Journal articles: 'Electroweak theory; Faraday rotation'

1

Aono, Shigeyuki. "Theory of optical rotation, Faraday effect, and inverse Faraday effect." International Journal of Quantum Chemistry 75, no. 1 (1999): 33–45. http://dx.doi.org/10.1002/(sici)1097-461x(1999)75:1<33::aid-qua4>3.0.co;2-y.

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Buss, C., S. Hugonnard-Bruyère, R. Frey, and C. Flytzanis. "Theory of Faraday rotation in semimagnetic semiconductors." Solid State Communications 92, no. 11 (1994): 929–33. http://dx.doi.org/10.1016/0038-1098(94)90931-8.

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Xia, T. K., P. M. Hui, and D. Stroud. "Theory of Faraday rotation in granular magnetic materials." Journal of Applied Physics 67, no. 6 (1990): 2736–41. http://dx.doi.org/10.1063/1.345438.

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Connerade, J. P. "The theory of Faraday rotation in an autoionising resonance." Journal of Physics B: Atomic, Molecular and Optical Physics 21, no. 18 (1988): L551—L555. http://dx.doi.org/10.1088/0953-4075/21/18/001.

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Ferrière, K., J. L. West, and T. R. Jaffe. "The correct sense of Faraday rotation." Monthly Notices of the Royal Astronomical Society 507, no. 4 (2021): 4968–82. http://dx.doi.org/10.1093/mnras/stab1641.

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ABSTRACT The phenomenon of Faraday rotation of linearly polarized synchrotron emission in a magneto-ionized medium has been understood and studied for decades. But since the sense of the rotation itself is irrelevant in most contexts, some uncertainty and inconsistencies have arisen in the literature about this detail. Here, we start from basic plasma theory to describe the propagation of polarized emission from a background radio source through a magnetized, ionized medium in order to re-derive the correct sense of Faraday rotation. We present simple graphics to illustrate the decomposition of a linearly polarized wave into right and left circularly polarized modes, the temporal and spatial propagation of the phases of those modes, and the resulting physical rotation of the polarization orientation. We then re-examine the case of a medium that both Faraday rotates and emits polarized radiation and show how a helical magnetic field can construct or destruct the Faraday rotation. This paper aims to resolve a source of confusion that has arisen between the plasma physics and radio astronomy communities and to help avoid common pitfalls when working with this unintuitive phenomenon.

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Marinescu, Monica, Alexei A. Kornyshev, and Michael E. Flatté. "Electrical control of Faraday rotation at a liquid–liquid interface." Faraday Discussions 178 (2015): 363–70. http://dx.doi.org/10.1039/c4fd00210e.

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A theory is developed for the Faraday rotation of light from a monolayer of charged magnetic nanoparticles at an electrified liquid–liquid interface. The polarization fields of neighboring nanoparticles enhance the Faraday rotation. At such interfaces, and for realistic sizes and charges of nanoparticles, their adsorption–desorption can be controlled with a voltage variation <1 V, providing electrovariable Faraday rotation. A calculation based on the Maxwell-Garnett theory predicts that the corresponding redistribution of 40 nm nanoparticles of yttrium iron garnet can switch a cavity with a quality factor larger than 10<sup>4</sup> for light of wavelength 500 nm at normal incidence.

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Östreich, Th, K. Schönhammer, and L. J. Sham. "Theory of Spin Beatings in the Faraday Rotation of Semiconductors." Physical Review Letters 75, no. 13 (1995): 2554–57. http://dx.doi.org/10.1103/physrevlett.75.2554.

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Hui, P. M., and D. Stroud. "Theory of Faraday rotation by dilute suspensions of small particles." Applied Physics Letters 50, no. 15 (1987): 950–52. http://dx.doi.org/10.1063/1.97996.

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Xu, You, and Mingqian Duan. "Theory of Faraday rotation and susceptibility of rare-earth trifluorides." Physical Review B 46, no. 18 (1992): 11636–41. http://dx.doi.org/10.1103/physrevb.46.11636.

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Davies, I. O. G., P. E. G. Baird, and J. L. Nicol. "Theory and observation of Faraday rotation obtained with strong light fields." Journal of Physics B: Atomic and Molecular Physics 20, no. 20 (1987): 5371–86. http://dx.doi.org/10.1088/0022-3700/20/20/015.

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Martinez, J. C., and M. B. A. Jalil. "Theory of giant Faraday rotation and Goos-Hänchen shift in graphene." EPL (Europhysics Letters) 96, no. 2 (2011): 27008. http://dx.doi.org/10.1209/0295-5075/96/27008.

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FINKELSTEIN, ROBERT J. "THE ELEMENTARY PARTICLES AS QUANTUM KNOTS IN ELECTROWEAK THEORY." International Journal of Modern Physics A 22, no. 24 (2007): 4467–80. http://dx.doi.org/10.1142/s0217751x0703707x.

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We explore a knot model of the elementary particles that is compatible with electroweak physics. The knots are quantized and their kinematic states are labeled by [Formula: see text], irreducible representations of SU q(2), where j = N/2, m = w/2, m′ = (r+1)/2 and (N, w, r) designate respectively the number of crossings, the writhe, and the rotation of the knot. The knot quantum numbers (N, w, r) are related to the standard isotopic spin quantum numbers (t, t3, t0) by (t = N/6, t3 = -w/6, t0 = -(r+1)/6), where t0 is the hypercharge. In this model the elementary fermions are low lying states of the quantum trefoil (N = 3) and the gauge bosons are ditrefoils (N = 6). The fermionic knots interact by the emission and absorption of bosonic knots.

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Gridnev, V. N. "Theory of Faraday rotation beats in quantum wells with large spin splitting." Journal of Experimental and Theoretical Physics Letters 74, no. 7 (2001): 380–83. http://dx.doi.org/10.1134/1.1427126.

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Dani, Raj Kumar, Hongwang Wang, Stefan H. Bossmann, Gary Wysin, and Viktor Chikan. "Faraday rotation enhancement of gold coated Fe2O3 nanoparticles: Comparison of experiment and theory." Journal of Chemical Physics 135, no. 22 (2011): 224502. http://dx.doi.org/10.1063/1.3665138.

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SHOVKOVY, IGOR A., and XINYANG WANG. "ANALYSIS OF FARADAY ROTATION AND MAGNETO-OPTICAL TRANSMISSION IN MONOLAYER GRAPHENE." International Journal of Modern Physics B 28, no. 08 (2014): 1450061. http://dx.doi.org/10.1142/s0217979214500611.

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The Faraday rotation angle and the magneto-optical transmission of light through the monolayer graphene with a magnetic field perpendicular to the plane of graphene are calculated within the framework of the low-energy effective quantum field theory of Dirac quasiparticles. The general results are applicable not only in the semi-classical, but also in the degenerate quantum regime. The theoretical results are in a good quantitative agreement with the available experimental data. The only fit parameter in the model is the value of the quasiparticle width.

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Alavi, Omid, and Arman Najafizadeh. "Estimation of Verdet Constant for KCl, KBr, MgCl₂ Using Faraday Rotator." International Letters of Chemistry, Physics and Astronomy 47 (February 2015): 208–19. http://dx.doi.org/10.18052/www.scipress.com/ilcpa.47.208.

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Nowadays, the rapid development of optics technology, especially for laser technology and scientific fields is important. One of this optics theory is Faraday rotation. Way of light propagation in a material medium can be influenced by an external field. The applied magnetic field causes rotation of the plane of polarized light. This effect is due to the optical activity, a property of the material that causes the rotation of the electric field of an incident linear wave. In this paper, we present an experiment to measure the Verdet constant through Faraday Effect using the Faraday rotator. Verdet constant is a factor for relation of magnetic field and the length of the path. When this effect is used in spectrographic studies, we can find information on the properties of higher energy states. Used materials for this experiment are KCl, KBr, and MgCl2. We used three lasers with different wavelengths 405nm, 450nm, and 515nm. We shows that the linear polarized light rotates after passing the applied magnetic field, when it's parallel with the magnetic field vector. Verdet constant are calculated about 382, 429.125, and 311.625 in 450nm for KCl, KBr, MgCl2 solutions.

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BRYNILDSEN, MIKKEL H., and HORIA D. CORNEAN. "ON THE VERDET CONSTANT AND FARADAY ROTATION FOR GRAPHENE-LIKE MATERIALS." Reviews in Mathematical Physics 25, no. 04 (2013): 1350007. http://dx.doi.org/10.1142/s0129055x13500074.

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We present a rigorous and rather self-contained analysis of the Verdet constant in graphene-like materials. We apply the gauge-invariant magnetic perturbation theory to a nearest-neighbor tight-binding model and obtain a relatively simple and exactly computable formula for the Verdet constant, at all temperatures and all frequencies of sufficiently large absolute value. Moreover, for the standard nearest-neighbor tight-binding model of graphene we show that the transverse component of the conductivity tensor has an asymptotic Taylor expansion in the external magnetic field where all the coefficients of even powers are zero.

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Huang, Min. "Faraday Rotation Spectra Analysis on TbYbBiIG Crystals in Optical Communication Band." Advanced Materials Research 562-564 (August 2012): 1753–56. http://dx.doi.org/10.4028/www.scientific.net/amr.562-564.1753.

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his paper is concerned with the FR spectra analysis on the Bi, Tb and Yb partially substituted iron garnet crystals of Tb3-x-yYbyBixFe5O12. A specific FR (-1617o/cm at 1.55μm), a low FWC (0.009%/nm at 25oC) of Tb0.91Yb1.38Bi0.71Fe5O12 crystals grown from Bi2O3 self-fluxed melts can be used as broadband optical communication components. In order to interpret their FR spectra, a theory based on molecular-orbital levels of Fe3+ in tetrahedral and octahedral sites is used. It is shown that in the case of higher Bi3+ substitution, FR is mainly determined by the contribution of Fe3+ in the octahedral site. Furthermore, two types of rare-earth ions (Tb3+ and Yb3+) moderate the contribution to FR from Fe3+ in octahedral and decahedral sites and eventually have caused that Bi-substituted mixed rare-earth iron garnet has a near-zero Faraday rotation wavelength coefficient (FWC).

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Brüggen, Marcus, Shane O’Sullivan, Annalisa Bonafede, and Franco Vazza. "Magnetic fields in the intergalactic medium and in the cosmic web." Proceedings of the International Astronomical Union 14, A30 (2018): 303–6. http://dx.doi.org/10.1017/s1743921319004460.

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AbstractIn these proceedings we discuss advances in the theory and observation of magnetic fields in the intergalactic medium and in the cosmic web. We make the point that, despite perhaps unsurmountable obstacles in simulating a small-scale dynamo, currently most cosmological magnetohydrodynamical simulations paint a similar picture of magnetic field amplification in the cosmos. However, observations of magnetic fields in the intergalactic medium turn out to be very difficult. As a case in point, we present recent work on Faraday rotation measurement in the direction of a giant galaxy with the Low Frequency Array (LOFAR). These observations demonstrate the currently unique capability of LOFAR to measure Faraday rotation at the high accuracy and angular resolution required to investigate the magnetisation of large-scale structure filaments of the cosmic web.

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Wolfe, Arthur M., Regina A. Jorgenson, Timothy Robishaw, Carl Heiles та Jason X. Prochaska. "An 84-μG Magnetic Field in a Galaxy at Z=0.692?" Proceedings of the International Astronomical Union 4, S254 (2008): 95–96. http://dx.doi.org/10.1017/s1743921308027439.

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AbstractThe magnetic field pervading our Galaxy is a crucial constituent of the interstellar medium: it mediates the dynamics of interstellar clouds, the energy density of cosmic rays, and the formation of stars (Beck 2005). The field associated with ionized interstellar gas has been determined through observations of pulsars in our Galaxy. Radio-frequency measurements of pulse dispersion and the rotation of the plane of linear polarization, i.e., Faraday rotation, yield an average value B ≈ 3 μG (Han et al. 2006). The possible detection of Faraday rotation of linearly polarized photons emitted by high-redshift quasars (Kronberg et al. 2008) suggests similar magnetic fields are present in foreground galaxies with redshifts z > 1. As Faraday rotation alone, however, determines neither the magnitude nor the redshift of the magnetic field, the strength of galactic magnetic fields at redshifts z > 0 remains uncertain.Here we report a measurement of a magnetic field of B ≈ 84 μG in a galaxy at z =0.692, using the same Zeeman-splitting technique that revealed an average value of B = 6 μG in the neutral interstellar gas of our Galaxy (Heiles et al. 2004). This is unexpected, as the leading theory of magnetic field generation, the mean-field dynamo model, predicts large-scale magnetic fields to be weaker in the past, rather than stronger (Parker 1970).The full text of this paper was published in Nature (Wolfe et al. 2008).

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Cai, Wei, Zhiyong Yang, Junhui Xing, and Youan Xu. "Study on the spatial roll angle measurement based on magneto-optic modulation." MATEC Web of Conferences 208 (2018): 03001. http://dx.doi.org/10.1051/matecconf/201820803001.

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Faraday rotation angle formula for polarized light propagating in magneto-optic medium is investigated theoretically. Based on the Biot-Savart Law and Maxwell's equations, a calculation model for electromagnetic field in solenoid paraxial region is deduced. Taking advantage of this model, together with the Bessel functions, the axial magnetic field in a typical medium is calculated and analyzed. In addition, to thoroughly analyze the influence mechanisms of the incident wavelength and temperature on the Verdet constant and then uncover its essence, a hypothesis which suggests the Faraday effect results from the combination of various factors is proposed. Furthermore, a theory of wave-transition contribution to the Verdet constant is deduced by adopting the theory of wave-particle duality. Taking the typical diamagnetic material ZF1 and paramagnetic material TGG as examples, the deduced theory together with the corresponding models is tested and verified by analyzing the relevant parameters and the test data. At last, a testing system for magneto-optical rotation together with its finite element model is introduced.

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Fujimoto, M., and T. Sawa. "Large-Scale Galactic and Intergalactic Magnetic Fields." Symposium - International Astronomical Union 140 (1990): 90–94. http://dx.doi.org/10.1017/s0074180900189648.

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Large-scale axisymmetric and bisymmetric spiral (ASS and BSS) structures are found of magnetic fields in spiral galaxies by measuring the Faraday rotation of polarized radio emission. Dynamo theory is introduced to explain the field structures, and strong magnetogravitational interaction is suggested to occur between the BSS magnetic fields and spiral density waves. Up-to-date data about the rotation measures RM and redshifts z of QSOs and distant radio galaxies are given for discussing large-scale intergalactic magnetic fields.

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Daschner, Maximilian, David I. Kaiser, and Joseph A. Formaggio. "Exploiting Faraday rotation to jam quantum key distribution via polarized photons." Quantum Information and Computation 19, no. 15&16 (2019): 1313–24. http://dx.doi.org/10.26421/qic19.15-16-4.

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Quantum key distribution (QKD) involving polarized photons could be vulnerable to a jamming (or denial-of-service) attack, in which a third party applies an external magnetic field to rotate the plane of polarization of photons headed toward one of the two intended recipients. Sufficiently large Faraday rotation of one of the polarized beams would prevent Alice and Bob from establishing a secure quantum channel. We investigate requirements to induce such rotation both for free-space transmission and for transmission via optical fiber, and find reasonable ranges of parameters in which a jamming attack could be successful against fiber-based QKD, even for systems that implement automated recalibration for polarization-frame alignment. The jamming attack could be applied selectively and indefinitely by an adversary without revealing her presence, and could be further combined with various eavesdropping attacks to yield unauthorized information.

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KONAR, SUSHAN. "PHOTON PROPAGATION IN A MAGNETIZED MEDIUM." International Journal of Modern Physics A 17, no. 06n07 (2002): 1055–58. http://dx.doi.org/10.1142/s0217751x02010509.

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Using the real time formalism of the finite temperature field theory we calculate the 1-loop polarization tensor in the presence of a background magnetic field in a medium. The expression is obtained to linear order in the background field strength. We discuss the Faraday rotation as well as the photon absorption probabilities in this context.

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Terasaki, Akira, Takuya Majima, and Tamotsu Kondow. "Zeeman splitting and Faraday rotation associated with Mn+ 7PJ←7S3absorption: Photon-trap spectroscopy and quantum-theory analysis." Journal of Physics: Conference Series 185 (September 1, 2009): 012045. http://dx.doi.org/10.1088/1742-6596/185/1/012045.

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Schuller, F., D. N. Stacey, R. B. Warrington, and K. P. Zetie. "Theory of Faraday rotation produced by atoms near a Jg= 1/2 to Je= 1/2 transition." Journal of Physics B: Atomic, Molecular and Optical Physics 28, no. 17 (1995): 3783–90. http://dx.doi.org/10.1088/0953-4075/28/17/016.

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Hutschenreuter, Sebastian, and Torsten A. Enßlin. "The Galactic Faraday depth sky revisited." Astronomy & Astrophysics 633 (January 2020): A150. http://dx.doi.org/10.1051/0004-6361/201935479.

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Context. The Galactic Faraday depth sky is a tracer for both the Galactic magnetic field and the thermal electron distribution. It was previously reconstructed from polarimetric measurements of extra-Galactic point sources. Aims. Here we improve on these works by using an updated inference algorithm and by taking into account the electron emission measure as traced by free–free emission measured by the Planck survey. In the future the data situation will improve drastically thanks to the next generation Faraday rotation measurements from the SKA and its pathfinders. Anticipating this, a further aim of this paper is to update the map reconstruction method with some of the latest developments in Bayesian imaging. Methods. To this end we made use of information field theory, an inference scheme that is particularly powerful in cases of noisy and incomplete data. Results. We demonstrate the validity of the new algorithm by applying it to an existing data compilation. Even though we used exactly the same data set, a number of novel findings are made; for example, a non-parametric reconstruction of an overall amplitude field resembles the free–free emission measure map of the Galaxy. Folding this emission measure map into the analysis provides more detailed predictions. The joint inference enables us to identify regions with deviations from the assumed correlations between the emission measure and Faraday data, thereby pointing us to Galactic structures with distinguishably different physics. We find evidence for an alignment of the magnetic field within the lines of sight along both directions of the Orion arm.

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Krause, M. "Multi-Frequency Radio Observations of Spiral Galaxies and Their Interpretation." Symposium - International Astronomical Union 140 (1990): 187–96. http://dx.doi.org/10.1017/s0074180900189934.

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After a brief historical summary of radio observations of spiral galaxies I review the methods of analyzing radio polarization data in view of the magnetic field. Special attention is drawn to the Faraday rotation and depolarization effects and to the identification of the large-scale magnetic field structure. The present observational results and open questions are discussed in terms of the predictions of the dynamo theory and prospects on future work are given.

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ALBA, DAVID, and LUCA LUSANNA. "CHARGED PARTICLES AND THE ELECTRO-MAGNETIC FIELD IN NONINERTIAL FRAMES OF MINKOWSKI SPACE–TIME II: "APPLICATIONS: ROTATING FRAMES, SAGNAC EFFECT, FARADAY ROTATION, WRAP-UP EFFECT"." International Journal of Geometric Methods in Modern Physics 07, no. 02 (2010): 185–213. http://dx.doi.org/10.1142/s0219887810004051.

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We apply the theory of noninertial frames in Minkowski space–time, developed in the previous paper, to various relevant physical systems. We give the 3 + 1 description without coordinate singularities of the rotating disk and the Sagnac effect, with added comments on pulsar magnetosphere and on a relativistic extension of the Earth-fixed coordinate system. Then we study properties of Maxwell equations in noninertial frames like the wrap-up effect and the Faraday rotation in astrophysics.

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Melrose, D. B., and P. A. Robinson. "Reversal of the Sense of Polarisation in Solar and Stellar Radio Flares." Publications of the Astronomical Society of Australia 11, no. 1 (1994): 16–20. http://dx.doi.org/10.1017/s1323358000019597.

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AbstractIt is shown that numerical integration of the equation of polarisation transfer for generalised Faraday rotation provides an alternative to mode-coupling theory for treating propagation through a quasi-transverse (QT) region. At a QT region, where the sign of the component of the magnetic field along the ray path reverses, the sense of circular polarisation reverses below a frequency ωt, and is unchanged above ωt. There is a long-standing difficulty in the interpretation of the polarisation of radio emission from bipolar regions on the Sun: observational and theoretical estimates of ωt appear inconsistent. The alternative approach may help resolve this difficulty.

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Beck, Rainer. "Galactic Dynamos — a Challenge for Observers." Symposium - International Astronomical Union 157 (1993): 283–97. http://dx.doi.org/10.1017/s0074180900174297.

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Results of linear αΩ-dynamo models are confronted with radio polarization observations of spiral galaxies. The general distribution of polarized emission and the magnetic field pitch angle can be described with sufficient accuracy. The occurrance of systematic large-scale variations in Faraday rotation (RM) is the strongest argument in favour of dynamo theory. However, the predominance of axisymmetric SO modes could not be confirmed by observations; S1 modes are about equally frequent. The azimuthal variations of field pitch angles and, in two cases, the phases of the RM variations are inconsistent with a classical αΩ-dynamo. Locally deviating RM values indicate field lines bending out of the plane. There is increasing evidence that galactic fields cannot be described by simple dynamo modes. This calls for more realistic dynamo models, taking into account non-axisymmetric velocity fields and galactic winds.Interpretation of radio observations is difficult because Faraday depolarization can seriously affect the data. Observations of small-scale field structures are summarized which show the path for future research. Instrumental needs for such investigations are discussed.

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Melrose, D. B. "Scintillations in a magnetized plasma. Part 2. The fourth-order moment." Journal of Plasma Physics 50, no. 2 (1993): 283–91. http://dx.doi.org/10.1017/s0022377800027070.

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The theory of strong scintillations in a weakly anisotropic plasma is used to derive an equation satisfied by the correlation functions for the Stokes parameters. The coefficients that describe these correlation functions are determined explicitly in terms of a matrix generalization of the standard phasestructure function. In discussing implications of the theory, emphasis is placed on terms that have no counterpart in an isotropic plasma. It is shown that the decay of the linear polarizaiton that results from differential Faraday rotation is different in the mean squares and the square means of the Stokes parameters. In principle, this allows one to determine properties relating to the fluctuations of the magnetic field along the ray path. A formal treatment of polarization dependent intensity fluctuations in a magnetized plasma is presented and discussed briefly.

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Shafer, Padraic, Pablo García-Fernández, Pablo Aguado-Puente, et al. "Emergent chirality in the electric polarization texture of titanate superlattices." Proceedings of the National Academy of Sciences 115, no. 5 (2018): 915–20. http://dx.doi.org/10.1073/pnas.1711652115.

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Chirality is a geometrical property by which an object is not superimposable onto its mirror image, thereby imparting a handedness. Chirality determines many important properties in nature—from the strength of the weak interactions according to the electroweak theory in particle physics to the binding of enzymes with naturally occurring amino acids or sugars, reactions that are fundamental for life. In condensed matter physics, the prediction of topologically protected magnetic skyrmions and related spin textures in chiral magnets has stimulated significant research. If the magnetic dipoles were replaced by their electrical counterparts, then electrically controllable chiral devices could be designed. Complex oxide BaTiO3/SrTiO3 nanocomposites and PbTiO3/SrTiO3 superlattices are perfect candidates, since “polar vortices,” in which a continuous rotation of ferroelectric polarization spontaneously forms, have been recently discovered. Using resonant soft X-ray diffraction, we report the observation of a strong circular dichroism from the interaction between circularly polarized light and the chiral electric polarization texture that emerges in PbTiO3/SrTiO3 superlattices. This hallmark of chirality is explained by a helical rotation of electric polarization that second-principles simulations predict to reside within complex 3D polarization textures comprising ordered topological line defects. The handedness of the texture can be topologically characterized by the sign of the helicity number of the chiral line defects. This coupling between the optical and novel polar properties could be exploited to encode chiral signatures into photon or electron beams for information processing.

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Babu, Arun, Shashi Kumar, and Shefali Agrawal. "RISAT-1 Compact Polarimetric Calibration and Decomposition." Proceedings 18, no. 1 (2019): 3. http://dx.doi.org/10.3390/ecrs-3-06189.

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Indian Space Research Organisation’s Radar Imaging Satellite (RISAT) -1 was the first Synthetic Aperture Radar (SAR) satellite equipped with the compact polarimetric (CP) mode for data acquisition. To exploit the advantages offered by the CP mode, the datasets need to be polarimetrically calibrated. The polarimetric calibration procedure estimates the polarimetric distortions in the datasets caused due to channel imbalance, crosstalk, and Faraday rotation. These polarimetric distortions cause the misinterpretation of the ground targets in the polarimetric decomposition techniques. The Freeman compact-pol polarimetric calibration algorithm is the most commonly used algorithm. In this study, the RISAT-1 Circular Transmit Linear Receive (CTLR) dataset of the RISAT Cal Val site was used to estimate the polarimetric distortion parameters and these distortion parameters were used to polarimetrically calibrate the RISAT-1 CTLR dataset of the Doon Valley region, Uttarakhand, India. The Cloude compact-pol decomposition algorithm was used to evaluate the ground target characterization accuracy before and after polarimetric calibration using the Freeman compact-pol polarimetric calibration algorithm. Before polarimetric calibration, urban targets were showing surface scattering behavior and river channels were showing increased double-bounce scattering behavior. After polarimetric calibration, the urban targets showed dominance in double-bounce scattering and river channels showed dominance in surface scattering as per the theory.

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UNNIKRISHNAN, C. S., and G. T. GILLIES. "GRAVITO-ELECTROMAGNETISM: GLIMPSES OF UNEXPLORED DEEP CONNECTIONS." International Journal of Modern Physics D 13, no. 10 (2004): 2321–27. http://dx.doi.org/10.1142/s0218271804006395.

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Any attempt at unification of the fundamental interactions will recognize its 'right path' when electromagnetism and gravity are seen together as manifestations of the same interaction. First excitement along this direction was the Kaluza–Klein program, and the unsuccessful attempt was Einstein's unified field theory. Over the years, the program has changed much, but the basic idea that there are links between gravity and electromagnetism, perhaps in a higher dimensional world, has not changed. There are several interesting and important phenomenological aspects related to this issue, to be experimentally explored at the classical level, which may reveal some of the deep connections between the two long range interactions. In this essay, we discuss a program to experimentally explore some connections between gravity and electromagnetism, not yet adequately studied. Some of the key issues we address are the complete absence of gravity for electrons inside a metal drift tube (Schiff–Barnhill effect) and its rotational variant, the Schuster–Blackett relation between rotation of neutral matter and generation of magnetic fields, and a variation of the Faraday unipolar induction. These experiments that probe macroscopic, low energy, and seemingly classical aspects, have the potential to reveal underlying microscopic, high energy, unification scale quantum connections between gravity and electromagnetism.

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Gelfreikh, G. B. "Radio Measurements of Coronal Magnetic Fields." International Astronomical Union Colloquium 144 (1994): 21–28. http://dx.doi.org/10.1017/s0252921100024933.

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AbstractA review of methods of measuring magnetic fields in the solar corona using spectral-polarization observations at microwaves with high spatial resolution is presented. The methods are based on the theory of thermal bremsstrahlung, thermal cyclotron emission, propagation of radio waves in quasi-transverse magnetic field and Faraday rotation of the plane of polarization. The most explicit program of measurements of magnetic fields in the atmosphere of solar active regions has been carried out using radio observations performed on the large reflector radio telescope of the Russian Academy of Sciences — RATAN-600. This proved possible due to good wavelength coverage, multichannel spectrographs observations and high sensitivity to polarization of the instrument. Besides direct measurements of the strength of the magnetic fields in some cases the peculiar parameters of radio sources, such as very steep spectra and high brightness temperatures provide some information on a very complicated local structure of the coronal magnetic field. Of special interest are the results found from combined RATAN-600 and large antennas of aperture synthesis (VLA and WSRT), the latter giving more detailed information on twodimensional structure of radio sources. The bulk of the data obtained allows us to investigate themagnetospheresof the solar active regions as the space in the solar corona where the structures and physical processes are controlled both by the photospheric/underphotospheric currents and surrounding “quiet” corona.

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JIMÉNEZ, JOSE BELTRÁN, and ANTONIO L. MAROTO. "THE DARK MAGNETISM OF THE UNIVERSE." Modern Physics Letters A 26, no. 40 (2011): 3025–39. http://dx.doi.org/10.1142/s0217732311037315.

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Despite the success of Maxwell's electromagnetism in the description of the electromagnetic interactions on small scales, we know very little about the behavior of electromagnetic fields on cosmological distances. Thus, it has been suggested recently that the problems of dark energy and the origin of cosmic magnetic fields could be pointing to a modification of Maxwell's theory on large scales. Here, we review such a proposal in which the scalar state which is usually eliminated by means of the Lorenz condition is allowed to propagate. On super-Hubble scales, the new mode is essentially given by the temporal component of the electromagnetic potential and contributes as an effective cosmological constant to the energy–momentum tensor. The new state can be generated from quantum fluctuations during inflation and it is shown that the predicted value for the cosmological constant agrees with observations, provided inflation took place at the electroweak scale. We also consider more general theories including non-minimal couplings to the spacetime curvature in the presence of the temporal electromagnetic background. We show that both in the minimal and non-minimal cases, the modified Maxwell's equations include new effective current terms which can generate magnetic fields from sub-galactic scales up to the present Hubble horizon. The corresponding amplitudes could be enough to seed a galactic dynamo or even to account for observations just by collapse and differential rotation in the protogalactic cloud.

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Rajpurohit, K., F. Vazza, M. Hoeft, et al. "A perfect power-law spectrum even at the highest frequencies: The Toothbrush relic." Astronomy & Astrophysics 642 (October 2020): L13. http://dx.doi.org/10.1051/0004-6361/202039165.

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Radio relics trace shock fronts generated in the intracluster medium (ICM) during cluster mergers. The particle acceleration mechanism at the shock fronts is not yet completely understood. We observed the Toothbrush relic with the Effelsberg and Sardinia Radio Telescope at 14.25 GHz and 18.6 GHz, respectively. Unlike previously claimed, the integrated spectrum of the relic closely follows a power law over almost three orders of magnitude in frequency, with a spectral index of α58 MHz18.6 GHz = −1.16 ± 0.03. Our finding is consistent with a power-law injection spectrum, as predicted by diffusive shock acceleration theory. The result suggests that there is only little magnetic field strength evolution downstream of the shock. From the lack of spectral steepening, we find that either the Sunyaev–Zeldovich decrement produced by the pressure jump is less extended than ∼600 kpc along the line of sight or, conversely, that the relic is located far behind in the cluster. For the first time, we detect linearly polarized emission from the “brush” at 18.6 GHz. Compared to 8.3 GHz, the degree of polarization across the brush increases at 18.6 GHz, suggesting a strong Faraday depolarization toward lower frequencies. The observed depolarization is consistent with an intervening magnetized screen that arises from the dense ICM containing turbulent magnetic fields. The depolarization, corresponding to a standard deviation of the rotation measures as high as σRM = 212 ± 23 rad m−2, suggests that the brush is located in or behind the ICM. Our findings indicate that the Toothbrush relic can be consistently explained by the standard scenario for relic formation.

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ALBA, DAVID, and LUCA LUSANNA. "CHARGED PARTICLES AND THE ELECTRO-MAGNETIC FIELD IN NONINERTIAL FRAMES OF MINKOWSKI SPACE-TIME I: ADMISSIBLE 3 + 1 SPLITTINGS OF MINKOWSKI SPACE-TIME AND THE NONINERTIAL REST FRAMES." International Journal of Geometric Methods in Modern Physics 07, no. 01 (2010): 33–93. http://dx.doi.org/10.1142/s021988781000394x.

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By using the 3 + 1 point of view and parametrized Minkowski theories we develop the theory of noninertial frames in Minkowski space-time. The transition from a noninertial frame to another one is a gauge transformation connecting the respective notions of instantaneous three-space (clock synchronization convention) and of the three-coordinates inside them. As a particular case we get the extension of the inertial rest-frame instant form of dynamics to the noninertial rest-frame one. We show that every isolated system can be described as an external decoupled noncovariant canonical center of mass (described by frozen Jacobi data) carrying a pole–dipole structure: the invariant mass and an effective spin. Moreover we identify the constraints eliminating the internal three-center of mass inside the instantaneous three-spaces. In the case of the isolated system of positive-energy scalar particles with Grassmann-valued electric charges plus the electro-magnetic field, we obtain both Maxwell equations and their Hamiltonian description in noninertial frames. Then by means of a noncovariant decomposition we define the noninertial radiation gauge and we find the form of the noncovariant Coulomb potential. We identify the coordinate-dependent relativistic inertial potentials and we show that they have the correct Newtonian limit. In the second paper we will study properties of Maxwell equations in noninertial frames like the wrap-up effect and the Faraday rotation in astrophysics. Also the 3 + 1 description without coordinate-singularities of the rotating disk and the Sagnac effect will be given, with added comments on pulsar magnetosphere and on a relativistic extension of the Earth-fixed coordinate system.

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Prabhu, A., A. Brandenburg, M. J. Käpylä, and A. Lagg. "Helicity proxies from linear polarisation of solar active regions." Astronomy & Astrophysics 641 (September 2020): A46. http://dx.doi.org/10.1051/0004-6361/202037614.

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Context. The α effect is believed to play a key role in the generation of the solar magnetic field. A fundamental test for its significance in the solar dynamo is to look for magnetic helicity of opposite signs both between the two hemispheres as well as between small and large scales. However, measuring magnetic helicity is compromised by the inability to fully infer the magnetic field vector from observations of solar spectra, caused by what is known as the π ambiguity of spectropolarimetric observations. Aims. We decompose linear polarisation into parity-even and parity-odd E and B polarisations, which are not affected by the π ambiguity. Furthermore, we study whether the correlations of spatial Fourier spectra of B and parity-even quantities such as E or temperature T are a robust proxy for magnetic helicity of solar magnetic fields. Methods. We analysed polarisation measurements of active regions observed by the Helioseismic and Magnetic Imager on board the Solar Dynamics observatory. Theory predicts the magnetic helicity of active regions to have, statistically, opposite signs in the two hemispheres. We then computed the parity-odd EB and TB correlations and tested for a systematic preference of their sign based on the hemisphere of the active regions. Results. We find that: (i) EB and TB correlations are a reliable proxy for magnetic helicity, when computed from linear polarisation measurements away from spectral line cores; and (ii) E polarisation reverses its sign close to the line core. Our analysis reveals that Faraday rotation does not have a significant influence on the computed parity-odd correlations. Conclusions. The EB decomposition of linear polarisation appears to be a good proxy for magnetic helicity independent of the π ambiguity. This allows us to routinely infer magnetic helicity directly from polarisation measurements.

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Pedersen, Thomas G. "Tight-binding theory of Faraday rotation in graphite." Physical Review B 68, no. 24 (2003). http://dx.doi.org/10.1103/physrevb.68.245104.

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Aebischer, Jason, and Jacky Kumar. "Flavour violating effects of Yukawa running in SMEFT." Journal of High Energy Physics 2020, no. 9 (2020). http://dx.doi.org/10.1007/jhep09(2020)187.

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Abstract We study Yukawa Renormalization Group (RG) running effects in the context of the Standard Model Effective Theory (SMEFT). The Yukawa running being flavour dependent leads to RG-induced off-diagonal entries, so that initially diagonal Yukawa matrices at the high scale have to be rediagonalized at the electroweak (EW) scale. Performing such flavour rotations can lead to flavour violating operators which differ from the ones obtained through SMEFT RG evolution. We show, that these flavour rotations can have a large impact on low-energy phenomenology. In order to demonstrate this effect, we com- pare the two sources of flavour violation numerically as well as analytically and study their influence on several examples of down-type flavour transitions. For this purpose we con- sider $$ {B}_s-{\overline{B}}_s $$ B s − B ¯ s mixing, b → sγ, b → sℓℓ as well as electroweak precision observables. We show that the rotation effect can be comparable or even larger than the contribution from pure RGE evolution of the Wilson coefficients.

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McInnes, Brett. "About magnetic AdS black holes." Journal of High Energy Physics 2021, no. 3 (2021). http://dx.doi.org/10.1007/jhep03(2021)068.

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Abstract There has recently been a strong revival of interest in quasi-extremal magnetically charged black holes. In the asymptotically flat case, it is possible to choose the magnetic charge of such an object in such a manner that the black hole is surrounded by a corona in which electroweak symmetry is restored on macroscopic scales, a result of very considerable interest. We argue that holographic duality indicates that the asymptotically AdS analogues of these black holes have several interesting properties: the dual theory is only physical if the black hole is required to rotate; in the rotating case, the magnetic field at the poles does not attain its maximum on the event horizon, but rather somewhat outside it; the magnetic field at the equator is not a monotonically decreasing function of the magnetic charge; the electric fields induced by the rotation, while smaller than their magnetic counterparts, are by no means negligible; the maximal electric field often occurs neither at the poles nor at the equator; and so on. Most importantly, in the magnetically charged case it is possible to avoid the superradiant instability to which neutral AdS-Kerr black holes are subject; but the need to avoid this instability imposes upper bounds on the magnetic and electric fields. In some circumstances, therefore, the corona may not exist in the asymptotically AdS case.

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Co, Raymond T., Nicolas Fernandez, Akshay Ghalsasi, Lawrence J. Hall, and Keisuke Harigaya. "Lepto-axiogenesis." Journal of High Energy Physics 2021, no. 3 (2021). http://dx.doi.org/10.1007/jhep03(2021)017.

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Abstract We propose a baryogenenesis mechanism that uses a rotating condensate of a Peccei-Quinn (PQ) symmetry breaking field and the dimension-five operator that gives Majorana neutrino masses. The rotation induces charge asymmetries for the Higgs boson and for lepton chirality through sphaleron processes and Yukawa interactions. The dimension-five interaction transfers these asymmetries to the lepton asymmetry, which in turn is transferred into the baryon asymmetry through the electroweak sphaleron process. QCD axion dark matter can be simultaneously produced by dynamics of the same PQ field via kinetic misalignment or parametric resonance, favoring an axion decay constant fa ≲ 1010 GeV, or by conventional misalignment and contributions from strings and domain walls with fa ∼ 1011 GeV. The size of the baryon asymmetry is tied to the mass of the PQ field. In simple supersymmetric theories, it is independent of UV parameters and predicts the supersymmtry breaking mass scale to be $$ \mathcal{O} $$ O (10 − 104) TeV, depending on the masses of the neutrinos and whether the condensate is thermalized during a radiation or matter dominated era. The high supersymmetry breaking mass scale may be free from cosmological and flavor/CP problems. We also construct a theory where TeV scale supersymmetry is possible. Parametric resonance may give warm axions, and the radial component of the PQ field may give signals in rare kaon decays from mixing with the Higgs and in dark radiation.

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Wang, Zheng, and Shanhui Fan. "Two-dimensional Magneto-photonic Crystal Circulators." MRS Proceedings 846 (2004). http://dx.doi.org/10.1557/proc-846-dd12.9.

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ABSTRACTPrevious research has demonstrated enhanced Faraday rotation in one-dimensional magnetic photonic crystals, where nonreciprocity in magneto-optical cavities is resonantly enhanced to provide optical isolation in optical paths on the scale of a few microns. In this paper, we study the nonreciprocity of two-dimensional magnetic photonic crystal resonators to allow further miniaturization and monolithic in-plane integration with current integrated optical devices. The nonreciprocal magnetic resonators are constructed by alternating the magnetization directions of the ferromagnetic domains in cavities side-coupled to photonic crystal waveguides. We show analytically that the gyrotropic splitting and the strength of the magnetic hybridization of the cavity modes are determined by the overlap integral between the domain magnetization vector and the modal cross product. With a large overlap obtained from optimizing the domain structures, we circularly hybridize two nearly degenerate modes to form a pair of counter-rotating whispering-gallery like modes, oscillating at different frequencies. As a physical realization, we synthesize two singly-degenerate circularly-hybridized modes in a two-dimensional crystal formed of a triangular air hole lattice in bismuth iron garnet with a TE bandgap. We tune the magnetic splitting and the decay constants of the rotating modes to demonstrate numerically a three-port optical circulator with a 30dB extinction bandwidth of 35GHz at 1550nm. An alternative implementation of a four-port circulator is achieved by side-coupling a point defect to two parallel waveguides. Our numerical experiments are performed with finite-difference time-domain simulations and agree well with the analytical coupled-mode theory predictions.

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Journal articles on the topic 'Electroweak theory; Faraday rotation'

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