Anomaly-induced Quadrupole Moment of the Neutron in Magnetic Field

The neutrons cannot possess a quadrupole moment in the vacuum. Nevertheless, we show that in the presence of an external magnetic field the neutrons acquire a new type of quadrupole moment $Q^{ij}= \chi\,\sigma^i B^j$ involving the components of spin and magnetic field. This "chiral magnetic" quadrupole moment arises from the interplay of the chiral anomaly and the magnetic field; we estimate its value for the neutron in the static limit, and find $\chi \simeq 1.35\cdot10^{-2}\,{\rm fm}^4$. The detection of the quadrupole moment of the neutron would provide a novel test of the role of the chiral anomaly in low-energy QCD and can be possible in the presence of both magnetic and inhomogeneous electric fields. The quadrupole moment of the neutron may affect e.g. the properties of neutron stars and magnetars.Comment: 2 pages; extended versio

Fourier Transform Infrared Spectroscopy Study on Cation adsorption on Viscose Rayon Succinate

Ion-exchange materials have been considered as suitable material for the recovery of heavy metals in water. A viscose rayon succinate, synthesized from viscose rayon and succinic anhydride in presence of DMSO, to remove trace bivalent metal ions such as Ag+, Cu2+, Ni2+, Pb2+, Zn2+ and Cr3+, was studied using FT-IR for the behavior of metal adsorption. Both esterification and carboxyl bonding of viscose rayon succinate were assigned essentially at 1729 and 1693cm-1, respectively. And the essential band of bonding between metal and the material was determined at 1625cm-1. The available adsorption capacity of this fiber was 6.2 mequiv/g. The adsorption of metal ions on the viscose rayon succinate follows the order of Cu2+>Cr3+>Ni2+>Pb2+>Zn2+>Ag+ with maximum adsorptions capacities 4.2, 1.42, 0.91, 0.83, 0.69 and 0.35 mmol/g, respectively.DOI: http://dx.doi.org/10.5564/mjc.v12i0.189 Mongolian Journal of Chemistry Vol.12 2011: 136-14

Nucleon Form Factors and Hidden Symmetry in Holographic QCD

The vector dominance of the electromagnetic form factors both for mesons and baryons arises naturally in holographic QCD, where both the number of colors and the 't Hooft coupling are taken to be very large, offering a bona-fide derivation of the notion of vector dominance. The crucial ingredient for this is the infinite tower of vector mesons in the approximations made which share features that are characteristic of the quenched approximation in lattice QCD. We approximate the infinite sum by contributions from the lowest four vector mesons of the tower which turn out to saturate the charge and magnetic moment sum rules within a few percent and compute them totally free of unknown parameters for momentum transfers Q^2 less than 1GeV^2. We identify certain observables that can be reliably computed within the approximations and others that are not, and discuss how the improvement of the latter can enable one to bring holographic QCD closer to QCD proper.Comment: 18 pages, 4 figures, revtex4; one reference added, final version to appear in Phys. Rev.

Evaluating Receiver Noise Temperature of a Radio Telescope in the Presence of Mutual Coupling: Comparison of Current Methodologies

© 2019 European Association on Antennas and Propagation. We present the computation of receiver noise temperature which includes the effects of mutual coupling of two different radio telescopes deployed in the Murchison Radio-astronomy Observatory, namely the Murchison Widefield Array and the prototype Engineering Development Array. We used three different formulations that only require information of measured noise parameters of the low noise amplifier as used in the radio telescope and simulated S-parameter of the array to perform the calculation. In addition, we show convergence in computed receiver noise temperature for various pointing angles and array configurations (uniform and pseudo-random) that indicate agreement with existing literature

Coexistence of charge density wave and spin-Peierls orders in quarter-filled quasi-one dimensional correlated electron systems

Charge and spin-Peierls instabilities in quarter-filled (n=1/2) compounds consisting of coupled ladders and/or zig-zag chains are investigated. Hubbard and t-J models including local Holstein and/or Peierls couplings to the lattice are studied by numerical techniques. Next nearest neighbor hopping and magnetic exchange, and short-range Coulomb interactions are also considered. We show that, generically, these systems undergo instabilities towards the formation of Charge Density Waves, Bond Order Waves and (generalized) spin-Peierls modulated structures. Moderate electron-electron and electron-lattice couplings can lead to a coexistence of these three types of orders. In the ladder, a zig-zag pattern is stabilized by the Holstein coupling and the nearest-neighbor Coulomb repulsion. In the case of an isolated chain, bond-centered and site-centered 2k_F and 4k_F modulations are induced by the local Holstein coupling. In addition, we show that, in contrast to the ladders, a small charge ordering in the chains, strongly enhances the spin-Peierls instability. Our results are applied to the NaV_2O_5 compound (trellis lattice) and various phases with coexisting charge disproportionation and spin-Peierls order are proposed and discussed in the context of recent experiments. The role of the long-range Coulomb potential is also outlined.Comment: 10 pages, Revtex, 10 encapsulated figure

Chiral magnetic wave at finite baryon density and the electric quadrupole moment of quark-gluon plasma in heavy ion collisions

Chiral Magnetic Wave (CMW) is a gapless collective excitation of quark-gluon plasma in the presence of external magnetic field that stems from the interplay of Chiral Magnetic (CME) and Chiral Separation Effects (CSE); it is composed by the waves of the electric and chiral charge densities coupled by the axial anomaly. We consider CMW at finite baryon density and find that it induces the electric quadrupole moment of the quark-gluon plasma produced in heavy ion collisions: the "poles" of the produced fireball (pointing outside of the reaction plane) acquire additional positive electric charge, and the "equator" acquires additional negative charge. We point out that this electric quadrupole deformation lifts the degeneracy between the elliptic flows of positive and negative pions leading to $v_2(\pi^+) < v_2(\pi^-)$, and estimate the magnitude of the effect.Comment: 4 pages, 3 figure

Towards quality control of food using terahertz

Copyright © 2007 SPIE - The International Society for Optical Engineering. Copyright 2007 Society of Photo-Optical Instrumentation Engineers. This paper was published in BioMEMS and Nanotechnology III, edited by Dan V. Nicolau, Derek Abbott, Kourosh Kalantar-Zadeh, Tiziana Di Matteo, Sergey M. Bezrukov, Proc. of SPIE Vol. 6799, 67991E and is made available as an electronic reprint with permission of SPIE. One print or electronic copy may be made for personal use only. Systematic or multiple reproduction, distribution to multiple locations via electronic or other means, duplication of any material in this paper for a fee or for commercial purposes, or modification of the content of the paper are prohibited.Terahertz radiation or T-rays, show promise in quality control of food products. As T-rays are inherently sensitive to water, they are very suitable for moisture detection. This proves to be a valuable asset in detecting the moisture content of dried food, a critical area for some products. As T-rays are transparent to plastics, food additives can also be probed through the packaging, providing checks against a manufacturer's claims, such as the presence of certain substances in foods.B. S. -Y. Ung and B. M. Fischer and B. W. -H. Ng and D. Abbot

Universality of plasmon excitations in Dirac semimetals

The recent experimental discovery of ${\rm Cd_3 As_2}$ and ${\rm Na_3 Bi}$ Dirac semimetals enables the study of the properties of chiral quasi-particles in three spatial dimensions. As demonstrated by photoemission, Dirac semimetals are characterized by a linear dispersion relation for fermion quasi-particles, and thus represent three dimensional analogs of graphene. While the distinctive behavior of chiral fermions (e.g. Klein tunneling) is already evident in two dimensional graphene, the physics of chirality in three dimensions opens a number of new possibilities. In this paper we investigate the properties of the collective plasmon excitations in Dirac semimetals by using the methods of relativistic field theory. We find a strong and narrow plasmon excitation whose frequency is in the terahertz (THz) range which may be important for practical applications. The properties of the plasmon appear universal for all Dirac semimetals, due to the large degeneracy of the quasi-particles and the small Fermi velocity, $v_F \ll c$. This universality is closely analogous to the phenomenon of "dimensional transmutation", that is responsible for the emergence of dimensionful scales in relativistic field theories such as Quantum Chromodynamics, the modern theory of nuclear physics.Comment: 11 pages, 3 figure