Journal articles: 'Vector chirality'

1

Belinsky, Moisey I. "Inelastic Neutron Scattering, EPR and Spin Chirality in Spin-Frustrated V3 and Cu3 Nanomagnets with Dzialoshinsky-Moriya Exchange." Chemistry Journal of Moldova 4, no. 1 (June 2009): 103–10. http://dx.doi.org/10.19261/cjm.2009.04(1).04.

Full text

Abstract:

The inelastic neutron scattering (INS) and EPR transitions are considered for the spin-frustrated V3 and Cu3 nanomagnets. It is shown that the DM exchange and distortions determine the Q-dependence and redistribution of the intensities of the intra- and inter-doublet INS transitions in the 2(S=1/2) states as well as the intensities of the EPR transitions. The peculiarities of the INS and EPR spectra of the V3 ring of V15 quantum molecular magnet and EPR spectra of the V3 and Cu3 nanomagnets are described by the isosceles Heisenberg model with the DM exchange. Spin chirality and spin structure of the Cu3 and V3 nanomagnets with the Dzialoshinsky-Moriya (DM) exchange interaction are analysed in the vector and scalar spin chirality models. The vector chirality model describes the field, orientation and deformation dependence of the spin chirality κn. The spin chirality is formed by the DM interaction and depends on the sign of the DM parameter Gz. The DM exchange and distortions determine the degree of chirality κn<1 in the isosceles clusters.

APA, Harvard, Vancouver, ISO, and other styles

2

Bystrov, Vladimir, Ilya Likhachev, Alla Sidorova, Sergey Filippov, Aleksey Lutsenko, Denis Shpigun, and Ekaterina Belova. "Molecular Dynamics Simulation Study of the Self-Assembly of Phenylalanine Peptide Nanotubes." Nanomaterials 12, no. 5 (March 3, 2022): 861. http://dx.doi.org/10.3390/nano12050861.

Full text

Abstract:

In this paper, we propose and use a new approach for a relatively simple technique for conducting MD simulation (MDS) of various molecular nanostructures, determining the trajectory of the MD run and forming the final structure using external force actions. A molecular dynamics manipulator (MD manipulator) is a controlled MDS type. As an example, the applicability of the developed algorithm for assembling peptide nanotubes (PNT) from linear phenylalanine (F or Phe) chains of different chirality is presented. The most adequate regimes for the formation of nanotubes of right chirality D from the initial L-F and nanotubes of left chirality L of their initial dipeptides D-F modes were determined. We use the method of a mixed (vector–scalar) product of the vectors of the sequence of dipole moments of phenylalanine molecules located along the nanotube helix to calculate the magnitude and sign of chirality of self-assembled helical phenylalanine nanotubes, which shows the validity of the proposed approach. As result, all data obtained correspond to the regularity of the chirality sign change of the molecular structures with a hierarchical complication of their organization.

APA, Harvard, Vancouver, ISO, and other styles

3

Sharma, Pragya, Singh Rohitkumar Shailendra, M. Aarthy, and Hidenori Mimura. "Process Variation analysis of 1-bit ALU based on GAA-CNTFET." IOP Conference Series: Materials Science and Engineering 1219, no. 1 (January 1, 2022): 012039. http://dx.doi.org/10.1088/1757-899x/1219/1/012039.

Full text

Abstract:

Abstract This paper is based on a technique of Carbon Nanotube Field-Effect Transistors (CNTFET) for Arithmetic Logical Unit (ALU) using 10nm technology. For the past few decades, global demand for smaller dimension transistors with ultra-speed and low power consumption processor is a challenge for device designers. According to Moore’s law, the number of transistors on an integrated circuit (IC) doubles every two years. Traditional Si transistors, scaled down to its limit sub 10nm, suffer from short channel effects, direct tunneling from source to drain, drain induced barrier lowering, and hot carrier degradation. Hence device designer is looking for nano devices which can replace traditional Si. Carbon Nanotube Field Effect Transistors (CNTFET) are promising Nano device for the next generation. A parametric analysis has been performed for various measurements such as delay, power, and PDP by varying chirality vector. Here we discuss four Different configurations such as Single channel Single chirality (SCSC), Single Channel Dual chirality (SCDC), Double Channel Single Chirality (DCSC), Double Channel Dual chirality (DCDC). Based on the results it was observed that as the chirality vector increases delay decreases. It is also observed that the delay in Double channel configuration is less than in Single-channel configuration.

APA, Harvard, Vancouver, ISO, and other styles

4

Li, Manman, Shaohui Yan, Yanan Zhang, and Baoli Yao. "Generation of controllable chiral optical fields by vector beams." Nanoscale 12, no. 28 (2020): 15453–59. http://dx.doi.org/10.1039/d0nr02693j.

Full text

APA, Harvard, Vancouver, ISO, and other styles

5

Zhang, Qiang, Zhirong Liu, and Ziqiang Cheng. "Chiral Mechanical Effect of the Tightly Focused Chiral Vector Vortex Fields Interacting with Particles." Nanomaterials 13, no. 15 (August 4, 2023): 2251. http://dx.doi.org/10.3390/nano13152251.

Full text

Abstract:

The coupling of the spin-orbit angular momentum of photons in a focused spatial region can enhance the localized optical field’s chirality. In this paper, a scheme for producing a superchiral optical field in a 4π microscopic system is presented by tightly focusing two counter-propagating spiral wavefronts. We calculate the optical forces and torques exerted on a chiral dipole by the chiral light field and reveal the chiral forces by combining the light field and dipoles. Results indicate that, in addition to the general optical force, particles’ motion would be affected by a chiral force that is directly related to the particle chirality. This chiral mechanical effect experienced by the electromagnetic dipoles excited on a chiral particle could be characterized by the behaviors of chirality density and flux, which are, respectively, associated with the reactive and dissipative components of the chiral forces. This work facilitates the advancement of optical separation and manipulation techniques for chiral particles.

APA, Harvard, Vancouver, ISO, and other styles

6

LI, L. J., and R. J. NICHOLAS. "MAGNETO-PHOTOLUMINESCENCE OF CHIRALITY-CHARACTERIZED SINGLE-WALLED CARBON NANOTUBES." International Journal of Modern Physics B 18, no. 27n29 (November 30, 2004): 3509–12. http://dx.doi.org/10.1142/s0217979204026913.

Full text

Abstract:

We have studied the mangeto-photoluminescence (PL) of single-walled carbon nanotubes (SWCNTs) with different chiral vector indices (n,m). A novel strain method is used to assign the quantum number q and chiral vector indices. The PL intensities and energies were found to be a strong function of magnetic field at low temperature, but were field independent up to 19.5T at 300K. All emission energies show a significant red shift caused by the action of Aharanov-Bohm flux threading the tubes.

APA, Harvard, Vancouver, ISO, and other styles

7

Kawamura, H. "Spin- and chirality-orderings of frustrated magnets stacked-triangular anti-ferromagnets and spin glasses." Canadian Journal of Physics 79, no. 11-12 (December 1, 2001): 1447–58. http://dx.doi.org/10.1139/p01-111.

Full text

Abstract:

"Chirality" is a multispin quantity representing the sense or the handedness of the noncollinear spin structures induced by spin frustration. Recent studies have revealed that the chirality often plays an important role in the ordering of certain frustrated magnets. Here I take up two such examples, stacked-triangular anti-ferromagnets and spin glasses, where the inherent chiral degree of freedom affects underlying physics and might lead to novel ordering phenomena. The first topic is the criticality of the magnetic-phase transition of vector (i.e., XY or Heisenberg) anti-ferromagnets on the three-dimensional stacked-triangular lattice. The second topic is the nature of the spin-glass ordering. I will review the recent theoretical and experimental works on these topics, with particular emphasis on the important role played by the chirality. PACS Nos.: 67.70+n, 67.57Lm

APA, Harvard, Vancouver, ISO, and other styles

8

Okunishi, Kouichi. "On Calculation of Vector Spin Chirality for Zigzag Spin Chains." Journal of the Physical Society of Japan 77, no. 11 (November 15, 2008): 114004. http://dx.doi.org/10.1143/jpsj.77.114004.

Full text

APA, Harvard, Vancouver, ISO, and other styles

9

Ramiharimanana, Fenia Diane, Mbolatiana Tovo Andrianjafy, Niry Hasinandrianina Ramarosandratana, Toavina Elodie Andrianarijaona, Ny Aina Harivony Rambala Rakotomena, Estelle Metay, Marie-Christine Duclos, et al. "Chirality Effects on Repellent Properties of 4-Alkoxycoumarins Against Asian Tiger Mosquito (Diptera: Culicidae)." Journal of Medical Entomology 59, no. 2 (January 18, 2022): 430–39. http://dx.doi.org/10.1093/jme/tjab176.

Full text

Abstract:

Abstract The use of semiochemicals as repellents and attractants has been proposed to complement insecticides used for the control of vector mosquito populations. In several studies, the optical purities of the molecules tested have been described as having little or no effect on repellent activity. However, these observations seem difficult to explain because of the chirality effect of molecules on the olfactory system of insects and humans. Thus, the purpose of this study is to assess the effects of chirality on the repellent properties of 4-alcoxycoumarins against Aedes albopictus Skuse, mosquito vector of arboviruses. We report here that the racemic (R/S)-4-sec-butoxycoumarin had the highest repellent effect (Repellent Index = 49.9%) followed by (R) enantiomer (Repellent Index = 24.2%) for the dose of 5 mg/mL. Contrary, no significant repellent activity was recorded for S-(+)-4-sec-butoxycoumarin. This experiment demonstrates the close relationship between the molecules’ optical purities and the behavioral response of mosquitoes.

APA, Harvard, Vancouver, ISO, and other styles

10

Belinsky, Moisey I. "Spin Chirality of Cu3 and V3 Nanomagnets. 1. Rotation Behavior of Vector Chirality, Scalar Chirality, and Magnetization in the Rotating Magnetic Field, Magnetochiral Correlations." Inorganic Chemistry 55, no. 9 (April 12, 2016): 4078–90. http://dx.doi.org/10.1021/acs.inorgchem.5b02202.

Full text

APA, Harvard, Vancouver, ISO, and other styles

11

BROWN, J. B., TAKASHI URATA, TAKEYUKI TAMURA, MIDORI A. ARAI, TAKEO KAWABATA, and TATSUYA AKUTSU. "COMPOUND ANALYSIS VIA GRAPH KERNELS INCORPORATING CHIRALITY." Journal of Bioinformatics and Computational Biology 08, supp01 (December 2010): 63–81. http://dx.doi.org/10.1142/s0219720010005117.

Full text

Abstract:

High accuracy is paramount when predicting biochemical characteristics using Quantitative Structural-Property Relationships (QSPRs). Although existing graph-theoretic kernel methods combined with machine learning techniques are efficient for QSPR model construction, they cannot distinguish topologically identical chiral compounds which often exhibit different biological characteristics. In this paper, we propose a new method that extends the recently developed tree pattern graph kernel to accommodate stereoisomers. We show that Support Vector Regression (SVR) with a chiral graph kernel is useful for target property prediction by demonstrating its application to a set of human vitamin D receptor ligands currently under consideration for their potential anti-cancer effects.

APA, Harvard, Vancouver, ISO, and other styles

12

Chanyal, B. C. "Linearized electromagnetic and gravito-Heavisidian chirality in split octonion space-time." International Journal of Geometric Methods in Modern Physics 15, no. 07 (May 24, 2018): 1850109. http://dx.doi.org/10.1142/s0219887818501098.

Full text

Abstract:

In this paper, we construct a split octonionic mathematical approach to generalized electromagnetic and gravito-Heavisidian chirality of dyons by modification of the Drude–Born–Fedorov constitutive relations. In this context, we describe dual Euclidean space-times structure associated with [Formula: see text] Zorn’s vector matrix realization of split octonion. As such, using the Zorn’s vector matrix realization, an alternative form of generalized Proca–Maxwell equations of massive dyons is obtained in chiral media. It is well known that in weak unified gravito-Heavisidian field, the Einstein’s equations become Maxwell-like equations under the first approximation. Thus, we study the gravito-Heavisidian analogous theory to electromagnetic theory, and discuss the Drude–Born–Fedorov constitutive relations, gravito-Heavisidian field, Proca–Maxwell equations and gravito-Heavisidian wave equations for linear gravitational chiral field of gravito-dyons in flat split octonion space-time.

APA, Harvard, Vancouver, ISO, and other styles

13

Guo, Xing, Yaojin Li, and Chenglong Jia. "Vector-spin-chirality bound state driven by the inverse Dzyaloshinskii–Moriya mechanism." New Journal of Physics 20, no. 5 (May 11, 2018): 053032. http://dx.doi.org/10.1088/1367-2630/aac0d9.

Full text

APA, Harvard, Vancouver, ISO, and other styles

14

Ishizuka, Hiroaki, and Naoto Nagaosa. "Impurity-induced vector spin chirality and anomalous Hall effect in ferromagnetic metals." New Journal of Physics 20, no. 12 (December 21, 2018): 123027. http://dx.doi.org/10.1088/1367-2630/aaf510.

Full text

APA, Harvard, Vancouver, ISO, and other styles

15

COHEN, MARCUS. "INERTIAL MASS FROM SPIN NONLINEARITY." International Journal of Modern Physics D 07, no. 05 (October 1998): 663–99. http://dx.doi.org/10.1142/s0218271898000450.

Full text

Abstract:

The inertial mass of a Fermion shows up as chiral cross-coupling in its Dirac system. No scalar term can invariantly couple left and right chirality fields; the Dirac matrices must be spin tensors of mixed chirality. We show how such tensor couplings could arise from nonlinear mixing of four spinor fields, two representing the local electron fields and two inertial spinor fields sourced in the distant masses. We thus give a model that implements Mach's principle. Following Mendel Sachs,1 we let the inertial spinors factor the moving spacetime tetrads qα(x) and [Formula: see text] that appear in the Dirac operator. The inertial spinors do more than set the spacetime "stage;" they are players in the chiral dynamics. Specifically, we show how the massive Dirac system arises as the envelope modulation equations coupling left and right chirality electron fields on a Friedmann universe via nonlinear "spin gratings" with the inertial spinor fields. These gratings implement Penrose's "mass-scatterings," which keep the null zig-zags of the bispinor wave function confined to a timelike world tube. Local perturbations to the inertial spinor fields appear in the Dirac system as Abelian and non-Abelian vector potentials.

APA, Harvard, Vancouver, ISO, and other styles

16

Guo, Y., B. Schmieder, P. Démoulin, T. Wiegelmann, G. Aulanier, T. Török, and V. Bommier. "A filament supported by different magnetic field configurations." Proceedings of the International Astronomical Union 6, S273 (August 2010): 328–32. http://dx.doi.org/10.1017/s174392131101547x.

Full text

Abstract:

AbstractA nonlinear force-free magnetic field extrapolation of vector magnetogram data obtained by THEMIS/MTR on 2005 May 27 suggests the simultaneous existence of different magnetic configurations within one active region filament: one part of the filament is supported by field line dips within a flux rope, while the other part is located in dips within an arcade structure. Although the axial field chirality (dextral) and the magnetic helicity (negative) are the same along the whole filament, the chiralities of the filament barbs at different sections are opposite, i.e., right-bearing in the flux rope part and left-bearing in the arcade part. This argues against past suggestions that different barb chiralities imply different signs of helicity of the underlying magnetic field. This new finding about the chirality of filaments will be useful to associate eruptive filaments and magnetic cloud using the helicity parameter in the Space Weather Science.

APA, Harvard, Vancouver, ISO, and other styles

17

Pasini, Antonello. "Precessions of opposite chirality for the spin vector in a Riemann-Cartan framework." Physics Letters A 151, no. 9 (December 1990): 459–63. http://dx.doi.org/10.1016/0375-9601(90)90461-v.

Full text

APA, Harvard, Vancouver, ISO, and other styles

18

Dandoloff, Rossen. "New Topological Configurations in the Continuous Heisenberg Spin Chain: Lower Bound for the Energy." Advances in Condensed Matter Physics 2015 (2015): 1–3. http://dx.doi.org/10.1155/2015/954524.

Full text

Abstract:

In order to study the spin configurations of the classical one-dimensional Heisenberg model, we map the normalized unit vector, representing the spin, on a space curve. We show that the total chirality of the configuration is a conserved quantity. If, for example, one end of the space curve is rotated by an angle of 2πrelative to the other, the Frenet frame traces out a noncontractible loop inSO(3)and this defines a new class of topological spin configurations for the Heisenberg model.

APA, Harvard, Vancouver, ISO, and other styles

19

Sato, Taku, Yusuke Nambu, Tao Hong, Masaaki Matsuda, Huibo Cao, Masataka Kinoshita, Shinichiro Seki, Shintaro Ishiwata, and Yoshinori Tokura. "Magnetic structure of the chiral triangular magnet MnSb2O6." Acta Crystallographica Section A Foundations and Advances 70, a1 (August 5, 2014): C387. http://dx.doi.org/10.1107/s2053273314096120.

Full text

Abstract:

Incommensurate helical (or cycloidal) magnetic structure may have left- and right-wound states (helicity), which are in principle equally populated in a magnet with inversion symmetry. In addition, for a Heisenberg triangular antiferromagnet, clockwise and counter-clockwise rotations of the 120 degree spin structure provide another intriguing degree of freedom. Hence, a triangular magnet that has incommensurate helical ordering along the stacking direction will show intriguing interplay of the helicity (of the helical structure) and chirality (in the triangular plane). Such phenomenon is, however, rarely studied in the past since only one example, the Ba3NbFe3Si2O14 langathite, has been known to date [1]. In this work, we study MnSb2O6, which consists of distorted triangular lattice stacking along the c-axis [2,3]. MnSb2O6 belongs to the space group P321, and hence lacks inversion symmetry. Due to this fact, unique selection of the helicity and chirality may be expected. However, the earlier studies were carried out using unpolarized neutron diffraction with mostly the powder sample, and thus helicity and chirality selection cannot be concluded. Here, we have performed single-crystal diffraction experiment using polarized neutrons in addition to the unpolarized ones, and have succeeded in determination of the magnetic structure of MnSb2O6. The resulting magnetic structure is nearly cycloidal with the magnetic modulation vector q = (0, 0, 0.182) (see figure below). The spin rotation plane is, however, inclined from the ac-plane toward the b-axis for approximately 30 degrees. Polarization analysis indicates that both the helicity of the (nearly-) cycloidal structure and chirality of the in-plane 120 degree structure are uniquely selected. The 30 degree inclination from the ac-plane is a key finding of this work, allowing new kind of multiferroicity in this material.

APA, Harvard, Vancouver, ISO, and other styles

20

Johnson, Roger, Laurent Chapon, Kun Cao, Pascal Manuel, Alessandro Bombardi, Sunil Nair, Sang-Wook Cheong, and Paolo Radaelli. "The roles of chirality and polarity in novel multiferroics: MnSb2O6and Cu3Nb2O8." Acta Crystallographica Section A Foundations and Advances 70, a1 (August 5, 2014): C386. http://dx.doi.org/10.1107/s2053273314096132.

Full text

Abstract:

At room temperature Cu3Nb2O8 has a centrosymmetric, triclinic crystal structure. If cooled below 24 K, the copper magnetic moments order with a complex, generalized helicoidal magnetic structure that breaks inversion symmetry, giving rise to ferroelectricity. Unusually, the direction of the induced electric polarization vector with respect to the helicoidal spin rotation cannot be reconciled by conventional theories of magneto-electric coupling. Instead, we show that the observed multiferroic properties of Cu3Nb2O8 may be explained through a phenomenological analysis based upon coupling between the magnetic chirality, electric polarity, and a structural axial rotation. Trigonal MnSb2O6 crystallizes with a chiral crystal structure. Typically, magnetic materials with a chiral crystal lattice order with a chiral magnetic structure, where the magnetic exchange interactions and anisotropies follow the symmetry of the lattice. The magnetism of MnSi is a classic example of this scenario, in which exotic skyrmion phases emerge out of a helical magnetic state. To the contrary, we show that the low temperature magnetic structure of MnSb2O6 is cycloidal, described by a magnetic polarity as opposed to a chirality. We demonstrate through ab-initio calculations that this magnetic structure is in fact the ground state of the symmetric-exchange Heisenberg spin Hamiltonian, which has higher symmetry than the underlying crystal lattice. Furthermore, the phenomenology may be understood by considering the coupling between structural chirality, magnetic polarity, and a magnetic axial rotation. As a result, we predict MnSb2O6 to be multiferroic with a weak ferroelectric polarization.

APA, Harvard, Vancouver, ISO, and other styles

21

Ansari, Reza, Mahdi Mirnezhad, Hessam Rouhi, and Majid Bazdid-Vahdati. "Prediction of torsional buckling behaviour of single-walled SiC nanotubes based on molecular mechanics." Engineering Computations 32, no. 6 (August 3, 2015): 1837–66. http://dx.doi.org/10.1108/ec-10-2014-0198.

Full text

Abstract:

Purpose – Based on the molecular mechanics approach, the purpose of this paper is to analytically investigate the torsional buckling behavior of single-walled silicon carbide nanotubes (SiCNTs) with different values of diameter and chiral angles. Design/methodology/approach – To this end, the mechanical properties and atomic structure of a silicon carbide (SiC) sheet are evaluated based on the density functional theory (DFT) within the framework of the generalized gradient approximation. After that force constants of the total potential energy are theoretically obtained through establishing a linkage between the viewpoints of the quantum mechanics and molecular mechanics. Explicit expressions are presented to obtain the critical buckling shear strain corresponding to different types of chirality. The present model is capable to calculate the torsional buckling behavior of SiCNTs related to various chiral angles. The critical buckling shear strain is obtained for various types of chirality and compared with each other. Findings – It is concluded that for all diameters, zigzag nanotubes are more stable than armchair ones. Besides it is found that the minimum critical buckling shear strain is for nanotubes with (n, n/2) chiral vector. Originality/value – Investigating the torsional buckling behavior of single-walled SiCNTs with different values of diameter and chiral angle. Obtaining the mechanical properties and atomic structure of the SiC sheet based on the DFT calculations. Establishing a linkage between the molecular mechanics and quantum mechanics and obtaining the force constants of the molecular mechanics. Presenting the closed-form expression to calculate the critical buckling shear strain of single-walled SiCNTs corresponding to various types of chirality.

APA, Harvard, Vancouver, ISO, and other styles

22

Dikandé, Alain M., Bernard Y. Nyanga, and S. E. Mkam Tchouobiap. "Solitons in discrete linear chains of chiral smectic liquid crystals with competing interactions." Modern Physics Letters B 32, no. 32 (November 20, 2018): 1850392. http://dx.doi.org/10.1142/s021798491850392x.

Full text

Abstract:

Chiral liquid crystals exhibit in-plane spontaneous polarizations, however, in their smectic (Sm) phase the primary-order parameter is the tilt vector associated with molecular rotations around the long axis parallel to the molecular directors. These molecular rotations can lead to several distinct phases among which an incommensurate order with a domain-wall texture is referred to as soliton. In this study, the formation of domain walls in smectic chiral (SmC) liquid crystals is analyzed, with emphasis on the competition between an Ising-like symmetric intermolecular interaction, an anti-symmetric intermolecular interaction due to molecular chirality and an applied in-plane electric field. It is found that the anti-symmetric intermolecular interaction increases the width of kink structures in the domain wall at moderate intensity of the y-component of the applied in-plane electric field. Increasing the x-component of the electric field creates unstable condition for soliton formation irrespective of magnitudes of the symmetric and chiral intermolecular interactions. The stability condition for single-kink structures in the discrete molecular chain is discussed, by estimating the Peierls stress experienced by the single-kink soliton. Results suggest that chirality lowers the Peierls–Nabarro barrier, hence increasing the lifetime of single-kink structures in the discrete medium.

APA, Harvard, Vancouver, ISO, and other styles

23

Gogberashvili, Merab, and Otari Sakhelashvili. "Geometrical Applications of Split Octonions." Advances in Mathematical Physics 2015 (2015): 1–14. http://dx.doi.org/10.1155/2015/196708.

Full text

Abstract:

It is shown that physical signals and space-time intervals modeled on split-octonion geometry naturally exhibit properties from conventional (3 + 1)-theory (e.g., number of dimensions, existence of maximal velocities, Heisenberg uncertainty, and particle generations). This paper demonstrates these properties using an explicit representation of the automorphisms on split-octonions, the noncompact form of the exceptional Lie groupG2. This group generates specific rotations of (3 + 4)-vector parts of split octonions with three extra time-like coordinates and in infinitesimal limit imitates standard Poincare transformations. In this picture translations are represented by noncompact Lorentz-type rotations towards the extra time-like coordinates. It is shown how theG2algebra’s chirality yields an intrinsic left-right asymmetry of a certain 3-vector (spin), as well as a parity violating effect on light emitted by a moving quantum system. Elementary particles are connected with the special elements of the algebra which nullify octonionic intervals. Then the zero-norm conditions lead to free particle Lagrangians, which allow virtual trajectories also and exhibit the appearance of spatial horizons governing by mass parameters.

APA, Harvard, Vancouver, ISO, and other styles

24

LI, MINGHAI, and JUEPING LIU. "OFF-SHELL TWIST-FOUR PHOTON LIGHT-CONE WAVEFUNCTION FOR THE CHIRALITY-CONSERVING QUARK–ANTIQUARK VECTOR CURRENT IN THE LOW-ENERGY EFFECTIVE THEORY OF QCD." International Journal of Modern Physics E 18, no. 08 (September 2009): 1801–7. http://dx.doi.org/10.1142/s0218301309013853.

Full text

Abstract:

Within the framework of the low-energy effective theory arising from the instanton vacuum model of QCD, the twist-four virtual photon wavefunction, gγ3(u, P2), corresponding to the nonlocal quark–antiquark vector current is calculated at the low-energy scale. The coupling constant, fγ(P2), of the quark–antiquark vector current to the virtual photon state is also obtained. The behavior of the coupling as well as the obtained photon wave function especially at the end points is discussed.

APA, Harvard, Vancouver, ISO, and other styles

25

DASS, N. D. HARI. "REGULARISATION OF CHIRAL GAUGE THEORIES." International Journal of Modern Physics B 14, no. 19n20 (August 10, 2000): 1989–2010. http://dx.doi.org/10.1142/s0217979200001138.

Full text

Abstract:

This article gives a review of the topic of regularising chiral gauge theories and is aimed at a general audience. It begins by clarifying the meaning of chirality and goes on to discussing chiral projections in field theory, parity violation and the distinction between vector and chiral field theories. It then discusses the standard model of electroweak interactions from the perspective of chirality. It also reviews at length the phenomenon of anomalies in quantum field theories including the intuitive understanding of anomalies based on the Dirac sea picture as given by Nielsen and Ninomiya. It then raises the issue of a non-perturbative and constructive definition of the standard model as well as the importance of such formulations. The second Nielsen–Ninomiya theorem about the impossibility of regularising chiral gauge theories under some general assumptions is also discussed. After a brief review of lattice regularisation of field theories, it discusses the issue of fermions on the lattice with special emphasis on the problem of species doubling. The implications of these problems to introducing chiral fermions on the lattice as well as the interpretations of anomalies within the lattice formulations and the lattice Dirac sea picture are then discussed. Finally the difficulties of formulating the standard model on the lattice are illustrated through detailed discussions of the Wilson–Yukawa method, the domain wall fermions method and the recently popular Ginsparg–Wilson method.

APA, Harvard, Vancouver, ISO, and other styles

26

Schmieder, Brigitte, Guillaume Aulanier, and Tibor Török. "Solar prominences." Proceedings of the International Astronomical Union 4, S257 (September 2008): 223–32. http://dx.doi.org/10.1017/s1743921309029330.

Full text

Abstract:

AbstractSolar filaments (or prominences) are magnetic structures in the corona. They can be represented by twisted flux ropes in a bipolar magnetic environment. In such models, the dipped field lines of the flux rope carry the filament material and parasitic polarities in the filament channel are responsible for the existence of the lateral feet of prominences.Very simple laws do exist for the chirality of filaments, the so-called “filament chirality rules”: commonly dextral/sinistral filaments corresponding to left- (resp. right) hand magnetic twists are in the North/South hemisphere. Combining these rules with 3D weakly twisted flux tube models, the sign of the magnetic helicity in several filaments were identified. These rules were also applied to the 180° disambiguation of the direction of the photospheric transverse magnetic field around filaments using THEMIS vector magnetograph data (López Ariste et al. 2006). Consequently, an unprecedented evidence of horizontal magnetic support in filament feet has been observed, as predicted by former magnetostatic and recent MHD models.The second part of this review concerns the role of emerging flux in the vicinity of filament channels. It has been suggested that magnetic reconnection between the emerging flux and the pre-existing coronal field can trigger filament eruptions and CMEs. For a particular event, observed with Hinode/XRT, we observe signatures of such a reconnection, but no eruption of the filament. We present a 3D numerical simulation of emerging flux in the vicinity of a flux rope which was performed to reproduce this event and we briefly discuss, based on the simulation results, why the filament did not erupt.

APA, Harvard, Vancouver, ISO, and other styles

27

Lee, Min-Sang, Andreas Westphalen, Arndt Remhof, Alexandra Schumann, and Harmut Zabel. "Extended longitudinal vector and Bragg magneto-optic Kerr effect for the determination of the chirality distribution in magnetic vortices." Journal of Applied Physics 103, no. 9 (May 2008): 093913. http://dx.doi.org/10.1063/1.2919160.

Full text

APA, Harvard, Vancouver, ISO, and other styles

28

Fujiki, Sumiyoshi, and Donald D. Betts. "High Temperature Series Expansion of the Fluctuation of the Vector Chirality for the Spin-1/2XYAntiferromagnet onthe Triangular Lattice." Journal of the Physical Society of Japan 60, no. 2 (February 15, 1991): 435–40. http://dx.doi.org/10.1143/jpsj.60.435.

Full text

APA, Harvard, Vancouver, ISO, and other styles

29

Garcia de Andrade, L. C. "Generation of Primordial Magnetic Fields from QED and Higgs-like Domain Walls in Einstein–Cartan Gravity." Universe 8, no. 12 (December 14, 2022): 658. http://dx.doi.org/10.3390/universe8120658.

Full text

Abstract:

Spacetime torsion is known to be highly suppressed at the end of inflation, which is called preheating. This result was recently shown in (EPJ C (2022)) in the frame of Einstein–Cartan–Brans–Dicke inflation. In this paper, it is shown that a torsionful magnetogenesis in QED effective Lagrangean drives a torsion damping in order to be subsequently amplified by the dynamo effect after the generation of these magnetic fields seeds. This damping on amplification would depend upon the so-called torsion chirality. Here, a cosmic factor gkK is present where K is the contortion vector and k is the wave vector which is connected to the inverse of magnetic coherence length. In a second example, we find Higgs inlationary fields in Einstein–Cartan gravity thick domain walls (DWs). Recently, a modified Einstein–Cartan gravity was given by Shaposhnikov et al. [PRL (2020)] to obtain Higgs-like inflatons as a portal to dark energy. In the case of thick DW, we assume that there is a torsion squared influence, since we are in the early universe where torsion is not so weak as in the late universe as shown by Paul and SenGupta [EPJ C (2019)] in a 5D brane-world. A static DW solution is obtained when the inflationary potential vanishes and Higgs potential is a helical function. Recently, in the absence of inflation, domain wall dynamos were obtained in Einstein–Cartan gravity (EC) where the spins of the nucleons were orthogonal to the wall.

APA, Harvard, Vancouver, ISO, and other styles

30

Aulanier, G., and P. Démoulin. "3-D Twisted Flux-Tube in a Linear Force-Free Equilibrium." International Astronomical Union Colloquium 167 (1998): 86–89. http://dx.doi.org/10.1017/s0252921100047345.

Full text

Abstract:

AbstractIt is now commonly accepted that prominence plasma is supported in magnetic dips, in particular in twisted flux tubes. But present two-dimensional models are unable to explain the observed presence and structure of prominence feet. This requires three-dimensional models. We modelled the field using linear force-free field equations. Combining a small number of harmonics, and using observational constraints, we have found the area in the parameter space where prominences are likely to be present. Then, adding 3-D harmonics, we show that feet appear periodically underneath the prominence body. For great helicity, the parameter space is mostly fulfilled by configurations which have feet alternating between both sides of the prominence axis, as observed. The lateral feet are formed by dips in the vicinity of small magnetic polarities, that are located in a low field corridor where the prominence stands. The modelled configurations show in a natural fashion many observational aspects of prominences, such as the vector magnetic field measurements in prominences and the chirality patterns.

APA, Harvard, Vancouver, ISO, and other styles

31

Bielski, Roman, and Michal Tencer. "Macroscopically chiral system of three independent orientational effects as a condition for absolute asymmetric synthesis." Canadian Journal of Chemistry 81, no. 9 (September 1, 2003): 1029–37. http://dx.doi.org/10.1139/v03-128.

Full text

Abstract:

The paper introduces the concept of using three independent, macroscopic factors affecting mutual orientation of the reactant molecules to accomplish absolute asymmetric synthesis. Unlike with other methodologies of asymmetric synthesis in physical fields, none of the utilized factors is chiral in itself (as, e.g., circularly polarized light would be), but the combination of the three constitutes a macroscopically chiral influence. Examples of applicable directional factors are time-even vector fields (e.g., electric field and the directional effects of surfaces and interfaces) and the time-odd directional transport with encounter control. The directional factors employed may act simultaneously or, if their effect can be preserved, consecutively, thus allowing, e.g., a repeat use of the electric field. The electric field strength needed to achieve a practically useful degree of molecular orientation was estimated to be ca. 3 MV/cm, which is now commonly achieved with organic materials in the area of nonlinear optics. Practical implications are discussed, as well as the implications for the origins of natural homochirality.Key words: macroscopic chirality, absolute asymmetric synthesis, homochirality, physical fields.

APA, Harvard, Vancouver, ISO, and other styles

32

Kilina, Svetlana, Dzmitry A. Yarotski, A. Alec Talin, Sergei Tretiak, Antoinette J. Taylor, and Alexander V. Balatsky. "Unveiling Stability Criteria of DNA-Carbon Nanotubes Constructs by Scanning Tunneling Microscopy and Computational Modeling." Journal of Drug Delivery 2011 (March 20, 2011): 1–9. http://dx.doi.org/10.1155/2011/415621.

Full text

Abstract:

We present a combined approach that relies on computational simulations and scanning tunneling microscopy (STM) measurements to reveal morphological properties and stability criteria of carbon nanotube-DNA (CNT-DNA) constructs. Application of STM allows direct observation of very stable CNT-DNA hybrid structures with the well-defined DNA wrapping angle of 63.4° and a coiling period of 3.3 nm. Using force field simulations, we determine how the DNA-CNT binding energy depends on the sequence and binding geometry of a single strand DNA. This dependence allows us to quantitatively characterize the stability of a hybrid structure with an optimal π-stacking between DNA nucleotides and the tube surface and better interpret STM data. Our simulations clearly demonstrate the existence of a very stable DNA binding geometry for (6,5) CNT as evidenced by the presence of a well-defined minimum in the binding energy as a function of an angle between DNA strand and the nanotube chiral vector. This novel approach demonstrates the feasibility of CNT-DNA geometry studies with subnanometer resolution and paves the way towards complete characterization of the structural and electronic properties of drug-delivering systems based on DNA-CNT hybrids as a function of DNA sequence and a nanotube chirality.

APA, Harvard, Vancouver, ISO, and other styles

33

Balasubramanian, Krishnan. "Symmetry and Combinatorial Concepts for Cyclopolyarenes, Nanotubes and 2D-Sheets: Enumerations, Isomers, Structures Spectra & Properties." Symmetry 14, no. 1 (December 28, 2021): 34. http://dx.doi.org/10.3390/sym14010034.

Full text

Abstract:

This review article highlights recent developments in symmetry, combinatorics, topology, entropy, chirality, spectroscopy and thermochemistry pertinent to 2D and 1D nanomaterials such as circumscribed-cyclopolyarenes and their heterocyclic analogs, carbon and heteronanotubes and heteronano wires, as well as tessellations of cyclopolyarenes, for example, kekulenes, septulenes and octulenes. We establish that the generalization of Sheehan’s modification of Pólya’s theorem to all irreducible representations of point groups yields robust generating functions for the enumeration of chiral, achiral, position isomers, NMR, multiple quantum NMR and ESR hyperfine patterns. We also show distance, degree and graph entropy based topological measures combined with techniques for distance degree vector sequences, edge and vertex partitions of nanomaterials yield robust and powerful techniques for thermochemistry, bond energies and spectroscopic computations of these species. We have demonstrated the existence of isentropic tessellations of kekulenes which were further studied using combinatorial, topological and spectral techniques. The combinatorial generating functions obtained not only enumerate the chiral and achiral isomers but also aid in the machine construction of various spectroscopic and ESR hyperfine patterns of the nanomaterials that were considered in this review. Combinatorial and topological tools can become an integral part of robust machine learning techniques for rapid computation of the combinatorial library of isomers and their properties of nanomaterials. Future applications to metal organic frameworks and fullerene polymers are pointed out.

APA, Harvard, Vancouver, ISO, and other styles

34

Belinsky, Moisey I. "Field-dependent spin chirality and frustration in V3 and Cu3 nanomagnets in transverse magnetic field. 1. Correlations between variable planar spin configurations, vector and scalar chiralities and magnetization." Chemical Physics 435 (May 2014): 62–94. http://dx.doi.org/10.1016/j.chemphys.2013.11.012.

Full text

APA, Harvard, Vancouver, ISO, and other styles

35

Tiwari, Sanjiv Kumar. "Helicity of the solar magnetic field." Proceedings of the International Astronomical Union 6, S273 (August 2010): 21–27. http://dx.doi.org/10.1017/s1743921311014955.

Full text

Abstract:

AbstractHelicity measures complexity in the field. Magnetic helicity is given by a volume integral over the scalar product of magnetic field B and its vector potential A. A direct computation of magnetic helicity in the solar atmosphere is not possible due to unavailability of the observations at different heights and also due to non-uniqueness of A. The force-free parameter α has been used as a proxy of magnetic helicity for a long time. We have clarified the physical meaning of α and its relationship with the magnetic helicity. We have studied the effect of polarimetric noise on estimation of various magnetic parameters. Fine structures of sunspots in terms of vertical current (Jz) and α have been examined. We have introduced the concept of signed shear angle (SSA) for sunspots and established its importance for non force-free fields. We find that there is no net current in sunspots even in presence of a significant twist, showing consistency with their fibril-bundle nature. The finding of existence of a lower limit of SASSA for a given class of X-ray flare will be very useful for space weather forecasting. A good correlation is found between the sign of helicity in the sunspots and the chirality of the associated chromospheric and coronal features. We find that a large number of sunspots observed in the declining phase of solar cycle 23 do not follow the hemispheric helicity rule whereas most of the sunspots observed in the beginning of new solar cycle 24 do follow. This indicates a long term behaviour of the hemispheric helicity patterns in the Sun. The above sums up my PhD thesis.

APA, Harvard, Vancouver, ISO, and other styles

36

Nakagawa, Kenta, Kazuhiko Isikawa, and Toru Asahi. "Chiroptical study on benzil crystal using G-HAUP." Acta Crystallographica Section A Foundations and Advances 70, a1 (August 5, 2014): C383. http://dx.doi.org/10.1107/s2053273314096168.

Full text

Abstract:

There has been a great interest in understanding chiroptical properties such as optical rotatory power (ORP) and circular dichroism (CD) in anisotropic materials because these properties provide valuable information on molecular/crystal structure. In particular, generation of chiroptical properties in crystals composed of achiral compounds is considered as one of the most intriguing topics in the field of crystal optics. Benzil (C6H5COCOC6H5), which consists of two phenyl rings and two carbonyl groups, is achiral in solution, but exhibits chirality in the crystalline state. In the crystalline state, the molecules are arranged in a helical form and are put along three-fold left-handed screw axis or right-handed one. The benzil crystal belongs to trigonal crystal system with non-centrosymmetric space group P3121 or P3221. Hence, the crystal symmetry allows the benzil crystal to exhibit ORP and CD and indeed it is often used as a chiral reference crystal in visible/ultraviolet region (S. Chandrasekhar, 1954; N. K. Chaudhuri & M. A. El-Sayed, 1967) as well as α-quartz and nickel sulphate hexahydrate crystals. Meanwhile, ORP and CD reflect spatial dispersion of a second-rank permittivity tensor that depends on not only frequency but also wave vector of an electromagnetic wave. Furthermore, the magnitude of ORP and CD usually vary with the direction of an incident light. It is therefore much important in chiral science to discuss the relationship between ORP and CD along the principal axes and the molecular arrangements along them, respectively. In the case of benzil crystal, it is expected to show different ORP and CD along the a and c axes because of its trigonal crystal system, D3. In this study, we attempt to measure the ORP and CD of benzil crystal in the direction of the c and a axes with the Generalized-High Accuracy Universal Polarimeter (G-HAUP)(M. Tanaka et al., 2012).

APA, Harvard, Vancouver, ISO, and other styles

37

Chan, K. T., N. G. Stephen, and S. R. Reid. "Helical structure of the waves propagating in a spinning Timoshenko beam." Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences 461, no. 2064 (October 4, 2005): 3913–34. http://dx.doi.org/10.1098/rspa.2005.1524.

Full text

Abstract:

The aim of the paper is to study the cause of a frequency-splitting phenomenon that occurs in a spinning Timoshenko beam. The associated changes in the structure of the progressive waves are investigated to shed light on the relationship between the wave motion in a spinning beam and the whirling of a shaft. The main result is that travelling bending waves in a beam spinning about its central axis have the topological structure of a revolving helix traced by the centroidal axis with right-handed or left-handed chirality. Each beam element behaves like a gyroscopic disc in precession being rotated at the wave frequency with anticlockwise or clockwise helicity. The gyroscopic effect is identified as the cause of the frequency splitting and is shown to induce a coupling between two interacting travelling waves lying in mutually orthogonal planes. Two revolving waves travelling in the same direction in space appear, one at a higher and one at a lower frequency compared with the pre-split frequency value. With reference to a given spinning speed, taken as clockwise, the higher one revolves clockwise and the lower one has anticlockwise helicity, each wave being represented by a characteristic four-component vector wavefunction. Two factors are identified as important, the shear-deformation factor q and the gyroscopic-coupling phase factor θ . The q -factor is related to the wavenumber and the geometric shape of the helical wave. The θ -factor is related to the wave helicity and has two values, + π /2 and − π /2 corresponding to the anticlockwise and clockwise helicity, respectively. The frequency-splitting phenomenon is addressed by analogy with other physical phenomena such as the Jeffcott whirling shaft and the property of the local energy equality of a travelling wave. The relationship between Euler's formula and the present result relating to the helical properties of the waves is also explored.

APA, Harvard, Vancouver, ISO, and other styles

38

Sidorova, Alla, Vladimir Bystrov, Aleksey Lutsenko, Denis Shpigun, Ekaterina Belova, and Ilya Likhachev. "Quantitative Assessment of Chirality of Protein Secondary Structures and Phenylalanine Peptide Nanotubes." Nanomaterials 11, no. 12 (December 5, 2021): 3299. http://dx.doi.org/10.3390/nano11123299.

Full text

Abstract:

In this study we consider the features of spatial-structure formation in proteins and their application in bioengineering. Methods for the quantitative assessment of the chirality of regular helical and irregular structures of proteins are presented. The features of self-assembly of phenylalanine (F) into peptide nanotubes (PNT), which form helices of different chirality, are also analyzed. A method is proposed for calculating the magnitude and sign of the chirality of helix-like peptide nanotubes using a sequence of vectors for the dipole moments of individual peptides.

APA, Harvard, Vancouver, ISO, and other styles

39

Sidorova, Alla E., Ekaterina V. Malyshko, Aleksey O. Lutsenko, Denis K. Shpigun, and Olga E. Bagrova. "Protein Helical Structures: Defining Handedness and Localization Features." Symmetry 13, no. 5 (May 15, 2021): 879. http://dx.doi.org/10.3390/sym13050879.

Full text

Abstract:

The quantitative evaluation of the chirality of macromolecule structures remains one of the exciting issues in biophysics. In this paper, we propose methods for quantitative analysis of the chirality of protein helical and superhelical structures. The analysis of the chirality sign of the protein helical structures (α-helices and 310-helices) is based on determining the mixed product of every three consecutive vectors between neighboring reference points—α-carbons atoms. The method for evaluating the chirality sign of coiled-coil structures is based on determining the direction and value of the angle between the coiled-coil axis and the α-helices axes. The chirality sign of the coiled coil is calculated by averaging the value of the cosine of the corresponding angle for all helices forming the superhelix. Chirality maps of helical and superhelical protein structures are presented. Furthermore, we propose an analysis of the distributions of helical and superhelical structures in polypeptide chains of several protein classes. The features common to all studied classes and typical for each protein class are revealed. The data obtained, in all likelihood, can reflect considerations about molecular machines as chiral formations.

APA, Harvard, Vancouver, ISO, and other styles

40

PARGANLIJA, DENIS, FRANCESCO GIACOSA, DIRK H. RISCHKE, PÉTER KOVÁCS, and GYŐRGY WOLF. "A LINEAR SIGMA MODEL WITH THREE FLAVORS AND VECTOR AND AXIAL-VECTOR MESONS." International Journal of Modern Physics A 26, no. 03n04 (February 10, 2011): 607–9. http://dx.doi.org/10.1142/s0217751x11052189.

Full text

Abstract:

We outline the extension of the globally chirally invariant Nf = 2 linear sigma model with vector and axial-vector degrees of freedom to Nf = 3. We present preliminary results concerning the scalar meson masses.

APA, Harvard, Vancouver, ISO, and other styles

41

Urban, M., M. Buballa, and J. Wambach. "Vector and axial-vector correlators in a chirally symmetric model." Nuclear Physics A 697, no. 1-2 (January 2002): 338–71. http://dx.doi.org/10.1016/s0375-9474(01)01248-9.

Full text

APA, Harvard, Vancouver, ISO, and other styles

42

Dryzun, Chaim, and David Avnir. "Chirality Measures for Vectors, Matrices, Operators and Functions." ChemPhysChem 12, no. 1 (December 29, 2010): 197–205. http://dx.doi.org/10.1002/cphc.201000715.

Full text

APA, Harvard, Vancouver, ISO, and other styles

43

NOVOZHILOV, VICTOR, and YURI NOVOZHILOV. "COLOR BOSONIZATION, CHIRAL PARAMETRIZATION OF GLUONIC FIELD AND QCD EFFECTIVE ACTION." Modern Physics Letters A 21, no. 35 (November 20, 2006): 2649–61. http://dx.doi.org/10.1142/s0217732306021815.

Full text

Abstract:

We develop a color bosonization approach to treat QCD gauge field ("gluons") at low energies in order to derive an effective color action of QCD taking into account the quark chiral anomaly in the case of SU(2) color. We have found that there exists such a region in the chiral sector of color space, where a gauge field coincides with chirally rotated vector field, while an induced axial vector field disappears. In this region, the unit color vector of chiral field plays a defining role, and a gauge field is parametrized in terms of chiral parameters, so that no additional degrees of freedom are introduced by the chiral field. A QCD gauge field decomposition in color bosonization is a sum of a chirally rotated gauge field and an induced axial-vector field expressed in terms of gluonic variables. An induced axial-vector field defines the chiral color anomaly and an effective color action of QCD. This action admits existence of a gauge invariant d = 2 condensate of induced axial-vector field and mass.

APA, Harvard, Vancouver, ISO, and other styles

44

LEUPOLD, STEFAN, and MARKUS WAGNER. "CHIRAL PARTNERS IN A CHIRALLY BROKEN WORLD." International Journal of Modern Physics A 24, no. 02n03 (January 30, 2009): 229–36. http://dx.doi.org/10.1142/s0217751x09043523.

Full text

Abstract:

The isovector–vector and the isovector–axial-vector current are related by a chiral transformation. These currents can be called chiral partners at the fundamental level. In a world where chiral symmetry was not broken, the corresponding current-current correlators would show the same spectral information. In the real world chiral symmetry is spontaneously broken. A prominent peak — the ρ-meson — shows up in the vector spectrum (measured in e+e--collisions and τ-decays). On the other hand, in the axial-vector spectrum a broad bump appears — the a1-meson (also accessible in τ-decays). It is tempting to call ρ and a1 chiral partners at the hadronic level. Strong indications are brought forward that these "chiral partners" do not only differ in mass but even in their nature: The ρ-meson appears dominantly as a quark-antiquark state with small modifications from an attractive pion-pion interaction. The a1-meson, on the other hand, can be understood as a meson-molecule state mainly formed by the attractive interaction between pion and ρ-meson. A key issue here is that the meson-meson interactions are fixed by chiral symmetry breaking. It is demonstrated that one can understand the vector and the axial-vector spectrum very well within this interpretation. It is also shown that the opposite cases, namely ρ as a pion-pion molecule or a1 as a quark-antiquark state lead to less satisfying results. Finally speculations on possible in-medium changes of hadron properties are presented.

APA, Harvard, Vancouver, ISO, and other styles

45

BORASOY, B., and ULF-G. MEIßNER. "CHIRAL LAGRANGIANS FOR BARYONS COUPLED TO MASSIVE SPIN-1 FIELDS." International Journal of Modern Physics A 11, no. 29 (November 20, 1996): 5183–202. http://dx.doi.org/10.1142/s0217751x96002376.

Full text

Abstract:

We analyze the effective low energy field theory of Goldstone bosons and baryons chirally coupled to massive spin-1 fields. We use the electromagnetic baryon form factors to demonstrate the formal equivalence between the vector and the tensor field formulation for the spin-1 fields. We also discuss the origin of the so-called Weinberg term in pion–nucleon scattering and the role of ρ meson exchange. Chirally coupled vector mesons do not give rise to this two-pion nucleon seagull interaction but rather to higher order corrections. Some problems of the formal equivalence arising in higher orders and related to loops are touched upon.

APA, Harvard, Vancouver, ISO, and other styles

46

Lee, Hyoung-In. "Anti-Symmetric Medium Chirality Leading to Symmetric Field Helicity in Response to a Pair of Circularly Polarized Plane Waves in Counter-Propagating Configuration." Symmetry 14, no. 9 (September 10, 2022): 1895. http://dx.doi.org/10.3390/sym14091895.

Full text

Abstract:

We examine how a chiral medium responds to a pair of plane waves of circular polarizations. To this goal, we assume the chiral medium to be spatially homogeneous for simplicity. By assuming the medium to be a lossless, we provide analytic formulas of key bilinear parameters such as the pair of electromagnetic and reactive Poynting vectors in addition to the pair of electromagnetic and reactive helicities. By examining two obliquely colliding plane waves, we learned that most of those key parameters are asymmetric with respect to the medium chirality. Only for a counter-propagating pair, some of those key parameters are found to exhibit symmetry with respect to the medium chirality. We will discuss the implications of those asymmetries and symmetries from the viewpoints of typical applications in optics and physics.

APA, Harvard, Vancouver, ISO, and other styles

47

Ambrožič, Milan, Apparao Gudimalla, Charles Rosenblatt, and Samo Kralj. "Multiple Twisted Chiral Nematic Structures in Cylindrical Confinement." Crystals 10, no. 7 (July 4, 2020): 576. http://dx.doi.org/10.3390/cryst10070576.

Full text

Abstract:

In this article, we theoretically and numerically study the chirality and saddle-splay elastic constant ( K 24 ) -enabled stability of multiple twist-like nematic liquid crystal (LC) structures in cylindrical confinement. We focus on the so-called radially z-twisted (RZT) and radially twisted (RT) configurations, which simultaneously exhibit twists in different spatial directions. We express the free energies of the structures in terms of dimensionless wave vectors, which characterise the structures and play the roles of order parameters. The impact of different confinement anchoring conditions is explored. A simple Landau-type analysis provides an insight into how different model parameters influence the stability of structures. We determine conditions for which the structures are stable in chiral and also nonchiral LCs. In particular, we find that the RZT structure could exhibit macroscopic chirality inversion upon varying the relevant parameters. This phenomenon could be exploited for the measurement of K 24 .

APA, Harvard, Vancouver, ISO, and other styles

48

NOVOZHILOV, VICTOR, and YURI NOVOZHILOV. "CHIRAL PARAMETRIZATION OF QCD VECTOR FIELD IN SU(3)." Modern Physics Letters A 23, no. 39 (December 21, 2008): 3285–97. http://dx.doi.org/10.1142/s0217732308028685.

Full text

Abstract:

The chiral parametrization of gluons in SU(3) QCD is proposed extending an approach developed earlier for SU(2) case. A color chiral field is introduced, gluons are chirally rotated, and vector component of rotated gluons is defined on condition that no new color variables appeared with the chiral field. This condition associates such a vector component with SU(3)/U(2) coset plus a U(2) field. The topological action in SU(3) QCD is derived. It is expressed in terms of axial vector component of rotated gluons. The vector field in CP2 sector is studied in new variables of chiral parametrization.

APA, Harvard, Vancouver, ISO, and other styles

49

Resende, Diana I. S. P., Amalia M. Estévez, Andre M. Alker, Rainer E. Martin, and Hans Peter Wessel. "A carbohydrate-derived trifunctional scaffold for medicinal chemistry library synthesis." Mediterranean Journal of Chemistry 7, no. 2 (September 5, 2018): 135–44. http://dx.doi.org/10.13171/mjc72/01809051415-wessel.

Full text

Abstract:

For the generation of compound libraries for drug discovery a central scaffold containing three exit vectors with defined chirality was devised starting from commercially available tri-O-acetyl-glucal. Surprisingly, the reaction of a 4-O-mesylate with sodium azide did not lead to the expected 4-azido-4-deoxy derivative but to a 3-azido-3-deoxy regioisomer via intermediate epoxide formation. The absolute stereochemical configuration of the final tetrahydropyran building block was proven by X-ray crystallography. This scaffold endowed with a carboxylic acid, a secondary alcohol, and an azide functionality may be connected to a DNA tag at any of the three distinct exit vectors, thus providing ready access to several different compound libraries.Â

APA, Harvard, Vancouver, ISO, and other styles

50

LI, Bingjue. "Chirality sorting using structured caustic vector vortex field." Journal of the Optical Society of America B, May 10, 2022. http://dx.doi.org/10.1364/josab.462509.

Full text

APA, Harvard, Vancouver, ISO, and other styles

Journal articles on the topic 'Vector chirality'

Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles