions of noncommutative electrodynamics on flat space, which lead to gauge theories of gravitation. For a general class of such reductions, we show that the noncommutative gauge fields naturally yield a Weitzenböck geometry on spacetime and that the induced diffeomorphism invariant field theory can be made equivalent to a teleparallel formulation of gravity which macroscopically describes general relativity. The Planck length is determined in this setting by the Yang-Mills coupling constant and the noncommutativity scale. The effective field theory can also contain higher curvature and non-local terms which are characteristic of string theory. Some applications to D-brane dynamics and generalizations to include the coupling of ordinary Yang-Mills theory to gravity are also described.
Cosmological production of noncommutative black holes
International Nuclear Information System (INIS)
Mann, Robert B.; Nicolini, Piero
2011-01-01
We investigate the pair creation of noncommutative black holes in a background with a positive cosmological constant. As a first step we derive the noncommutative geometry inspired Schwarzschild-de Sitter solution. By varying the mass and the cosmological constant parameters, we find several spacetimes compatible with the new solution: positive-mass spacetimes admit one cosmological horizon and two, one, or no black hole horizons, while negative-mass spacetimes have just a cosmological horizon. These new black holes share the properties of the corresponding asymptotically flat solutions, including the nonsingular core and thermodynamic stability in the final phase of the evaporation. As a second step we determine the action which generates the matter sector of gravitational field equations and we construct instantons describing the pair production of black holes and the other admissible topologies. As a result we find that for current values of the cosmological constant the de Sitter background is quantum mechanically stable according to experience. However, positive-mass noncommutative black holes and solitons would have plentifully been produced during inflationary times for Planckian values of the cosmological constant. As a special result we find that, in these early epochs of the Universe, Planck size black holes production would have been largely disfavored. We also find a potential instability for production of negative-mass solitons.
Non-commutative analytic geometry and a new model for the field theory of closed bosonic strings
International Nuclear Information System (INIS)
Awada, M.A.
1986-07-01
We propose a new model for the field theory of interacting closed bosonic strings. The key ingredient in our constructions is based on the assumption that the action is written in terms of two independent states rather than one state. The first state is chiral while the second state is antichiral. The new picture of the corresponding vertex operator is not just an overlap ''δ'' functional
Saturnino, Diana; Langlais, Benoit; Amit, Hagay; Civet, François; Mandea, Mioara; Beucler, Éric
2018-03-01
A detailed description of the main geomagnetic field and of its temporal variations (i.e., the secular variation or SV) is crucial to understanding the geodynamo. Although the SV is known with high accuracy at ground magnetic observatory locations, the globally uneven distribution of the observatories hampers the determination of a detailed global pattern of the SV. Over the past two decades, satellites have provided global surveys of the geomagnetic field which have been used to derive global spherical harmonic (SH) models through some strict data selection schemes to minimise external field contributions. However, discrepancies remain between ground measurements and field predictions by these models; indeed the global models do not reproduce small spatial scales of the field temporal variations. To overcome this problem we propose to directly extract time series of the field and its temporal variation from satellite measurements as it is done at observatory locations. We follow a Virtual Observatory (VO) approach and define a global mesh of VOs at satellite altitude. For each VO and each given time interval we apply an Equivalent Source Dipole (ESD) technique to reduce all measurements to a unique location. Synthetic data are first used to validate the new VO-ESD approach. Then, we apply our scheme to data from the first two years of the Swarm mission. For the first time, a 2.5° resolution global mesh of VO time series is built. The VO-ESD derived time series are locally compared to ground observations as well as to satellite-based model predictions. Our approach is able to describe detailed temporal variations of the field at local scales. The VO-ESD time series are then used to derive global spherical harmonic models. For a simple SH parametrization the model describes well the secular trend of the magnetic field both at satellite altitude and at the surface. As more data will be made available, longer VO-ESD time series can be derived and consequently used to
Two roads to noncommutative causality
International Nuclear Information System (INIS)
Besnard, Fabien
2015-01-01
We review the physical motivations and the mathematical results obtained so far in the isocone-based approach to noncommutative causality. We also give a briefer account of the alternative framework of Franco and Eckstein which is based on Lorentzian spectral triples. We compare the two theories on the simple example of the product geometry of the Minkowski plane by the finite noncommutative space with algebra M 2 (C). (paper)
In Search of a Dipole Field during the Plio-Pleistocene
Asefaw, H. F.; Tauxe, L.; Staudigel, H.; Shaar, R.; Cai, S.; Cromwell, G.; Behar, N.; Koppers, A. A. P.
2017-12-01
A geocentric axial dipole (GAD) field accounts for the majority of the modern field and is assumed to be a good first order approximation for the time averaged ancient field. A GAD field predicts a latitudinal dependence of intensity. Given this relationship, the intensity of the field measured at the North and South poles should be twice as strong as the intensity recorded at the equator. The current paleointensity database- archived at both http://earth.liv.ac.uk/pint/ and http://earthref.org/MagIC - shows no such dependency over the last 5 Myr (e.g. Lawrence et al., 2009, doi: 10.1029/2008GC002072; Cromwell et al., 2015; doi: 10.1002/2014JB011828). In order to investigate whether better experimental protocol or data selection approaches could resolve the problem, we: 1) applied a new data selection protocol (CCRIT) which has recovered historical field values with high precision and accuracy (Cromwell et al., 2015), 2) re-sampled the fine grained tops of lava flows in Antarctica (77.9° S) that were previously studied for paleodirections but failed to meet our strict selection criteria, 3) sampled cinder cones in the Golan Heights (33.08° N), and 4) acquired data from lava flows from the HSDP2 drill core in Hawaii (19.71° N ). New and published Ar-Ar dates demonstrate that all the samples formed in the last 5 Myr. We conducted IZZI modified Thellier-Thellier experiments and then calculated paleointensities from the samples that passed a set of strict selection criteria. After applying the CCRIT criteria to our data, we find a time averaged paleointensity of 35.7 ±6.86 μT in the Golan Heights, 34.5 μT in Hawaii, and 34.22 ±3.4 μT in Antarctica. New results from Iceland (64° N), published by Cromwell et al. (2015, doi: 10.1002/2014JB011828), also pass the CCRIT criteria and record an average intensity of 33.1 ± 8.3 μT. The average paleointensities from the Golan Heights, Antarctica, Iceland and Hawaii, that span the last 5 Myr and pass the CCRIT criteria
International Nuclear Information System (INIS)
Shimada, Rintaro; Hamaguchi, Hiro-o
2014-01-01
We quantitatively interpret the recently discovered intriguing phenomenon related to resonance Hyper-Raman (HR) scattering. In resonance HR spectra of all-trans-β-carotene (β-carotene) in solution, vibrations of proximate solvent molecules are observed concomitantly with the solute β-carotene HR bands. It has been shown that these solvent bands are subject to marked intensity enhancements by more than 5 orders of magnitude under the presence of β-carotene. We have called this phenomenon the molecular-near field effect. Resonance HR spectra of β-carotene in benzene, deuterated benzene, cyclohexane, and deuterated cyclohexane have been measured precisely for a quantitative analysis of this effect. The assignments of the observed peaks are made by referring to the infrared, Raman, and HR spectra of neat solvents. It has been revealed that infrared active and some Raman active vibrations are active in the HR molecular near-field effect. The observed spectra in the form of difference spectra (between benzene/deuterated benzene and cyclohexane/deuterated cyclohexane) are quantitatively analyzed on the basis of the extended vibronic theory of resonance HR scattering. The theory incorporates the coupling of excited electronic states of β-carotene with the vibrations of a proximate solvent molecule through solute–solvent dipole–dipole and dipole–quadrupole interactions. It is shown that the infrared active modes arise from the dipole–dipole interaction, whereas Raman active modes from the dipole–quadrupole interaction. It is also shown that vibrations that give strongly polarized Raman bands are weak in the HR molecular near-field effect. The observed solvent HR spectra are simulated with the help of quantum chemical calculations for various orientations and distances of a solvent molecule with respect to the solute. The observed spectra are best simulated with random orientations of the solvent molecule at an intermolecular distance of 10 Å
Energy Technology Data Exchange (ETDEWEB)
Shimada, Rintaro; Hamaguchi, Hiro-o, E-mail: hhama@nctu.edu.tw [Department of Applied Chemistry and Institute of Molecular Science, National Chiao Tung University, 1001 University Road, Hsinchu 30010, Taiwan (China)
2014-05-28
We quantitatively interpret the recently discovered intriguing phenomenon related to resonance Hyper-Raman (HR) scattering. In resonance HR spectra of all-trans-β-carotene (β-carotene) in solution, vibrations of proximate solvent molecules are observed concomitantly with the solute β-carotene HR bands. It has been shown that these solvent bands are subject to marked intensity enhancements by more than 5 orders of magnitude under the presence of β-carotene. We have called this phenomenon the molecular-near field effect. Resonance HR spectra of β-carotene in benzene, deuterated benzene, cyclohexane, and deuterated cyclohexane have been measured precisely for a quantitative analysis of this effect. The assignments of the observed peaks are made by referring to the infrared, Raman, and HR spectra of neat solvents. It has been revealed that infrared active and some Raman active vibrations are active in the HR molecular near-field effect. The observed spectra in the form of difference spectra (between benzene/deuterated benzene and cyclohexane/deuterated cyclohexane) are quantitatively analyzed on the basis of the extended vibronic theory of resonance HR scattering. The theory incorporates the coupling of excited electronic states of β-carotene with the vibrations of a proximate solvent molecule through solute–solvent dipole–dipole and dipole–quadrupole interactions. It is shown that the infrared active modes arise from the dipole–dipole interaction, whereas Raman active modes from the dipole–quadrupole interaction. It is also shown that vibrations that give strongly polarized Raman bands are weak in the HR molecular near-field effect. The observed solvent HR spectra are simulated with the help of quantum chemical calculations for various orientations and distances of a solvent molecule with respect to the solute. The observed spectra are best simulated with random orientations of the solvent molecule at an intermolecular distance of 10 Å.
Test results of HD2, a high field Nb$_{3}$Sn dipole with a 36 mm bore
Ferracin, P
2009-01-01
The Superconducting Magnet Program at Lawrence Berkeley National Laboratory (LBNL) has developed the 1 m long Nb3Sn dipole magnet HD2. With tilted (flared) ends to avoid obstructing a 36 mm clear bore, HD2 represents a step towards the use of block-type coils in high-field accelerator magnets. The coil design has been optimized to minimize geometric harmonics and reduce the conductor peak field in the end region, resulting in an expected short sample dipole field of 15 T. The support structure is composed by an external aluminum shell pretensioned with pressurized bladders and interference keys, and by two stainless steel end plates compressing the coil ends through four aluminum axial rods. We report on magnet design, assembly, and test results, including training performance, quench locations, and strain gauge measurements
Instantons, quivers and noncommutative Donaldson-Thomas theory
Energy Technology Data Exchange (ETDEWEB)
Cirafici, Michele, E-mail: cirafici@math.ist.utl.pt [Centro de Analise Matematica, Geometria e Sistemas Dinamicos, Departamento de Matematica, Instituto Superior Tecnico, Av. Rovisco Pais, 1049-001 Lisboa (Portugal); Sinkovics, Annamaria, E-mail: A.Sinkovics@damtp.cam.ac.uk [Department of Applied Mathematics and Theoretical Physics, Centre for Mathematical Sciences, University of Cambridge, Wilberforce Road, Cambridge CB3 0WA (United Kingdom); Szabo, Richard J., E-mail: R.J.Szabo@ma.hw.ac.uk [Department of Mathematics, Heriot-Watt University, Colin Maclaurin Building, Riccarton, Edinburgh EH14 4AS (United Kingdom); Maxwell Institute for Mathematical Sciences, Edinburgh (United Kingdom)
2011-12-11
We construct noncommutative Donaldson-Thomas invariants associated with abelian orbifold singularities by analyzing the instanton contributions to a six-dimensional topological gauge theory. The noncommutative deformation of this gauge theory localizes on noncommutative instantons which can be classified in terms of three-dimensional Young diagrams with a colouring of boxes according to the orbifold group. We construct a moduli space for these gauge field configurations which allows us to compute its virtual numbers via the counting of representations of a quiver with relations. The quiver encodes the instanton dynamics of the noncommutative gauge theory, and is associated to the geometry of the singularity via the generalized McKay correspondence. The index of BPS states which compute the noncommutative Donaldson-Thomas invariants is realized via topological quantum mechanics based on the quiver data. We illustrate these constructions with several explicit examples, involving also higher rank Coulomb branch invariants and geometries with compact divisors, and connect our approach with other ones in the literature.
Noncommutative Blackwell-Ross martingale inequality
Talebi, Ali; Moslehian, Mohammad Sal; Sadeghi, Ghadir
We establish a noncommutative Blackwell-Ross inequality for supermartingales under a suitable condition which generalizes Khan’s work to the noncommutative setting. We then employ it to deduce an Azuma-type inequality.
Electromagnetic fields at the sea bottom induced by a line of immersed electric dipoles
Directory of Open Access Journals (Sweden)
Edson E.S. Sampaio
2011-09-01
Full Text Available The analysis of electromagnetic fields caused by alternate or transient electric currents flowing along a cable in sea water has several applications. It supports the interpretation of electromagnetic geophysical data and safety procedures against the threat of sea mines. The approach to the problem employs a magnetic vector potential in the frequency domain due to a pulse source electric dipole, and performs Laplace and Hankel transforms and integration along the cable, to describe the variation of the magnetic induction field due to an electric dipole of finite length. The result is applicable to shallow or deep sea water environments, adaptable to any transmitting current waveform and useful for wave-field separation. The prospects relate to a horizontal receiving coil at the sea bottom and simulate: a minesweeper campaign with a current source at the sea surface or a geophysical survey with a current source close to the sea floor. Therefore, the present analysis may serve: to define parameters in counter-sweeping of submarine mines; to map the conductivity of sediments under shallow waters for the prevention and control of contamination; and as a first approach in the characterization of offshore mineral and oil economic deposits.A análise de campos eletromagnéticos causados por correntes alternadas ou transientes fluindo ao longo de um cabo na água do mar tem várias aplicações. Ela prove suporte à interpretação de dados geofísicos eletromagnéticos e aos procedimentos de segurança contra a ameaça de minas submarinas. A abordagem do problema emprega um potencial vetorial magnético, no domínio da frequência, devido a um dipolo elétrico com uma fonte tipo pulso e calcula transformações de Laplace e de Hankel e integração ao longo do comprimento do cabo, para descrever a variação temporal do campo magnético de indução devido a um dipolo elétrico de comprimento finito. O resultado é aplicável em ambientes de água do
The Field Radiated by a Ring Quasi-Array of an Infinite Number of Tangential or Radial Dipoles
DEFF Research Database (Denmark)
Knudsen, H. L.
1953-01-01
A homogeneous ring array of axial dipoles will radiate a vertically polarized field that concentrates to an increasing degree around the horizontal plane with increasing increment of the current phase per revolution. There is reason to believe that by using a corresponding antenna system with tan......A homogeneous ring array of axial dipoles will radiate a vertically polarized field that concentrates to an increasing degree around the horizontal plane with increasing increment of the current phase per revolution. There is reason to believe that by using a corresponding antenna system...... with tangential or radial dipoles, a field may be obtained that has a similar useful structure as the above-mentioned ring array, but which in contrast to the latter is essentially horizontally polarized. In this paper a systematic investigation has been made of the field from such an antenna system...... of the antenna systems treated here converges towards infinity, too, i.e. supergain occurs. Based on the theory of supergain an approximate expression has been derived for the minimum value of the radius of the antenna system, which it is possible to use in practice....
Energy Technology Data Exchange (ETDEWEB)
Silenko, Alexander J. [Belarusian State University, Research Institute for Nuclear Problems, Minsk (Belarus); Joint Institute for Nuclear Research, Bogoliubov Laboratory of Theoretical Physics, Dubna (Russian Federation)
2017-10-15
We calculate the corrections for constant radial magnetic field in muon g - 2 and electric-dipole-moment experiments in storage rings. While the correction is negligible for the current generation of g - 2 experiments, it affects the upcoming muon electric-dipole-moment experiment at Fermilab. (orig.)
Li, Rui; Gan, Ye; Song, Qun Liang; Zhu, Zhi Hong; Shi, Jingsheng; Yang, Hongbin; Wang, Wei; Chen, Peng; Li, Chang Ming
2010-08-01
Bacteriorhodopsin-embedded purple membrane (bR-PM) is one of the most promising biomaterials for various bioelectronics applications. In this work, we demonstrate that a dipole bio-originated from bR-PM can bidirectionally mediate the performance of a bottom-contact TiO2 nanowire field effect transistor (FET) for performance improvement. When negative gate voltage is applied, both transfer and output characteristics of the TiO2 nanowire FET are enhanced by the bR-PM modification, resulting in a hole mobility increased by a factor of 2. The effect of the number of the deposited bR-PM layers on the normalized ΔID of the FET suggests that the additional electric field generated by the dipole moment natively existing in bR-PM actually boosts the performance of the TiO2 nanowires FET.
Klein-Gordon oscillators in noncommutative phase space
International Nuclear Information System (INIS)
Wang Jianhua
2008-01-01
We study the Klein-Gordon oscillators in non-commutative (NC) phase space. We find that the Klein-Gordon oscillators in NC space and NC phase-space have a similar behaviour to the dynamics of a particle in commutative space moving in a uniform magnetic field. By solving the Klein-Gordon equation in NC phase space, we obtain the energy levels of the Klein-Gordon oscillators, where the additional terms related to the space-space and momentum-momentum non-commutativity are given explicitly. (authors)
DEFF Research Database (Denmark)
Arslanagic, Samel; Meincke, Peter; Jørgensen, Erik
2003-01-01
We derive a line integral representation of the physical optics scattered far field that yields the exact same result as the conventional surface radiation integral. This representation applies to a perfectly electrically conducting plane scatterer illuminated by electric or magnetic Hertzian...... dipoles. The source and observation points can take on almost arbitrary positions. To illustrate the exactness and efficiency of the new line integral, numerical comparisons with the conventional surface radiation integral are carried out....
Mideksa, K G; Hellriegel, H; Hoogenboom, N; Krause, H; Schnitzler, A; Deuschl, G; Raethjen, J; Heute, U; Muthuraman, M
2013-01-01
Various source localization techniques have indicated the generators of each identifiable component of movement-related cortical potentials, since the discovery of the surface negative potential prior to self-paced movement by Kornhuber and Decke. Readiness potentials and fields preceding self-paced finger movements were recorded simultaneously using multichannel electroencephalography (EEG) and magnetoencephalography (MEG) from five healthy subjects. The cortical areas involved in this paradigm are the supplementary motor area (SMA) (bilateral), pre-SMA (bilateral), and contralateral motor area of the moving finger. This hypothesis is tested in this paper using the dipole source analysis independently for only EEG, only MEG, and both combined. To localize the sources, the forward problem is first solved by using the boundary-element method for realistic head models and by using a locally-fitted-sphere approach for spherical head models consisting of a set of connected volumes, typically representing the scalp, skull, and brain. In the source reconstruction it is to be expected that EEG predominantly localizes radially oriented sources while MEG localizes tangential sources at the desired region of the cortex. The effect of MEG on EEG is also observed when analyzing both combined data. When comparing the two head models, the spherical and the realistic head models showed similar results. The significant points for this study are comparing the source analysis between the two modalities (EEG and MEG) so as to assure that EEG is sensitive to mostly radially orientated sources while MEG is only sensitive to only tangential sources, and comparing the spherical and individual head models.
Moon, Haksu; Teixeira, Fernando L.; Donderici, Burkay
2014-09-01
Computation of electromagnetic fields due to point sources (Hertzian dipoles) in cylindrically stratified media is a classical problem for which analytical expressions of the associated tensor Green's function have been long known. However, under finite-precision arithmetic, direct numerical computations based on the application of such analytical (canonical) expressions invariably lead to underflow and overflow problems related to the poor scaling of the eigenfunctions (cylindrical Bessel and Hankel functions) for extreme arguments and/or high-order, as well as convergence problems related to the numerical integration over the spectral wavenumber and to the truncation of the infinite series over the azimuth mode number. These problems are exacerbated when a disparate range of values is to be considered for the layers' thicknesses and material properties (resistivities, permittivities, and permeabilities), the transverse and longitudinal distances between source and observation points, as well as the source frequency. To overcome these challenges in a systematic fashion, we introduce herein different sets of range-conditioned, modified cylindrical functions (in lieu of standard cylindrical eigenfunctions), each associated with nonoverlapped subdomains of (numerical) evaluation to allow for stable computations under any range of physical parameters. In addition, adaptively-chosen integration contours are employed in the complex spectral wavenumber plane to ensure convergent numerical integration in all cases. We illustrate the application of the algorithm to problems of geophysical interest involving layer resistivities ranging from 1000 Ω m to 10-8 Ω m, frequencies of operation ranging from 10 MHz down to the low magnetotelluric range of 0.01 Hz, and for various combinations of layer thicknesses.
Giant dipole resonances in hot nuclear matter in the model of self-relaxing mean field
International Nuclear Information System (INIS)
Okolowicz, J.; Ploszajczak, M.; Drozdz, S.; Caurier, E.
1989-01-01
The extended time-dependent Hartree-Fock approach is applied for the description of the isovector giant dipole resonance in 40 Ca at finite temperatures. The thermalization process is described using the relaxation-time ansatz for the collision integral. Strong inhibition of the giant-dipole-resonance γ-decay is found due to the fast vaporization of the nuclear surface for thermal excitation energies above E * /A ≅ 4.5 MeV. This pre-equilibrium emission of particles in the vapor phase is associated with the radial expansion of nucleus and with the vanishing particle binding energies mainly for protons. (orig.)
A review of non-commutative gauge theories
Indian Academy of Sciences (India)
B. (7). The limit m. 0 corresponds to the projection of the quantum mechanical spectrum to the lowest Landau level. 1.2 String theory origin of non-commutation. If one writes action of Neveu–Schwartz open string moving in a flat Eucliden space with metric gij in the presence of a constant background field B, we have. SΣ = 1.
On Subgroups of Non-Commutative General Rhotrix Group ...
African Journals Online (AJOL)
On Subgroups of Non-Commutative General Rhotrix Group. A Mohammed, UE Okon. Abstract. This paper considers the pair (GRn(F),o) consisting of the set of all invertible rhotrices of size n over an arbitrary field F; and together with the binary operation of row-column based method for rhotrix multiplication; 'o' , in order to ...
The M5-brane and non-commutative open strings
Bergshoeff, E.; Berman, D.S.; Schaar, J.P. van der; Sundell, P.
2001-01-01
The M-theory origin of non-commutative open-string theory is examined by investigating the M-theory 5-brane at near critical field strength. In particular, it is argued that the open-membrane metric provides the appropriate moduli when calculating the duality relations between M and II
Newton's second law in a non-commutative space
International Nuclear Information System (INIS)
Romero, Juan M.; Santiago, J.A.; Vergara, J. David
2003-01-01
In this Letter we show that corrections to Newton's second law appear if we assume a symplectic structure consistent with the commutation rules of the non-commutative quantum mechanics. For central field we find that the correction term breaks the rotational symmetry. For the Kepler problem, this term is similar to a Coriolis force
International Nuclear Information System (INIS)
Rossi, Dominic M.
2010-01-01
The electric dipole response of neutron-rich nickel isotopes has been investigated using the LAND setup at GSI in Darmstadt (Germany). Relativistic secondary beams of 56-57 Ni and 67-72 Ni at approximately 500 AMeV have been generated using projectile fragmentation of stable ions on a 4 g/cm 2 Be target and subsequent separation in the magnetic dipole fields of the FRagment Separator (FRS). After reaching the LAND setup in Cave C, the radioactive ions were excited electromagnetically in the electric field of a Pb target. The decay products have been measured in inverse kinematics using various detectors. Neutron-rich 67-69 Ni isotopes decay by the emission of neutrons, which are detected in the LAND detector. The present analysis concentrates on the (γ,n) and (γ,2n) channels in these nuclei, since the proton and three-neutron thresholds are unlikely to be reached considering the virtual photon spectrum for nickel ions at 500 AMeV. A measurement of the stable 58 Ni isotope is used as a benchmark to check the accuracy of the present results with previously published data. The measured (γ,n) and (γ,np) channels are compared with an inclusive photoneutron measurement by Fultz and coworkers, which are consistent within the respective errors. The measured excitation energy distributions of 67-69 Ni contain a large portion of the Giant Dipole Resonance (GDR) strength predicted by the Thomas-Reiche-Kuhn energy-weighted sum rule, as well as a significant amount of low-lying E1 strength, that cannot be attributed to the GDR alone. The GDR distribution parameters are calculated using well-established semi-empirical systematic models, providing the peak energies and widths. The GDR strength is extracted from the χ 2 minimization of the model GDR to the measured data of the (γ,2n) channel, thereby excluding any influence of eventual low-lying strength. The subtraction of the obtained GDR distribution from the total measured E1 strength provides the low-lying E1 strength
Noncommutative mathematics for quantum systems
Franz, Uwe
2016-01-01
Noncommutative mathematics is a significant new trend of mathematics. Initially motivated by the development of quantum physics, the idea of 'making theory noncommutative' has been extended to many areas of pure and applied mathematics. This book is divided into two parts. The first part provides an introduction to quantum probability, focusing on the notion of independence in quantum probability and on the theory of quantum stochastic processes with independent and stationary increments. The second part provides an introduction to quantum dynamical systems, discussing analogies with fundamental problems studied in classical dynamics. The desire to build an extension of the classical theory provides new, original ways to understand well-known 'commutative' results. On the other hand the richness of the quantum mathematical world presents completely novel phenomena, never encountered in the classical setting. This book will be useful to students and researchers in noncommutative probability, mathematical physi...
NONCOMMUTATIVE MOTIVES OF AZUMAYA ALGEBRAS
Tabuada, Goncalo; VAN DEN BERGH, Michel
2015-01-01
Let k be a base commutative ring, R a commutative ring of coefficients, X a quasi-compact quasi-separated k-scheme with m connected components, A a sheaf of Azumaya algebras over X of rank (r[subscript 1], . . . , r[subscript m]), and Hmo0(k)[subscript R] the category of noncommutative motives with R-coefficients. Assume that 1/r ∈ R with r := r[subscript 1] ×· · ·×r[subscript m]. Under these assumptions, we prove that the noncommutative motives with R-coefficients of X and A are isomorphic. ...
International Nuclear Information System (INIS)
Lamoreaux, S.K.
1999-01-01
A simple formulation for calculating the magnetic field external to an extended nonpermeable conducting body due to thermal current fluctuations within the body is developed, and is applied to a recent experimental search for the atomic electric-dipole moment (EDM) of 199 Hg. It is shown that the thermal fluctuation field is only slightly smaller in magnitude than other noise sources in that experiment. The formulation is extended to permeable bodies, and the implications for general EDM experiments are discussed. copyright 1999 The American Physical Society
Wang, Xiaorong; Caspi, Shlomo; Dietderich, Daniel R.; Ghiorso, William B.; Gourlay, Stephen A.; Higley, Hugh C.; Lin, Andy; Prestemon, Soren O.; van der Laan, Danko; Weiss, Jeremy D.
2018-04-01
REBCO coated conductors maintain a high engineering current density above 16 T at 4.2 K. That fact will significantly impact markets of various magnet applications including high-field magnets for high-energy physics and fusion reactors. One of the main challenges for the high-field accelerator magnet is the use of multi-tape REBCO cables with high engineering current density in magnet development. Several approaches developing high-field accelerator magnets using REBCO cables are demonstrated. In this paper, we introduce an alternative concept based on the canted cos θ (CCT) magnet design using conductor on round core (CORC®) wires that are wound from multiple REBCO tapes with a Cu core. We report the development and test of double-layer three-turn CCT dipole magnets using CORC® wires at 77 and 4.2 K. The scalability of the CCT design allowed us to effectively develop and demonstrate important magnet technology features such as coil design, winding, joints and testing with minimum conductor lengths. The test results showed that the CCT dipole magnet using CORC® wires was a viable option in developing a REBCO accelerator magnet. One of the critical development needs is to increase the engineering current density of the 3.7 mm diameter CORC® wire to 540 A mm-2 at 21 T, 4.2 K and to reduce the bending radius to 15 mm. This would enable a compact REBCO dipole insert magnet to generate a 5 T field in a background field of 16 T at 4.2 K.
International Nuclear Information System (INIS)
Rochepault, E.
2012-01-01
In the framework of LHC upgrades, significant efforts are provided to design accelerator magnets using the superconducting alloy Nb 3 Sn, which allows to reach higher magnetic fields (≥12 T). The aim of this thesis is to propose new computation and manufacturing methods for high field Nb 3 Sn dipoles. A ceramic insulation, previously designed at CEA Saclay, has been tested for the first time on cables, in an accelerator magnet environment. Critical current measures, under magnetic field and mechanical stress, have been carried out in particular. With this test campaign, the current ceramic insulation has been shown to be too weak mechanically and the critical current properties are degraded. Then a study has been conducted, with the objective to improve the mechanical strength of the insulation and better distribute the stress inside the cable. Methods of magnetic design have also been proposed, in order to optimize the coils shape, while fulfilling constraints of field homogeneity, operational margins, forces minimization... Consequently, several optimization codes have been set up. They are based on new methods using analytical formulas. A 2D code has first been written for block designs. Then two 3D codes have been realized for the optimization of dipole ends. The former consists in modeling the coil with elementary blocs and the latter is based on a modeling of the superconducting cables with ribbons. These optimization codes allowed to propose magnetic designs for high field accelerator magnets. (author) [fr
UV/IR mixing in noncommutative QED defined by Seiberg-Witten map
International Nuclear Information System (INIS)
Schupp, Peter; You Jiangyang
2008-01-01
Noncommutative gauge theories defined via Seiberg-Witten map have desirable properties that theories defined directly in terms of noncommutative fields lack, covariance and unrestricted choice of gauge group and charge being among them, but nonperturbative results in the deformation parameter θ are hard to obtain. In this article we use a θ-exact approach to study UV/IR mixing in a noncommutative quantum electrodynamics (NCQED) model defined via Seiberg-Witten map. The fermion contribution of the one loop correction to the photon propagator is computed and it is found that it gives the same UV/IR mixing term as a NCQED model without Seiberg-Witten map.
Magnetic field measurements of full length 50 mm aperture SSC dipole magnets at Fermilab
International Nuclear Information System (INIS)
Strait, J.; Bossert, R.; Carson, J.; Delchamps, S.W.; Gourlay, S.; Hanft, R.; Koska, W.; Kuchnir, M.; Lamm, M.J.; Mazur, P.O.; Mokhtarani, A.; Orris, D.; Ozelis, J.; Wake, M.; Devred, A.; DiMarco, J.; Kuzminski, J.; Puglisi, M.; Tompkins, J.C.; Yu, Y.; Zhao, Y.; Zheng, H.; Ogitsu, T.
1992-09-01
Thirteen 16 m long, 50 mm aperture SSC dipole magnets, designed jointly by Fermilab, Brookhaven National Laboratory, Lawrence Berkeley Laboratory and the SSC Laboratory, have been built at Fermilab. The first nine magnets have been fully tested to date. The allowed harmonics are systematically shifted from zero by amounts larger than the specification. The unallowed harmonics, with the exception of the skew sextupole, are consistent with zero. The magnet-to-magnet RMS variation of all harmonics is much smaller than the specification
Noncommutative Riemannian geometry from quantum spacetime generated by twisted Poincaré group
Aguillón, Cesar A.; Much, Albert; Rosenbaum, Marcos; Vergara, J. David
2017-11-01
We investigate a quantum geometric space in the context of what could be considered an emerging effective theory from quantum gravity. Specifically we consider a two-parameter class of twisted Poincaré algebras, from which Lie-algebraic noncommutativities of the translations are derived as well as associative star-products, deformed Riemannian geometries, Lie-algebraic twisted Minkowski spaces, and quantum effects that arise as noncommutativities. Starting from a universal differential algebra of forms based on the above-mentioned Lie-algebraic noncommutativities of the translations, we construct the noncommutative differential forms and inner and outer derivations, which are the noncommutative equivalents of the vector fields in the case of commutative differential geometry. Having established the essentials of this formalism, we construct a bimodule, which is required to be central under the action of the inner derivations in order to have well-defined contractions and from where the algebraic dependence of its coefficients is derived. This again then defines the noncommutative equivalent of the geometrical line-element in commutative differential geometry. We stress, however, that even though the components of the twisted metric are by construction symmetric in their algebra valuation, it is not so for their inverse, and thus to construct it, we made use of Gel'fand's theory of quasi-determinants, which is conceptually straightforward but computationally quite complicated beyond an algebra of 3 generators. The consequences of the noncommutativity of the Lie-algebra twisted geometry are further discussed.
Noncommuting Momenta of Topological Solitons
Watanabe, Haruki; Murayama, Hitoshi
2014-05-01
We show that momentum operators of a topological soliton may not commute among themselves when the soliton is associated with the second cohomology H2 of the target space. The commutation relation is proportional to the winding number, taking a constant value within each topological sector. The noncommutativity makes it impossible to specify the momentum of a topological soliton, and induces a Magnus force.
International Nuclear Information System (INIS)
Shaikhislamov, I F; Antonov, V M; Zakharov, Yu P; Boyarintsev, E L; Melekhov, A V; Posukh, V G; Ponomarenko, A G
2009-01-01
In an experiment on a magnetic dipole interacting with a laser-produced plasma the generation of an intense field aligned current (FAC) system was observed for the first time in a laboratory. The detailed measurements of the total value and local current density, of the magnetic field at the poles and in the equatorial magnetopause, and particular features of electron motion in the current channels revealed its similarity to the Region-1 current system in the Earth magnetosphere. Such currents were found to exist only if they can close via conductive cover of the dipole. Comparison of conductive and dielectric cases revealed specific magnetic features produced by FAC and their connection with electric potential generated in the equatorial part of the magnetopause. To interpret the data we consider a model of electric potential generation in the boundary layer which agrees with experiment and with measurements of the Earth's transpolar potential in the absence of an interplanetary magnetic field as well. The results could be of importance for the investigation of Mercury as a magnetic disturbance due to FAC could be especially large because of the small size of the Hermean magnetosphere.
Proposal for a cryogenic magnetic field measurement system for SSC dipole magnets
International Nuclear Information System (INIS)
Green, M.I.; Hansen, L.
1991-03-01
This proposal describes the research and development required, and the subsequent fabrication of, a system capable of making integrated magnetic multipole measurements of cryogenic 40-mm-bore SSC dipole magnets utilizing a cryogenic probe. Our experience and some preliminary studies indicate that it is highly unlikely that a 16-meter-long probe can be fabricated that will have a twist below several milliradians at cryogenic temperatures. We would anticipate a twist of several milliradians just as a result of cooldown stresses. Consequently, this proposal describes a segmented 16-meter-long probe, for which we intend to calibrate the phase of each segment to within 0.1 milliradians. The data for all segments will be acquired simultaneously, and integrated data will be generated from the vector sums of the individual segments. The calibration techniques and instrumentation required to implement this system will be described. The duration of an integral measurement at one current is expected to be under 10 seconds. The system is based on an extrapolation of the techniques used at LBL to measure cryogenic 1-meter models of SSC magnets with a cryogenic probe. It should be noted that the expansion of the dipole bore from 40 to 50 mm may make a warm-finger device practical at a cost of approximately one quarter of the cryogenic probe. A warm quadrupole measurement system can be based upon the same principles. 5 refs., 9 figs., 1 tab
Bellesia, B; Scandale, Walter; Todesco, Ezio; Völlinger, C
2004-01-01
The Large Hadron Collider (LHC) [1], a proton-proton superconducting accelerator, will consist of about 8400 superconducting magnet units, all operating in superfluid helium at a temperature of 1.9 K. The design of the superconducting main dipole magnets for the LHC is guided by the requirement of an extremely high field quality in the magnet aperture which is mainly defined by the layout of the superconducting coil and the position of the conductors. In order to avoid conductor movements within the magnet cross-section, the superconducting coils are held in place by surrounding stainless steel collars. In this paper, we review the dependence of field harmonics in the LHC main dipoles on dimensions of the hardware components of the collared coils. An analysis of the dimensional measurements of these compo-nents which are used in the collared coils produced so far is given. Sensitivity tables which are worked out through a coupled magneto-static model give the variation of the multipoles on collars, copper we...
Noncommutative geometry and twisted conformal symmetry
International Nuclear Information System (INIS)
Matlock, Peter
2005-01-01
The twist-deformed conformal algebra is constructed as a Hopf algebra with twisted coproduct. This allows for the definition of conformal symmetry in a noncommutative background geometry. The twisted coproduct is reviewed for the Poincare algebra and the construction is then extended to the full conformal algebra. The case of Moyal-type noncommutativity of the coordinates is considered. It is demonstrated that conformal invariance need not be viewed as incompatible with noncommutative geometry; the noncommutativity of the coordinates appears as a consequence of the twisting, as has been shown in the literature in the case of the twisted Poincare algebra
Energy Technology Data Exchange (ETDEWEB)
Rossi, Dominic M.
2010-01-25
The electric dipole response of neutron-rich nickel isotopes has been investigated using the LAND setup at GSI in Darmstadt (Germany). Relativistic secondary beams of {sup 56-57}Ni and {sup 67-72}Ni at approximately 500 AMeV have been generated using projectile fragmentation of stable ions on a 4 g/cm{sup 2} Be target and subsequent separation in the magnetic dipole fields of the FRagment Separator (FRS). After reaching the LAND setup in Cave C, the radioactive ions were excited electromagnetically in the electric field of a Pb target. The decay products have been measured in inverse kinematics using various detectors. Neutron-rich {sup 67-69}Ni isotopes decay by the emission of neutrons, which are detected in the LAND detector. The present analysis concentrates on the ({gamma},n) and ({gamma},2n) channels in these nuclei, since the proton and three-neutron thresholds are unlikely to be reached considering the virtual photon spectrum for nickel ions at 500 AMeV. A measurement of the stable {sup 58}Ni isotope is used as a benchmark to check the accuracy of the present results with previously published data. The measured ({gamma},n) and ({gamma},np) channels are compared with an inclusive photoneutron measurement by Fultz and coworkers, which are consistent within the respective errors. The measured excitation energy distributions of {sup 67-69}Ni contain a large portion of the Giant Dipole Resonance (GDR) strength predicted by the Thomas-Reiche-Kuhn energy-weighted sum rule, as well as a significant amount of low-lying E1 strength, that cannot be attributed to the GDR alone. The GDR distribution parameters are calculated using well-established semi-empirical systematic models, providing the peak energies and widths. The GDR strength is extracted from the {chi}{sup 2} minimization of the model GDR to the measured data of the ({gamma},2n) channel, thereby excluding any influence of eventual low-lying strength. The subtraction of the obtained GDR distribution from the
Noncommutativity into Dirac Equation with mass dependent on the position
Energy Technology Data Exchange (ETDEWEB)
Bastos, Samuel Batista; Almeida, Carlos Alberto Santos [Universidade Federal do Ceara - UFC, Fortaleza, CE (Brazil); Nunes, Luciana Angelica da Silva [Universidade Federal Rural do Semi-arido - UFERSA, Mossoro, RN (Brazil)
2013-07-01
Full text: In recent years, there is growing interest in the study of theories in non-commutative spaces. Non-commutative fields theories are related with compactifications of M theory, string theory and the quantum Hall effect. Moreover, the role of the non-commutativity of theories of a particle finds large applications when analyzed in scenarios of quantum mechanics and relativistic quantum mechanics. In these contexts investigations on the Schrodinger and Dirac equations with mass depending on the position (MDP) has attracted much attention in the literature. Systems endowed with MDP models are useful for the study of many physical problems. In particular, they are used to study the energy density in problems of many bodies, determining the electronic properties of semiconductor heterostructures and also to describe the properties of heterojunctions and quantum dots. In particular, the investigation of relativistic effects it is important for systems containing heavy atoms or doping by heavy ions. For these types of materials, the study of the properties of the Dirac equation, in the case where the mass becomes variable is of great interest. In this paper, we seek for the non-relativistic limit of the Dirac Hamiltonian in the context of a theory of effective mass, through a Foldy-Wouthuysen transformation. We analyse the Dirac equation with mass dependent on the position, in a smooth step shape mass distribution, in non-commutative space (NC). This potential type kink was recently discussed by several authors in the commutative context and now we present our results in the non-commutative context. (author)
Non-commutative Nash inequalities
International Nuclear Information System (INIS)
Kastoryano, Michael; Temme, Kristan
2016-01-01
A set of functional inequalities—called Nash inequalities—are introduced and analyzed in the context of quantum Markov process mixing. The basic theory of Nash inequalities is extended to the setting of non-commutative L p spaces, where their relationship to Poincaré and log-Sobolev inequalities is fleshed out. We prove Nash inequalities for a number of unital reversible semigroups
Tichit, Paul-Henri; Burokur, Shah Nawaz; Qiu, Cheng-Wei; de Lustrac, André
2013-09-01
It has long been conjectured that isotropic radiation by a simple coherent source is impossible due to changes in polarization. Though hypothetical, the isotropic source is usually taken as the reference for determining a radiator’s gain and directivity. Here, we demonstrate both theoretically and experimentally that an isotropic radiator can be made of a simple and finite source surrounded by electric-field-driven LC resonator metamaterials designed by space manipulation. As a proof-of-concept demonstration, we show the first isotropic source with omnidirectional radiation from a dipole source (applicable to all distributed sources), which can open up several possibilities in axion electrodynamics, optical illusion, novel transformation-optic devices, wireless communication, and antenna engineering. Owing to the electric- field-driven LC resonator realization scheme, this principle can be readily applied to higher frequency regimes where magnetism is usually not present.
International Nuclear Information System (INIS)
Drechsler, W.; Havas, P.; Rosenblum, A.
1984-01-01
In two recent papers, the general form of the laws of motion for point particles which are multipole sources of the classical coupled Yang-Mills-Higgs fields was determined by Havas, and for the special case of monopole singularities of a Yang-Mills field an iteration procedure was developed by Drechsler and Rosenblum to obtain the equations of motion of mass points, i.e., the laws of motion including the explicit form of the fields of all interacting particles. In this paper we give a detailed derivation of the laws of motion of monopole-dipole singularities of the coupled Yang-Mills-Higgs fields for point particles with mass and spin, following a procedure first applied by Mathisson and developed by Havas. To obtain the equations of motion, a systematic approximation method is developed in the following paper for the solution of the nonlinear field equations and determination of the fields entering the laws of motion found here to any given order in the coupling constant g
Energy Technology Data Exchange (ETDEWEB)
Gupta, Ramesh; Scanlan, Ronald; Ghosh, Arup K.; Weggel, Robert J.; Palmer, Robert; Anerella, Michael D.; Schmalzle, Jesse
2017-10-17
A dipole-magnet system and method for producing high-magnetic-fields, including an open-region located in a radially-central-region to allow particle-beam transport and other uses, low-temperature-superconducting-coils comprised of low-temperature-superconducting-wire located in radially-outward-regions to generate high magnetic-fields, high-temperature-superconducting-coils comprised of high-temperature-superconducting-tape located in radially-inward-regions to generate even higher magnetic-fields and to reduce erroneous fields, support-structures to support the coils against large Lorentz-forces, a liquid-helium-system to cool the coils, and electrical-contacts to allow electric-current into and out of the coils. The high-temperature-superconducting-tape may be comprised of bismuth-strontium-calcium-copper-oxide or rare-earth-metal, barium-copper-oxide (ReBCO) where the rare-earth-metal may be yttrium, samarium, neodymium, or gadolinium. Advantageously, alignment of the large-dimension of the rectangular-cross-section or curved-cross-section of the high-temperature-superconducting-tape with the high-magnetic-field minimizes unwanted erroneous magnetic fields. Alignment may be accomplished by proper positioning, tilting the high-temperature-superconducting-coils, forming the high-temperature-superconducting-coils into a curved-cross-section, placing nonconducting wedge-shaped-material between windings, placing nonconducting curved-and-wedge-shaped-material between windings, or by a combination of these techniques.
Noncommutative analysis, operator theory and applications
Cipriani, Fabio; Colombo, Fabrizio; Guido, Daniele; Sabadini, Irene; Sauvageot, Jean-Luc
2016-01-01
This book illustrates several aspects of the current research activity in operator theory, operator algebras and applications in various areas of mathematics and mathematical physics. It is addressed to specialists but also to graduate students in several fields including global analysis, Schur analysis, complex analysis, C*-algebras, noncommutative geometry, operator algebras, operator theory and their applications. Contributors: F. Arici, S. Bernstein, V. Bolotnikov, J. Bourgain, P. Cerejeiras, F. Cipriani, F. Colombo, F. D'Andrea, G. Dell'Antonio, M. Elin, U. Franz, D. Guido, T. Isola, A. Kula, L.E. Labuschagne, G. Landi, W.A. Majewski, I. Sabadini, J.-L. Sauvageot, D. Shoikhet, A. Skalski, H. de Snoo, D. C. Struppa, N. Vieira, D.V. Voiculescu, and H. Woracek.
Derivations of the Moyal Algebra and Noncommutative Gauge Theories
Directory of Open Access Journals (Sweden)
Jean-Christophe Wallet
2009-01-01
Full Text Available The differential calculus based on the derivations of an associative algebra underlies most of the noncommutative field theories considered so far. We review the essential properties of this framework and the main features of noncommutative connections in the case of non graded associative unital algebras with involution. We extend this framework to the case of Z2-graded unital involutive algebras. We show, in the case of the Moyal algebra or some related Z2-graded version of it, that the derivation based differential calculus is a suitable framework to construct Yang-Mills-Higgs type models on Moyal (or related algebras, the covariant coordinates having in particular a natural interpretation as Higgs fields. We also exhibit, in one situation, a link between the renormalisable NC φ4-model with harmonic term and a gauge theory model. Some possible consequences of this are briefly discussed.
Black Hole Complementary Principle and Noncommutative Membrane
International Nuclear Information System (INIS)
Wei Ren
2006-01-01
In the spirit of black hole complementary principle, we have found the noncommutative membrane of Scharzchild black holes. In this paper we extend our results to Kerr black hole and see the same story. Also we make a conjecture that spacetimes are noncommutative on the stretched membrane of the more general Kerr-Newman black hole.
Noncommutative de Sitter and FRW spaces
International Nuclear Information System (INIS)
Burić, Maja; Madore, John
2015-01-01
Several versions of fuzzy four-dimensional de Sitter space are constructed using the noncommutative frame formalism. Although all noncommutative spacetimes which are found have commutative de Sitter metric as a classical limit, the algebras and the differential calculi which define them have many differences, which we derive and discuss
Noncommutative de Sitter and FRW spaces
Energy Technology Data Exchange (ETDEWEB)
Burić, Maja, E-mail: majab@ipb.ac.rs [Faculty of Physics, University of Belgrade, P.O. Box 44, 11001, Belgrade (Serbia); Madore, John, E-mail: madore@th.u-psud.fr [Laboratoire de Physique Théorique, 91405, Orsay (France)
2015-10-24
Several versions of fuzzy four-dimensional de Sitter space are constructed using the noncommutative frame formalism. Although all noncommutative spacetimes which are found have commutative de Sitter metric as a classical limit, the algebras and the differential calculi which define them have many differences, which we derive and discuss.
Group theoretical construction of planar noncommutative phase spaces
Energy Technology Data Exchange (ETDEWEB)
Ngendakumana, Ancille, E-mail: nancille@yahoo.fr; Todjihoundé, Leonard, E-mail: leonardt@imsp.uac.org [Institut de Mathématiques et des Sciences Physiques (IMSP), Porto-Novo (Benin); Nzotungicimpaye, Joachim, E-mail: kimpaye@kie.ac.rw [Kigali Institute of Education (KIE), Kigali (Rwanda)
2014-01-15
Noncommutative phase spaces are generated and classified in the framework of centrally extended anisotropic planar kinematical Lie groups as well as in the framework of noncentrally abelian extended planar absolute time Lie groups. Through these constructions the coordinates of the phase spaces do not commute due to the presence of naturally introduced fields giving rise to minimal couplings. By symplectic realizations methods, physical interpretations of generators coming from the obtained structures are given.
PREFACE: International Conference on Noncommutative Geometry and Physics
Wallet, Jean-Christophe
2008-03-01
The `International Conference on Noncommutative Geometry and Physics' was held on 23-27 April 2007 at the Laboratoire de Physique Théorique d'Orsay located at the Université Paris-Sud 11 campus. It brought together about 70 scientists, either mathematicians or physicists, actively working on the most recent aspects of noncommutative geometry, with a particular emphasis on some promising applications of noncommutative geometry in physics. The present volume involves most of the invited talks given by leading experts in the related areas of mathematics or physics and may therefore provide a view of the state of the art in this rapidly evolving domain. The talks covering the mathematical aspects either focused on recent new results or on reviews of some useful tools of noncommutative geometry, such as for instance deformation quantizations or derivation-based differential calculus. Other talks were centered on noncommutative field theories (NCFT). NCFT is now one of the main organized attempts to go beyond the present formulation of fundamental physics, aiming in particular at the elaboration of mathematical tools that may be used in the construction of a consistent theory of quantum gravity at the Planck scale. Two other such organized attempts are string theory and loop gravity. NCFT is now witnessing exciting developments, either on various classical aspects or in the recent construction of new renormalizable field theories, in particular those defined on the so-called noncommutative Moyal-Weyl space that seems to be related to some regime of string theory. The corresponding talks covered new developments related e.g. to solvable models, instantons or solitons, applications of spectral triples including a reformulation of the standard model, new results on renormalization group flow properties of interesting NCFT on Moyal spaces together with progress on renormalization of gauge theories on these spaces. The talks were completed by a poster session aiming at
Martínez Hardigree, Josué F; Dawidczyk, Thomas J; Ireland, Robert M; Johns, Gary L; Jung, Byung-Jun; Nyman, Mathias; Osterbacka, Ronald; Marković, Nina; Katz, Howard E
2013-08-14
Leakage currents through the gate dielectric of thin film transistors remain a roadblock to the fabrication of organic field-effect transistors (OFETs) on ultrathin dielectrics. We report the first investigation of a self-assembled monolayer (SAM) dipole as an electrostatic barrier to reduce leakage currents in n-channel OFETs fabricated on a minimal, leaky ∼10 nm SiO2 dielectric on highly doped Si. The electric field associated with 1H,1H,2H,2H-perfluoro-octyltriethoxysilane (FOTS) and octyltriethoxysilane (OTS) dipolar chains affixed to the oxide surface of n-Si gave an order of magnitude decrease in gate leakage current and subthreshold leakage and a two order-of-magnitude increase in ON/OFF ratio for a naphthalenetetracarboxylic diimide (NTCDI) transistor. Identically fabricated devices on p-Si showed similarly reduced leakage and improved performance for oxides treated with the larger dipole FOTS monolayer, while OTS devices showed poorer transfer characteristics than those on bare oxide. Comparison of OFETs on both substrates revealed that relative device performance from OTS and FOTS treatments was dictated primarily by the organosilane chain and not the underlying siloxane-substrate bond. This conclusion is supported by the similar threshold voltages (VT) extrapolated for SAM-treated devices, which display positive relative VT shifts for FOTS on either substrate but opposite VT shifts for OTS treatment on n-Si and p-Si. Our results highlight the potential of dipolar SAMs as performance-enhancing layers for marginal quality dielectrics, broadening the material spectrum for low power, ultrathin organic electronics.
Supergravity and Light-Like Non-commutativity
Alishahiha, M; Russo, Jorge G; Alishahiha, Mohsen; Oz, Yaron; Russo, Jorge G.
2000-01-01
We construct dual supergravity descriptions of field theories and little string theories with light-like non-commutativity. The field theories are realized on the world-volume of Dp branes with light-like NS $B$ field and M5 branes with light-like $C$ field. The little string theories are realized on the world-volume of NS5 branes with light-like RR $A$ fields. The supergravity backgrounds are closely related to the $A=0,B=0,C=0$ backgrounds. We discuss the implications of these results. We also construct dual supergravity descriptions of ODp theories realized on the worldvolume of NS5 branes with RR backgrounds.
Noncommutative spaces from matrix models
Lu, Lei
Noncommutative (NC) spaces commonly arise as solutions to matrix model equations of motion. They are natural generalizations of the ordinary commutative spacetime. Such spaces may provide insights into physics close to the Planck scale, where quantum gravity becomes relevant. Although there has been much research in the literature, aspects of these NC spaces need further investigation. In this dissertation, we focus on properties of NC spaces in several different contexts. In particular, we study exact NC spaces which result from solutions to matrix model equations of motion. These spaces are associated with finite-dimensional Lie-algebras. More specifically, they are two-dimensional fuzzy spaces that arise from a three-dimensional Yang-Mills type matrix model, four-dimensional tensor-product fuzzy spaces from a tensorial matrix model, and Snyder algebra from a five-dimensional tensorial matrix model. In the first part of this dissertation, we study two-dimensional NC solutions to matrix equations of motion of extended IKKT-type matrix models in three-space-time dimensions. Perturbations around the NC solutions lead to NC field theories living on a two-dimensional space-time. The commutative limit of the solutions are smooth manifolds which can be associated with closed, open and static two-dimensional cosmologies. One particular solution is a Lorentzian fuzzy sphere, which leads to essentially a fuzzy sphere in the Minkowski space-time. In the commutative limit, this solution leads to an induced metric that does not have a fixed signature, and have a non-constant negative scalar curvature, along with singularities at two fixed latitudes. The singularities are absent in the matrix solution which provides a toy model for resolving the singularities of General relativity. We also discussed the two-dimensional fuzzy de Sitter space-time, which has irreducible representations of su(1,1) Lie-algebra in terms of principal, complementary and discrete series. Field
Construction of gauge theories on curved noncommutative spacetime
International Nuclear Information System (INIS)
Behr, Wolfgang; Sykora, Andreas
2004-01-01
We present a method where derivations of star-product algebras are used to build covariant derivatives for noncommutative gauge theory. We write down a noncommutative action by linking these derivations to a frame field induced by a nonconstant metric. An example is given where the action reduces in the classical limit to scalar electrodynamics on a curved background. We further use the Seiberg-Witten map to extend the formalism to arbitrary gauge groups. A proof of the existence of the Seiberg-Witten map for an Abelian gauge potential is given for the formality star-product . We also give explicit formulas for the Weyl-ordered star-product and its Seiberg-Witten maps up to second order
Chirality Quantum Phase Transition in Noncommutative Dirac Oscillator
International Nuclear Information System (INIS)
Wang Shao-Hua; Hou Yu-Long; Jing Jian; Wang Qing; Long Zheng-Wen
2014-01-01
The charged Dirac oscillator on a noncommutative plane coupling to a uniform perpendicular magnetic held is studied in this paper. We map the noncommutative plane to a commutative one by means of Bopp shift and study this problem on the commutative plane. We find that this model can be mapped onto a quantum optics model which contains Anti—Jaynes—Cummings (AJC) or Jaynes—Cummings (JC) interactions when a dimensionless parameter ζ (which is the function of the intensity of the magnetic held) takes values in different regimes. Furthermore, this model behaves as experiencing a chirality quantum phase transition when the dimensionless parameter ζ approaches the critical point. Several evidences of the chirality quantum phase transition are presented. We also study the non-relativistic limit of this model and find that a similar chirality quantum phase transition takes place in its non-relativistic limit. (physics of elementary particles and fields)
The shear viscosity of the non-commutative plasma
Landsteiner, Karl; Mas, Javier
2007-07-01
We compute the shear viscosity of the non-commutative N = 4 super Yang-Mills quantum field theory at strong coupling using the dual supergravity background. Special interest derives from the fact that the background presents an intrinsic anisotropy in space through the distinction of commutative and non-commutative directions. Despite this anisotropy the analysis exhibits the ubiquitous result η/s = 1/4π for two different shear channels. In order to derive this result, we show that the boundary energy momentum tensor must couple to the open string metric. As a byproduct we compute the renormalised holographic energy momentum tensor and show that it coincides with one in the commutative theory.
Stringy Fuzziness as the Custodial of Time-Space Noncommutativity
Barbón, José L F
2000-01-01
We study aspects of obtaining field theories with noncommuting time-space coordinates as limits of open-string theories in constant electric-field backgrounds. We find that, within the standard closed-string backgrounds, there is an obstruction to decoupling the time-space noncommutativity scale from that of the string fuzziness scale. We speculate that this censorship may be string-theory's way of protecting the causality and unitarity structure. We study the moduli space of the obstruction in terms of the open- and closed-string backgrounds. Cases of both zero and infinite brane tensions as well as zero string couplings are obtained. A decoupling can be achieved formally by considering complex values of the dilaton and inverting the role of space and time of the light cone. This is reminiscent of a black-hole horizon. We study the corresponding supergravity solution in the large-N limit and find that the geometry has a naked singularity at the physical scale of noncommutativity.
Stringy fuzziness as the custodian of time-space noncommutativity
Barbón, José L F
2000-01-01
We study aspects of obtaining field theories with noncommuting time- space coordinates as limits of open-string theories in constant electric-field backgrounds. We find that, within the standard closed- string backgrounds, there is an obstruction to decoupling the time- space noncommutativity scale from that of the string fuzziness scale. We speculate that this censorship may be string-theory's way of protecting the causality and unitarity structure. We study the moduli space of the obstruction in terms of the open- and closed-string backgrounds. Cases of both zero and infinite brane tensions as well as zero string couplings are obtained. A decoupling can be achieved formally by considering complex values of the dilaton and inverting the role of space and time in the light cone. This is reminiscent of a black-hole horizon. We study the corresponding supergravity solution in the large-N limit and find that the geometry has a naked singularity at the physical scale of noncommutativity. (23 refs).
Perturbative Noncommutative Regularization
Hawkins, E J
1999-01-01
I propose a nonperturbative regularization of quantum field theories with contact interactions (primarily, scalar field theories). This is given by the geometric quantization of compact Kähler manifolds and generalizes what has already been proposed by Madore, Grosse, Klimčík, and Prešnajder for the two-sphere. I discuss the perturbation theory derived from this regularized model and propose an approximation technique for evaluating the Feynman diagrams. This amounts to a momentum cutoff combined with phase factors at vertices. To illustrate the exact and approximate calculations, I present, as examples, the simplest diagrams for the lf4 model on the spaces S2,S 2×S2 , and CP2 . This regularization fails for noncompact spaces. I give a brief dimensional analysis argument as to why this is so. I also discuss the relevance of the topology of Feynman diagrams to their ultra-violet and infra-red divergence behavior in this model.
Electric dipole moments of light nuclei in chiral effective field theory
International Nuclear Information System (INIS)
Bsaisou, Jan
2014-01-01
Electric dipole moments (EDMs) break parity (P) and time-reversal (T) symmetry and thus, by the CPT theorem, CP-symmetry. Once measured, they will be unambiguous signs of new physics since CP violation from the complex phase of the Cabibbo-Kobayashi-Maskawa matrix in the Standard Model predicts EDMs that are experimentally inaccessible in the foreseeable future. The θ-term of Quantum Chromodynamics (QCD) and extensions of the Standard Model such as supersymmetry and multi-Higgs scenarios comprise P- and T-violating interactions which are capable of inducing significantly larger EDMs. The extensions of the Standard Model give rise to a set of effective non-renormalizable operators of canonical dimension six at energies Λ had >or similar 1 GeV when the heavy degrees of freedom are integrated out. The effective dimension-six operators are known as the quark EDM, the quark-chromo EDM, four-quark left-right operator, the gluon-chromo EDM and the four-quark operator. Starting from the QCD θ-term and this set of P- and T-violating effective dimension-six operators, we present a scheme to derive the induced effective Lagrangians at energies below Λ QCD ∝ 200 MeV within the framework of Chiral Perturbation Theory (ChPT) for two quark flavors in the formulation of Gasser and Leutwyler. The differences among the sources of P and T violation manifest themselves at energies below Λ QCD in specific hierarchies of coupling constants of P- and T-violating vertices. We compute the relevant coupling constants of P- and T-violating hadronic vertices which are induced by the QCD θ-term with well-defined uncertainties as functions of the parameter anti θ. The relevant coupling constants induced by the effective dimension-six operators are given as functions of yet unknown Low Energy Constants (LECs) which can not be determined within the framework of ChPT itself. Since the required supplementary input from e.g. Lattice QCD is not yet available, we present Naive Dimensional
Electric dipole moments of light nuclei in chiral effective field theory
Energy Technology Data Exchange (ETDEWEB)
Bsaisou, Jan
2014-04-25
Electric dipole moments (EDMs) break parity (P) and time-reversal (T) symmetry and thus, by the CPT theorem, CP-symmetry. Once measured, they will be unambiguous signs of new physics since CP violation from the complex phase of the Cabibbo-Kobayashi-Maskawa matrix in the Standard Model predicts EDMs that are experimentally inaccessible in the foreseeable future. The θ-term of Quantum Chromodynamics (QCD) and extensions of the Standard Model such as supersymmetry and multi-Higgs scenarios comprise P- and T-violating interactions which are capable of inducing significantly larger EDMs. The extensions of the Standard Model give rise to a set of effective non-renormalizable operators of canonical dimension six at energies Λ{sub had} >or similar 1 GeV when the heavy degrees of freedom are integrated out. The effective dimension-six operators are known as the quark EDM, the quark-chromo EDM, four-quark left-right operator, the gluon-chromo EDM and the four-quark operator. Starting from the QCD θ-term and this set of P- and T-violating effective dimension-six operators, we present a scheme to derive the induced effective Lagrangians at energies below Λ{sub QCD} ∝ 200 MeV within the framework of Chiral Perturbation Theory (ChPT) for two quark flavors in the formulation of Gasser and Leutwyler. The differences among the sources of P and T violation manifest themselves at energies below Λ{sub QCD} in specific hierarchies of coupling constants of P- and T-violating vertices. We compute the relevant coupling constants of P- and T-violating hadronic vertices which are induced by the QCD θ-term with well-defined uncertainties as functions of the parameter anti θ. The relevant coupling constants induced by the effective dimension-six operators are given as functions of yet unknown Low Energy Constants (LECs) which can not be determined within the framework of ChPT itself. Since the required supplementary input from e.g. Lattice QCD is not yet available, we present Naive
Noncommuting observables and local realism
International Nuclear Information System (INIS)
Malley, James D.; Fine, Arthur
2005-01-01
A standard approach in the foundations of quantum mechanics studies local realism and hidden variables models exclusively in terms of violations of Bell-like inequalities. Thus quantum nonlocality is tied to the celebrated no-go theorems, and these comprise a long list that includes the Kochen-Specker and Bell theorems, as well as elegant refinements by Mermin, Peres, Hardy, GHZ, and many others. Typically entanglement or carefully prepared multipartite systems have been considered essential for violations of local realism and for understanding quantum nonlocality. Here we show, to the contrary, that sharp violations of local realism arise almost everywhere without entanglement. The pivotal fact driving these violations is just the noncommutativity of quantum observables. We demonstrate how violations of local realism occur for arbitrary noncommuting projectors, and for arbitrary quantum pure states. Finally, we point to elementary tests for local realism, using single particles and without reference to entanglement, thus avoiding experimental loopholes and efficiency issues that continue to bedevil the Bell inequality related tests
Noncommutative quantum mechanics and Bohm's ontological interpretation
International Nuclear Information System (INIS)
Barbosa, G.D.; Pinto-Neto, N.
2004-01-01
We carry out an investigation into the possibility of developing a Bohmian interpretation based on the continuous motion of point particles for noncommutative quantum mechanics. The conditions for such an interpretation to be consistent are determined, and the implications of its adoption for noncommutativity are discussed. A Bohmian analysis of the noncommutative harmonic oscillator is carried out in detail. By studying the particle motion in the oscillator orbits, we show that small-scale physics can have influence at large scales, something similar to the IR-UV mixing
Wormhole inspired by non-commutative geometry
Energy Technology Data Exchange (ETDEWEB)
Rahaman, Farook, E-mail: rahaman@iucaa.ernet.in [Department of Mathematics, Jadavpur University, Kolkata 700032, West Bengal (India); Karmakar, Sreya, E-mail: sreya.karmakar@gmail.com [Department of Physics, Calcutta Institute of Engineering and Management, Kolkata 700040, West Bengal (India); Karar, Indrani, E-mail: indrani.karar08@gmail.com [Department of Mathematics, Saroj Mohan Institute of Technology, Guptipara, West Bengal (India); Ray, Saibal, E-mail: saibal@iucaa.ernet.in [Department of Physics, Government College of Engineering & Ceramic Technology, Kolkata 700010, West Bengal (India)
2015-06-30
In the present Letter we search for a new wormhole solution inspired by noncommutative geometry with the additional condition of allowing conformal Killing vectors (CKV). A special aspect of noncommutative geometry is that it replaces point-like structures of gravitational sources with smeared objects under Gaussian distribution. However, the purpose of this letter is to obtain wormhole solutions with noncommutative geometry as a background where we consider a point-like structure of gravitational object without smearing effect. It is found through this investigation that wormhole solutions exist in this Lorentzian distribution with viable physical properties.
Wormhole inspired by non-commutative geometry
Directory of Open Access Journals (Sweden)
Farook Rahaman
2015-06-01
Full Text Available In the present Letter we search for a new wormhole solution inspired by noncommutative geometry with the additional condition of allowing conformal Killing vectors (CKV. A special aspect of noncommutative geometry is that it replaces point-like structures of gravitational sources with smeared objects under Gaussian distribution. However, the purpose of this letter is to obtain wormhole solutions with noncommutative geometry as a background where we consider a point-like structure of gravitational object without smearing effect. It is found through this investigation that wormhole solutions exist in this Lorentzian distribution with viable physical properties.
The noncommutative standard model. Construction beyond leading order in θ and collider phenomenology
International Nuclear Information System (INIS)
Alboteanu, A.M.
2007-01-01
Within this work we study the phenomenological consequences of a possible realization of QFT on noncommutative space-time. In the first part we performed a phenomenological analysis of the hadronic process pp → Z γ → l + l - γ at the LHC and of electron-positron pair annihilation into a Z boson and a photon at the International Linear Collider (ILC). The noncommutative extension of the SM considered within this work relies on two building blocks: the Moyal-Weyl *-product of functions on ordinary space-time and the Seiberg-Witten maps. A consequence of the noncommutativity of space-time is the violation of rotational invariance with respect to the beam axis. This effect shows up in the azimuthal dependence of cross sections, which is absent in the SM as well as in other models beyond the SM. We have found this dependence to be best suited for deriving the sensitivity bounds on the noncommutative scale NC. By studying pp→Z γ →l + l - γ to first order in the noncommutative parameter θ, we show in the first part of this work that measurements at the LHC are sensitive to noncommutative effects only in certain cases, giving bounds on the noncommutative scale of Λ NC >or similar 1.2 TeV. By means of e + e - → Z γ → l + l - γ to O(θ) we have shown that ILC measurements are complementary to LHC measurements of the noncommutative parameters. In addition, the bounds on Λ NC derived from the ILC are significantly higher and reach Λ NC >or similar 6 TeV. In the second part of this work we expand the neutral current sector of the noncommutative SM to second order in θ. We found that, against the general expectation, the theory must be enlarged by additional parameters. The new parameters enter the theory as ambiguities of the Seiberg-Witten maps. The latter are not uniquely determined and differ by homogeneous solutions of the gauge equivalence equations. The expectation was that the ambiguities correspond to field redefinitions and therefore should
Orientation of dipole molecules and clusters upon adiabatic entry into an external field
Bulthuis, J.; Becker, J.A.; Moro, R.; Kresin, V. V.
2008-01-01
The induced polarization of a beam of polar clusters or molecules passing through an electric or magnetic field region differs from the textbook Langevin-Debye susceptibility. This distinction, which is important for the interpretation of deflection and focusing experiments, arises because instead
Aspects of a noncommutative scalar/tensor duality
International Nuclear Information System (INIS)
Ajith, K. M.; Harikumar, E.; Sivakumar, M.; Rivelles, Victor O.
2008-01-01
We study the noncommutative massless Kalb-Ramond gauge field coupled to a dynamical U(1) gauge field in the adjoint representation together with a compensating vector field. We derive the Seiberg-Witten map and obtain the corresponding mapped action to first order in θ. The (emergent) gravity structure found in other situations is not present here. The off-shell dual scalar theory is derived and it does not coincide with the Seiberg-Witten mapped scalar theory. Dispersion relations are also discussed. The p-form generalization of the Seiberg-Witten map to order θ is also derived.
Noncommutative effects of spacetime on holographic superconductors
Energy Technology Data Exchange (ETDEWEB)
Ghorai, Debabrata, E-mail: debanuphy123@gmail.com [S.N. Bose National Centre for Basic Sciences, JD Block, Sector III, Salt Lake, Kolkata 700098 (India); Gangopadhyay, Sunandan, E-mail: sunandan.gangopadhyay@gmail.com [Department of Physics, West Bengal State University, Barasat (India); Inter University Centre for Astronomy & Astrophysics, Pune (India)
2016-07-10
The Sturm–Liouville eigenvalue method is employed to analytically investigate the properties of holographic superconductors in higher dimensions in the framework of Born–Infeld electrodynamics incorporating the effects of noncommutative spacetime. In the background of pure Einstein gravity in noncommutative spacetime, we obtain the relation between the critical temperature and the charge density. We also obtain the value of the condensation operator and the critical exponent. Our findings suggest that the higher value of noncommutative parameter and Born–Infeld parameter make the condensate harder to form. We also observe that the noncommutative structure of spacetime makes the critical temperature depend on the mass of the black hole and higher value of black hole mass is favourable for the formation of the condensate.
Noncommutative effects of spacetime on holographic superconductors
Directory of Open Access Journals (Sweden)
Debabrata Ghorai
2016-07-01
Full Text Available The Sturm–Liouville eigenvalue method is employed to analytically investigate the properties of holographic superconductors in higher dimensions in the framework of Born–Infeld electrodynamics incorporating the effects of noncommutative spacetime. In the background of pure Einstein gravity in noncommutative spacetime, we obtain the relation between the critical temperature and the charge density. We also obtain the value of the condensation operator and the critical exponent. Our findings suggest that the higher value of noncommutative parameter and Born–Infeld parameter make the condensate harder to form. We also observe that the noncommutative structure of spacetime makes the critical temperature depend on the mass of the black hole and higher value of black hole mass is favourable for the formation of the condensate.
Entropic force, noncommutative gravity, and ungravity
International Nuclear Information System (INIS)
Nicolini, Piero
2010-01-01
After recalling the basic concepts of gravity as an emergent phenomenon, we analyze the recent derivation of Newton's law in terms of entropic force proposed by Verlinde. By reviewing some points of the procedure, we extend it to the case of a generic quantum gravity entropic correction to get compelling deviations to the Newton's law. More specifically, we study: (1) noncommutative geometry deviations and (2) ungraviton corrections. As a special result in the noncommutative case, we find that the noncommutative character of the manifold would be equivalent to the temperature of a thermodynamic system. Therefore, in analogy to the zero temperature configuration, the description of spacetime in terms of a differential manifold could be obtained only asymptotically. Finally, we extend the Verlinde's derivation to a general case, which includes all possible effects, noncommutativity, ungravity, asymptotically safe gravity, electrostatic energy, and extra dimensions, showing that the procedure is solid versus such modifications.
Holography and noncommutative yang-mills theory
Li; Wu
2000-03-06
In this Letter a recently proposed gravity dual of noncommutative Yang-Mills theory is derived from the relations between closed string moduli and open string moduli recently suggested by Seiberg and Witten. The only new input one needs is a simple form of the running string tension as a function of energy. This derivation provides convincing evidence that string theory integrates with the holographical principle and demonstrates a direct link between noncommutative Yang-Mills theory and holography.
Non-commutative tomography and signal processing
International Nuclear Information System (INIS)
Mendes, R Vilela
2015-01-01
Non-commutative tomography is a technique originally developed and extensively used by Professors M A Man’ko and V I Man’ko in quantum mechanics. Because signal processing deals with operators that, in general, do not commute with time, the same technique has a natural extension to this domain. Here, a review is presented of the theory and some applications of non-commutative tomography for time series as well as some new results on signal processing on graphs. (paper)
Phenomenological Consequences of Non-commutative QED
Arfaei, H.; Yavartanoo, M. H.
2000-01-01
In the context of the noncommutative QED we consider few phenomena which reflect the noncommutativity. In all of them the new interactions in the Feynmann diagrams that are responsible for the deviation from the standard QED results. These deviations appear as the violations of Lorentz symmetry. We suggest experimental situations where these effects may be observed. The extra phases have far reaching consequences including violation of crossing symmetry. Considering the e-p scattering and Com...
Dispersion relations in the noncommutative φ3 and Wess-Zumino model in the Yang-Feldman formalism
International Nuclear Information System (INIS)
Doescher, C.; Zahn, J.
2006-05-01
We study dispersion relations in the noncommutative φ 3 and Wess-Zumino model in the Yang-Feldman formalism at one-loop order. Non-planar graphs lead to a distortion of the dispersion relation. We find that this effect is small if the scale of noncommutativity is identified with the Planck scale and parameters typical for a Higgs field are employed. (Orig.)
Non-commutative standard model: model building
Chaichian, Masud; Presnajder, P
2003-01-01
A non-commutative version of the usual electro-weak theory is constructed. We discuss how to overcome the two major problems: (1) although we can have non-commutative U(n) (which we denote by U sub * (n)) gauge theory we cannot have non-commutative SU(n) and (2) the charges in non-commutative QED are quantized to just 0,+-1. We show how the latter problem with charge quantization, as well as with the gauge group, can be resolved by taking the U sub * (3) x U sub * (2) x U sub * (1) gauge group and reducing the extra U(1) factors in an appropriate way. Then we proceed with building the non-commutative version of the standard model by specifying the proper representations for the entire particle content of the theory, the gauge bosons, the fermions and Higgs. We also present the full action for the non-commutative standard model (NCSM). In addition, among several peculiar features of our model, we address the inherentCP violation and new neutrino interactions. (orig.)
Quench Performance and Field Quality of FNAL Twin-Aperture 11 T Nb3Sn Dipole Model for LHC Upgrades
Stoynev, S; Apollinari, G; Auchmann, B; Barzi, E; Izquierdo Bermudez, S; Bossert, R; Chlachidze, G; DiMarco, J; Karppinen, M; Nobrega, F; Novitski, I; Rossi, F; Savary, F; Smekens, D; Strauss, T; Turrioni, D; Velev, G; Zlobin, A V
2016-01-01
A 2 m long single-aperture dipole demonstrator and two 1 m long single-aperture models based on Nb3Sn superconductor have been built and tested at FNAL. The two 1 m long collared coils were then assembled in a twin-aperture Nb3Sn dipole demonstrator compatible with the LHC main dipole and tested in two thermal cycles. This paper summarizes the quench performance of the FNAL twin-aperture Nb3Sn 11 T dipole in the temperature range of 1.9-4.5 K. The results of magnetic measurements for one of the two apertures are also presented. Test results are compared to the performance of coils in a single-aperture configuration. A summary of quench propagation studies in both apertures is given.
Backfire antennas with dipole elements
DEFF Research Database (Denmark)
Nielsen, Erik Dragø; Pontoppidan, Knud
1970-01-01
A method is set up for a theoretical investigation of arbitrary backfire antennas based upon dipole structures. The mutual impedance between the dipole elements of the antenna is taken into account, and the field radiated due to a surface wave reflector of finite extent is determined by calculating...
Magnetic dipoles and electric currents
Corbó, Guido; Testa, Massimo
2009-01-01
We discuss several similarities and differences between the concepts of electric and magnetic dipoles. We then consider the relation between the magnetic dipole and a current loop and show that in the limit of a pointlike circuit, their magnetic fields coincide. The presentation is accessible to undergraduate students with a knowledge of the basic ideas of classical electromagnetism.
International Nuclear Information System (INIS)
Chaichian, M.; Tureanu, A.; Demichev, A.; Presnajder, P.; Sheikh-Jabbari, M.M.
2001-02-01
After discussing the peculiarities of quantum systems on noncommutative (NC) spaces with nontrivial topology and the operator representation of the *-product on them, we consider the Aharonov-Bohm and Casimir effects for such spaces. For the case of the Aharonov-Bohm effect, we have obtained an explicit expression for the shift of the phase, which is gauge invariant in the NC sense. The Casimir energy of a field theory on a NC cylinder is divergent, while it becomes finite on a torus, when the dimensionless parameter of noncommutativity is a rational number. The latter corresponds to a well-defined physical picture. Certain distinctions from other treatments based on a different way of taking the noncommutativity into account are also discussed. (author)
Two-dimensional black holes and non-commutative spaces
International Nuclear Information System (INIS)
Sadeghi, J.
2008-01-01
We study the effects of non-commutative spaces on two-dimensional black hole. The event horizon of two-dimensional black hole is obtained in non-commutative space up to second order of perturbative calculations. A lower limit for the non-commutativity parameter is also obtained. The observer in that limit in contrast to commutative case see two horizon
Mapping spaces and automorphism groups of toric noncommutative spaces
Barnes, Gwendolyn E.; Schenkel, Alexander; Szabo, Richard J.
2017-09-01
We develop a sheaf theory approach to toric noncommutative geometry which allows us to formalize the concept of mapping spaces between two toric noncommutative spaces. As an application, we study the `internalized' automorphism group of a toric noncommutative space and show that its Lie algebra has an elementary description in terms of braided derivations.
Non-commutative relativistic equation with a Coulomb potential
Energy Technology Data Exchange (ETDEWEB)
Zaim, Slimane; Khodja, Lamine; Delenda, Yazid [Departement de Physique, Faculte des Sciences, Universite Hadj Lakhdar - Batna (Algeria); Departement de Physique, Faculte des Sciences Exactes, Universite de Bejaia (Algeria); Departement de Physique, Faculte des Sciences, Universite Hadj Lakhdar - Batna (Algeria)
2012-06-27
We improve the previous study of the Klein-Gordon equation in a non-commutative space-time as applied to the Hydrogen atom to extract the energy levels, by considering the secondorder corrections in the non-commutativity parameter. Phenomenologically we show that noncommutativity plays the role of spin.
Quantum electrodynamics with arbitrary charge on a noncommutative space
International Nuclear Information System (INIS)
Zhou Wanping; Long Zhengwen; Cai Shaohong
2009-01-01
Using the Seiberg-Witten map, we obtain a quantum electrodynamics on a noncommutative space, which has arbitrary charge and keep the gauge invariance to at the leading order in theta. The one-loop divergence and Compton scattering are reinvestigated. The noncommutative effects are larger than those in ordinary noncommutative quantum electrodynamics. (authors)
Non-commutative geometry inspired charged black holes
International Nuclear Information System (INIS)
Ansoldi, Stefano; Nicolini, Piero; Smailagic, Anais; Spallucci, Euro
2007-01-01
We find a new, non-commutative geometry inspired, solution of the coupled Einstein-Maxwell field equations describing a variety of charged, self-gravitating objects, including extremal and non-extremal black holes. The metric smoothly interpolates between de Sitter geometry, at short distance, and Reissner-Nordstrom geometry far away from the origin. Contrary to the ordinary Reissner-Nordstrom spacetime there is no curvature singularity in the origin neither 'naked' nor shielded by horizons. We investigate both Hawking process and pair creation in this new scenario
Descent of the last LHC dipole magnet
Maximilien Brice
2007-01-01
The last of 1746 superconducting magnets is lowered into the LHC tunnel via a specially constructed pit at 12:00 on 26 April. This 15-m long dipole magnet is one of 1232 dipoles positioned around the 27-km circumference of the collider. Dipole magnets produce a magnetic field that bends the particle beams around the circular accelerator.
Non-isospectral flows of noncommutative differential-difference KP equation
International Nuclear Information System (INIS)
Huang, Lin; Ilangovane, R.; Tamizhmani, K.M.; Zhang, Da-jun
2013-01-01
We present master symmetries of noncommutative differential-difference KP equation by considering Sato approach, where the field variables are defined over associative algebras. The Lie algebraic structures of generalized and master symmetries are given. They form a Virasoro Lie algebraic structure
The Noncommutative Doplicher-Fredenhagen-Roberts-Amorim Space
Directory of Open Access Journals (Sweden)
Everton M.C. Abreu
2010-10-01
Full Text Available This work is an effort in order to compose a pedestrian review of the recently elaborated Doplicher, Fredenhagen, Roberts and Amorim (DFRA noncommutative (NC space which is a minimal extension of the DFR space. In this DRFA space, the object of noncommutativity (θ^{μν} is a variable of the NC system and has a canonical conjugate momentum. Namely, for instance, in NC quantum mechanics we will show that θ^{ij} (i,j=1,2,3 is an operator in Hilbert space and we will explore the consequences of this so-called ''operationalization''. The DFRA formalism is constructed in an extended space-time with independent degrees of freedom associated with the object of noncommutativity θμν. We will study the symmetry properties of an extended x+θ space-time, given by the group P', which has the Poincaré group P as a subgroup. The Noether formalism adapted to such extended x+θ (D=4+6 space-time is depicted. A consistent algebra involving the enlarged set of canonical operators is described, which permits one to construct theories that are dynamically invariant under the action of the rotation group. In this framework it is also possible to give dynamics to the NC operator sector, resulting in new features. A consistent classical mechanics formulation is analyzed in such a way that, under quantization, it furnishes a NC quantum theory with interesting results. The Dirac formalism for constrained Hamiltonian systems is considered and the object of noncommutativity θ^{ij} plays a fundamental role as an independent quantity. Next, we explain the dynamical spacetime symmetries in NC relativistic theories by using the DFRA algebra. It is also explained about the generalized Dirac equation issue, that the fermionic field depends not only on the ordinary coordinates but on θ^{μν} as well. The dynamical symmetry content of such fermionic theory is discussed, and we show that its action is invariant under P'. In the last part of this work we analyze the
Non-commutativity in polar coordinates
Energy Technology Data Exchange (ETDEWEB)
Edwards, James P. [Universidad Michoacana de San Nicolas de Hidalgo, Ciudad Universitaria, Instituto de Fisica y Matematicas, Morelia, Michoacan (Mexico)
2017-05-15
We reconsider the fundamental commutation relations for non-commutative R{sup 2} described in polar coordinates with non-commutativity parameter θ. Previous analysis found that the natural transition from Cartesian coordinates to the traditional polar system led to a representation of [r, φ] as an everywhere diverging series. In this article we compute the Borel resummation of this series, showing that it can subsequently be extended throughout parameter space and hence provide an interpretation of this commutator. Our analysis provides a complete solution for arbitrary r and θ that reproduces the earlier calculations at lowest order and benefits from being generally applicable to problems in a two-dimensional non-commutative space. We compare our results to previous literature in the (pseudo-)commuting limit, finding a surprising spatial dependence for the coordinate commutator when θ >> r{sup 2}. Finally, we raise some questions for future study in light of this progress. (orig.)
Noncommutative FRW Apparent Horizon and Hawking Radiation
Bouhallouf, H.; Mebarki, N.; Aissaoui, H.
2017-11-01
In the context of noncommutative (NCG) gauge gravity, and using a cosmic time power law formula for the scale factor, a Friedman-Robertson-Walker (FRW) like metric is obtained. Within the fermions tunneling effect approach and depending on the various intervals of the power parameter, expressions of the apparent horizon are also derived. It is shown that in some regions of the parameter space, a pure NCG trapped horizon does exist leading to new interpretation of the role played by the noncommutativity of the space-time.
Noncommutative Black Holes at the LHC
Villhauer, Elena Michelle
2017-12-01
Based on the latest public results, 13 TeV data from the Large Hadron Collider at CERN has not indicated any evidence of hitherto tested models of quantum black holes, semiclassical black holes, or string balls. Such models have predicted signatures of particles with high transverse momenta. Noncommutative black holes remain an untested model of TeV-scale gravity that offers the starkly different signature of particles with relatively low transverse momenta. Considerations for a search for charged noncommutative black holes using the ATLAS detector will be discussed.
Exact multi-line soliton solutions of noncommutative KP equation
International Nuclear Information System (INIS)
Wang, Ning; Wadati, Miki
2003-01-01
A method of solving noncommutative linear algebraic equations plays a key role in the extension of the ∂-bar -dressing on the noncommutative space-time manifold. In this paper, a solution-generating method of noncommutative linear algebraic equations is proposed. By use of the proposed method, a class of multi-line soliton solutions of noncommutative KP (ncKP) equation is constructed explicitly. The method is expected to be of use for constructions of noncommutative soliton equations. The significance of the noncommutativity of coordinates is investigated. It is found that the noncommutativity of the space-time coordinate has a role to split the spatial waveform of the classical multi-line solitons and reform it to a new configuration. (author)
Classification of digital affine noncommutative geometries
Majid, Shahn; Pachoł, Anna
2018-03-01
It is known that connected translation invariant n-dimensional noncommutative differentials dxi on the algebra k[x1, …, xn] of polynomials in n-variables over a field k are classified by commutative algebras V on the vector space spanned by the coordinates. These data also apply to construct differentials on the Heisenberg algebra "spacetime" with relations [xμ, xν] = λΘμν, where Θ is an antisymmetric matrix, as well as to Lie algebras with pre-Lie algebra structures. We specialise the general theory to the field k =F2 of two elements, in which case translation invariant metrics (i.e., with constant coefficients) are equivalent to making V a Frobenius algebra. We classify all of these and their quantum Levi-Civita bimodule connections for n = 2, 3, with partial results for n = 4. For n = 2, we find 3 inequivalent differential structures admitting 1, 2, and 3 invariant metrics, respectively. For n = 3, we find 6 differential structures admitting 0, 1, 2, 3, 4, 7 invariant metrics, respectively. We give some examples for n = 4 and general n. Surprisingly, not all our geometries for n ≥ 2 have zero quantum Riemann curvature. Quantum gravity is normally seen as a weighted "sum" over all possible metrics but our results are a step towards a deeper approach in which we must also "sum" over differential structures. Over F2 we construct some of our algebras and associated structures by digital gates, opening up the possibility of "digital geometry."
Possible displacement of mercury's dipole
International Nuclear Information System (INIS)
Ng, K.H.; Beard, D.B.
1979-01-01
Earlier attempts to model the Hermean magnetospheric field based on a planet-centered magnetic multipole field have required the addition of a quadrupole moment to obtain a good fit to space vehicle observations. In this work we obtain an equally satisfactory fit by assuming a null quadrupole moment and least squares fitting of the displacement of the planetary dipole from the center of the planet. We find a best fit for a dipole displacement from the planet center of 0.033 R/sub m/ away from the solar direction, 0.025 R/sub m/ toward dawn in the magnetic equatorial plane, and 0.189 R/sub m/ northward along the magnetic dipole axis, where R/sub m/ is the planet radius. Therefore the presence of a magnetic quadrupole moment is not ruled out. The compressed dipole field more completely represents the field in the present work than in previous work where the intrinsic quadrupole field was not included in the magnetopause surface and field calculations. Moreover, we have corrected a programing error in previous work in the computation of dipole tilt lambda away from the sun. We find a slight increase for the planet dipole moment of 190γR/sub m/ 3 and a dipole tilt angle lambda away from the sun. We find a slight increase for the planet moment of 190γR/sub m/ 3 and a dipole tilt angle lambda of only 1.2 0 away from the sun. All other parameters are essentially unchanged
Gravitational amplitudes in black hole evaporation: the effect of non-commutative geometry
International Nuclear Information System (INIS)
Grezia, Elisabetta Di; Esposito, Giampiero; Miele, Gennaro
2006-01-01
Recent work in the literature has studied the quantum-mechanical decay of a Schwarzschild-like black hole, formed by gravitational collapse, into almost-flat spacetime and weak radiation at a very late time. The relevant quantum amplitudes have been evaluated for bosonic and fermionic fields, showing that no information is lost in collapse to a black hole. On the other hand, recent developments in non-commutative geometry have shown that, in general relativity, the effects of non-commutativity can be taken into account by keeping the standard form of the Einstein tensor on the left-hand side of the field equations and introducing a modified energy-momentum tensor as a source on the right-hand side. The present paper, relying on the recently obtained non-commutativity effect on a static, spherically symmetric metric, considers from a new perspective the quantum amplitudes in black hole evaporation. The general relativity analysis of spin-2 amplitudes is shown to be modified by a multiplicative factor F depending on a constant non-commutativity parameter and on the upper limit R of the radial coordinate. Limiting forms of F are derived which are compatible with the adiabatic approximation here exploited. Approximate formulae for the particle emission rate are also obtained within this framework
Propagators and matrix basis on noncommutative Minkowski space
International Nuclear Information System (INIS)
Fischer, Andre; Szabo, Richard J.
2011-01-01
We describe an analytic continuation of the Euclidean Grosse-Wulkenhaar and Langmann-Szabo-Zarembo models which defines a one-parameter family of duality covariant noncommutative field theories interpolating between Euclidean and Minkowski space versions of these models, and provides an alternative regularization to the usual Feynman prescription. This regularization allows for a matrix model representation of the field theories in terms of a complex generalization of the usual basis of Landau wave functions. The corresponding propagators are calculated and identified with the Feynman propagators of the field theories. The regulated quantum field theories are shown to be UV/IR-duality covariant. We study the asymptotics of the regularized propagators in position and matrix space representations, and confirm that they generically possess a comparably good decay behavior as in the Euclidean case.
Finite quantum physics and noncommutative geometry
International Nuclear Information System (INIS)
Balachandran, A.P.; Ercolessi, E.; Landi, G.; Teotonio-Sobrinho, P.; Lizzi, F.; Sparano, G.
1994-04-01
Conventional discrete approximations of a manifold do not preserve its nontrivial topological features. In this article we describe an approximation scheme due to Sorkin which reproduces physically important aspects of manifold topology with striking fidelity. The approximating topological spaces in this scheme are partially ordered sets (posets). Now, in ordinary quantum physics on a manifold M, continuous probability densities generate the commutative C * -algebra C(M) of continuous functions on M. It has a fundamental physical significance, containing the information to reconstruct the topology of M, and serving to specify the domains of observables like the Hamiltonian. For a poset, the role of this algebra is assumed by a noncommutative C * -algebra A. As noncommutative geometries are based on noncommutative C * -algebra, we therefore have a remarkable connection between finite approximations to quantum physics and noncommutative geometries. Varies methods for doing quantum physics using A are explored. Particular attention is paid to developing numerically viable approximation schemes which at the same time preserve important topological features of continuum physics. (author). 21 refs, 13 figs
Abe, M.; Prasannaa, V. S.; Das, B. P.
2018-03-01
Heavy polar diatomic molecules are currently among the most promising probes of fundamental physics. Constraining the electric dipole moment of the electron (e EDM ), in order to explore physics beyond the standard model, requires a synergy of molecular experiment and theory. Recent advances in experiment in this field have motivated us to implement a finite-field coupled-cluster (FFCC) approach. This work has distinct advantages over the theoretical methods that we had used earlier in the analysis of e EDM searches. We used relativistic FFCC to calculate molecular properties of interest to e EDM experiments, that is, the effective electric field (Eeff) and the permanent electric dipole moment (PDM). We theoretically determine these quantities for the alkaline-earth monofluorides (AEMs), the mercury monohalides (Hg X ), and PbF. The latter two systems, as well as BaF from the AEMs, are of interest to e EDM searches. We also report the calculation of the properties using a relativistic finite-field coupled-cluster approach with single, double, and partial triples' excitations, which is considered to be the gold standard of electronic structure calculations. We also present a detailed error estimate, including errors that stem from our choice of basis sets, and higher-order correlation effects.
Electric Chern-Simons term, enlarged exotic Galilei symmetry and noncommutative plane
International Nuclear Information System (INIS)
Olmo, Mariano A. del; Plyushchay, Mikhail S.
2006-01-01
The extended exotic planar model for a charged particle is constructed. It includes a Chern-Simons-like term for a dynamical electric field, but produces usual equations of motion for the particle in background constant uniform electric and magnetic fields. The electric Chern-Simons term is responsible for the noncommutativity of the boost generators in the 10-dimensional enlarged exotic Galilei symmetry algebra of the extended system. The model admits two reduction schemes by the integrals of motion, one of which reproduces the usual formulation for the charged particle in external constant electric and magnetic fields with associated field-deformed Galilei symmetry, whose commuting boost generators are identified with the nonlocal in time Noether charges reduced on-shell. Another reduction scheme, in which electric field transmutes into the commuting space translation generators, extracts from the model a free particle on the noncommutative plane described by the twofold centrally extended Galilei group of the nonrelativistic anyons
Renormalization group equations and the Lifshitz point in noncommutative Landau-Ginsburg theory
International Nuclear Information System (INIS)
Chen, G.-H.; Wu, Y.-S.
2002-01-01
A one-loop renormalization group (RG) analysis is performed for noncommutative Landau-Ginsburg theory in an arbitrary dimension. We adopt a modern version of the Wilsonian RG approach, in which a shell integration in momentum space bypasses the potential IR singularities due to UV-IR mixing. The momentum-dependent trigonometric factors in interaction vertices, characteristic of noncommutative geometry, are marginal under RG transformations, and their marginality is preserved at one loop. A negative Θ-dependent anomalous dimension is discovered as a novel effect of the UV-IR mixing. We also found a noncommutative Wilson-Fisher (NCWF) fixed point in less than four dimensions. At large noncommutativity, a momentum space instability is induced by quantum fluctuations, and a consequential first-order phase transition is identified together with a Lifshitz point in the phase diagram. In the vicinity of the Lifshitz point, we introduce two critical exponents ν m and β k , whose values are determined to be 1/4 and 1/2, respectively, at mean-field level
Quantum groups and noncommutative spacetimes with cosmological constant
Ballesteros, A.; Gutiérrez-Sagredo, I.; Herranz, F. J.; Meusburger, C.; Naranjo, P.
2017-08-01
Noncommutative spacetimes are widely believed to model some properties of the quantum structure of spacetime at the Planck regime. In this contribution the construction of (anti-)de Sitter noncommutative spacetimes obtained through quantum groups is reviewed. In this approach the quantum deformation parameter z is related to a Planck scale, and the cosmological constant plays the role of a second deformation parameter of geometric nature, whose limit Λ → 0 provides the corresponding noncommutative Minkowski spacetimes.
Quantum correction to the entropy of noncommutative BTZ black hole
Anacleto, M. A.; Brito, F. A.; Cavalcanti, A. G.; Passos, E.; Spinelly, J.
2018-02-01
In this paper we consider the generalized uncertainty principle (GUP) in the tunneling formalism via Hamilton-Jacobi method to determine the quantum-corrected Hawking temperature and entropy for noncommutative BTZ black hole. In our results we obtain several types of corrections including the expected logarithmic correction to the area entropy associated with the noncommutative BTZ black holes. We also show that the area entropy product of the noncommutative BTZ black holes is dependent on mass and by analyzing the nature of the specific heat capacity we have observed that the noncommutative BTZ black hole is stable at some range of parameters.
Classical mechanics in non-commutative phase space
International Nuclear Information System (INIS)
Wei Gaofeng; Long Chaoyun; Long Zhengwen; Qin Shuijie
2008-01-01
In this paper the laws of motion of classical particles have been investigated in a non-commutative phase space. The corresponding non-commutative relations contain not only spatial non-commutativity but also momentum non-commutativity. First, new Poisson brackets have been defined in non-commutative phase space. They contain corrections due to the non-commutativity of coordinates and momenta. On the basis of this new Poisson brackets, a new modified second law of Newton has been obtained. For two cases, the free particle and the harmonic oscillator, the equations of motion are derived on basis of the modified second law of Newton and the linear transformation (Phys. Rev. D, 2005, 72: 025010). The consistency between both methods is demonstrated. It is shown that a free particle in commutative space is not a free particle with zero-acceleration in the non-commutative phase space, but it remains a free particle with zero-acceleration in non-commutative space if only the coordinates are non-commutative. (authors)
Noncommutative Quantum Anisotropic cosmology in K-essence
International Nuclear Information System (INIS)
Espinoza-García, Abraham; Socorro, J
2014-01-01
We study a canonical noncommutative extension of the Bianchi type I Minisuperspace, with a barotropic perfect fluid, in the context of a simplified form of k-essence known as the Sáez-Ballester theory. Noncommutativity is implemented in the pure gravitational sector. The corresponding noncommutative Wheeler-DeWitt equation is constructed and solved. Quantum solutions are obtained for any value of the barotropic parameter. It is seen that the effect of this particular noncommutativity is that of modulating the amplitude of the commutative wave function
Noncommutative Quantum Anisotropic cosmology in K-essence
Espinoza-García, Abraham; Socorro, J.
2014-11-01
We study a canonical noncommutative extension of the Bianchi type I Minisuperspace, with a barotropic perfect fluid, in the context of a simplified form of k-essence known as the Sáez-Ballester theory. Noncommutativity is implemented in the pure gravitational sector. The corresponding noncommutative Wheeler-DeWitt equation is constructed and solved. Quantum solutions are obtained for any value of the barotropic parameter. It is seen that the effect of this particular noncommutativity is that of modulating the amplitude of the commutative wave function.
Dimensional Reduction via Noncommutative Spacetime: Bootstrap and Holography
Li, Miao
2002-05-01
Unlike noncommutative space, when space and time are noncommutative, it seems necessary to modify the usual scheme of quantum mechanics. We propose in this paper a simple generalization of the time evolution equation in quantum mechanics to incorporate the feature of a noncommutative spacetime. This equation is much more constraining than the usual Schrödinger equation in that the spatial dimension noncommuting with time is effectively reduced to a point in low energy. We thus call the new evolution equation the spacetime bootstrap equation, the dimensional reduction called for by this evolution seems close to what is required by the holographic principle. We will discuss several examples to demonstrate this point.
Seiberg-Witten maps and noncommutative Yang-Mills theories for arbitrary gauge groups
International Nuclear Information System (INIS)
Barnich, Glenn; Brandt, Friedemann; Grigoriev, Maxim
2002-01-01
Seiberg-Witten maps and a recently proposed construction of noncommutative Yang-Mills theories (with matter fields) for arbitrary gauge groups are reformulated so that their existence to all orders is manifest. The ambiguities of the construction which originate from the freedom in the Seiberg-Witten map are discussed with regard to the question whether they can lead to inequivalent models, i.e., models not related by field redefinitions. (author)
International Nuclear Information System (INIS)
Holanda, B A; Cordeiro, R C; Blak, A R
2010-01-01
Dipole defects in gamma irradiated and thermally treated beryl (Be 3 Al 2 Si 6 O 18 ) samples have been studied using the Thermally Stimulated Depolarization Currents (TSDC) technique. TSDC experiments were performed in pink (morganite), green (emerald), blue (aquamarine) and colourless (goshenite) natural beryl. TSDC spectra present dipole peaks at 190K, 220K, 280K and 310K that change after gamma irradiation and thermal treatments. In morganite samples, for thermal treatments between 700K and 1100K, the 280K peak increase in intensity and the band at 220K disappears. An increase of the 280K peak and a decrease of the 190K peak were observed in the TSDC spectra of morganite after a gamma irradiation of 25kGy performed after the thermal treatments. In the case of emerald samples, thermal treatments enhanced the 280K peak and gamma irradiation partially destroyed this band. The goshenite TSDC spectra present only one band at 280K that is not affected either by thermal treatments or by gamma irradiation. All the observed peaks are of dipolar origin because the intensity of the bands is linearly dependent on the polarization field, behaviour of dipole defects. The systematic study, by means of TSDC measurements, of ionizing irradiation effects and thermal treatments in these crystals makes possible a better understanding of the role played by the impurities in beryl crystals.
Solving the Noncommutative Batalin-Vilkovisky Equation
Barannikov, Serguei
2013-06-01
Given an odd symmetry acting on an associative algebra, I show that the summation over arbitrary ribbon graphs gives the construction of the solutions to the noncommutative Batalin-Vilkovisky equation, introduced in (Barannikov in IMRN, rnm075, 2007), and to the equivariant version of this equation. This generalizes the known construction of A ∞-algebra via summation over ribbon trees. I give also the generalizations to other types of algebras and graph complexes, including the stable ribbon graph complex. These solutions to the noncommutative Batalin-Vilkovisky equation and to its equivariant counterpart, provide naturally the supersymmetric matrix action functionals, which are the gl( N)-equivariantly closed differential forms on the matrix spaces, as in (Barannikov in Comptes Rendus Mathematique vol 348, pp. 359-362.
Giant Primeval Magnetic Dipoles
Thompson, Christopher
2017-07-01
Macroscopic magnetic dipoles are considered cosmic dark matter. Permanent magnetism in relativistic field structures can involve some form of superconductivity, one example being current-carrying string loops (“springs”) with vanishing net tension. We derive the cross-section for free classical dipoles to collide, finding it depends weakly on orientation when mutual precession is rapid. The collision rate of “spring” loops with tension { T }˜ {10}-8{c}4/G in galactic halos approaches the measured rate of fast radio bursts (FRBs) if the loops compose most of the dark matter. A large superconducting dipole (LSD) with mass ˜1020 g and size ˜1 mm will form a ˜100 km magnetosphere moving through interstellar plasma. Although hydromagnetic drag is generally weak, it is strong enough to capture some LSDs into long-lived rings orbiting supermassive black holes (SMBHs) that form by the direct collapse of massive gas clouds. Repeated collisions near young SMBHs could dominate the global collision rate, thereby broadening the dipole mass spectrum. Colliding LSDs produce tiny, hot electromagnetic explosions. The accompanying paper shows that these explosions couple effectively to propagating low-frequency electromagnetic modes, with output peaking at 0.01-1 THz. We describe several constraints on, and predictions of, LSDs as cosmic dark matter. The shock formed by an infalling LSD triggers self-sustained thermonuclear burning in a C/O (ONeMg) white dwarf (WD) of mass ≳1 M ⊙ (1.3 M ⊙). The spark is generally located off the center of the WD. The rate of LSD-induced explosions matches the observed rate of Type Ia supernovae.
DEFF Research Database (Denmark)
Johansen, Peter M.; Breinbjerg, Olav
1995-01-01
An exact line integral representation of the electric physical optics scattered field is presented. This representation applies to scattering configurations with perfectly electrically conducting polyhedral structures illuminated by a finite number of electric Hertzian dipoles. The positions...... of the source and observation points can be almost arbitrary. The line integral representation yields the exact same result as the conventional surface radiation integral; however, it is potentially less time consuming and particularly useful when the physical optics field can be augmented by a fringe wave...... contribution as calculated from physical theory of diffraction equivalent edge currents. The final expression for the line integral representation is lengthy but involves only simple functions and is thus suited for numerical calculation. To illustrate the exactness of the line integral representation...
Distances on a lattice from noncommutative geometry
International Nuclear Information System (INIS)
Bimonte, G.; Lizzi, F.; Sparano, G.
1994-04-01
Using the tools of noncommutative geometry we calculate the distances between the points of a lattice on which the usual discretized Dirac operator has been defined. We find that these distances do not have the expected behaviour, revealing that from the metric point of view the lattice does not look at all as a set of points sitting on the continuum manifold. We thus have an additional criterion for the choice of the discretization of the Dirac operator. (author). 11 refs, 1 tab
Exact BPS bound for noncommutative baby Skyrmions
Energy Technology Data Exchange (ETDEWEB)
Domrin, Andrei, E-mail: domrin@mi.ras.ru [Department of Mathematics and Mechanics, Moscow State University, Leninskie gory, 119992, GSP-2, Moscow (Russian Federation); Lechtenfeld, Olaf, E-mail: lechtenf@itp.uni-hannover.de [Institut für Theoretische Physik and Riemann Center for Geometry and Physics, Leibniz Universität Hannover, Appelstraße 2, 30167 Hannover (Germany); Linares, Román, E-mail: lirr@xanum.uam.mx [Departamento de Física, Universidad Autónoma Metropolitana Iztapalapa, San Rafael Atlixco 186, C.P. 09340, México D.F. (Mexico); Maceda, Marco, E-mail: mmac@xanum.uam.mx [Departamento de Física, Universidad Autónoma Metropolitana Iztapalapa, San Rafael Atlixco 186, C.P. 09340, México D.F. (Mexico)
2013-11-25
The noncommutative baby Skyrme model is a Moyal deformation of the two-dimensional sigma model plus a Skyrme term, with a group-valued or Grassmannian target. Exact abelian solitonic solutions have been identified analytically in this model, with a singular commutative limit. Inside any given Grassmannian, we establish a BPS bound for the energy functional, which is saturated by these baby Skyrmions. This asserts their stability for unit charge, as we also test in second-order perturbation theory.
Probing noncommutative theories with quantum optical experiments
Directory of Open Access Journals (Sweden)
Sanjib Dey
2017-11-01
Full Text Available One of the major difficulties of modern science underlies at the unification of general relativity and quantum mechanics. Different approaches towards such theory have been proposed. Noncommutative theories serve as the root of almost all such approaches. However, the identification of the appropriate passage to quantum gravity is suffering from the inadequacy of experimental techniques. It is beyond our ability to test the effects of quantum gravity thorough the available scattering experiments, as it is unattainable to probe such high energy scale at which the effects of quantum gravity appear. Here we propose an elegant alternative scheme to test such theories by detecting the deformations emerging from the noncommutative structures. Our protocol relies on the novelty of an opto-mechanical experimental setup where the information of the noncommutative oscillator is exchanged via the interaction with an optical pulse inside an optical cavity. We also demonstrate that our proposal is within the reach of current technology and, thus, it could uncover a feasible route towards the realization of quantum gravitational phenomena thorough a simple table-top experiment.
List, Nanna Holmgaard; Kauczor, Joanna; Saue, Trond; Jensen, Hans Jørgen Aagaard; Norman, Patrick
2015-06-28
We present a formulation of molecular response theory for the description of a quantum mechanical molecular system in the presence of a weak, monochromatic, linearly polarized electromagnetic field without introducing truncated multipolar expansions. The presentation focuses on a description of linear absorption by adopting the energy-loss approach in combination with the complex polarization propagator formulation of response theory. Going beyond the electric-dipole approximation is essential whenever studying electric-dipole-forbidden transitions, and in general, non-dipolar effects become increasingly important when addressing spectroscopies involving higher-energy photons. These two aspects are examined by our study of the near K-edge X-ray absorption fine structure of the alkaline earth metals (Mg, Ca, Sr, Ba, and Ra) as well as the trans-polyenes. In following the series of alkaline earth metals, the sizes of non-dipolar effects are probed with respect to increasing photon energies and a detailed assessment of results is made in terms of studying the pertinent transition electron densities and in particular their spatial extension in comparison with the photon wavelength. Along the series of trans-polyenes, the sizes of non-dipolar effects are probed for X-ray spectroscopies on organic molecules with respect to the spatial extension of the chromophore.
Energy Technology Data Exchange (ETDEWEB)
List, Nanna Holmgaard, E-mail: nhl@sdu.dk; Jensen, Hans Jørgen Aagaard [Department of Physics, Chemistry and Pharmacy, University of Southern Denmark, Campusvej 55, DK-5230 Odense M (Denmark); Kauczor, Joanna; Norman, Patrick, E-mail: panor@ifm.liu.se [Department of Physics, Chemistry and Biology, Linköping University, Linköping SE 58183 (Sweden); Saue, Trond [Laboratoire de Chimie et Physique Quantiques, UMR 5626—CNRS/Université Toulouse III (Paul Sabatier), 118 route de Narbonne, F-31062 Toulouse Cedex (France)
2015-06-28
We present a formulation of molecular response theory for the description of a quantum mechanical molecular system in the presence of a weak, monochromatic, linearly polarized electromagnetic field without introducing truncated multipolar expansions. The presentation focuses on a description of linear absorption by adopting the energy-loss approach in combination with the complex polarization propagator formulation of response theory. Going beyond the electric-dipole approximation is essential whenever studying electric-dipole-forbidden transitions, and in general, non-dipolar effects become increasingly important when addressing spectroscopies involving higher-energy photons. These two aspects are examined by our study of the near K-edge X-ray absorption fine structure of the alkaline earth metals (Mg, Ca, Sr, Ba, and Ra) as well as the trans-polyenes. In following the series of alkaline earth metals, the sizes of non-dipolar effects are probed with respect to increasing photon energies and a detailed assessment of results is made in terms of studying the pertinent transition electron densities and in particular their spatial extension in comparison with the photon wavelength. Along the series of trans-polyenes, the sizes of non-dipolar effects are probed for X-ray spectroscopies on organic molecules with respect to the spatial extension of the chromophore.
Eliashberg, Yakov; Maeda, Yoshiaki; Symplectic, Poisson, and Noncommutative geometry
2014-01-01
Symplectic geometry originated in physics, but it has flourished as an independent subject in mathematics, together with its offspring, symplectic topology. Symplectic methods have even been applied back to mathematical physics. Noncommutative geometry has developed an alternative mathematical quantization scheme based on a geometric approach to operator algebras. Deformation quantization, a blend of symplectic methods and noncommutative geometry, approaches quantum mechanics from a more algebraic viewpoint, as it addresses quantization as a deformation of Poisson structures. This volume contains seven chapters based on lectures given by invited speakers at two May 2010 workshops held at the Mathematical Sciences Research Institute: Symplectic and Poisson Geometry in Interaction with Analysis, Algebra and Topology (honoring Alan Weinstein, one of the key figures in the field) and Symplectic Geometry, Noncommutative Geometry and Physics. The chapters include presentations of previously unpublished results and ...
Dirac oscillator in a Galilean covariant non-commutative space
Energy Technology Data Exchange (ETDEWEB)
Melo, G.R. de [Universidade Federal do Reconcavo da Bahia, BA (Brazil); Montigny, M. [University of Alberta (Canada); Pompeia, P.J. [Instituto de Fomento e Coordecacao Industrial, Sao Jose dos Campos, SP (Brazil); Santos, Esdras S. [Universidade Federal da Bahia, Salvador (Brazil)
2013-07-01
Full text: Even though Galilean kinematics is only an approximation of the relativistic kinematics, the structure of Galilean kinematics is more intricate than relativistic kinematics. For instance, the Galilean algebra admits a nontrivial central extension and projective representations, whereas the Poincare algebra does not. It is possible to construct representations of the Galilei algebra with three possible methods: (1) directly from the Galilei algebra, (2) from contractions of the Poincare algebra with the same space-time dimension, or (3) from the Poincare algebra in a space-time with one additional dimension. In this paper, we follow the third approach, which we refer to as 'Galilean covariance' because the equations are Lorentz covariant in the extended manifold. These equations become Galilean invariant after projection to the lower dimension. Our motivation is that this covariant approach provides one more unifying feature of field theory models. Indeed, particle physics (with Poincare kinematics) and condensed matter physics (with Galilean kinematics) share many tools of quantum field theory (e.g. gauge invariance, spontaneous symmetry breaking, Goldstone bosons), but the Galilean kinematics does not admit a metric structure. However, since the Galilean Lie algebra is a subalgebra of the Poincare Lie algebra if one more space-like dimension is added, we can achieve 'Galilean covariance' with a metric in an extended manifold; that makes non-relativistic models look similar to Lorentz-covariant relativistic models. In this context we study the Galilei covariant five-dimensional formulation applied to Galilean Dirac oscillator in a non-commutative situation, with space-space and momentum-momentum non-commutativity. The wave equation is obtained via a 'Galilean covariant' approach, which consists in projecting the covariant motion equations from a (4, l)-dimensional manifold with light-cone coordinates, to a (3, l
Stochastic resonance in a surface dipole
Energy Technology Data Exchange (ETDEWEB)
Heinsalu, E., E-mail: els@ifisc.uib-csic.es [IFISC, Instituto de Fisica Interdisciplinar y Sistemas Complejos (CSIC-UIB), E-07122 Palma de Mallorca (Spain); National Institute of Chemical Physics and Biophysics, Raevala 10, 15042 Tallinn (Estonia); Patriarca, M. [IFISC, Instituto de Fisica Interdisciplinar y Sistemas Complejos (CSIC-UIB), E-07122 Palma de Mallorca (Spain); National Institute of Chemical Physics and Biophysics, Raevala 10, 15042 Tallinn (Estonia); Marchesoni, F. [Dipartimento di Fisica, Universita di Camerino, I-62032 Camerino (Italy)
2010-10-05
The dynamics of a neutral dipole diffusing on a one-dimensional symmetric periodic substrate is numerically investigated in the presence of an ac electric field. It is observed that the amplitude of the forced oscillations of the dipole can be enhanced by tuning the noise strength, i.e., the substrate temperature. Such a manifestation of stochastic resonance turns out to be extremely sensitive to the mechanical properties of the dipole. This phenomenon has immediate applications in surface physics and nanodevice technology.
Noncommutative U(1) gauge theory from a worldline perspective
Ahmadiniaz, Naser; Corradini, Olindo; D'Ascanio, Daniela; Estrada-Jiménez, Sendic; Pisani, Pablo
2015-11-01
We study pure noncommutative U(1) gauge theory representing its one-loop effective action in terms of a phase space worldline path integral. We write the quadratic action using the background field method to keep explicit gauge invariance, and then employ the worldline formalism to write the one-loop effective action, singling out UV-divergent parts and finite (planar and non-planar) parts, and study renormalization properties of the theory. This amounts to employ worldline Feynman rules for the phase space path integral, that nicely incorporate the Fadeev-Popov ghost contribution and efficiently separate planar and non-planar contributions. We also show that the effective action calculation is independent of the choice of the worldline Green's function, that corresponds to a particular way of factoring out a particle zero-mode. This allows to employ homogeneous string-inspired Feynman rules that greatly simplify the computation.
Essay on physics and non-commutative geometry
International Nuclear Information System (INIS)
Connes, A.
1990-01-01
Our aim, in this article, is to try to discover what physics would be like if the space in which it took place was not a set of points, but a non-commutative space. We shall not go very far in this direction, and the consequences of this investigation are for the moment either mathematical or only applied to a commutative space-time. It is clear, however, that a tool as remarkable as the Dixmier trace for analyzing logarithmic divergences should be useful to physicists. Moreover we have been able to show that a small modification of our picture of space-time gives a conceptual explanation of the Higgs fields and of the way they appear in the Weinberg-Salam model. This should allow us to make at the classical level explicit predictions of the Higgs mass: a very crude one is discussed. (author)
Noncommutative U(1) gauge theory from a worldline perspective
Energy Technology Data Exchange (ETDEWEB)
Ahmadiniaz, Naser [Facultad de Ciencias en Física y Matemáticas, Universidad Autónoma de Chiapas,Ciudad Universitaria, Tuxtla Gutiérrez 29050 (Mexico); Corradini, Olindo [Facultad de Ciencias en Física y Matemáticas, Universidad Autónoma de Chiapas,Ciudad Universitaria, Tuxtla Gutiérrez 29050 (Mexico); Dipartimento di Scienze Fisiche, Informatiche e Matematiche,Università di Modena e Reggio Emilia,Via Campi 213/A, I-41125 Modena (Italy); D’Ascanio, Daniela [Instituto de Física La Plata - CONICET, Universidad Nacional de La Plata,CC 67 (1900), La Plata (Argentina); Estrada-Jiménez, Sendic [Facultad de Ciencias en Física y Matemáticas, Universidad Autónoma de Chiapas,Ciudad Universitaria, Tuxtla Gutiérrez 29050 (Mexico); Pisani, Pablo [Instituto de Física La Plata - CONICET, Universidad Nacional de La Plata,CC 67 (1900), La Plata (Argentina)
2015-11-10
We study pure noncommutative U(1) gauge theory representing its one-loop effective action in terms of a phase space worldline path integral. We write the quadratic action using the background field method to keep explicit gauge invariance, and then employ the worldline formalism to write the one-loop effective action, singling out UV-divergent parts and finite (planar and non-planar) parts, and study renormalization properties of the theory. This amounts to employ worldline Feynman rules for the phase space path integral, that nicely incorporate the Fadeev-Popov ghost contribution and efficiently separate planar and non-planar contributions. We also show that the effective action calculation is independent of the choice of the worldline Green’s function, that corresponds to a particular way of factoring out a particle zero-mode. This allows to employ homogeneous string-inspired Feynman rules that greatly simplify the computation.
Parabosonic string and space-time non-commutativity
Energy Technology Data Exchange (ETDEWEB)
Seridi, M. A.; Belaloui, N. [Laboratoire de Physique Mathematique et Subatomique, Universite Mentouri Constantine (Algeria)
2012-06-27
We investigate the para-quantum extension of the bosonic strings in a non-commutative space-time. We calculate the trilinear relations between the mass-center variables and the modes and we derive the Virasoro algebra where a new anomaly term due to the non-commutativity is obtained.
On tea, donuts and non-commutative geometry
Directory of Open Access Journals (Sweden)
Igor V. Nikolaev
2018-03-01
Full Text Available As many will agree, it feels good to complement a cup of tea by a donut or two. This sweet relationship is also a guiding principle of non-commutative geometry known as Serre Theorem. We explain the algebra behind this theorem and prove that elliptic curves are complementary to the so-called non-commutative tori.
Thermodynamics of Classical Systems on Noncommutative Phase Space
Najafizadeh, Mojtaba; Saadat, Mehdi
2011-01-01
We study the formulation of statistical mechanics on noncommutative classical phase space, and construct the corresponding canonical ensemble theory. For illustration, some basic and important examples are considered in the framework of noncommutative statistical mechanics: such as the ideal gas, the extreme relativistic gas, and the 3-dimensional harmonic oscillator.
Gauge gravity in noncommutative de Sitter space and pair creation
Energy Technology Data Exchange (ETDEWEB)
Mebarki, N; Khodja, L; Aisaoui, H [Laboratoire de Physique Mathematique et Subatomique, Faculte des Sciences, Mentouri University, Constantine (Algeria); Zaim, S [Departement de Physique, Faculte des Sciences, Universite Hadj Lakhdar, Batna (Algeria)], E-mail: zaimslimane@yahoo.fr
2008-10-15
From the invariance of the generalized space-time non-commutative commutation relations, local Poincare and general coordinate transformations are derived. Moreover, a generalized Dirac equation is obtained. Applied to the de Sitter universe, it is shown that the space-time non-commutativity contributes to the particle creation process and induces a Casimir-like effect.
One-Loop Renormalizable Wess-Zumino Model on Bosonic-Fermionic Noncommutative Superspace
Miao, Yan-Gang; Wang, Xu-Dong
2014-01-01
We construct a deformed Wess-Zumino model on the noncommutative superspace where the Bosonic and Fermionic coordinates are no longer commutative with each other. Using the background field method, we calculate the primary one-loop effective action based on the deformed action. By comparing the two actions, we find that the deformed Wess-Zumino model is not renormalizable. To obtain a renormalizable model, we combine the primary one-loop effective action with the deformed action, and then calc...
Numerical Based Linear Model for Dipole Magnets
Energy Technology Data Exchange (ETDEWEB)
Li,Y.; Krinsky, S.; Rehak, M.
2009-05-04
In this paper, we discuss an algorithm for constructing a numerical linear optics model for dipole magnets from a 3D field map. The difference between the numerical model and K. Brown's analytic approach is investigated and clarified. It was found that the optics distortion due to the dipoles' fringe focusing must be properly taken into account to accurately determine the chromaticities. In NSLS-II, there are normal dipoles with 35-mm gap and dipoles for infrared sources with 90-mm gap. This linear model of the dipole magnets is applied to the NSLS-II lattice design to match optics parameters between the DBA cells having dipoles with different gaps.
Iron saturation control in RHIC dipole magnets
International Nuclear Information System (INIS)
Thompson, P.A.; Gupta, R.C.; Kahn, S.A.; Hahn, H.; Morgan, G.H.; Wanderer, P.J.; Willen, E.
1991-01-01
The Relativistic Heavy Ion Collider (RHIC) will require 360 dipoles of 80 mm bore. This paper discusses the field perturbations produced by the saturation of the yoke iron. Changes have been made to the yoke to reduce these perturbations, in particular, decapole -4 . Measurements and calculations for 6 series of dipole magnets are presented. 2 refs., 2 figs., 1 tab
Non-commutative geometry, non-associative geometry and the standard model of particle physics
International Nuclear Information System (INIS)
Boyle, Latham; Farnsworth, Shane
2014-01-01
Connes’ notion of non-commutative geometry (NCG) generalizes Riemannian geometry and yields a striking reinterepretation of the standard model of particle physics, coupled to Einstein gravity. We suggest a simple reformulation with two key mathematical advantages: (i) it unifies many of the traditional NCG axioms into a single one; and (ii) it immediately generalizes from non-commutative to non-associative geometry. Remarkably, it also resolves a long-standing problem plaguing the NCG construction of the standard model, by precisely eliminating from the action the collection of seven unwanted terms that previously had to be removed by an extra, non-geometric, assumption. With this problem solved, the NCG algorithm for constructing the standard model action is tighter and more explanatory than the traditional one based on effective field theory. (paper)
International Nuclear Information System (INIS)
McInturff, A.D.; Bossert, R.; Carson, J.; Fisk, H.E.; Hanft, R.; Kuchnir, M.; Lundy, R.; Mantech, P.; Strait, J.
1986-01-01
The results obtained during the evolution of the design, construction, and testing program of the design ''B'' dipole are presented here. Design ''B'' is one of the original three competing designs for the Superconducting Super Collider ''SSC'' arc dipoles. The final design parameters were as follows: air cored (less than a few percent of the magnetic field derived from any iron present), aluminum collared, two layered winding, 5.5T maximum operating field, and a 5 cm cold aperture. There have been fourteen 64 cm long 5 cm aperture model dipoles cold tested (at 4.3K and less) in this program so far. There was a half length full size (6m) mechanical analog (M-10) built and tested to check the cryostat's mechanical design under ramping and quench conditions. Several deviations from the ''Tevatron'' dipole fabrication technique were incorporated, for example the use of aluminum collars instead of stainless steel. The winding technique variations explored were ''dry welding,'' a technique with the cable covered with Kapton insulation only and ''wet winding'' where the Kapton was covered with a light coat of ''B'' stage epoxy. Test data include quench currents, field quality (Fourier multipole co-efficients), coil magnetization, conductor current performance, and coil loading. Quench current, loss per cycle, and harmonics were measured as a function of the magnitude and rate of change of the magnetic field, and helium bath temperature
1974-01-01
Stacks of SPS Dipole Magnets ready for installation in the tunnel. The SPS uses a separated function lattice with dipoles for bending and quadrupoles for focusing. The 6.2 m long normal conducting dipoles are of H-type with coils that are bent-up at the ends. There are two types, B1 (total of 360) and B2 (384). Both are for a maximum field of 1.8 Tesla and have the same outer dimensions (450x800 mm2 vxh) but with different gaps (B1: 39x129 mm2, B2: 52x92 mm2) tailored to the beam size. The yoke, made of 1.5 mm thick laminations, consists of an upper and a lower half joined together in the median plane once the coils have been inserted.
Classical mechanics on noncommutative space with Lie-algebraic structure
International Nuclear Information System (INIS)
Miao Yangang; Wang Xudong; Yu Shaojie
2011-01-01
Highlights: → Suggest a useful method to look for new Lie-algebraic noncommutative spaces. → Find out two new Lie-algebraic noncommutative spaces. → Derive Newton and Hamilton equations that present unimaginable extra forces. → Analyse the source of unimaginable extra forces from space noncummutativity. → Provide various intriguing classical trajectories. - Abstract: We investigate the kinetics of a nonrelativistic particle interacting with a constant external force on a Lie-algebraic noncommutative space. The structure constants of a Lie algebra, also called noncommutative parameters, are constrained in general due to some algebraic properties, such as the antisymmetry and Jacobi identity. Through solving the constraint equations the structure constants satisfy, we obtain two new sorts of algebraic structures, each of which corresponds to one type of noncommutative spaces. Based on such types of noncommutative spaces as the starting point, we analyze the classical motion of the particle interacting with a constant external force by means of the Hamiltonian formalism on a Poisson manifold. Our results not only include that of a recent work as our special cases, but also provide new trajectories of motion governed mainly by marvelous extra forces. The extra forces with the unimaginable tx-dot-,(xx-dot)-, and (xx-double dot)-dependence besides with the usual t-, x-, and x-dot-dependence, originating from a variety of noncommutativity between different spatial coordinates and between spatial coordinates and momenta as well, deform greatly the particle's ordinary trajectories we are quite familiar with on the Euclidean (commutative) space.
Three-dimensional noncommutative Yukawa theory: Induced effective action and propagating modes
Bufalo, R.; Ghasemkhani, M.
2017-02-01
In this paper, we establish the analysis of noncommutative Yukawa theory, encompassing neutral and charged scalar fields. We approach the analysis by considering carefully the derivation of the respective effective actions. Hence, based on the obtained results, we compute the one-loop contributions to the neutral and charged scalar field self-energy, as well as to the Chern-Simons polarization tensor. In order to properly define the behavior of the quantum fields, the known UV/IR mixing due to radiative corrections is analyzed in the one-loop physical dispersion relation of the scalar and gauge fields.
ALICE Muon Arm Dipole Magnet - Conceptual Design Report
Swoboda, D; CERN. Geneva
1998-01-01
A large Dipole Magnet is required for the Muon Arm spectrometer of the ALICE experiment 1,2[Figure 1]. The main parameters and basic design options of the dipole magnet have been described in 3. The absence of criteria for the necessary symmetry and homogeneity of the magnetic field has lead to a design dominated by economical and feasibility considerations. List of Figures: Figure 1 ALICE Experiment. Figure 2 Dipole Magnet Assembly. Figure 3 Dipole Magnet Yoke. Figure 4 Dipole Magnet Coil System. Figure 5 Schematic of Heat Screen. Figure 6 Dipole Magnet Moving Base.
Noncommutative Biology: Sequential Regulation of Complex Networks.
Directory of Open Access Journals (Sweden)
William Letsou
2016-08-01
Full Text Available Single-cell variability in gene expression is important for generating distinct cell types, but it is unclear how cells use the same set of regulatory molecules to specifically control similarly regulated genes. While combinatorial binding of transcription factors at promoters has been proposed as a solution for cell-type specific gene expression, we found that such models resulted in substantial information bottlenecks. We sought to understand the consequences of adopting sequential logic wherein the time-ordering of factors informs the final outcome. We showed that with noncommutative control, it is possible to independently control targets that would otherwise be activated simultaneously using combinatorial logic. Consequently, sequential logic overcomes the information bottleneck inherent in complex networks. We derived scaling laws for two noncommutative models of regulation, motivated by phosphorylation/neural networks and chromosome folding, respectively, and showed that they scale super-exponentially in the number of regulators. We also showed that specificity in control is robust to the loss of a regulator. Lastly, we connected these theoretical results to real biological networks that demonstrate specificity in the context of promiscuity. These results show that achieving a desired outcome often necessitates roundabout steps.
Non-Commutative Mechanics in Mathematical & in Condensed Matter Physics
Directory of Open Access Journals (Sweden)
Peter A. Horváthy
2006-12-01
Full Text Available Non-commutative structures were introduced, independently and around the same time, in mathematical and in condensed matter physics (see Table 1. Souriau's construction applied to the two-parameter central extension of the planar Galilei group leads to the ''exotic'' particle, which has non-commuting position coordinates. A Berry-phase argument applied to the Bloch electron yields in turn a semiclassical model that has been used to explain the anomalous/spin/optical Hall effects. The non-commutative parameter is momentum-dependent in this case, and can take the form of a monopole in momentum space.
Computational commutative and non-commutative algebraic geometry
Cojocaru, S; Ufnarovski, V
2005-01-01
This publication gives a good insight in the interplay between commutative and non-commutative algebraic geometry. The theoretical and computational aspects are the central theme in this study. The topic is looked at from different perspectives in over 20 lecture reports. It emphasizes the current trends in commutative and non-commutative algebraic geometry and algebra. The contributors to this publication present the most recent and state-of-the-art progresses which reflect the topic discussed in this publication. Both researchers and graduate students will find this book a good source of information on commutative and non-commutative algebraic geometry.
Introduction to Dubois-Violette's non-commutative differential geometry
International Nuclear Information System (INIS)
Djemai, A.E.F.
1994-07-01
In this work, one presents a detailed review of Dubois-Violette et al. approach to non-commutative differential calculus. The non-commutative differential geometry of matrix algebras and the non-commutative Poisson structures are treated in some details. We also present the analog of the Maxwell's theory and the new models of Yang-Mills-Higgs theories that can be constructed in this framework. In particular, some simple models are compared with the standard model. Finally, we discuss some perspectives and open questions. (author). 32 refs
International Nuclear Information System (INIS)
Nguyen, H.; Banerjea, E.; Herman, L.; Drawin, H.W.
1964-01-01
The quantum mechanical perturbation theory as used in a foregoing paper, for the determination of the frequencies of the Stark components of hydrogen in an uniform external electric field is taken up again to calculate the intensities of the line components. The numerical results show that the influence of the perturbing electric field is important also in higher orders. In the first paragraph of this report we give a theoretical justification of our calculations; the second paragraph contains the equations used for the numerical calculations, and the third paragraph contains the numerical results for the components of the first lines of the Lyman and Balmer series. (authors) [fr
High-resolution records of non-dipole variations in the intensity of the Earth's magnetic field
de Groot, L.V.
2013-01-01
Our understanding of the short-term behavior of the Earth’s magnetic field is currently mainly hampered by a lack of high-resolution records of geomagnetic intensity variations that are well distributed over the globe and cover the same timespan. Over the past decades many efforts have been made to
Energy Technology Data Exchange (ETDEWEB)
Gravador, E.; Yoshiki, Hajime; Feizeng, H. [Ibaraki Univ., Mito (Japan)
1996-08-01
A superthermal UCN edm measuring machine is currently under construction at KEK. It utilizes a magnetically shielded superconducting solenoid at liquid helium temperature to generate a stable and homogeneous magnetic field at 10 milligauss. The design of the magnetic shield and solenoid and preliminary evaluation of shielding effectiveness is presented. (author)
International Nuclear Information System (INIS)
Gravador, E.; Yoshiki, Hajime; Feizeng, H.
1996-01-01
A superthermal UCN edm measuring machine is currently under construction at KEK. It utilizes a magnetically shielded superconducting solenoid at liquid helium temperature to generate a stable and homogeneous magnetic field at 10 milligauss. The design of the magnetic shield and solenoid and preliminary evaluation of shielding effectiveness is presented. (author)
Lectures on matrix field theory
Ydri, Badis
2017-01-01
These lecture notes provide a systematic introduction to matrix models of quantum field theories with non-commutative and fuzzy geometries. The book initially focuses on the matrix formulation of non-commutative and fuzzy spaces, followed by a description of the non-perturbative treatment of the corresponding field theories. As an example, the phase structure of non-commutative phi-four theory is treated in great detail, with a separate chapter on the multitrace approach. The last chapter offers a general introduction to non-commutative gauge theories, while two appendices round out the text. Primarily written as a self-study guide for postgraduate students – with the aim of pedagogically introducing them to key analytical and numerical tools, as well as useful physical models in applications – these lecture notes will also benefit experienced researchers by providing a reference guide to the fundamentals of non-commutative field theory with an emphasis on matrix models and fuzzy geometries.
The construction of tensor operators in a D=10 noncommutative space
Energy Technology Data Exchange (ETDEWEB)
Amorim, Ricardo [Universidade Federal do Rio de Janeiro (UFRJ), RJ (Brazil); Abreu, Everton M.C. [Universidade Federal Rural do Rio de Janeiro (UFRRJ), Seropedica, RJ (Brazil)
2009-07-01
Full text. In a recent work a new version of noncommutative quantum mechanics (NCQM) has been presented by one of us, where not only the coordinates x{sup m}u and their canonical momenta pmu are considered as operators in Hilbert space H, but also the objects of noncommutativity theta{sub m}u{sub n}u and their canonical conjugate momenta pi{sub m}u{sub n}u. All these operators belong to the same algebra and have the same hierarchical level. This enlargement of the usual set of Hilbert space operators allows the theory to be invariant under the rotation group SO(D). Rotation invariance in a nonrelativistic theory, is fundamental if one intends to describe any physical system in a consistent way. In other words it was proposed a minimal canonical extension of the DFR algebra, which permits to implement Poincare invariance as a dynamical symmetry in NCQM. The main motivation of DFR to study the noncommutative relations was the belief that exact measurements of space-time localization could confine photons through energy yield to test particles in order to create a gravitational field. In this work we construct new operators in order to formulate a D=10 Fock space using a new framework where the object of noncommutativity theta{sub m}u{sub n}u represents independent degrees of freedom. Namely, theta{sub m}u{sub n}u is an operator as well as its canonical momentum pi{sub m}u{sub n}u and both live in an augmented D = 10 Hilbert space. This structure comprises the minimal canonical extension of the Doplicher-Fredenhagen-Roberts (DFR) algebra and consequently a modified Poincare group of symmetry. (author)
Noncommutative geometry a functorial approach
Nikolaev, Igor V
2017-01-01
The series is devoted to the publication of monographs and high-level textbooks in mathematics, mathematical methods and their applications. Apart from covering important areas of current interest, a major aim is to make topics of an interdisciplinary nature accessible to the non-specialist. The works in this series are addressed to advanced students and researchers in mathematics and theoretical physics. In addition, it can serve as a guide for lectures and seminars on a graduate level. The series de Gruyter Studies in Mathematics was founded ca. 30 years ago by the late Professor Heinz Bauer and Professor Peter Gabriel with the aim to establish a series of monographs and textbooks of high standard, written by scholars with an international reputation presenting current fields of research in pure and applied mathematics. While the editorial board of the Studies has changed with the years, the aspirations of the Studies are unchanged. In times of rapid growth of mathematical knowledge carefully written monogr...
Constraints on exotic dipole-dipole couplings between electrons at the micron scale
Kotler, Shlomi; Ozeri, Roee; Jackson Kimball, Derek
2015-05-01
Until recently, the magnetic dipole-dipole coupling between electrons had not been directly observed experimentally. This is because at the atomic scale dipole-dipole coupling is dominated by the exchange interaction and at larger distances the dipole-dipole coupling is overwhelmed by ambient magnetic field noise. In spite of these challenges, the magnetic dipole-dipole interaction between two electron spins separated by 2.4 microns was recently measured using the valence electrons of trapped Strontium ions [S. Kotler, N. Akerman, N. Navon, Y. Glickman, and R. Ozeri, Nature 510, 376 (2014)]. We have used this measurement to directly constrain exotic dipole-dipole interactions between electrons at the micron scale. For light bosons (mass 0.1 eV), we find that coupling constants describing pseudoscalar and axial-vector mediated interactions must be | gPegPe/4 πℏc | <= 1 . 5 × 10-3 and | gAegAe/4 πℏc | <= 1 . 2 × 10-17 , respectively, at the 90% confidence level. These bounds significantly improve on previous constraints in this mass range: for example, the constraints on axial-vector interactions are six orders of magnitude stronger than electron-positron constraints based on positronium spectroscopy. Supported by the National Science Foundation, I-Core: the Israeli excellence center, and the European Research Council.
Some aspects of noncommutative integrable systems a la Moyal
International Nuclear Information System (INIS)
Dafounansou, O.; El Boukili, A.; Sedra, M.B.
2005-12-01
Besides its various applications in string and D-brane physics, the non commutativity of space (-time) coordinates, based on the *-product, behaves as a more general framework providing more mathematical and physical information about the associated system. Similar to the Gelfand-Dickey framework of pseudo differential operators, the non commutativity a la Moyal applied to physical problems makes the study more systematic. Using these facts, as well as the backgrounds of Moyal momentum algebra introduced in previous works, we look for the important task of studying integrability in the noncommutativity framework. The main focus is on the noncommutative version of the Lax representation of two principal examples: the noncommutative sl 2 KdV equation and the noncommutative version of Burgers systems. Important properties are presented. (author)
Exact master equation for a noncommutative Brownian particle
International Nuclear Information System (INIS)
Costa Dias, Nuno; Nuno Prata, Joao
2009-01-01
We derive the Hu-Paz-Zhang master equation for a Brownian particle linearly coupled to a bath of harmonic oscillators on the plane with spatial noncommutativity. The results obtained are exact to all orders in the noncommutative parameter. As a by-product we derive some miscellaneous results such as the equilibrium Wigner distribution for the reservoir of noncommutative oscillators, the weak coupling limit of the master equation and a set of sufficient conditions for strict purity decrease of the Brownian particle. Finally, we consider a high-temperature Ohmic model and obtain an estimate for the time scale of the transition from noncommutative to ordinary quantum mechanics. This scale is considerably smaller than the decoherence scale
Born series and unitarity in noncommutative quantum mechanics
Bemfica, F. S.; Girotti, H. O.
2008-01-01
This paper is dedicated to present model independent results for noncommutative quantum mechanics. We determine sufficient conditions for the convergence of the Born series and, in the sequel, unitarity is proved in full generality.
Wilson loop and dimensional reduction in noncommutative gauge theories
Lee, Sunggeun; Sin, Sang-Jin
2001-10-01
Using the anti-de Sitter (AdS) conformal field theory correspondence we study the UV behavior of Wilson loops in various noncommutative gauge theories. We get an area law in most cases and try to identify its origin. In the D3 case, we may identify the the origin as the D1 dominance over the D3: as we go to the boundary of AdS space, the effect of the flux of the D3 charge is highly suppressed, while the flux due to the D1 charge is enhanced. So near the boundary the theory is more like a theory on a D1-brane than that on a D3-brane. This phenomena is closely related to dimensional reduction due to the strong magnetic field in the charged particle in the magnetic field. The linear potential is not due to the confinement by IR effect but is the analogue of Coulomb's potential in 1+1 dimensions.
Models of Quantum Space Time: Quantum Field Planes
Mack, G.; Schomerus, V.
1994-01-01
Quantum field planes furnish a noncommutative differential algebra $\\Omega$ which substitutes for the commutative algebra of functions and forms on a contractible manifold. The data required in their construction come from a quantum field theory. The basic idea is to replace the ground field ${\\bf C}$ of quantum planes by the noncommutative algebra ${\\cal A}$ of observables of the quantum field theory.
Casimir force in noncommutative Randall-Sundrum models revisited
International Nuclear Information System (INIS)
Teo, L. P.
2010-01-01
We propose another method to compute the Casimir force in noncommutative Randall-Sundrum braneworld model considered by K. Nouicer and Y. Sabri, Phys. Rev. D 80, 086013 (2009). recently. Our method can be used to compute the Casimir force to any order in the noncommutative parameter. Contrary to the claim made by K. Nouicer and Y. Sabri that repulsive Casimir force can appear in the first order approximation, we show that the Casimir force is always attractive at any order of approximation.
Thermodynamics and evaporation of the noncommutative black hole
International Nuclear Information System (INIS)
Myung, Yun Soo; Kim, Yong-Wan; Park, Young-Jai
2007-01-01
We investigate the thermodynamics of the noncommutative black hole whose static picture is similar to that of the nonsingular black hole known as the de Sitter-Schwarzschild black hole. It turns out that the final remnant of extremal black hole is a thermodynamically stable object. We describe the evaporation process of this black hole by using the noncommutativity-corrected Vaidya metric. It is found that there exists a close relationship between thermodynamic approach and evaporation process
Differential forms and the noncommutative residue
Ugalde, William J.
2008-12-01
For a pseudo-differential operator S of order 0 acting on sections of a vector bundle B on a compact manifold M without boundary, we associate a differential form of order dimension of M acting on C∞(M)×C∞(M). This differential form Ω is given in terms of the noncommutative 1-density res([S,f][S,h]). In the particular case of an even-dimensional, compact, conformal manifold without boundary, we study this differential form for the case (B,S)=(H,F), that is, the Fredholm module associated by Connes [A. Connes, Quantized calculus and applications, in: XIth International Congress of Mathematical Physics (Paris, 1994), Internatl. Press, Cambridge, MA, 1995, pp. 15-36] to the manifold M. We give its explicit expression in the flat case and we address a possible approach to the computations for the general case.
A first course in noncommutative rings
Lam, T Y
2001-01-01
A First Course in Noncommutative Rings, an outgrowth of the author's lectures at the University of California at Berkeley, is intended as a textbook for a one-semester course in basic ring theory. The material covered includes the Wedderburn-Artin theory of semisimple rings, Jacobson's theory of the radical, representation theory of groups and algebras, prime and semiprime rings, local and semilocal rings, perfect and semiperfect rings, etc. By aiming the level of writing at the novice rather than the connoisseur and by stressing th the role of examples and motivation, the author has produced a text that is suitable not only for use in a graduate course, but also for self- study in the subject by interested graduate students. More than 400 exercises testing the understanding of the general theory in the text are included in this new edition.
Electric dipole moments reconsidered
International Nuclear Information System (INIS)
Rupertsberger, H.
1989-01-01
The electric dipole moments of elementary particles, atoms, molecules and their connection to the electric susceptibility are discussed for stationary states. Assuming rotational invariance it is emphasized that for such states only in the case of a parity and time reversal violating interaction the considered particles can obtain a nonvanishing expectation value for the electric dipole moment. 1 fig., 13 refs. (Author)
Stability analysis of lower dimensional gravastars in noncommutative geometry
Energy Technology Data Exchange (ETDEWEB)
Banerjee, Ayan [Jadavpur University, Department of Mathematics, Kolkata (India); Hansraj, Sudan [University of KwaZulu-Natal, Astrophysics and Cosmology Research Unit, School of Mathematics, Statistics and Computer Science, Durban (South Africa)
2016-11-15
The Banados et al. (Phys. Rev. Lett 69:1849, 1992), black hole solution is revamped from the Einstein field equations in (2 + 1)-dimensional anti-de Sitter spacetime, in a context of noncommutative geometry (Phys. Rev. D 87:084014, 2013). In this article, we explore the exact gravastar solutions in three-dimensional anti-de Sitter space given in the same geometry. As a first step we derive BTZ solution assuming the source of energy density as point-like structures in favor of smeared objects, where the particle mass M, is diffused throughout a region of linear size √(α) and is described by a Gaussian function of finite width rather than a Dirac delta function. We matched our interior solution to an exterior BTZ spacetime at a junction interface situated outside the event horizon. Furthermore, a stability analysis is carried out for the specific case when χ < 0.214 under radial perturbations about the static equilibrium solutions. To give theoretical support we are also trying to explore their physical properties and characteristics. (orig.)
Conformal quantum mechanics and holography in noncommutative space–time
Directory of Open Access Journals (Sweden)
Kumar S. Gupta
2017-09-01
Full Text Available We analyze the effects of noncommutativity in conformal quantum mechanics (CQM using the κ-deformed space–time as a prototype. Up to the first order in the deformation parameter, the symmetry structure of the CQM algebra is preserved but the coupling in a canonical model of the CQM gets deformed. We show that the boundary conditions that ensure a unitary time evolution in the noncommutative CQM can break the scale invariance, leading to a quantum mechanical scaling anomaly. We calculate the scaling dimensions of the two and three point functions in the noncommutative CQM which are shown to be deformed. The AdS2/CFT1 duality for the CQM suggests that the corresponding correlation functions in the holographic duals are modified. In addition, the Breitenlohner–Freedman bound also picks up a noncommutative correction. The strongly attractive regime of a canonical model of the CQM exhibit quantum instability. We show that the noncommutativity softens this singular behaviour and its implications for the corresponding holographic duals are discussed.
Quantum groups, non-commutative differential geometry and applications
Energy Technology Data Exchange (ETDEWEB)
Schupp, Peter [Lawrence Berkeley Lab., CA (United States); California Univ., Berkeley, CA (United States). Dept. of Physics
1993-12-09
The topic of this thesis is the development of a versatile and geometrically motivated differential calculus on non-commutative or quantum spaces, providing powerful but easy-to-use mathematical tools for applications in physics and related sciences. A generalization of unitary time evolution is proposed and studied for a simple 2-level system, leading to non-conservation of microscopic entropy, a phenomenon new to quantum mechanics. A Cartan calculus that combines functions, forms, Lie derivatives and inner derivations along general vector fields into one big algebra is constructed for quantum groups and then extended to quantum planes. The construction of a tangent bundle on a quantum group manifold and an BRST type approach to quantum group gauge theory are given as further examples of applications. The material is organized in two parts: Part I studies vector fields on quantum groups, emphasizing Hopf algebraic structures, but also introducing a ``quantum geometric`` construction. Using a generalized semi-direct product construction we combine the dual Hopf algebras A of functions and U of left-invariant vector fields into one fully bicovariant algebra of differential operators. The pure braid group is introduced as the commutant of {Delta}(U). It provides invariant maps A {yields} U and thereby bicovariant vector fields, casimirs and metrics. This construction allows the translation of undeformed matrix expressions into their less obvious quantum algebraic counter parts. We study this in detail for quasitriangular Hopf algebras, giving the determinant and orthogonality relation for the ``reflection`` matrix. Part II considers the additional structures of differential forms and finitely generated quantum Lie algebras -- it is devoted to the construction of the Cartan calculus, based on an undeformed Cartan identity.
Higher derivative Chern-Simons extension in the noncommutative QED3
Ghasemkhani, M.; Bufalo, R.
2015-06-01
The noncommutative (NC) massive quantum electrodynamics in 2 +1 dimensions is considered. We show explicitly that the one-loop effective action arising from integrating out the fermionic fields leads to the ordinary NC Chern-Simons and NC Maxwell action at the long wavelength limit (large fermion mass). In the next to leading order, the higher-derivative contributions to NC Chern-Simons are obtained. Moreover, the gauge invariance of the outcome action is carefully discussed. We then consider the higher-derivative modification into the pure NC Chern-Simons Lagrangian density and evaluate the one-loop correction to the pole of the photon propagator.
One-loop effects in a self-dual planar noncommutative theory
International Nuclear Information System (INIS)
Fosco, C.D.; Moreno, G.A.
2007-01-01
We study the UV properties, and derive the explicit form of the one-loop effective action, for a noncommutative complex scalar field theory in 2+1 dimensions with a Grosse-Wulkenhaar term, at the self-dual point. We also consider quantum effects around non-trivial minima of the classical action which appear when the potential allows for the spontaneous breaking of the U(1) symmetry. For those solutions, we show that the one-loop correction to the vacuum energy is a function of a special combination of the amplitude of the classical solution and the coupling constant
Marciano, William J
2010-01-01
This book provides a self-contained description of the measurements of the magnetic dipole moments of the electron and muon, along with a discussion of the measurements of the fine structure constant, and the theory associated with magnetic and electric dipole moments. Also included are the searches for a permanent electric dipole moment of the electron, muon, neutron and atomic nuclei. The related topic of the transition moment for lepton flavor violating processes, such as neutrinoless muon or tauon decays, and the search for such processes are included as well. The papers, written by many o
Cabouat, Baptiste; Sjöstrand, Torbjörn
2018-03-01
Parton showers have become a standard component in the description of high-energy collisions. Nowadays most final-state ones are of the dipole character, wherein a pair of partons branches into three, with energy and momentum preserved inside this subsystem. For initial-state showers a dipole picture is also possible and commonly used, but the older global-recoil strategy remains a valid alternative, wherein larger groups of partons share the energy-momentum preservation task. In this article we introduce and implement a dipole picture also for initial-state radiation in Pythia, and compare with the existing global-recoil one, and with data. For the case of Deeply Inelastic Scattering we can directly compare with matrix element expressions and show that the dipole picture gives a very good description over the whole phase space, at least for the first branching.
Non-commutative instantons and the Seiberg-Witten map
International Nuclear Information System (INIS)
Kraus, Per; Shigemori, Masaki
2002-01-01
We present several results concerning non-commutative instantons and the Seiberg-Witten map. Using a simple ansatz we find a large new class of instanton solutions in arbitrary even dimensional non-commutative Yang-Mills theory. These include the two dimensional 'shift operator' solutions and the four dimensional Nekrasov-Schwarz instantons as special cases. We also study how the Seiberg-Witten map acts on these instanton solutions. The infinitesimal Seiberg-Witten map is shown to take a very simple form in operator language, and this result is used to give a commutative description of non-commutative instantons. The instanton is found to be singular in commutative variables. (author)
Quantization, geometry and noncommutative structures in mathematics and physics
Morales, Pedro; Ocampo, Hernán; Paycha, Sylvie; Lega, Andrés
2017-01-01
This monograph presents various ongoing approaches to the vast topic of quantization, which is the process of forming a quantum mechanical system starting from a classical one, and discusses their numerous fruitful interactions with mathematics. The opening chapter introduces the various forms of quantization and their interactions with each other and with mathematics. A first approach to quantization, called deformation quantization, consists of viewing the Planck constant as a small parameter. This approach provides a deformation of the structure of the algebra of classical observables rather than a radical change in the nature of the observables. When symmetries come into play, deformation quantization needs to be merged with group actions, which is presented in chapter 2, by Simone Gutt. The noncommutativity arising from quantization is the main concern of noncommutative geometry. Allowing for the presence of symmetries requires working with principal fiber bundles in a non-commutative setup, where Hopf a...
Einstein-Podolski-Rosen experiment from noncommutative quantum gravity
International Nuclear Information System (INIS)
Heller, Michael; Sasin, Wieslaw
1998-01-01
It is shown that the Einstein-Podolski-Rosen type experiments are the natural consequence of the groupoid approach to noncommutative unification of general relativity and quantum mechanics. The geometry of this model is determined by the noncommutative algebra A=C c ∞ (G,C) of complex valued, compactly supported, functions (with convolution as multiplication) on the groupoid G=ExΓ. In the model considered in the present paper E is the total space of the frame bundle over space-time and Γ is the Lorentz group. The correlations of the EPR type should be regarded as remnants of the totally non-local physics below the Planck threshold which is modelled by a noncommutative geometry
A deformation quantization theory for noncommutative quantum mechanics
International Nuclear Information System (INIS)
Costa Dias, Nuno; Prata, Joao Nuno; Gosson, Maurice de; Luef, Franz
2010-01-01
We show that the deformation quantization of noncommutative quantum mechanics previously considered by Dias and Prata ['Weyl-Wigner formulation of noncommutative quantum mechanics', J. Math. Phys. 49, 072101 (2008)] and Bastos, Dias, and Prata ['Wigner measures in non-commutative quantum mechanics', e-print arXiv:math-ph/0907.4438v1; Commun. Math. Phys. (to appear)] can be expressed as a Weyl calculus on a double phase space. We study the properties of the star-product thus defined and prove a spectral theorem for the star-genvalue equation using an extension of the methods recently initiated by de Gosson and Luef ['A new approach to the *-genvalue equation', Lett. Math. Phys. 85, 173-183 (2008)].
Effects of dipole magnet inhomogeneities on the beam ellipsoid
International Nuclear Information System (INIS)
Tsoupas, N.; Colman, J.; Levine, M.; McKenzie-Wilson, R.; Ward, T.; Grand, P.
1986-01-01
The RAYTRACE computer code has been modified to accept magnetic fields measured in the median plane of a dipole magnet. This modification allows one to study the effects of a non-ideal dipole magnet on the beam ellipsoid (as defined by the TRANSPORT code manual). The effects on the beam ellipsoid are due to: field inhomogeneities in the interior region of the dipole, and discrepancies from design conditions of the magnetic field values in the fringe field region. The results of the RAYTRACE code calculations based on experimentally measured fields will be compared with the results derived using both an ideal (no inhomogeneities) dipole with SCOFF boundaries and an ideal dipole with perfect (according to design) fringe fields
Lorentz invariant noncommutative algebra for cosmological models coupled to a perfect fluid
Energy Technology Data Exchange (ETDEWEB)
Abreu, Everton M.C.; Marcial, Mateus V.; Mendes, Albert C.R.; Oliveira, Wilson [Universidade Federal Rural do Rio de Janeiro (UFRRJ), Seropedica, RJ (Brazil); Universidade Federal de Juiz de Fora, MG (Brazil)
2013-07-01
Full text: In current theoretical physics there is a relevant number of theoretical investigations that lead to believe that at the first moments of our Universe, the geometry was not commutative and the dominating physics at that time was ruled by the laws of noncommutative (NC) geometry. Therefore, the idea is that the physics of the early moments can be constructed based on these concepts. The first published work using the idea of a NC spacetime were carried out by Snyder who believed that NC principles could make the quantum field theory infinities disappear. However, it did not occur and Snyder's ideas were put to sleep for a long time. The main modern motivations that rekindle the investigation about NC field theories came from string theory and quantum gravity. In the context of quantum mechanics for example, R. Banerjee discussed how NC structures appear in planar quantum mechanics providing a useful way for obtaining them. The analysis was based on the NC algebra used in planar quantum mechanics that was originated from 't Hooft's analysis on dissipation and quantization. In this work we carry out a NC algebra analysis of the Friedmann-Robert-Walker model, coupled to a perfect fluid and in the presence of a cosmological constant. The classical field equations are modified, by the introduction of a shift operator, in order to introduce noncommutativity in these models. (author)
Infinite volume of noncommutative black hole wrapped by finite surface
Energy Technology Data Exchange (ETDEWEB)
Zhang, Baocheng, E-mail: zhangbc.zhang@yahoo.com [School of Mathematics and Physics, China University of Geosciences, Wuhan 430074 (China); You, Li, E-mail: lyou@mail.tsinghua.edu.cn [State Key Laboratory of Low Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084 (China)
2017-02-10
The volume of a black hole under noncommutative spacetime background is found to be infinite, in contradiction with the surface area of a black hole, or its Bekenstein–Hawking (BH) entropy, which is well-known to be finite. Our result rules out the possibility of interpreting the entropy of a black hole by counting the number of modes wrapped inside its surface if the final evaporation stage can be properly treated. It implies the statistical interpretation for the BH entropy can be independent of the volume, provided spacetime is noncommutative. The effect of radiation back reaction is found to be small and doesn't influence the above conclusion.
Relativistic Hydrogen-Like Atom on a Noncommutative Phase Space
Masum, Huseyin; Dulat, Sayipjamal; Tohti, Mutallip
2017-09-01
The energy levels of hydrogen-like atom on a noncommutative phase space were studied in the framework of relativistic quantum mechanics. The leading order corrections to energy levels 2 S 1/2, 2 P 1/2 and 2 P 3/2 were obtained by using the 𝜃 and the \\bar θ modified Dirac Hamiltonian of hydrogen-like atom on a noncommutative phase space. The degeneracy of the energy levels 2 P 1/2 and 2 P 3/2 were removed completely by 𝜃-correction. And the \\bar θ -correction shifts these energy levels.
Charged thin-shell gravastars in noncommutative geometry
Energy Technology Data Exchange (ETDEWEB)
Oevguen, Ali [Pontificia Universidad Catolica de Valparaiso, Instituto de Fisica, Valparaiso (Chile); Eastern Mediterranean University, Physics Department, Famagusta, Northern Cyprus (Turkey); Banerjee, Ayan [Jadavpur University, Department of Mathematics, Kolkata, West Bengal (India); Jusufi, Kimet [State University of Tetovo, Physics Department, Tetovo (Macedonia, The Former Yugoslav Republic of); Institute of Physics, Ss. Cyril and Methodius University, Faculty of Natural Sciences and Mathematics, Skopje (Macedonia, The Former Yugoslav Republic of)
2017-08-15
In this paper we construct a charged thin-shell gravastar model within the context of noncommutative geometry. To do so, we choose the interior of the nonsingular de Sitter spacetime with an exterior charged noncommutative solution by cut-and-paste technique and apply the generalized junction conditions. We then investigate the stability of a charged thin-shell gravastar under linear perturbations around the static equilibrium solutions as well as the thermodynamical stability of the charged gravastar. We find the stability regions, by choosing appropriate parameter values, located sufficiently close to the event horizon. (orig.)
Star product and invariant integration for Lie Type noncommutative spacetimes
International Nuclear Information System (INIS)
Chryssomalakos, Chryssomalis; Okon, Elias
2007-01-01
We present a star product for noncommutative spaces of Lie type, including the so called 'canonical' case by introducing a central generator, which is compatible with translations and admits a simple, manageable definition of an invariant integral. A quasi-cyclicity property for the latter is shown to hold, which reduces to exact cyclicity when the adjoint representation of the underlying Lie algebra is traceless. Several explicit examples illuminate the formalism, dealing with κ-Minkowski spacetime and the Heisenberg algebra ('canonical' noncommutative 2-plane)
Can noncommutativity resolve the Big-Bang singularity?
Maceda, M; Manousselis, P; Zoupanos, George
2004-01-01
A possible way to resolve the singularities of general relativity is proposed based on the assumption that the description of space-time using commuting coordinates is not valid above a certain fundamental scale. Beyond that scale it is assumed that the space-time has noncommutative structure leading in turn to a resolution of the singularity. As a first attempt towards realizing the above programme a noncommutative version of the Kasner metric is constructed which is nonsingular at all scales and becomes commutative at large length scales.
Noncommutative vector bundles over fuzzy CPN and their covariant derivatives
International Nuclear Information System (INIS)
Dolan, Brian P.; Huet, Idrish; Murray, Sean; O'Connor, Denjoe
2007-01-01
We generalise the construction of fuzzy CP N in a manner that allows us to access all noncommutative equivariant complex vector bundles over this space. We give a simplified construction of polarization tensors on S 2 that generalizes to complex projective space, identify Laplacians and natural noncommutative covariant derivative operators that map between the modules that describe noncommuative sections. In the process we find a natural generalization of the Schwinger-Jordan construction to su(n) and identify composite oscillators that obey a Heisenberg algebra on an appropriate Fock space
Noncommutative duality of Gelfand-Naimark and applications in gauge theory and spinc structure
International Nuclear Information System (INIS)
RATSIMBARISON, H.M.
2004-01-01
We use the GN (Gelfand-Naimark) duality and its generalizations in order to describe some physical constructions, our main tool is the categorical formalism. We start with the first GN theorem, a duality between a category of commutative unital C*-algebras and a category of compact Hausdorff spaces, which we interpret as equivalence between classical observables and classical states. Then, we give the GNS construction providing the 'Fock space' in Quantum Field Theory, and which is the constructive proof of the second GN theorem. A particular formulation of this latter, the Serre-Swan theorem introduces vector bundle structure, a new kind of classical states space. And this lead to K-theory, which we show compatible with a noncommutative concept : the Morita equivalence. From these ideas of Noncommutative geometry, we meet two important applications in QFT : Gauge theory and Spin c structure.The first application begin with the origin of gauge theory: it permit to obtain the interaction lagrangian term from the gauge non invariance of the free lagrangian of matter. Thanks to theories of principal bundles, the gauge potential and the gauge transformation are represented by connection and bundle G-automorphism on the identity of a principal bundle over the spacetime manifold. Finally, the Serre-Swan theorem gives the step of Connes's generalization to noncommutative case. In the second application, we show that the construction of Dirac operator lead to the definitions of Clifford algebra and spinor space. A categorical equivalent definition, similar to those of the Grothendieck group, is done. At the end, we make use of the structure of Clifford algebra and the Morita equivalence to reconstruct Plymen's definition of the spin c structure [fr
Dipole-dipole dispersion interactions between neutrons
Babb, James F.; Higa, Renato; Hussein, Mahir S.
2016-01-01
We investigate the long-range interactions between two neutrons utilizing recent data on the neutron static and dynamic electric and magnetic dipole polarizabilities. The resulting long-range potentials are used to make quantitative comparisons between the collisions of a neutron with a neutron and a neutron with a proton. We also assess the importance of the first pion production threshold and first excited state of the nucleon, the $\\Delta$-resonance ($J^{\\pi}$ = + 3/2, I = 3/2). We found b...
Coupling between crossed dipole feeds
DEFF Research Database (Denmark)
Andersen, J.; Schjær-Jacobsen, Hans; Lessow, H.
1974-01-01
as a function of orientation and feeding network properties. The antennas are used as feeds for a parabolic reflector, and the effect of coupling on the secondary fields is analyzed. Especially significant is the polarization loss and it may, to some extent, be reduced by a proper choice of feeding network.......Various effects of coupling between crossed-dipole antennas are analyzed and by using an arbitrary feeding network some generality is preserved. With one cross excited and another cross acting as a parasitic loaded antenna, coupling losses and gain and polarization losses are presented...
Electric and Magnetic Dipole Moments
CERN. Geneva
2005-01-01
The stringent limit on the electric dipole moment of the neutron forced the issue on the strong CP-problem. The most elegant solution of which is the axion field proposed by Peccei and Quinn. The current limit on the QCD parameter theta coming from the limit on the neutron EDM is of order 10-10. I am going to describe the present status on the neutron EDM searches and further prospects on getting down to theta_qcd sensitivity of 10-13 with the new deuteron EDM in storage rings proposal. For completeness the current status and prospects of the muon g-2 experiment will also be given.
On the dipole approximation with error estimates
Boßmann, Lea; Grummt, Robert; Kolb, Martin
2018-01-01
The dipole approximation is employed to describe interactions between atoms and radiation. It essentially consists of neglecting the spatial variation of the external field over the atom. Heuristically, this is justified by arguing that the wavelength is considerably larger than the atomic length scale, which holds under usual experimental conditions. We prove the dipole approximation in the limit of infinite wavelengths compared to the atomic length scale and estimate the rate of convergence. Our results include N-body Coulomb potentials and experimentally relevant electromagnetic fields such as plane waves and laser pulses.
Noncommutative geometry-inspired rotating black hole in three ...
Indian Academy of Sciences (India)
Abstract. We find a new rotating black hole in three-dimensional anti-de Sitter space using an anisotropic perfect fluid inspired by the noncommutative black hole. We deduce the thermodynam- ical quantities of this black hole and compare them with those of a rotating BTZ solution and give corrections to the area law to get ...
Thermodynamics on noncommutative geometry in coherent state formalism
International Nuclear Information System (INIS)
Huang, W.-H.; Huang, K.-W.
2009-01-01
The thermodynamics of ideal gas on the noncommutative geometry in the coherent state formalism is investigated. We first evaluate the statistical interparticle potential and see that there are residual 'attraction (repulsion) potential' between boson (fermion) in the high temperature limit. The characters could be traced to the fact that, the particle with mass m in noncommutative thermal geometry with noncommutativity θ and temperature T will correspond to that in the commutative background with temperature T(1+kTmθ) -1 . Such a correspondence implies that the ideal gas energy will asymptotically approach to a finite limiting value as that on commutative geometry at T θ =(kmθ) -1 . We also investigate the squeezed coherent states and see that they could have arbitrary mean energy. The thermal properties of those systems are calculated and compared to each other. We find that the heat capacity of the squeezed coherent states of boson and fermion on the noncommutative geometry have different values, contrast to that on the commutative geometry
Noncommutative geometry-inspired rotating black hole in three ...
Indian Academy of Sciences (India)
We ﬁnd a new rotating black hole in three-dimensional anti-de Sitter space using an anisotropic perfect ﬂuid inspired by the noncommutative black hole. We deduce the thermodynamical quantities of this black hole and compare them with those of a rotating BTZ solution and give corrections to the area law to get the exact ...
Einstein–Podolski–Rosen paradox, non-commuting operator ...
Indian Academy of Sciences (India)
Einstein, Podolski and Rosen (EPR) have shown that any wavefunction (subject to the Schrödinger equation) can describe the physical reality completely, and any two observables associated with two non-commuting operators can have simultaneous reality. In contrast, quantum theory claims that the wavefunction can ...
General classical solutions in the noncommutative CPN-1 model
International Nuclear Information System (INIS)
Foda, O.; Jack, I.; Jones, D.R.T.
2002-01-01
We give an explicit construction of general classical solutions for the noncommutative CP N-1 model in two dimensions, showing that they correspond to integer values for the action and topological charge. We also give explicit solutions for the Dirac equation in the background of these general solutions and show that the index theorem is satisfied
Einstein–Podolski–Rosen paradox, non-commuting operator ...
Indian Academy of Sciences (India)
Abstract. Einstein, Podolski and Rosen (EPR) have shown that any wavefunction (subject to the. Schrödinger equation) can describe the physical reality completely, and any two observables associ- ated with two non-commuting operators can have simultaneous reality. In contrast, quantum theory claims that the ...
((F, D1), D3) bound state, S-duality and noncommutative open string/Yang-Mills theory
International Nuclear Information System (INIS)
Lu, J.X.; Roy, S.; Singh, H.
2000-01-01
We study decoupling limits and S-dualities for noncommutative open string/Yang-Mills theory in a gravity setup by considering an SL(2,Z) invariant supergravity solution of the form ((F, D1), D3) bound state of type IIB string theory. This configuration can be regarded as D3-branes with both electric and magnetic fields turned on along one of the spatial directions of the brane and preserves half of the space-time supersymmetries of the string theory. Our study indicates that there exists a decoupling limit for which the resulting theory is an open string theory defined in a geometry with noncommutativity in both space-time and space-space directions. We study S-duality of this noncommutative open string (NCOS) and find that the same decoupling limit in the S-dual description gives rise to a space-space noncommutative Yang-Mills theory (NCYM). We also discuss independently the decoupling limit for NCYM in this D3 brane background. Here we find that S-duality of NCYM theory does not always give a NCOS theory. Instead, it can give an ordinary Yang-Mills with a singular metric and an infinitely large coupling. We also find that the open string coupling relation between the two S-duality related theories is modified such that S-duality of a strongly coupled open-string/Yang-Mills theory does not necessarily give a weakly coupled theory. The relevant gravity dual descriptions of NCOS/NCYM are also given. (author)
Korff, Christian
2010-10-01
Starting from the Verma module of U_{q}\\mathfrak {sl}(2) we consider the evaluation module for affine U_{q}\\widehat{\\mathfrak {sl}}(2) and discuss its crystal limit (q → 0). There exists an associated integrable statistical mechanics model on a square lattice defined in terms of vertex configurations. Its transfer matrix is the generating function for noncommutative complete symmetric polynomials in the generators of the affine plactic algebra, an extension of the finite plactic algebra first discussed by Lascoux and Schützenberger. The corresponding noncommutative elementary symmetric polynomials were recently shown to be generated by the transfer matrix of the so-called phase model discussed by Bogoliubov, Izergin and Kitanine. Here we establish that both generating functions satisfy Baxter's TQ-equation in the crystal limit by tying them to special U_{q}\\widehat{ \\mathfrak {sl}}(2) solutions of the Yang-Baxter equation. The TQ-equation amounts to the well-known Jacobi-Trudi formula leading naturally to the definition of noncommutative Schur polynomials. The latter can be employed to define a ring which has applications in conformal field theory and enumerative geometry: it is isomorphic to the fusion ring of the \\widehat{\\mathfrak {sl}}(n)_{k} Wess-Zumino-Novikov-Witten model whose structure constants are the dimensions of spaces of generalized θ-functions over the Riemann sphere with three punctures.
Black hole remnants in Hayward solutions and noncommutative effects
Mehdipour, S. Hamid; Ahmadi, M. H.
2018-01-01
In this paper, we explore the final stages of the black hole evaporation for Hayward solutions. Our results show that the behavior of Hawking's radiation changes considerably at the small radii regime such that the black hole does not evaporate completely and a stable remnant is left. We show that stability conditions hold for the Hayward solutions found in the Einstein gravity coupled with nonlinear electrodynamics. We analyze the effect that an inspired model of the noncommutativity of spacetime can have on the thermodynamics of Hayward spacetimes. This has been done by applying the noncommutative effects to the non-rotating and rotating Hayward black holes. In this setup, all point structures get replaced by smeared distributions owing to this inspired approach. The noncommutative effects result in a colder black hole in the small radii regime as Hayward's free parameter g increases. As well as the effects of noncommutativity and the rotation factor, the configuration of the remnant can be substantially affected by the parameter g. However, in the rotating solution it is not so sensitive to g with respect to the non-rotating case. As a consequence, Hayward's parameter, the noncommutativity and the rotation may raise the minimum value of energy for the possible formation of black holes in TeV-scale collisions. This observation can be used as a potential explanation for the absence of black holes in the current energy scales produced at particle colliders. However, it is also found that if extra dimensions do exist, then the possibility of the black hole production at energy scales accessible at the LHC for large numbers of extra dimensions will be larger.
Black hole remnants in Hayward solutions and noncommutative effects
Directory of Open Access Journals (Sweden)
S. Hamid Mehdipour
2018-01-01
Full Text Available In this paper, we explore the final stages of the black hole evaporation for Hayward solutions. Our results show that the behavior of Hawking's radiation changes considerably at the small radii regime such that the black hole does not evaporate completely and a stable remnant is left. We show that stability conditions hold for the Hayward solutions found in the Einstein gravity coupled with nonlinear electrodynamics. We analyze the effect that an inspired model of the noncommutativity of spacetime can have on the thermodynamics of Hayward spacetimes. This has been done by applying the noncommutative effects to the non-rotating and rotating Hayward black holes. In this setup, all point structures get replaced by smeared distributions owing to this inspired approach. The noncommutative effects result in a colder black hole in the small radii regime as Hayward's free parameter g increases. As well as the effects of noncommutativity and the rotation factor, the configuration of the remnant can be substantially affected by the parameter g. However, in the rotating solution it is not so sensitive to g with respect to the non-rotating case. As a consequence, Hayward's parameter, the noncommutativity and the rotation may raise the minimum value of energy for the possible formation of black holes in TeV-scale collisions. This observation can be used as a potential explanation for the absence of black holes in the current energy scales produced at particle colliders. However, it is also found that if extra dimensions do exist, then the possibility of the black hole production at energy scales accessible at the LHC for large numbers of extra dimensions will be larger.
Transportation studies: 40-MM collider dipole magnets
International Nuclear Information System (INIS)
Daly, E.
1992-01-01
Several fully functional 40-mm Collider Dipole Magnets (CDM) were instrumented with accelerometers to monitor shock and vibration loads during transport. The magnets were measured with optical tooling telescopes before and after transport. Changes in mechanical alignment due to shipping and handling were determined. The mechanical stability of the cryogen lines were checked using the same method. Field quality and dipole angle were measured warm before and after transport to determine changes in these parameters. Power spectra were calculated for accelerometers located on the cold mass, vacuum vessel, and trailer bed. Where available, plots of field quality and dipole roll both before and after were created. Shipping loads measured were largest in the vertical direction, where most of the structural deformation of the magnet was evident. It was not clear that magnetic performance was affected by the shipping and handling environment
Installation Strategy for the LHC Main Dipoles
Fartoukh, Stephane David
2004-01-01
All positions in the LHC machine are not equivalent in terms of beam requirements on the geometry and the field quality of the main dipoles. In the presence of slightly or strongly out-of tolerance magnets, a well-defined installation strategy will therefore contribute to preserve or even optimize the performance of the machine. Based on the present status of the production, we have anticipated a list of potential issues (geometry, transfer function, field direction and random b3) which, combined by order of priority, have been taken into account to define a simple but efficient installation algorithm for the LHC main dipoles. Its output is a prescription for installing the available dipoles in sequence while reducing to an absolute minimum the number of holes required by geometry or FQ issues.
LHC dipoles: the countdown has begun
Patrice Loiez
2002-01-01
At the entrance to the fourth floor corridor of the LHC-MMS (Main Magnets and Superconductors) Group in building 30, the Director-General has unveiled an electronic information panel indicating the number of LHC dipoles still to be delivered and the days remaining to the deadline (30 June 2006). The panel was the idea of Lucio Rossi, leader of the MMS Group, which is responsible for the construction of the dipole magnets. The unveiling ceremony took place on the morning of Friday 11 October 2002, at the end of a drink held to celebrate with MMS group and the LHC top management the exceptional performance of the latest dipoles, built by the French consortium Alstom-Jeumont. They are the first dipoles to achieve a magnetic field of 9 tesla in one go without quenching, thus exceeding the nominal operating field of 8.3 tesla. The challenge is now to increase the production rate from 2 to 35 dipoles per month by 2004 in order to meet the deadline, while maintaining this quality. Photo 01: The Director-General Luci...
Dipole-dipole dispersion interactions between neutrons
Energy Technology Data Exchange (ETDEWEB)
Babb, James F. [Harvard-Smithsonian Center for Astrophysics, ITAMP, Cambridge, MA (United States); Higa, Renato [Universidade de Sao Paulo, Instituto de Fisica, Sao Paulo (Brazil); Hussein, Mahir S. [Universidade de Sao Paulo, Instituto de Fisica, Sao Paulo (Brazil); Universidade de Sao Paulo, Instituto de Estudos Avancados, Sao Paulo (Brazil); Departamento de Fisica, Instituto Tecnologico de Aeronautica, CTA, Sao Jose dos Campos (Brazil)
2017-06-15
We investigate the long-range interactions between two neutrons utilizing recent data on the neutron static and dynamic electric and magnetic dipole polarizabilities. The resulting long-range potentials are used to make quantitative comparisons between the collisions of a neutron with a neutron and a neutron with a proton. We also assess the importance of the first pion production threshold and first excited state of the nucleon, the Δ-resonance (J{sup π} = +3/2, I = 3/2). We found both dynamical effects to be quite relevant for distances r between ∝ 50 fm up to ∝ 10{sup 3} fm in the nn system, the neutron-wall system and in the wall-neutron-wall system, reaching the expected asymptotic limit beyond that. Relevance of our findings to the confinement of ultra cold neutrons inside bottles is discussed. (orig.)
The status of the electric dipole moment of the neutron
International Nuclear Information System (INIS)
Grimus, W.
1990-01-01
The electric dipole moment of particles in quantum mechanics and quantum field theory is discussed. Furthermore, calculations of the neutron electric dipole moment in the standard model and several of its low-energy extensions are reviewed. 47 refs., 7 figs. (Author)
Yu, Yue; Luo, Zhuxi; Wang, Ziqiang
2014-07-01
We show that the dipole-dipole coupling between Wannier modes in cigar-shaped Bose-Einstein condensates (BECs) is significantly enhanced while the short-range coupling is strongly suppressed. As a result, the dipole-dipole interaction can become the dominant interaction between ultracold alkali Bose atoms. In the long length limit of a cigar-shaped BEC, the resulting effective one-dimensional models possess an effective inverse squared interacting potential, the Calogero-Sutherland potential, which plays a fundamental role in many fields of contemporary physics; but its direct experimental realization has been a challenge for a long time. We propose to realize the Calogero-Sutherland model in ultracold alkali Bose atoms and study the effects of the dipole-dipole interaction.
Razafindratsima, Stephen; Lataste, Jean-François
2014-01-01
Then, the influence of the remote electrode location was studied considering PsPD (Pseudo-Pole-Dipole i.e. when the exact location of the remote electrode is used even when finite) in comparison to PDbias (Pole-Dipole bias i.e. remote electrode is considered at infinity even when finite). Anomaly Effect (AE) with new consideration of the averaged mean resistivity value was used for the illustration, results with L1 and L2-norms were compared and Forward/Reverse measurements were considered. Angle α around 30° was identified as giving homogeneous spread error between PsPD and PDbias data treatments. For α ~ 140°, the error made when the true coordinates of the remote electrode is not informed is higher near layer's interface if L1-norm is used. Whereas this error is more visible in deep level if L2-norm is used. Finally, experimental results showed the influence of the location of the remote electrode when “Forward” measurements are completed by “Reverse” ones.
Van der Waals interactions and photoelectric effect in noncommutative quantum mechanics
International Nuclear Information System (INIS)
Li Kang; Chamoun, N.
2007-01-01
We calculate the long-range Van der Waals force and the photoelectric cross section in a noncommutative setup. It is argued that non-commutativity effects could not be discerned for the Van der Waals interactions. The result for the photoelectric effect shows deviation from the usual commutative one, which in principle can be used to put bounds on the space-space non-commutativity parameter. (authors)
Dipole-dipole interaction in cavity QED: The weak-coupling, nondegenerate regime
Donaire, M.; Muñoz-Castañeda, J. M.; Nieto, L. M.
2017-10-01
We compute the energies of the interaction between two atoms placed in the middle of a perfectly reflecting planar cavity, in the weak-coupling nondegenerate regime. Both inhibition and enhancement of the interactions can be obtained by varying the size of the cavity. We derive exact expressions for the dyadic Green's function of the cavity field which mediates the interactions and apply time-dependent quantum perturbation theory in the adiabatic approximation. We provide explicit expressions for the van der Waals potentials of two polarizable atomic dipoles and the electrostatic potential of two induced dipoles. We compute the van der Waals potentials in three different scenarios: two atoms in their ground states, two atoms excited, and two dissimilar atoms with one of them excited. In addition, we calculate the phase-shift rate of the two-atom wave function in each case. The effect of the two-dimensional confinement of the electromagnetic field on the dipole-dipole interactions is analyzed. This effect depends on the atomic polarization. For dipole moments oriented parallel to the cavity plates, both the electrostatic and the van der Waals interactions are exponentially suppressed for values of the cavity width much less than the interatomic distance, whereas for values of the width close to the interatomic distance, the strength of both interactions is higher than their values in the absence of cavity. For dipole moments perpendicular to the plates, the strength of the van der Waals interaction decreases for values of the cavity width close to the interatomic distance, while it increases for values of the width much less than the interatomic distance with respect to its strength in the absence of cavity. We illustrate these effects by computing the dipole-dipole interactions between two alkali atoms in circular Rydberg states.
LHC Dipoles: The countdown has begun
2002-01-01
One of the LHC dipole magnets has just achieved a record magnetic field of 9 Tesla in one go without quenching. The challenge now is to increase the production rate to 35 magnets a month by 2004. As a new information panel in Building 30 shows, the countdown has begun.
Results on Fermilab main injector dipole measurements
International Nuclear Information System (INIS)
Brown, B.C.; Baiod, R.; DiMarco, J.; Glass, H.D.; Harding, D.J.; Martin, P.S.; Mishra, S.; Mokhtarani, A.; Orris, D.F.; russell, O.A.; Tompkins, J.C.; Walbridge, D.G.C.
1995-06-01
Measurements of the Productions run of Fermilab Main Injector Dipole magnets is underway. Redundant strength measurements provide a set of data which one can fit to mechanical and magnetic properties of the assembly. Plots of the field contribution from the steel supplement the usual plots of transfer function (B/I) vs. I in providing insight into the measured results
Dipole model slice made in 1994 by Ansaldo. The high magnetic fields needed for guiding particles around the Large Hadron Collider (LHC) ring are created by passing 12’500 amps of current through coils of superconducting wiring. At very low temperatures, superconductors have no electrical resistance and therefore no power loss. The LHC is the largest superconducting installation ever built. The magnetic field must also be extremely uniform. This means the current flowing in the coils has to be very precisely controlled. Indeed, nowhere before has such precision been achieved at such high currents. 50’000 tonnes of steel sheets are used to make the magnet yokes that keep the wiring firmly in place. The yokes constitute approximately 80% of the accelerator's weight and, placed side by side, stretch over 20 km!
Realization of Cohen-Glashow very special relativity on noncommutative space-time.
Sheikh-Jabbari, M M; Tureanu, A
2008-12-31
We show that the Cohen-Glashow very special relativity (VSR) theory [A. G. Cohen and S. L. Glashow, Phys. Rev. Lett. 97, 021601 (2006)] can be realized as the part of the Poincaré symmetry preserved on a noncommutative Moyal plane with lightlike noncommutativity. Moreover, we show that the three subgroups relevant to VSR can also be realized in the noncommutative space-time setting. For all of these three cases, the noncommutativity parameter theta(mu upsilon) should be lightlike (theta(mu upsilon) theta mu upsilon = 0). We discuss some physical implications of this realization of the Cohen-Glashow VSR.
D-branes and the Non-commutative Structure of Quantum Spacetime
Mavromatos, Nikolaos E; Mavromatos, Nick E; Szabo, Richard J
1999-01-01
A worldsheet approach to the study of non-abelian D-particle dynamics is presented based on viewing matrix-valued D-brane coordinate fields as coupling constants of a deformed sigma-model which defines a logarithmic conformal field theory. The short-distance structure of spacetime is shown to be naturally captured by the Zamolodchikov metric on the corresponding moduli space which encodes the geometry of the string interactions between D-particles. Spacetime quantization is induced directly by the string genus expansion and leads to new forms of uncertainty relations which imply that general relativity at very short-distance scales is intrinsically described by a non-commutative geometry. The indeterminancies exhibit decoherence effects suggesting the natural incorporation of quantum gravity by short-distance D-particle probes. Some potential experimental tests are briefly described.
Wilson loop and dimensional reduction in non-commutative gauge theories
Lee, Sunggeun; Sin, Sang-Jin
2002-01-01
Using the AdS/CFT correspondence we study UV behavior of Wilson loops in various noncommutative gauge theories. We get an area law in most cases and try to identify its origin. In D3 case, we may identify the origin as the D1 dominance over the D3: as we go to the boundary of the AdS space, the effect of the flux of the D3 charge is highly suppressed, while the flux due to the D1 charge is enhanced. So near the boundary the theory is more like a theory on D1 brane than that on D3 brane. This phenomena is closely related to the dimensional reduction due to the strong magnetic field in the charged particle in the magnetic field. The linear potential is not due to the confinement by IR effect but is the analogue of Coulomb's potential in 1+1 dimension.
Noncommutative Lévy Processes for Generalized (Particularly Anyon) Statistics
Bożejko, Marek; Lytvynov, Eugene; Wysoczański, Janusz
2012-07-01
Let {T=R^d} . Let a function {QT^2toC} satisfy {Q(s,t)=overline{Q(t,s)}} and {|Q(s,t)|=1}. A generalized statistics is described by creation operators {partial_t^dagger} and annihilation operators ∂ t , {tin T}, which satisfy the Q-commutation relations: {partial_spartial^dagger_t = Q(s, t)partial^dagger_tpartial_s+δ(s, t)} , {partial_spartial_t = Q(t, s)partial_tpartial_s}, {partial^dagger_spartial^dagger_t = Q(t, s)partial^dagger_tpartial^dagger_s}. From the point of view of physics, the most important case of a generalized statistics is the anyon statistics, for which Q( s, t) is equal to q if s t. Here {qinC} , | q| = 1. We start the paper with a detailed discussion of a Q-Fock space and operators {(partial_t^dagger,partial_t)_{tin T}} in it, which satisfy the Q-commutation relations. Next, we consider a noncommutative stochastic process (white noise) {ω(t)=partial_t^dagger+partial_t+λpartial_t^daggerpartial_t} , {tin T} . Here {λinR} is a fixed parameter. The case λ = 0 corresponds to a Q-analog of Brownian motion, while λ ≠ 0 corresponds to a (centered) Q-Poisson process. We study Q-Hermite ( Q-Charlier respectively) polynomials of infinitely many noncommutatative variables {(ω(t))_{tin T}} . The main aim of the paper is to explain the notion of independence for a generalized statistics, and to derive corresponding Lévy processes. To this end, we recursively define Q-cumulants of a field {(ξ(t))_{tin T}}. This allows us to define a Q-Lévy process as a field {(ξ(t))_{tin T}} whose values at different points of T are Q-independent and which possesses a stationarity of increments (in a certain sense). We present an explicit construction of a Q-Lévy process, and derive a Nualart-Schoutens-type chaotic decomposition for such a process.
2004-01-01
The cold mass of a 15-metre main dipole magnet has some fifteen different components. All the main components are manufactured under CERN's direct responsibility. Four of them transit through CERN before being shipped to the dipole assembly contractors, namely the cable, which constitutes the magnet's superconducting core (see Bulletin 14/2004), the beam screens, the heat exchanger tubes and the cold bore beam tubes. The two latter components transit via Building 927 where they undergo part of the production process. The 58-mm diameter heat exchanger tubes will remove heat from the magnets using superfluid helium. The 53-mm diameter cold bore tubes will be placed under vacuum to allow the twin beams to circulate around the LHC.
On the state space of the dipole ghost
International Nuclear Information System (INIS)
Binegar, B.
1984-01-01
A particular representation of SO(4, 2) is identified with the state space of the free dipole ghost. This representation is then given an explicit realization as the solution space of a 4th-order wave equation on a spacetime locally isomorphic to Minkowski space. A discrete basis for this solution space is given, as well as an explicit expression for its SO(4, 2) invariant inner product. The connection between the modes of dipole field and those of the massless scalar field is clarified, and a recent conjecture concerning the restriction of the dipole representation to the Poincare subgroup is confirmed. A particular coordinate transformation then reveals the theory of the dipole ghost in Minkowski space. Finally, it is shown that the solution space of the dipole equation is not unitarizable in a Poincare invariant manner. (orig.)
Maximilien Brice
2004-01-01
The ALICE cavern receives a painting made specially to mark the 50th anniversary of CERN that is mounted on the L3 solenoid magnet, reused from the LEP experiment that ran from 1989 to 2000. The dipole, which is cooled by demineralised water, will bend the path of muons that leave the huge rectangular solenoid. These muons are heavy electrons that interact less with matter allowing them to be studied at large distances from the interaction point.
Non-commuting variations in mathematics and physics a survey
Preston, Serge
2016-01-01
This text presents and studies the method of so –called noncommuting variations in Variational Calculus. This method was pioneered by Vito Volterra who noticed that the conventional Euler-Lagrange (EL-) equations are not applicable in Non-Holonomic Mechanics and suggested to modify the basic rule used in Variational Calculus. This book presents a survey of Variational Calculus with non-commutative variations and shows that most basic properties of conventional Euler-Lagrange Equations are, with some modifications, preserved for EL-equations with K-twisted (defined by K)-variations. Most of the book can be understood by readers without strong mathematical preparation (some knowledge of Differential Geometry is necessary). In order to make the text more accessible the definitions and several necessary results in Geometry are presented separately in Appendices I and II Furthermore in Appendix III a short presentation of the Noether Theorem describing the relation between the symmetries of the differential equa...
Non-commutative covering spaces and their symmetries
DEFF Research Database (Denmark)
Canlubo, Clarisson
how these areclosely tied up. Coupled Hopf algebras will be presented to give a general description of coveringsof a point. We will give a complete description of the geometry of the central coverings ofcommutative spaces using the coverings of a point. A topologized version of Hopf categories willbe......The main goal of this thesis is to propose a notion analogous to covering spaces in classicalgeometry. This is motivated by the author's long term goal of dening the (etale) fundamentalgroup of a non-commutative space and put forth a good notion of monodromy.We will present a notion of a non......-commutative covering space using Galois theory of Hopfalgebroids. We will look at basic properties of classical covering spaces that generalize to thenon-commutative framework. Afterwards, we will explore a series of examples. We will startwith coverings of a point and central coverings of commutative spaces and see...
Noncommutative geometry inspired black holes in Rastall gravity
Energy Technology Data Exchange (ETDEWEB)
Ma, Meng-Sen [Shanxi Datong University, Institute of Theoretical Physics, Datong (China); Shanxi Datong University, Department of Physics, Datong (China); Zhao, Ren [Shanxi Datong University, Institute of Theoretical Physics, Datong (China)
2017-09-15
Under two different metric ansatzes, the noncommutative geometry inspired black holes (NCBH) in the framework of Rastall gravity are derived and analyzed. We consider the fluid-type matter with the Gaussian-distribution smeared mass density. Taking a Schwarzschild-like metric ansatz, it is shown that the noncommutative geometry inspired Schwarzschild black hole (NCSBH) in Rastall gravity, unlike its counterpart in general relativity (GR), is not a regular black hole. It has at most one event horizon. After showing a finite maximal temperature, the black hole will leave behind a point-like massive remnant at zero temperature. Considering a more general metric ansatz and a special equation of state of the matter, we also find a regular NCBH in Rastall gravity, which has a similar geometric structure and temperature to that of NCSBH in GR. (orig.)
Commutative and Non-commutative Parallelogram Geometry: an Experimental Approach
Bertram, Wolfgang
2013-01-01
By "parallelogram geometry" we mean the elementary, "commutative", geometry corresponding to vector addition, and by "trapezoid geometry" a certain "non-commutative deformation" of the former. This text presents an elementary approach via exercises using dynamical software (such as geogebra), hopefully accessible to a wide mathematical audience, from undergraduate students and high school teachers to researchers, proceeding in three steps: (1) experimental geometry, (2) algebra (linear algebr...
Implications of the Hopf algebra properties of noncommutative differential calculi
International Nuclear Information System (INIS)
Vladimirov, A.A.
1997-01-01
A noncommutative algebra of four basic objects is defined within a differential calculus on quantum groups - functions, 1-forms, Lie derivatives, and inner derivations - as the cross-product algebra associated with Woronowicz's (differential) algebra of functions and forms. This definition properly takes into account the Hopf algebra structure of the Woronowicz calculus. It also provides a direct proof of the Cartan identity. (author). 9 refs
Limit algebras of differential forms in non-commutative geometry
Indian Academy of Sciences (India)
The GNS-representation of ∞A defined by a d-dimensional non-commutative volume integral on a d+-summable K-cycle on A is realized as the representation induced by the left action of A on ∗A. This supplements the representation A on the space of forms discussed by Connes (Ch. VI.1, Prop. 5, p. 550 of [C]).
Noncommutative geometry inspired Einstein–Gauss–Bonnet black holes
Ghosh, Sushant G.
2018-04-01
Low energy limits of a string theory suggests that the gravity action should include quadratic and higher-order curvature terms, in the form of dimensionally continued Gauss–Bonnet densities. Einstein–Gauss–Bonnet is a natural extension of the general relativity to higher dimensions in which the first and second-order terms correspond, respectively, to general relativity and Einstein–Gauss–Bonnet gravity. We obtain five-dimensional (5D) black hole solutions, inspired by a noncommutative geometry, with a static spherically symmetric, Gaussian mass distribution as a source both in the general relativity and Einstein–Gauss–Bonnet gravity cases, and we also analyzes their thermodynamical properties. Owing the noncommutative corrected black hole, the thermodynamic quantities have also been modified, and phase transition is shown to be achievable. The phase transitions for the thermodynamic stability, in both the theories, are characterized by a discontinuity in the specific heat at r_+=rC , with the stable (unstable) branch for r ) rC . The metric of the noncommutative inspired black holes smoothly goes over to the Boulware–Deser solution at large distance. The paper has been appended with a calculation of black hole mass using holographic renormalization.
Bound dipole solitary solutions in anisotropic nonlocal self-focusing media
DEFF Research Database (Denmark)
Mamaev, A.V.; Zozulya, A.A.; Mezentsev, V.K.
1997-01-01
We find and analyze bound dipole solitary solutions in media with anisotropic nonlocal photorefractive material response. The dipole solutions consist of two elliptically shaped Gaussian-type beams separated by several diameters, and with a pi phase shift between their fields. Spatial evolution...... of two initially round Gaussian beams and their convergence to the above dipole solution is demonstrated experimentally....
The fractionated dipole antenna : A new antenna for body imaging at 7 Tesla
Raaijmakers, AJE; Italiaander, Michel; Voogt, Ingmar J; Luijten, Peter R; Hoogduin, JM; Klomp, DWJ; van den Berg, CAT
2016-01-01
PURPOSE: Dipole antennas in ultrahigh field MRI have demonstrated advantages over more conventional designs. In this study, the fractionated dipole antenna is presented: a dipole where the legs are split into segments that are interconnected by capacitors or inductors. METHODS: A parameter study has
Bożejko, M.; Lytvynov, E. W.; Rodionova, I. V.
2015-10-01
Let ν be a finite measure on R whose Laplace transform is analytic in a neighbourhood of zero. An anyon Lévy white noise on ( R^d,dx) is a certain family of noncommuting operators on the anyon Fock space over L^2( R^d× R,dx\\otimesν), where \\varphi=\\varphi(x) runs over a space of test functions on R^d, while ω=ω(x) is interpreted as an operator-valued distribution on R^d. Let L^2(τ) be the noncommutative L^2-space generated by the algebra of polynomials in the variables , where τ is the vacuum expectation state. Noncommutative orthogonal polynomials in L^2(τ) of the form are constructed, where f(n) is a test function on ( R^d)^n, and are then used to derive a unitary isomorphism U between L^2(τ) and an extended anyon Fock space \\mathbf F(L^2( R^d,dx)) over L^2( R^d,dx). The usual anyon Fock space \\mathscr F(L^2( R^d,dx)) over L^2( R^d,dx) is a subspace of \\mathbf F(L^2( R^d,dx)). Furthermore, the equality \\mathbf F(L^2( R^d,dx))=\\mathscr F(L^2( R^d,dx)) holds if and only if the measure ν is concentrated at a single point, that is, in the Gaussian or Poisson case. With use of the unitary isomorphism U, the operators are realized as a Jacobi (that is, tridiagonal) field in \\mathbf F(L^2( R^d,dx)). A Meixner-type class of anyon Lévy white noise is derived for which the corresponding Jacobi field in \\mathbf F(L^2( R^d,dx)) has a relatively simple structure. Each anyon Lévy white noise of Meixner type is characterized by two parameters, λ\\in R and η≥slant0. In conclusion, the representation ω(x)=\\partial_x^\\dag +λ \\partial_x^\\dag\\partialx +η\\partial_x^\\dag\\partial_x\\partial_x+\\partial_x is obtained, where \\partial_x and \\partial_x^\\dag are the annihilation and creation operators at the point x. Bibliography: 57 titles.
On Non-Commutative Rhotrix Groups over Finite Fields ...
African Journals Online (AJOL)
Journal of the Nigerian Association of Mathematical Physics. Journal Home · ABOUT THIS JOURNAL · Advanced Search · Current Issue · Archives · Journal Home > Vol 30 (2015) >. Log in or Register to get access to full text downloads.
Study of the photon's pole structure in the noncommutative Schwinger model
Energy Technology Data Exchange (ETDEWEB)
Ghasemkhani, M. [Shahid Beheshti University, Department of Physics, Tehran (Iran, Islamic Republic of); Institute for Research in Fundamental Sciences (IPM), School of Physics, P.O.Box 19395-5531, Tehran (Iran, Islamic Republic of)
2014-06-15
The photon self-energy of the noncommutative Schwinger model at two- and three-loop order is analyzed. It is shown that the mass spectrum of the model does not receive any correction from the noncommutativity parameter (θ) at these orders. Also it remains unchanged to all orders. The exact one-loop effective action for the photon is also calculated. (orig.)
Study of the photon's pole structure in the noncommutative Schwinger model.
Ghasemkhani, M
The photon self-energy of the noncommutative Schwinger model at two- and three-loop order is analyzed. It is shown that the mass spectrum of the model does not receive any correction from the noncommutativity parameter ([Formula: see text]) at these orders. Also it remains unchanged to all orders. The exact one-loop effective action for the photon is also calculated.
Superconducting Coil of Po Dipole
1983-01-01
The Po superconducting dipole was built as a prototype beam transport magnet for the SPS extracted proton beam P0. Its main features were: coil aperture 72 mm, length 5 m, room-temperature yoke, NbTi cable conductor impregnated with solder, nominal field 4.2 T at 4.7 K (87% of critical field). It reached its nominal field without any quench.After this successful test up to its nominal field of 4.2 T, the power was not raised to reach a quench. The magnet was not installed in a beam and had no other further use. Nevertheless its construction provided knowledges and experience which became useful in the design and construction of the LHC magnets. The photo shows a detail of the inner layer winding before superposing the outer layer to form the complete coil of a pole. Worth noticing is the interleaved glass-epoxy sheet (white) with grooved channels for the flow of cooling helium. See also 8211532X.
Noncommutative GUT inspired theories and the UV finiteness of the fermionic four point functions
International Nuclear Information System (INIS)
Martin, C. P.; Tamarit, C.
2009-01-01
We show at one loop and first order in the noncommutativity parameters that in any noncommutative GUT inspired theory the total contribution to the fermionic four point functions coming only from the interaction between fermions and gauge bosons, though not UV finite by power counting, is UV finite at the end of the day. We also show that this is at odds with the general case for noncommutative gauge theories - chiral or otherwise - defined by means of Seiberg-Witten maps that are the same - barring the gauge group representation - for left-handed spinors as for right-handed spinors. We believe that the results presented in this paper tilt the scales to the side of noncommutative GUTS and noncommutative GUT inspired versions of the standard model.
Energy Technology Data Exchange (ETDEWEB)
Amini, Nina H. [Stanford University, Edward L. Ginzton Laboratory, Stanford, CA (United States); CNRS, Laboratoire des Signaux et Systemes (L2S) CentraleSupelec, Gif-sur-Yvette (France); Miao, Zibo; Pan, Yu; James, Matthew R. [Australian National University, ARC Centre for Quantum Computation and Communication Technology, Research School of Engineering, Canberra, ACT (Australia); Mabuchi, Hideo [Stanford University, Edward L. Ginzton Laboratory, Stanford, CA (United States)
2015-12-15
The purpose of this paper is to study the problem of generalizing the Belavkin-Kalman filter to the case where the classical measurement signal is replaced by a fully quantum non-commutative output signal. We formulate a least mean squares estimation problem that involves a non-commutative system as the filter processing the non-commutative output signal. We solve this estimation problem within the framework of non-commutative probability. Also, we find the necessary and sufficient conditions which make these non-commutative estimators physically realizable. These conditions are restrictive in practice. (orig.)
Final Report: Levitated Dipole Experiment
Energy Technology Data Exchange (ETDEWEB)
Kesner, Jay [Massachusetts Institute of Technology, Cambridge, MA (United States); Mauel, Michael [Columbia Univ., New York, NY (United States)
2013-03-10
Since the very first experiments with the LDX, research progress was rapid and significant. Initial experiments were conducted with the high-field superconducting coil suspended by three thin rods. These experiments produced long-pulse, quasi-steady-state microwave discharges, lasting more than 10 s, having peak beta values of 20% [Garnier et al., Physics of Plasmas, 13 (2006) 056111]. High- beta, near steady-state discharges have been maintained in LDX for more than 20 seconds, and this capability made LDX the longest pulse fusion confinement experiment operating in the U.S. fusion program. A significant measure of progress in the LDX research program was the routine investigation of plasma confinement with a magnetically-levitated dipole and the resulting observations of confinement improvement. In both supported and levitated configurations, detailed measurements were made of discharge evolution, plasma dynamics and instability, and the roles of gas fueling, microwave power deposition profiles, and plasma boundary shape. High-temperature plasma was created by multi frequency electron cyclotron resonance heating at 2.45 GHz, 6.4 GHz, 10.5 GHz and 28 GHz allowing control of heating profiles. Depending upon neutral fueling rates, the LDX discharges contain a fraction of energetic electrons, with mean energies above 50 keV. Depending on whether or not the superconducting dipole was levitated or supported, the peak thermal electron temperature was estimated to exceed 500 eV and peak densities to approach 1e18 m^{-3}. We have found that levitation causes a strong inwards density pinch [Boxer et al., Nature Physics, 6 (2010) 207] and we have observed the central plasma density increase dramatically indicating a significant improvement in the confinement of a thermal plasma species.
Final Report: Levitated Dipole Experiment
Energy Technology Data Exchange (ETDEWEB)
Kesner, Jay; Mauel, Michael
2013-03-10
Since the very first experiments with the LDX, research progress was rapid and significant. Initial experiments were conducted with the high-field superconducting coil suspended by three thin rods. These experiments produced long-pulse, quasi-steady-state microwave discharges, lasting more than 10 s, having peak beta values of 20% [Garnier, Phys. Plasmas, v13, p. 056111, 2006]. High-beta, near steady-state discharges have been maintained in LDX for more than 20 seconds, and this capability makes LDX the longest pulse fusion confinement experiment now operating in the U.S. fusion program. In both supported and levitated configurations, detailed measurements are made of discharge evolution, plasma dynamics and instability, and the roles of gas fueling, microwave power deposition profiles, and plasma boundary shape. High-temperature plasma is created by multifrequency electron cyclotron resonance heating allowing control of heating profiles. Depending upon neutral fueling rates, the LDX discharges contain a fraction of energetic electrons, with mean energies above 50 keV. Depending on whether or not the superconducting dipole is levitated or supported, the peak thermal electron temperature is estimated to exceed 500 eV and peak densities reach 1.0E18 (1/m3). Several significant discoveries resulted from the routine investigation of plasma confinement with a magnetically-levitated dipole. For the first time, toroidal plasma with pressure approaching the pressure of the confining magnetic field was well-confined in steady-state without a toroidal magnetic field. Magnetic levitation proved to be reliable and is now routine. The dipole's cryostat allows up to three hours of "float time" between re-cooling with liquid helium and providing scientists unprecedented access to the physics of magnetizd plasma. Levitation eliminates field-aligned particle sources and sinks and results in a toroidal, magnetically-confined plasma where profiles are determined by cross-field
International Nuclear Information System (INIS)
Zhu Meng; Zhou Hui; Cheng Yinhui; Li Baozhong; Wu Wei; Li Jinxi; Ma Liang; Zhao Mo
2013-01-01
Electromagnetic pulse can be generated by the nuclear detonation in space via two radiation mechanisms. The electric dipole and magnetic dipole models were analyzed. The electric radiation in the far field generated by two models was calculated as well. Investigations show that in the case of one hundred TNT yield detonations, when electrons are emitted according to the Gaussian shape, two radiation models can give rise to the electric field in great distances with amplitudes of kV/m and tens of V/m, independently. Because the geomagnetic field in space is not strong and the electrons' angular motion is much weaker than the motion in the original direction, radiations from the magnetic dipole model are much weaker than those from the electric dipole model. (authors)
The LHC AC Dipole system: an introduction
Serrano, J; CERN. Geneva. BE Department
2010-01-01
The LHC AC Dipole is an instrument to study properties of the LHC lattice by inducing large transverse displacements in the beam. These displacements are generated by exciting the beam with an oscillating magnetic field at a frequency close to the tune. This paper presents the system requirements and the technical solution chosen to meet them, based of high-power audio amplifiers and a resonant parallel RLC circuit.
Noncommutative extension of AdS–CFT and holographic superconductors
Directory of Open Access Journals (Sweden)
Souvik Pramanik
2015-03-01
Full Text Available In this Letter, we consider a Non-Commutative (NC extension of AdS–CFT correspondence and its effects on holographic superconductors. NC corrections are incorporated via the NC generalization of Schwarzschild black hole metric in AdS with the probe limit. We study NC effects on the relations connecting the charge density and the critical temperature of the Holographic Superconductors. Furthermore, condensation operator of the superconductor has been analyzed. Our results suggest that generically, NC effects increase the critical temperature of the holographic superconductor.
Noncommutative extension of AdS-CFT and holographic superconductors
Pramanik, Souvik; Das, Sudipta; Ghosh, Subir
2015-03-01
In this Letter, we consider a Non-Commutative (NC) extension of AdS-CFT correspondence and its effects on holographic superconductors. NC corrections are incorporated via the NC generalization of Schwarzschild black hole metric in AdS with the probe limit. We study NC effects on the relations connecting the charge density and the critical temperature of the Holographic Superconductors. Furthermore, condensation operator of the superconductor has been analyzed. Our results suggest that generically, NC effects increase the critical temperature of the holographic superconductor.
Noncommutative extension of AdS–CFT and holographic superconductors
Energy Technology Data Exchange (ETDEWEB)
Pramanik, Souvik, E-mail: souvick.in@gmail.com; Das, Sudipta, E-mail: sudipta_jumaths@yahoo.co.in; Ghosh, Subir, E-mail: subir_ghosh2@rediffmail.com
2015-03-06
In this Letter, we consider a Non-Commutative (NC) extension of AdS–CFT correspondence and its effects on holographic superconductors. NC corrections are incorporated via the NC generalization of Schwarzschild black hole metric in AdS with the probe limit. We study NC effects on the relations connecting the charge density and the critical temperature of the Holographic Superconductors. Furthermore, condensation operator of the superconductor has been analyzed. Our results suggest that generically, NC effects increase the critical temperature of the holographic superconductor.
The Hagedorn transition in noncommutative open string theory
Energy Technology Data Exchange (ETDEWEB)
Gubser, S. S.; Gukov, S.; Klebanov, I. R.; Rangamani, M.; Witten, E.
2001-07-01
The Hagedorn transition in noncommutative open string theory (NCOS) is relatively simple because gravity decouples. For NCOS theories in no more than five space--time dimensions, the Hagedorn transition is second order, and the high temperature phase involves long, nearly straight fundamental strings separating from the D-brane on which the NCOS theory is defined. Above five spacetime dimensions interaction effects become important below the Hagedorn temperature. Although this complicates studies of the transition, we believe that the high temperature phase again involves long strings liberated from the bound state.
Non-commutative finite associative algebras of 2-dimensional vectors
Directory of Open Access Journals (Sweden)
Alexander Moldovyan
2017-12-01
Full Text Available In this paper properties of the non-commutative finite associative algebra of two-dimensional vectors are presented. Interesting features of algebra are mutual associativity of all modifications of the defined parameterized multiplication operation and existing of a large set of single-side unit elements. In the ordinary case one unique two-side unit element is connected with each element of the algebra, except the elements that are square roots from zero element. There are also presented four different variants of defining commutative associative algebras of 2-dimension vectors. For the case of commutativity the algebra has common unit element for all its elements.
Nielsen-Olesen Vortices in Noncommutative Abelian Higgs Model
Jatkar, D P; Wadia, S R; Jatkar, Dileep P.; Mandal, Gautam; Wadia, Spenta R.
2000-01-01
We construct Nielsen-Olesen vortex solution in the noncommutative abelian Higgs model. We derive the quantized topological flux of the vortex solution. We find that the flux is integral by explicit computation in the large $\\theta$ limit as well as in the small $\\theta$ limit. In the context of a tachyon vortex on the brane-antibrane system we demonstrate that it is this topological charge that gives rise to the RR charge of the resulting BPS D-brane. We also consider the left-right-symmetric gauge theory which does not have a commutative limit and construct an exact vortex solution in it.
Strong limit theorems in noncommutative L2-spaces
Jajte, Ryszard
1991-01-01
The noncommutative versions of fundamental classical results on the almost sure convergence in L2-spaces are discussed: individual ergodic theorems, strong laws of large numbers, theorems on convergence of orthogonal series, of martingales of powers of contractions etc. The proofs introduce new techniques in von Neumann algebras. The reader is assumed to master the fundamentals of functional analysis and probability. The book is written mainly for mathematicians and physicists familiar with probability theory and interested in applications of operator algebras to quantum statistical mechanics.
Noncommutative Differential Calculus and Its Application on Discrete Spaces
International Nuclear Information System (INIS)
Liu Zhen; Bai Yongqiang; Wu Ke; Guo Hanying
2008-01-01
We present the noncommutative differential calculus on the function space of the infinite set and construct a homotopy operator to prove the analogue of the Poincare lemma for the difference complex. Then the horizontal and vertical complexes are introduced with the total differential map and vertical exterior derivative. As the application of the differential calculus, we derive the schemes with the conservation of symplecticity and energy for Hamiltonian system and a two-dimensional integral models with infinite sequence of conserved currents. Then an Euler-Lagrange cohomology with symplectic structure-preserving is given in the discrete classical mechanics.
Can non-commutativity resolve the big-bang singularity?
Energy Technology Data Exchange (ETDEWEB)
Maceda, M.; Madore, J. [Laboratoire de Physique Theorique, Universite de Paris-Sud, Batiment 211, 91405, Orsay (France); Manousselis, P. [Department of Engineering Sciences, University of Patras, 26110, Patras (Greece); Physics Department, National Technical University, Zografou Campus, 157 80, Zografou, Athens (Greece); Zoupanos, G. [Physics Department, National Technical University, Zografou Campus, 157 80, Zografou, Athens (Greece); Theory Division, CERN, 1211, Geneva 23 (Switzerland)
2004-08-01
A possible way to resolve the singularities of general relativity is proposed based on the assumption that the description of space-time using commuting coordinates is not valid above a certain fundamental scale. Beyond that scale it is assumed that the space-time has non-commutative structure leading in turn to a resolution of the singularity. As a first attempt towards realizing the above programme a modification of the Kasner metric is constructed which is commutative only at large time scales. At small time scales, near the singularity, the commutation relations among the space coordinates diverge. We interpret this result as meaning that the singularity has been completely delocalized. (orig.)
Lorentz Distributed Noncommutative F(T,TG Wormhole Solutions
Directory of Open Access Journals (Sweden)
M. Sharif
2018-01-01
Full Text Available The aim of this paper is to study static spherically symmetric noncommutative F(T,TG wormhole solutions along with Lorentzian distribution. Here, T and TG are torsion scalar and teleparallel equivalent Gauss-Bonnet term, respectively. We take a particular redshift function and two F(T,TG models. We analyze the behavior of shape function and also examine null as well as weak energy conditions graphically. It is concluded that there exist realistic wormhole solutions for both models. We also studied the stability of these wormhole solutions through equilibrium condition and found them stable.
Quantum thetas on noncommutative Td with general embeddings
International Nuclear Information System (INIS)
Chang-Young, Ee; Kim, Hoil
2008-01-01
In this paper, we construct quantum theta functions over noncommutative T d with general embeddings. Manin has constructed quantum theta functions from the lattice embedding into vector space x finite group. We extend Manin's construction of quantum thetas to the case of general embedding of vector space x lattice x torus. It turns out that only for the vector space part of the embedding there exists the holomorphic theta vector, while for the lattice part there does not. Furthermore, the so-called quantum translations from embedding into the lattice part become non-additive, while those from the vector space part are additive
Quantum Thetas on Noncommutative T^d with General Embeddings
Chang-Young, Ee; Kim, Hoil
2007-01-01
In this paper we construct quantum theta functions over noncommutative T^d with general embeddings. Manin has constructed quantum theta functions from the lattice embedding into vector space x finite group. We extend Manin's construction of quantum thetas to the case of general embedding of vector space x lattice x torus. It turns out that only for the vector space part of the embedding there exists the holomorphic theta vector, while for the lattice part there does not. Furthermore, the so-c...
Analysis and design of short, iron-free dipole magnets
International Nuclear Information System (INIS)
Harvey, A.R.
1981-01-01
Iron-free, dipole magnets are used extensively as steering magnets to correct for the bending, induced by extraneous magnetic fields, of particle beams that are being transported in vacuum. Generally, the dipoles are long enough that the space occupied by the end conductors is small compared to the overall magnet length. In a recent application, however, this criteria did not apply. This has motivated a reanalysis of the characteristics of a system of small aspect ratio (length/diameter) dipoles that are spaced at relatively large axial distances
Quantum field theory in generalised Snyder spaces
International Nuclear Information System (INIS)
Meljanac, S.; Meljanac, D.; Mignemi, S.; Štrajn, R.
2017-01-01
We discuss the generalisation of the Snyder model that includes all possible deformations of the Heisenberg algebra compatible with Lorentz invariance and investigate its properties. We calculate perturbatively the law of addition of momenta and the star product in the general case. We also undertake the construction of a scalar field theory on these noncommutative spaces showing that the free theory is equivalent to the commutative one, like in other models of noncommutative QFT.
Quantum field theory in generalised Snyder spaces
Energy Technology Data Exchange (ETDEWEB)
Meljanac, S.; Meljanac, D. [Rudjer Bošković Institute, Bijenička cesta 54, 10002 Zagreb (Croatia); Mignemi, S., E-mail: smignemi@unica.it [Dipartimento di Matematica e Informatica, Università di Cagliari, viale Merello 92, 09123 Cagliari (Italy); INFN, Sezione di Cagliari, Cittadella Universitaria, 09042 Monserrato (Italy); Štrajn, R. [Dipartimento di Matematica e Informatica, Università di Cagliari, viale Merello 92, 09123 Cagliari (Italy); INFN, Sezione di Cagliari, Cittadella Universitaria, 09042 Monserrato (Italy)
2017-05-10
We discuss the generalisation of the Snyder model that includes all possible deformations of the Heisenberg algebra compatible with Lorentz invariance and investigate its properties. We calculate perturbatively the law of addition of momenta and the star product in the general case. We also undertake the construction of a scalar field theory on these noncommutative spaces showing that the free theory is equivalent to the commutative one, like in other models of noncommutative QFT.
Electric dipole moments of highly excited molecular vibrational states
Theulé, Patrice; Rizzo, Thomas
2005-01-01
In this work, new spectroscopic techniques have been developed to measure electric dipole moments of highly excited rovibrational states of small polyatomic molecules in the gas phase. These techniques make use of lasers arid of microwave synthesizers. They enable one to measure the change on a molecular system caused by applying an external electric field, which is called Stark effect and from this, extract the dipole moment. The first technique, called microwave Stark spectroscopy, makes us...
Evseev, M. M.; Bashkirov, E. K.
2017-11-01
In this paper we investigated the entanglement dynamics between two superconducting qubits interacting with two microwave modes of independent coplanar cavities taking into account the direct dipole-dipole interaction. The model with different qubit-field couplings and detunings is under consideration. Using the dressed-states representation technique we derived the exact solution for considered model with qubits prepared initially in entangled states and vacuum field modes. We have carried out the dependence of the atom-atom entanglement on the strength of the dipole-dipole interaction and other parameters of the considered system such as different coupling constants and detunings. The results showed that the presence of a sufficiently large dipole-dipole interaction leads to stabilization of entanglement.
Novel Noncommutative Cryptography Scheme Using Extra Special Group
Directory of Open Access Journals (Sweden)
Gautam Kumar
2017-01-01
Full Text Available Noncommutative cryptography (NCC is truly a fascinating area with great hope of advancing performance and security for high end applications. It provides a high level of safety measures. The basis of this group is established on the hidden subgroup or subfield problem (HSP. The major focus in this manuscript is to establish the cryptographic schemes on the extra special group (ESG. ESG is showing one of the most appropriate noncommutative platforms for the solution of an open problem. The working principle is based on the random polynomials chosen by the communicating parties to secure key exchange, encryption-decryption, and authentication schemes. This group supports Heisenberg, dihedral order, and quaternion group. Further, this is enhanced from the general group elements to equivalent ring elements, known by the monomials generations for the cryptographic schemes. In this regard, special or peculiar matrices show the potential advantages. The projected approach is exclusively based on the typical sparse matrices, and an analysis report is presented fulfilling the central cryptographic requirements. The order of this group is more challenging to assail like length based, automorphism, and brute-force attacks.
A View on Optimal Transport from Noncommutative Geometry
Directory of Open Access Journals (Sweden)
Francesco D'Andrea
2010-07-01
Full Text Available We discuss the relation between the Wasserstein distance of order 1 between probability distributions on a metric space, arising in the study of Monge-Kantorovich transport problem, and the spectral distance of noncommutative geometry. Starting from a remark of Rieffel on compact manifolds, we first show that on any - i.e. non-necessary compact - complete Riemannian spin manifolds, the two distances coincide. Then, on convex manifolds in the sense of Nash embedding, we provide some natural upper and lower bounds to the distance between any two probability distributions. Specializing to the Euclidean space R^n, we explicitly compute the distance for a particular class of distributions generalizing Gaussian wave packet. Finally we explore the analogy between the spectral and the Wasserstein distances in the noncommutative case, focusing on the standard model and the Moyal plane. In particular we point out that in the two-sheet space of the standard model, an optimal-transport interpretation of the metric requires a cost function that does not vanish on the diagonal. The latest is similar to the cost function occurring in the relativistic heat equation.
Lorentz distributed noncommutative wormhole solutions in extended teleparallel gravity
Energy Technology Data Exchange (ETDEWEB)
Jawad, Abdul; Rani, Shamaila [COMSATS Institute of Information Technology, Department of Mathematics, Lahore (Pakistan)
2015-04-01
In this paper, we study static spherically symmetric wormhole solutions in extended teleparallel gravity with the inclusion of noncommutative geometry under a Lorentzian distribution. We obtain expressions of matter components for a non-diagonal tetrad. The effective energy-momentum tensor leads to the violation of energy conditions which impose a condition on the normal matter to satisfy these conditions. We explore the noncommutative wormhole solutions by assuming a viable power-law f(T) and shape function models. For the first model, we discuss two cases in which one leads to teleparallel gravity and the other is for f(T) gravity. The normal matter violates the weak energy condition for the first case, while there exists a possibility for micro physically acceptable wormhole solution. There exists a physically acceptable wormhole solution for the power-law b(r) model. Also, we check the equilibrium condition for these solutions, which is only satisfied for the teleparallel case, while for the f(T) case, these solutions are less stable. (orig.)
Noncommutative unification of general relativity and quantum mechanics
International Nuclear Information System (INIS)
Heller, Michael; Pysiak, Leszek; Sasin, Wieslaw
2005-01-01
We present a model unifying general relativity and quantum mechanics based on a noncommutative geometry. This geometry is developed in terms of a noncommutative algebra A which is defined on a transformation groupoid Γ given by the action of a noncompact group G on the total space E of a principal fiber bundle over space-time M. The case is important since to obtain physical effects predicted by the model we should assume that G is a Lorentz group or some of its representations. We show that the generalized Einstein equation of the model has the form of the eigenvalue equation for the generalized Ricci operator, and all relevant operators in the quantum sector of the model are random operators; we study their dynamics. We also show that the model correctly reproduces general relativity and the usual quantum mechanics. It is interesting that the latter is recovered by performing the measurement of any observable. In the act of such a measurement the model 'collapses' to the usual quantum mechanics
On the Landau system in noncommutative phase-space
Energy Technology Data Exchange (ETDEWEB)
Gangopadhyay, Sunandan, E-mail: sunandan.gangopadhyay@gmail.com [Department of Physics, West Bengal State University, Barasat, Kolkata 700126 (India); Saha, Anirban, E-mail: anirban@iucaa.ernet.in [Department of Physics, West Bengal State University, Barasat, Kolkata 700126 (India); Halder, Aslam, E-mail: aslamhalder.phy@gmail.com [Kolorah H.A.W. Institution, Kolorah, Howrah 711411 (India)
2015-12-04
We consider the Landau system in a canonically noncommutative phase-space. A set of generalized transformations containing scaling parameters is derived which maps the NC problem to an equivalent commutative problem. The energy spectrum admits NC corrections which are computed using the explicit NC variables as well as the commutative-equivalent variables. Their exact matching solidifies the evidence of the equivalence of the two approaches. We also obtain the magnetic length and level degeneracy, which admit NC corrections. We further study the Aharonov–Bohm effect where the phase-shift is found to alter due to noncommutativity and also depends on the scaling parameters. - Highlights: • An exact map between commutative and NC algebras with an effective Planck's constant. • Connection of this generalized mapping with Moyal star product. • Physically relevant quantities (magnetic-length, level-degeneracy, spectrum) computed using alternative variables. • Demonstration of equivalence of the two alternative variables sets. • Physically relevant quantities admit NC corrections which matches existing literature.
Spherically symmetric potential in noncommutative spacetime with a compactified extra dimensions
Energy Technology Data Exchange (ETDEWEB)
Guedezounme, Secloka Lazare [University of Abomey-Calavi, International Chair in Mathematical Physics and Applications (ICMPA-UNESCO Chair), Cotonou (Benin); Kanfon, Antonin Danvide [University of Abomey-Calavi, International Chair in Mathematical Physics and Applications (ICMPA-UNESCO Chair), Cotonou (Benin); University of d' Abomey-Calavi, Faculte des Sciences et Techniques, Cotonou (Benin); Samary, Dine Ousmane [University of Abomey-Calavi, International Chair in Mathematical Physics and Applications (ICMPA-UNESCO Chair), Cotonou (Benin); University of d' Abomey-Calavi, Faculte des Sciences et Techniques, Cotonou (Benin); Albert Einstein Institute, Max Planck Institute for Gravitational Physics, Potsdam (Germany)
2016-09-15
The Schroedinger equation of the spherically symmetrical quantum models such as the hydrogen atom problem seems to be analytically non-solvable in higher dimensions. When we try compactifying one or several dimensions this question can maybe solved. This paper presents a study of the spherically symmetrical quantum models on noncommutative spacetime with compactified extra dimensions. We provide analytically the resulting spectrum of the hydrogen atom and Yukawa problem in 4 + 1 dimensional noncommutative spacetime in the first order approximation of the noncommutative parameter. The case of higher dimensions D ≥ 4 is also discussed. (orig.)
Statistical mechanics of free particles on space with Lie-type noncommutativity
International Nuclear Information System (INIS)
Shariati, Ahmad; Khorrami, Mohammad; Fatollahi, Amir H
2010-01-01
Effects of Lie-type noncommutativity on thermodynamic properties of a system of free identical particles are investigated. A definition for finite volume of the configuration space is given, and the grandcanonical partition function in the thermodynamic limit is calculated. Two possible definitions for the pressure are discussed, which are equivalent when the noncommutativity vanishes. The thermodynamic observables are extracted from the partition function. Different limits are discussed where either the noncommutativity or the quantum effects are important. Finally, specific cases are discussed where the group is SU(2) or SO(3), and the partition function of a nondegenerate gas is calculated.
Noncommutative Gröbner bases and filtered-graded transfer
Li, Huishi
2002-01-01
This self-contained monograph is the first to feature the intersection of the structure theory of noncommutative associative algebras and the algorithmic aspect of Groebner basis theory. A double filtered-graded transfer of data in using noncommutative Groebner bases leads to effective exploitation of the solutions to several structural-computational problems, e.g., an algorithmic recognition of quadric solvable polynomial algebras, computation of GK-dimension and multiplicity for modules, and elimination of variables in noncommutative setting. All topics included deal with algebras of (q-)differential operators as well as some other operator algebras, enveloping algebras of Lie algebras, typical quantum algebras, and many of their deformations.
DEFF Research Database (Denmark)
Arslanagic, S.; Meincke, Peter; Jørgensen, E.
2002-01-01
We derive a line integral representation of the physical optics (PO) scattered far field that yields the exact same result as the conventional surface radiation integral. This representation applies to a perfectly electrically conducting plane scatterer illuminated by electric or magnetic Hertzian...
Transitions landau-zener de paires d'atomes de Rydberg froids en interaction dipole-dipole
Cournol, Anne
2011-01-01
This thesis deals with the study of dipole-dipole interaction between Rydberg atoms, in particular of Landau-Zener transitions around a Förster resonance for Rydberg atoms pairs. The adiabaticity of the transition depends of the interatomic distance and is controlled by a time-dependant electric field. The adiabatic transition efficiency is the control knob to probe the nearest neighbour distribution. We infer a new and original method to measure the density of a gas very accurately by probin...
Is there a fundamental cosmological dipole?
Perivolaropoulos, Leandros
2014-01-01
Early hints for deviation from the cosmological principle and statistical isotropy are being accumulated. After reviewing these hints, I focus on four cosmologically observed axes which appear to be either marginally consistent or in conflict with the standard ΛCDM isotropic and homogeneous cosmology. These axes are abnormally aligned with each other and include: (a) The Fine Structure Constant α Dipole (b) the Dark Energy Dipole (c) the Dark Velocity Flow and (d) the CMB Maximum Temperature Asymmetry. I also discuss a simple physical model (extended topological quintessence) that has the potential to explain the existence and alignment of these axes. The model is based on the recent formation of a global monopole with Hubble scale core by an O(3) symmetric scalar field, non-minimally coupled to electromagnetism.
Dipole vortices in the Great Australian Bight
DEFF Research Database (Denmark)
Cresswell, George R.; Lund-Hansen, Lars C.; Nielsen, Morten Holtegaard
2015-01-01
Shipboard measurements from late 2006 made by the Danish Galathea 3 Expedition and satellite sea surface temperature images revealed a chain of cool and warm mushroom' dipole vortices that mixed warm, salty, oxygen-poor waters on and near the continental shelf of the Great Australian Bight (GAB......) with cooler, fresher, oxygen-rich waters offshore. The alternating jets' flowing into the mushrooms were directed mainly northwards and southwards and differed in temperature by only 1.5 degrees C; however, the salinity difference was as much as 0.5, and therefore quite large. The GAB waters were slightly...... denser than the cooler offshore waters. The field of dipoles evolved and distorted, but appeared to drift westwards at 5km day-1 over two weeks, and one new mushroom carried GAB water southwards at 7km day(-1). Other features encountered between Cape Leeuwin and Tasmania included the Leeuwin Current...
2001-01-01
Andrezej Siemko (left), Peter Sievers (centre), and Lucio Rossi (right), have the exciting challenge of preparing and testing 2000 magnets for the LHC. The LHC is going to require a lot of powerful magnets by the time it begins operation in 2006. More specifically, it is going to need 130 special magnets, 400 quadrupoles, and a whopping 1250 dipoles! Preparing and testing these magnets for the conditions they will encounter in the LHC is not an easy task. But evaluation of the most recently received magnet, from the German company Noell, is showing that while the monumental task of receiving and testing nearly 2000 magnets is going to be exhausting, the goals are definitely attainable. At the moment and over the next year, pre-series magnets (the magnets that CERN uses to fine tune performance) are arriving slowly (90 in total will arrive), but by 2003 the rate of series magnet arrival will accelerate to 9 per week, that's over 450 in a single year! And working with these magnets when they arrive is tough. ...
Dipoles, unintentional antennas and EMC
Directory of Open Access Journals (Sweden)
Berend Danker
2008-01-01
Full Text Available Radiated emissions from equipment commonly originate from electronic circuits that act as electric dipoles created by the signal voltage between the signal conductors or as magnetic dipoles formed by the signal current flowing in a loop. Direct emission is mostly small, but circuits often couple to long conductors or large wiring loops which act as antennas and are efficient radiators. A comparable situation exists when short dipole antennas or small wiring loops receive ambient noise (susceptibility. Usually the amplitude of noise sources or the susceptibility of circuits is an invariable. The dipole strength increases with the distance between the conductors and the area. Shielding and proper grounding decreases the interaction via unintentional antennas. Short-circuiting and the insertion of lossy ferrite cores reduce the efficiency of unintentional antennas.
Energy Technology Data Exchange (ETDEWEB)
Kashikhin, V. V. [Fermilab; Novitski, I. [Fermilab; Zlobin, A. V. [Fermilab
2017-05-01
High filed accelerator magnets with operating fields of 15-16 T based on the $Nb_3Sn$ superconductor are being considered for the LHC energy upgrade or a future Very High Energy pp Collider. Magnet design studies are being conducted in the U.S., Europe and Asia to explore the limits of the $Nb_3Sn$ accelerator magnet technology while optimizing the magnet design and performance parame-ters, and reducing magnet cost. The first results of these studies performed at Fermilab in the framework of the US-MDP are reported in this paper.
Ocular dominance affects magnitude of dipole moment: an MEG study.
Shima, Hiroshi; Hasegawa, Mitsuhiro; Tachibana, Osamu; Nomura, Motohiro; Yamashita, Junkoh; Ozaki, Yuzo; Kawai, Jun; Higuchi, Masanori; Kado, Hisashi
2010-08-23
To investigate whether the ocular dominance affects laterality in the activity of the primary visual cortex, we examined the relationship between the ocular dominance and latency or dipole moment measured by checkerboard-pattern and magnetoencephalography in 11 right-handed healthy male participants. Participants with left-eye dominance showed a dipole moment of 21.5+/-6.1 nAm with left-eye stimulation and 16.1+/-3.6 nAm with right, whereas those with right-eye dominance showed a dipole moment of 18.0+/-5.2 and 21.5+/-2.7 nAm with left-eye and right-eye stimulation of the infero-medial quadrant visual field, respectively. Thus, the dipole moment was higher when the dominant eye was stimulated, which implies that ocular dominance is regulated by the ipsilateral occipital lobe.
A Green's function approach to giant-dipole systems
Stielow, Thomas; Scheel, Stefan; Kurz, Markus
2018-01-01
In this work we perform a Green’s function analysis of giant-dipole systems. First, we derive the Green’s functions of different magnetically field-dressed systems, in particular of electronically highly excited atomic species in crossed electric and magnetic fields—so-called giant-dipole states. We determine the dynamical polarizability of atomic giant-dipole states as well as the adiabatic potential energy surfaces of giant-dipole molecules in the framework of the Green’s function approach. Furthermore, we perform an comparative analysis of the latter to an exact diagonalization scheme and show the general divergence behavior of the widely applied Fermi-pseudopotential approach. Finally, we derive the giant-dipole’s regularized Green’s function representation.
Late time acceleration in a non-commutative model of modified cosmology
International Nuclear Information System (INIS)
Malekolkalami, B.; Atazadeh, K.; Vakili, B.
2014-01-01
We investigate the effects of non-commutativity between the position–position, position–momentum and momentum–momentum of a phase space corresponding to a modified cosmological model. We show that the existence of such non-commutativity results in a Moyal Poisson algebra between the phase space variables in which the product law between the functions is of the kind of an α-deformed product. We then transform the variables in such a way that the Poisson brackets between the dynamical variables take the form of a usual Poisson bracket but this time with a noncommutative structure. For a power law expression for the function of the Ricci scalar with which the action of the gravity model is modified, the exact solutions in the commutative and noncommutative cases are presented and compared. In terms of these solutions we address the issue of the late time acceleration in cosmic evolution
Late time acceleration in a non-commutative model of modified cosmology
Energy Technology Data Exchange (ETDEWEB)
Malekolkalami, B., E-mail: b.malakolkalami@uok.ac.ir [Department of Physics, University of Kurdistan, Pasdaran St., Sanandaj (Iran, Islamic Republic of); Atazadeh, K., E-mail: atazadeh@azaruniv.ac.ir [Department of Physics, Azarbaijan Shahid Madani University, 53714-161, Tabriz (Iran, Islamic Republic of); Vakili, B., E-mail: b-vakili@iauc.ac.ir [Department of Physics, Central Tehran Branch, Islamic Azad University, Tehran (Iran, Islamic Republic of)
2014-12-12
We investigate the effects of non-commutativity between the position–position, position–momentum and momentum–momentum of a phase space corresponding to a modified cosmological model. We show that the existence of such non-commutativity results in a Moyal Poisson algebra between the phase space variables in which the product law between the functions is of the kind of an α-deformed product. We then transform the variables in such a way that the Poisson brackets between the dynamical variables take the form of a usual Poisson bracket but this time with a noncommutative structure. For a power law expression for the function of the Ricci scalar with which the action of the gravity model is modified, the exact solutions in the commutative and noncommutative cases are presented and compared. In terms of these solutions we address the issue of the late time acceleration in cosmic evolution.
Remarks on the formulation of quantum mechanics on noncommutative phase spaces
International Nuclear Information System (INIS)
Muthukumar, Balasundaram
2007-01-01
We consider the probabilistic description of nonrelativistic, spinless one-particle classical mechanics, and immerse the particle in a deformed noncommutative phase space in which position coordinates do not commute among themselves and also with canonically conjugate momenta. With a postulated normalized distribution function in the quantum domain, the square of the Dirac delta density distribution in the classical case is properly realised in noncommutative phase space and it serves as the quantum condition. With only these inputs, we pull out the entire formalisms of noncommutative quantum mechanics in phase space and in Hilbert space, and elegantly establish the link between classical and quantum formalisms and between Hilbert space and phase space formalisms of noncommutative quantum mechanics. Also, we show that the distribution function in this case possesses 'twisted' Galilean symmetry
Determinants of self-employment among commuters and non-commuters
DEFF Research Database (Denmark)
Backman, M.; Karlsson, C.
2016-01-01
We analyse the determinants of self-employment and focus on the contextual environment. By distinguishing between commuters and non-commuters we are able to analyse the influence from the work and home environment, respectively. Our results indicate a significant difference between non-commuters ......We analyse the determinants of self-employment and focus on the contextual environment. By distinguishing between commuters and non-commuters we are able to analyse the influence from the work and home environment, respectively. Our results indicate a significant difference between non......-commuters and commuters in terms of the role of networks for becoming self-employed. Our results indicate that it is the business networks where people work, rather than where they live that exerts a positive influence on the probability of becoming self-employed. These effects are further robust over educational...
Continuous millennial decrease of the Earth's magnetic axial dipole
Poletti, Wilbor; Biggin, Andrew J.; Trindade, Ricardo I. F.; Hartmann, Gelvam A.; Terra-Nova, Filipe
2018-01-01
Since the establishment of direct estimations of the Earth's magnetic field intensity in the first half of the nineteenth century, a continuous decay of the axial dipole component has been observed and variously speculated to be linked to an imminent reversal of the geomagnetic field. Furthermore, indirect estimations from anthropologically made materials and volcanic derivatives suggest that this decrease began significantly earlier than direct measurements have been available. Here, we carefully reassess the available archaeointensity dataset for the last two millennia, and show a good correspondence between direct (observatory/satellite) and indirect (archaeomagnetic) estimates of the axial dipole moment creating, in effect, a proxy to expand our analysis back in time. Our results suggest a continuous linear decay as the most parsimonious long-term description of the axial dipole variation for the last millennium. We thus suggest that a break in the symmetry of axial dipole moment advective sources occurred approximately 1100 years earlier than previously described. In addition, based on the observed dipole secular variation timescale, we speculate that the weakening of the axial dipole may end soon.
LAPLACE-RUNGE-LENZ VECTOR IN QUANTUM MECHANICS IN NONCOMMUTATIVE SPACE
Directory of Open Access Journals (Sweden)
Peter Prešnajder
2014-04-01
Full Text Available The object under scrutiny is the dynamical symmetry connected with conservation of the Laplace-Runge-Lenz vector (LRL in the hydrogen atom problem solved by means of noncommutative quantum mechanics (NCQM. The considered noncommutative configuration space has such a “fuzzy”structure that the rotational invariance is not spoilt. An analogy with the LRL vector in the NCQM is brought to provide our results and also a comparison with the standard QM predictions.
SPS Dipole Multipactor Test and TEWave Diagnostics
Caspers, F; Edwards, P; Federmann, S; Holz, M; Taborelli, M
2013-01-01
Electron cloud accumulation in particle accelerators can be mitigated by coating the vacuum beam pipe with thin films of low secondary electron yield (SEY) material. The SEY of small coated samples are usually measured in the laboratory. To further test the properties of different coating materials, RF-induced multipacting in a coaxial waveguide configuration can be performed. The technique is applied to two main bending dipoles of the SPS, where the RF power is fed through a tungsten wire stretched along the vacuum chamber (6.4 m). A dipole with a bare stainless steel chamber shows a clear power threshold initiating an abrupt rise in reflected power and pressure. The effect is enhanced at RF frequencies corresponding to electron cyclotron resonances for given magnetic fields. Preliminary results show that the dipole with a carbon coated vacuum chamber does not exhibit any pressure rise or reflected RF power up to the maximum available input power. In the case of a large scale coating production this techniqu...
Dipole Map For Divertor Tokamaks
International Nuclear Information System (INIS)
Ali, Halima; Punjabi, Alkesh; Boozer, Allen
2003-01-01
Heat flux impinging on the collector plates of divertor tokamaks can be prodigious. Therefore, the problem of spreading the heat flux on plates is a crucial issue for divertor tokamaks such as ITER. Here we use method of maps /1,2/ to investigate this problem. Magnetic field lines in non-axisymmetric divertor tokamaks are a one and a half degree of freedom Hamiltonian system /1-3/. We represent the unperturbed magnetic topology by the Symmetric Simple Map (SSM) /4/ given by yn+1 = yn + 2kxn - 2k2yn (1 - yn), xn+1 = xn - kyn (1 - yn) - 2k2yn+1 (1 - yn+1). The effects of a current carrying coil placed externally across from X-point is represented by Dipole Map (DP) /4,5/ given by x n+1 = x n + 2δs 3 x n+1 (y n - y s + s/[x n+1 2 + (y n - y s + s) 2 ] 2 ), y n+1 = y n + δs 3 x n+1 ((y n - y s + s) 2 - x n+1 2 /[x n+1 2 + (y n - y s + s) 2 ] 2 ) δ is amplitude of high MN magnetic perturbation, s is the distance of coil from last good surface across from X point, and is the y coordinate of last good surface where it crosses the axis joining X point and O point across from X point. We fix k=0.3 and s = (1/2)|y s |. We calculate the increase in width of stochastic layer and area of footprint of field lines on divertor plate as δ is increased. We also calculate how connection length, toroidal and poloidal circuits and their fractal structures, the number, location and density of hot spots change with δ. Finally, we make conclusions about how the heat flux can be possibly controlled and reduced by applying external magnetic perturbation in divertor tokamaks
Bacon-Shor code with continuous measurement of noncommuting operators
Atalaya, Juan; Bahrami, Mohammad; Pryadko, Leonid P.; Korotkov, Alexander N.
2017-03-01
We analyze the operation of a four-qubit Bacon-Shor code with simultaneous continuous measurement of noncommuting gauge operators. The error syndrome in this case is monitored via time-averaged cross-correlators of the output signals. We find the logical error rate for several models of decoherence, and also find the termination rate for this quantum error detecting code. The code operation is comparable to that based on projective measurements when the collapse time scale due to continuous measurements is an order of magnitude less than the time period between the projective measurements. An advantage of the continuous-measurement implementation is the absence of time dependence in the code operation, with passive continuous monitoring of the error syndrome.
Winter School on Operator Spaces, Noncommutative Probability and Quantum Groups
2017-01-01
Providing an introduction to current research topics in functional analysis and its applications to quantum physics, this book presents three lectures surveying recent progress and open problems. A special focus is given to the role of symmetry in non-commutative probability, in the theory of quantum groups, and in quantum physics. The first lecture presents the close connection between distributional symmetries and independence properties. The second introduces many structures (graphs, C*-algebras, discrete groups) whose quantum symmetries are much richer than their classical symmetry groups, and describes the associated quantum symmetry groups. The last lecture shows how functional analytic and geometric ideas can be used to detect and to quantify entanglement in high dimensions. The book will allow graduate students and young researchers to gain a better understanding of free probability, the theory of compact quantum groups, and applications of the theory of Banach spaces to quantum information. The l...
Noncommutative Wormhole Solutions in Einstein Gauss-Bonnet Gravity
Directory of Open Access Journals (Sweden)
Shamaila Rani
2016-01-01
Full Text Available We explore static spherically symmetric wormhole solutions in the framework of n-dimensional Einstein Gauss-Bonnet gravity. Our objective is to find out wormhole solutions that satisfy energy conditions. For this purpose, we consider two frameworks such as Gaussian distributed and Lorentzian distributed noncommutative geometry. Taking into account constant redshift function, we obtain solutions in the form of shape function. The fifth and sixth dimensional solutions with positive as well as negative Gauss-Bonnet coefficient are discussed. Also, we check the equilibrium condition for the wormhole solutions with the help of generalized Tolman-Oppenheimer-Volkoff equation. It is interesting to mention here that we obtain fifth dimensional stable wormhole solutions in both distributions that satisfy the energy conditions.
Self-sustained traversable wormholes in noncommutative geometry
Energy Technology Data Exchange (ETDEWEB)
Garattini, Remo [Universita degli Studi di Bergamo, Facolta di Ingegneria, Viale Marconi 5, 24044 Dalmine (Bergamo) (Italy); INFN, Sezione di Milano, Via Celoria 16, Milano (Italy)], E-mail: remo.garattini@unibg.it; Lobo, Francisco S.N. [Institute of Gravitation and Cosmology, University of Portsmouth, Portsmouth PO1 2EG (United Kingdom); Centro de Astronomia e Astrofisica da Universidade de Lisboa, Campo Grande, Ed. C8 1749-016 Lisboa (Portugal)], E-mail: flobo@cosmo.fis.fc.ul.pt
2009-01-12
In this work, we find exact wormhole solutions in the context of noncommutative geometry, and further explore their physical properties and characteristics. The energy density of these wormhole geometries is a smeared and particle-like gravitational source, where the mass is diffused throughout a region of linear dimension {radical}({alpha}) due to the intrinsic uncertainty encoded in the coordinate commutator. Furthermore, we also analyze these wormhole geometries considering that the equation governing quantum fluctuations behaves as a backreaction equation. In particular, the energy density of the graviton one loop contribution to a classical energy in a traversable wormhole background and the finite one loop energy density is considered as a self-consistent source for these wormhole geometries. Interesting solutions are found for an appropriate range of the parameters, validating the perturbative computation introduced in this semi-classical approach.
Integrability of classical strings dual for noncommutative gauge theories
Energy Technology Data Exchange (ETDEWEB)
Matsumoto, Takuya [Institute for Theoretical Physics and Spinoza Institute, Utrecht University, Leuvenlaan 4, 3854 CE Utrecht (Netherlands); Yoshida, Kentaroh [Department of Physics, Kyoto University, Kyoto 606-8502 (Japan)
2014-06-27
We derive the gravity duals of noncommutative gauge theories from the Yang-Baxter sigma model description of the AdS{sub 5}×S{sup 5} superstring with classical r-matrices. The corresponding classical r-matrices are 1) solutions of the classical Yang-Baxter equation (CYBE), 2) skew-symmetric, 3) nilpotent and 4) abelian. Hence these should be called abelian Jordanian deformations. As a result, the gravity duals are shown to be integrable deformations of AdS{sub 5}×S{sup 5}. Then, abelian twists of AdS{sub 5} are also investigated. These results provide a support for the gravity/CYBE correspondence proposed in arXiv:1404.1838.
Separation of noncommutative differential calculus on quantum Minkowski space
International Nuclear Information System (INIS)
Bachmaier, Fabian; Blohmann, Christian
2006-01-01
Noncommutative differential calculus on quantum Minkowski space is not separated with respect to the standard generators, in the sense that partial derivatives of functions of a single generator can depend on all other generators. It is shown that this problem can be overcome by a separation of variables. We study the action of the universal L-matrix, appearing in the coproduct of partial derivatives, on generators. Powers of the resulting quantum Minkowski algebra valued matrices are calculated. This leads to a nonlinear coordinate transformation which essentially separates the calculus. A compact formula for general derivatives is obtained in form of a chain rule with partial Jackson derivatives. It is applied to the massive quantum Klein-Gordon equation by reducing it to an ordinary q-difference equation. The rest state solution can be expressed in terms of a product of q-exponential functions in the separated variables
Aspects of noncommutative (1+1)-dimensional black holes
Mureika, Jonas R.; Nicolini, Piero
2011-08-01
We present a comprehensive analysis of the spacetime structure and thermodynamics of (1+1)-dimensional black holes in a noncommutative framework. It is shown that a wider variety of solutions are possible than the commutative case considered previously in the literature. As expected, the introduction of a minimal length θ cures singularity pathologies that plague the standard two-dimensional general relativistic case, where the latter solution is recovered at large length scales. Depending on the choice of input parameters (black hole mass M, cosmological constant Λ, etc.), black hole solutions with zero, up to six, horizons are possible. The associated thermodynamics allows for the either complete evaporation, or the production of black hole remnants.
Constraining the noncommutative spectral action via astrophysical observations.
Nelson, William; Ochoa, Joseph; Sakellariadou, Mairi
2010-09-03
The noncommutative spectral action extends our familiar notion of commutative spaces, using the data encoded in a spectral triple on an almost commutative space. Varying a rather simple action, one can derive all of the standard model of particle physics in this setting, in addition to a modified version of Einstein-Hilbert gravity. In this Letter we use observations of pulsar timings, assuming that no deviation from general relativity has been observed, to constrain the gravitational sector of this theory. While the bounds on the coupling constants remain rather weak, they are comparable to existing bounds on deviations from general relativity in other settings and are likely to be further constrained by future observations.
Accretion onto a noncommutative geometry inspired black hole
Energy Technology Data Exchange (ETDEWEB)
Kumar, Rahul [Jamia Millia Islamia, Centre for Theoretical Physics, New Delhi (India); Ghosh, Sushant G. [Jamia Millia Islamia, Centre for Theoretical Physics, New Delhi (India); Jamia Millia Islamia, Multidisciplinary Centre for Advanced Research and Studies (MCARS), New Delhi (India); University of KwaZulu-Natal, Astrophysics and Cosmology Research Unit, School of Mathematics, Statistics and Computer Science, Durban (South Africa)
2017-09-15
The spherically symmetric accretion onto a noncommutative (NC) inspired Schwarzschild black hole is treated for a polytropic fluid. The critical accretion rate M, sonic speed a{sub s} and other flow parameters are generalized for the NC inspired static black hole and compared with the results obtained for the standard Schwarzschild black holes. Also explicit expressions for gas compression ratios and temperature profiles below the accretion radius and at the event horizon are derived. This analysis is a generalization of Michel's solution to the NC geometry. Owing to the NC corrected black hole, the accretion flow parameters also have been modified. It turns out that M ∼ M{sup 2} is still achievable but r{sub s} seems to be substantially decreased due to the NC effects. They in turn do affect the accretion process. (orig.)
The noncommutative family Atiyah-Patodi-Singer index theorem
Wang, Yong
2016-12-01
In this paper, we define the eta cochain form and prove its regularity when the kernel of a family of Dirac operators is a vector bundle. We decompose the eta form as a pairing of the eta cochain form with the Chern character of an idempotent matrix and we also decompose the Chern character of the index bundle for a fibration with boundary as a pairing of the family Chern-Connes character for a manifold with boundary with the Chern character of an idempotent matrix. We define the family b-Chern-Connes character and then we prove that it is entire and give its variation formula. By this variation formula, we prove another noncommutative family Atiyah-Patodi-Singer index theorem. Thus, we extend the results of Getzler and Wu to the family case.
Quantum thetas on noncommutative T4 from embeddings into lattice
International Nuclear Information System (INIS)
Chang-Young, Ee; Kim, Hoil
2007-01-01
In this paper, we investigate the theta vector and quantum theta function over noncommutative T 4 from the embedding of RxZ 2 . Manin has constructed the quantum theta functions from the lattice embedding into vector space (x finite group). We extend Manin's construction of the quantum theta function to the embedding of vector space x lattice case. We find that the holomorphic theta vector exists only over the vector space part of the embedding, and over the lattice part we can only impose the condition for the Schwartz function. The quantum theta function built on this partial theta vector satisfies the requirement of the quantum theta function. However, two subsequent quantum translations from the embedding into the lattice part are nonadditive, contrary to the additivity of those from the vector space part
Ion-dipole interactions in concentrated organic electrolytes.
Chagnes, Alexandre; Nicolis, Stamatios; Carré, Bernard; Willmann, Patrick; Lemordant, Daniel
2003-06-16
An algorithm is proposed for calculating the energy of ion-dipole interactions in concentrated organic electrolytes. The ion-dipole interactions increase with increasing salt concentration and must be taken into account when the activation energy for the conductivity is calculated. In this case, the contribution of ion-dipole interactions to the activation energy for this transport process is of the same order of magnitude as the contribution of ion-ion interactions. The ion-dipole interaction energy was calculated for a cell of eight ions, alternatingly anions and cations, placed on the vertices of an expanded cubic lattice whose parameter is related to the mean interionic distance (pseudolattice theory). The solvent dipoles were introduced randomly into the cell by assuming a randomness compacity of 0.58. The energy of the dipole assembly in the cell was minimized by using a Newton-Raphson numerical method. The dielectric field gradient around ions was taken into account by a distance parameter and a dielectric constant of epsilon = 3 at the surfaces of the ions. A fair agreement between experimental and calculated activation energy has been found for systems composed of gamma-butyrolactone (BL) as solvent and lithium perchlorate (LiClO4), lithium tetrafluoroborate (LiBF4), lithium hexafluorophosphate (LiPF6), lithium hexafluoroarsenate (LiAsF6), and lithium bis(trifluoromethylsulfonyl)imide (LiTFSI) as salts.
Magnetic dipole interactions in crystals
Johnston, David C.
2016-01-01
The influence of magnetic dipole interactions (MDIs) on the magnetic properties of local-moment Heisenberg spin systems is investigated. A general formulation is presented for calculating the eigenvalues λ and eigenvectors μ ̂ of the MDI tensor of the magnetic dipoles in a line (one dimension, 1D), within a circle (2D) or a sphere (3D) of radius r surrounding a given moment μ⃗i for given magnetic propagation vectors k for collinear and coplanar noncollinear magnetic structures on both Bravais and non-Bravais spin lattices. Results are calculated for collinear ordering on 1D chains, 2D square and simple-hexagonal (triangular) Bravais lattices, 2D honeycomb and kagomé non-Bravais lattices, and 3D cubic Bravais lattices. The λ and μ ̂ values are compared with previously reported results. Calculations for collinear ordering on 3D simple tetragonal, body-centered tetragonal, and stacked triangular and honeycomb lattices are presented for c /a ratios from 0.5 to 3 in both graphical and tabular form to facilitate comparison of experimentally determined easy axes of ordering on these Bravais lattices with the predictions for MDIs. Comparisons with the easy axes measured for several illustrative collinear antiferromagnets (AFMs) are given. The calculations are extended to the cycloidal noncollinear 120∘ AFM ordering on the triangular lattice where λ is found to be the same as for collinear AFM ordering with the same k. The angular orientation of the ordered moments in the noncollinear coplanar AFM structure of GdB4 with a distorted stacked 3D Shastry-Sutherland spin-lattice geometry is calculated and found to be in disagreement with experimental observations, indicating the presence of another source of anisotropy. Similar calculations for the undistorted 2D and stacked 3D Shastry-Sutherland lattices are reported. The thermodynamics of dipolar magnets are calculated using the Weiss molecular field theory for quantum spins, including the magnetic transition
Temperature dependence of giant dipole resonance width
International Nuclear Information System (INIS)
Vdovin, A.I.; Storozhenko, A.N.
2005-01-01
The quasiparticle-phonon nuclear model extended to finite temperature within the framework of the thermo field dynamics is applied to calculate a temperature dependence of the spreading width Γ d own of a giant dipole resonance. Numerical calculations are made for 12S n and 208 Pb nuclei. It is found that the width Γ d own increases with T. The reason of this effect is discussed as well as a relation of the present approach to other ones existing in the literature
Prototype steel-concrete LEP dipole magnet
1981-01-01
The magnetic field needed in the LEP dipole magnets was rather low, of a fraction of tesla. This lead to the conception of a novel yoke structure consisting of stacks of 1.5 mm thick low-carbon steel laminations spaced by 4.1 mm with the spaces filled with concrete. The excitation coils were also very simple: aluminium bars insulated by polyester boxes in this prototype, by glass-epoxy in the final magnets. For details see LEP-Note 118,1978 and LEP-Note 233 1980. See also 8111529,7908528X.
Sound pressure around dipole source above porous surface.
Prezelj, Jurij; Steblaj, Peter; Cudina, Mirko
2014-06-01
A technique for in situ measurements of acoustic properties of a fibrous porous material is proposed in this paper. Proposed technique exploits a directivity pattern of a dipole source in its very near field. Theoretical analysis for the proposed technique is based on the Rayleigh integral with a complex reflection included. Results are compared with results of FEM analysis and show that flow resistivity of a porous material placed in the very near field of the dipole source has significant influence on the sound pressure at its ring. Results provide an excellent starting point for the design of the sensor for sound absorption.
Dipole location using SQUID based measurements: Application to magnetocardiography
Mariyappa, N.; Parasakthi, C.; Sengottuvel, S.; Gireesan, K.; Patel, Rajesh; Janawadkar, M. P.; Sundar, C. S.; Radhakrishnan, T. S.
2012-07-01
We report a method of inferring the dipole location using iterative nonlinear least square optimization based on Levenberg-Marquardt algorithm, wherein, we use different sets of pseudo-random numbers as initial parameter values. The method has been applied to (i) the simulated data representing the calculated magnetic field distribution produced by a point dipole placed at a known position, (ii) the experimental data from SQUID based measurements of the magnetic field distribution produced by a source coil carrying current, and (iii) the actual experimentally measured magnetocardiograms of human subjects using a SQUID based system.
State of the Short Dipole Model Program for the LHC
Andreyev, N I; Kurtyka, T; Oberli, L R; Perini, D; Russenschuck, Stephan; Siegel, N; Siemko, A; Tommasini, D; Vanenkov, I; Walckiers, L
1998-01-01
Superconducting single and twin aperture 1-m long dipole magnets are currently being fabricated at CERN at a rate of about one per month in the framework of the short dipole model program for the LHC. The program allows to study performance improvements coming from refinements in design, components and assembly options and to accumulate statistics based on a small-scale production. The experience thus gained provides in turn feedback into the long magnet program in industry. In recent models initial quenching fields above 9 T have been obtained and after a short training the conductor limit at 2 K is reached, resulting in a central bore field exceeding 10 T. The paper describes the features of recent single aperture models, the results obtained during cold tests and the plans to ensure the continuation of a vigorous model program providing input for the fabrication of the main LHC dipoles.
Energy Technology Data Exchange (ETDEWEB)
Wilke, Josefin; Wilke, Martin; Schmitt, Michael, E-mail: mschmitt@uni-duesseldorf.de [Institut für Physikalische Chemie, Heinrich-Heine-Universität, D-40225 Düsseldorf (Germany); Meerts, W. Leo, E-mail: leo.meerts@science.ru.nl [Institute for Molecules and Materials, Radboud University, NL-6525 AS Nijmegen (Netherlands)
2016-01-28
The dipole moments of the ground and lowest electronically excited singlet state of 5-methoxyindole have been determined by means of optical Stark spectroscopy in a molecular beam. The resulting spectra arise from a superposition of different field configurations, one with the static electric field almost parallel to the polarization of the exciting laser radiation, the other nearly perpendicular. Each field configuration leads to different intensities in the rovibronic spectrum. With an automated evolutionary algorithm approach, the spectra can be fit and the ratio of both field configurations can be determined. A simultaneous fit of two spectra with both field configurations improved the precision of the dipole moment determination by a factor of two. We find a reduction of the absolute dipole moment from 1.59(3) D to 1.14(6) D upon electronic excitation to the lowest electronically excited singlet state. At the same time, the dipole moment orientation rotates by 54{sup ∘} showing the importance of the determination of the dipole moment components. The dipole moment in the electronic ground state can approximately be obtained from a vector addition of the indole and the methoxy group dipole moments. However, in the electronically excited state, vector addition completely fails to describe the observed dipole moment. Several reasons for this behavior are discussed.
Directory of Open Access Journals (Sweden)
L. Alfano
1998-06-01
Full Text Available We present some results of a geoelectrical investigation program conducted in the Northern Apennines, namely in the Val d'Aveto and Bobbio window and surrounding areas. Field activity included the execution of more than 50 vertical electrical soundings with continuous polar dipole-dipole spread. We image the geometries of some deep geological structures; in particular we found a resistive background, whose resistivity is different along the geoelectrical profiles. In our interpretation the resistive background consists of subligurid and tuscan units underlying the alloctone Ligurid units in the area surrounding the Val d'Aveto and Bobbio window. The resistive background was not found, at least at the same depths, toward north-east. Therefore, the geoelectrical survey revealed the position of the front of the subligurid and Tuscan nappes toward the plain for a depth of about one kilometer.
Open branes in space-time non-commutative little string theory
International Nuclear Information System (INIS)
Harmark, T.
2001-01-01
We conjecture the existence of two new non-gravitational six-dimensional string theories, defined as the decoupling limit of NS5-branes in the background of near-critical electrical two- and three-form RR fields. These theories are space-time non-commutative Little String Theories with open branes. The theory with (2,0) supersymmetry has an open membrane in the spectrum and reduces to OM theory at low energies. The theory with (1,1) supersymmetry has an open string in the spectrum and reduces to (5+1)-dimensional NCOS theory for weak NCOS coupling and low energies. The theories are shown to be T-dual with the open membrane being T-dual to the open string. The theories therefore provide a connection between (5+1)-dimensional NCOS theory and OM theory. We study the supergravity duals of these theories and we consider a chain of dualities that shows how the T-duality between the two theories is connected with the S-duality between (4+1)-dimensional NCOS theory and OM theory
Dipole-sheet multipole magnets for accelerators
International Nuclear Information System (INIS)
Walstrom, P.L.
1993-01-01
The dipole-sheet formalism can be used to describe both cylindrical current-sheet multipole magnets and cylindrical-bore magnets made up of permanent magnet blocks. For current sheets, the formalism provides a natural way of finding a finite set of turns that approximate a continuous distribution. The formalism is especially useful In accelerator applications where large-bore, short, high-field-quality magnets that are dominated by fringe fields are needed. A further advantage of the approach is that in systems with either open or cylindrically symmetric magnetic boundaries, analytical expressions for the three-dimensional fields that are suitable for rapid numerical evaluation can be derived. This development is described in some detail. Also, recent developments in higher-order particle-beam optics codes based on the formalism are described briefly
System of coefficients for charged-particle beam linear transformation by a magnetic dipole element
International Nuclear Information System (INIS)
Tarantin, N.I.
1979-01-01
A new technique for consideration of dipole magnet ion-optical effect has been developed to study the problems of commutation and monochromatization of a charged particle beam. In a new form obtained are systematized coefficients of linear transformation (CLT) of the charged particle beam for radial and axial motions in a magnetic dipole element (MDE) including a dipole magnet and two gaps without magnetic field. Given is a method of graphic determination of MDE parameters and main CLT. The new form of coefficients and conditions of the transformations feasibility considerably facilitates the choice and calculation of dipole elements
Maximilien Brice
2002-01-01
The last of the 3280 dipole magnets from the Large Electron-Positron (LEP) collider is seen on its journey to the surface on 12 February 2002. The LEP era, which began at CERN in 1989 and ended 2000, comes to an end.
Particle electric dipole-moments
Energy Technology Data Exchange (ETDEWEB)
Pendlebury, J.M. [Sussex Univ., Brighton (United Kingdom)
1997-04-01
The incentive to detect particle electric dipole-moments, as a window on time-reversal violation, remains undiminished. Efforts to improve the measurements for the neutron, the electron and some nuclei are still making rapid progress as more powerful experimental methods are brought to bear. A new measurement for the neutron at ILL is presented. (author). 7 refs.
The theory of pseudo-differential operators on the noncommutative n-torus
Tao, J.
2018-02-01
The methods of spectral geometry are useful for investigating the metric aspects of noncommutative geometry and in these contexts require extensive use of pseudo-differential operators. In a foundational paper, Connes showed that, by direct analogy with the theory of pseudo-differential operators on finite-dimensional real vector spaces, one may derive a similar pseudo-differential calculus on noncommutative n-tori, and with the development of this calculus came many results concerning the local differential geometry of noncommutative tori for n=2,4, as shown in the groundbreaking paper in which the Gauss-Bonnet theorem on the noncommutative two-torus is proved and later papers. Certain details of the proofs in the original derivation of the calculus were omitted, such as the evaluation of oscillatory integrals, so we make it the objective of this paper to fill in all the details. After reproving in more detail the formula for the symbol of the adjoint of a pseudo-differential operator and the formula for the symbol of a product of two pseudo-differential operators, we extend these results to finitely generated projective right modules over the noncommutative n-torus. Then we define the corresponding analog of Sobolev spaces and prove equivalents of the Sobolev and Rellich lemmas.
Multiscale dipole relaxation in dielectric materials
DEFF Research Database (Denmark)
Hansen, Jesper Schmidt
2016-01-01
Dipole relaxation from thermally induced perturbations is investigated on different length scales for dielectric materials. From the continuum dynamical equations for the polarisation, expressions for the transverse and longitudinal dipole autocorrelation functions are derived in the limit where...
Density wave instabilities of tilted fermionic dipoles in a multilayer geometry
DEFF Research Database (Denmark)
Block, Jens; Zinner, Nikolaj Thomas; Bruun, Georg
2012-01-01
We consider the density wave instability of fermionic dipoles aligned by an external field and moving in equidistant layers at zero temperature. Using a conserving Hartree–Fock approximation, we show that correlations between dipoles in different layers significantly decrease the critical coupling...
Self-assembly of spherical colloidal particles with off-centered magnetic dipoles
Abrikosov, A.I.; Sacanna, S.; Philipse, A.P.; Linse, P.
2013-01-01
Fluids of spherical colloids possessing an off-centered embedded magnetic dipole were investigated by using Monte Carlo simulations. Systems of colloids with different strengths and directions of the embedded dipole moment confined in a 2D space without and with an external magnetic field applied
Isoscalar and isovector collective dipole states
International Nuclear Information System (INIS)
Poelhekken, T.D.
1989-01-01
This thesis presents an experimental study on the excitation of isoscalar and isovector dipole collective states by inelastic alpha scattering. In ch. 2 the experimental techniques and the characteristics of the α-particle and the γ-ray detection system are summarized. The details of the relevant theory, such as the distorted-wave Born approximation (DWBA) formalism, the energy-weighted sum rules and the α-γ angular correlations are given in ch. 3. Ch. 4 presents the results of the search for low-energy isoscalar giant dipole resonance (ISLEDR) strength by studying inelastic scattering at very forward angles, including 0 deg, of 120 MeV α-particles in coincidence with γ-ray decay. For the identification of these ISLEDR states use has been made of the fact that the α-γ angular correlations show a very characteristic pattern for γ-decay to the ) + ground state of the nuclei. Results are shown for 208 Pb, 90 Zr, 58 Ni and 40 Ca. A second experiment used the same reaction but focussed on the excitation of the isovector giant dipole resonance (IVGDR) in 208 Pb, located in a different excitation energy region (ch. 5). With the help of the (α,α'γ)-reaction it could be shown that at most 12 (± 4) % of the observed resonance strength around 13.6MeV in 208 Pb could be caused by IVGDR excitation. Finally a summary is presented in ch. 6 together with the future prospects for this particular branch in the field of giant resonances. (author). 209 refs.; 68 figs.; 42 tabs
Planck-Scale Dual-Curvature Lensing and Spacetime Noncommutativity
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Giovanni Amelino-Camelia
2017-01-01
Full Text Available It was recently realized that Planck-scale momentum-space curvature, which is expected in some approaches to the quantum-gravity problem, can produce dual-curvature lensing, a feature which mainly affects the direction of observation of particles emitted by very distant sources. Several gray areas remain in our understanding of dual-curvature lensing, including the possibility that it might be just a coordinate artifact and the possibility that it might be in some sense a by-product of the better studied dual-curvature redshift. We stress that data reported by the IceCube neutrino telescope should motivate a more vigorous effort of investigation of dual-curvature lensing, and we observe that studies of the recently proposed “ρ-Minkowski noncommutative spacetime” could be valuable from this perspective. Through a dedicated ρ-Minkowski analysis, we show that dual-curvature lensing is not merely a coordinate artifact and that it can be present even in theories without dual-curvature redshift.