Anomalies, Horizons and Hawking radiation

Hawking radiation is obtained from the Reissner-Nordstr\"{o}m blackhole with a global monopole and the Garfinkle-Horowitz-Strominger blackhole falling in the class of the most general spherically symmetric blackholes $(\sqrt{-g}\neq1)$, using only chiral anomaly near the event horizon and covariant boundary condition at the event horizon. The approach differs from the anomaly cancellation approach since apart from the covariant boundary condition, the chiral anomaly near the horizon is the only input to derive the Hawking flux.Comment: minor corrections made, To appear in Euro. Phys. Letter

Hawking Radiation from Charged Black Holes via Gauge and Gravitational Anomalies

Extending gr-qc/0502074, we show that in order to avoid a breakdown of general covariance and gauge invariance at the quantum level the total flux of charge and energy in each outgoing partial wave of a charged quantum field in a Reissner-Nordstrom black hole background must be equal to that of a (1+1) dimensional blackbody at the Hawking temperature with the appropriate chemical potential.Comment: 4 pages, typos corrected, references added, version to appear in Phys. Rev. Let

Aspects of Confinement and Chiral Dynamics in 2-d QED at Finite Temperature

We evaluate the Polyakov loop and string tension at zero and finite temperature in $QED_2.$ Using bozonization the problem is reduced to solving the Schr\"odinger equation with a particular potential determined by the ground state. In the presence of two sources of opposite charges the vacuum angle parameter $\theta$ changes by $2\pi (q/e)$, independent of the number of flavors. This, in turn, alters the chiral condensate. Particularly, in the one flavor case through a simple computer algorithm, we explore the chiral dynamics of a heavy fermion.Comment: 4 pages, 2 ps files, uses sprocl.sty. To appear in Proceedings of DPF96 (August, Minnesota

Standardisation of magnetic nanoparticles in liquid suspension

Suspensions of magnetic nanoparticles offer diverse opportunities for technology innovation, spanning a large number of industry sectors from imaging and actuation based applications in biomedicine and biotechnology, through large-scale environmental remediation uses such as water purification, to engineering-based applications such as position-controlled lubricants and soaps. Continuous advances in their manufacture have produced an ever-growing range of products, each with their own unique properties. At the same time, the characterisation of magnetic nanoparticles is often complex, and expert knowledge is needed to correctly interpret the measurement data. In many cases, the stringent requirements of the end-user technologies dictate that magnetic nanoparticle products should be clearly defined, well characterised, consistent and safe; or to put it another way—standardised. The aims of this document are to outline the concepts and terminology necessary for discussion of magnetic nanoparticles, to examine the current state-of-the-art in characterisation methods necessary for the most prominent applications of magnetic nanoparticle suspensions, to suggest a possible structure for the future development of standardisation within the field, and to identify areas and topics which deserve to be the focus of future work items. We discuss potential roadmaps for the future standardisation of this developing industry, and the likely challenges to be encountered along the way

Confinement and Chiral Dynamics in the Multi-flavor Schwinger Model

Two-dimensional QED with $N$ flavor fermions is solved at zero and finite temperature with arbitrary fermion masses to explore QCD physics such as chiral condensate and string tension. The problem is reduced to solving a Schr\"odinger equation for $N$ degrees of freedom with a specific potential determined by the ground state of the Schr\"odinger problem itself.Comment: 9 pages. 3 ps files and sprocl.sty attached. To appear in the Proceedings of the QCD 96 workshop (March, Minnesota

Chern-Simons matrix model: coherent states and relation to Laughlin wavefunctions

Using a coherent state representation we derive many-body probability distributions and wavefunctions for the Chern-Simons matrix model proposed by Polychronakos and compare them to the Laughlin ones. We analyze two different coherent state representations, corresponding to different choices for electron coordinate bases. In both cases we find that the resulting probability distributions do not quite agree with the Laughlin ones. There is agreement on the long distance behavior, but the short distance behavior is different.Comment: 15 pages, LaTeX; one reference added, abstract and section 5 expanded, typos correcte

Microscopic Theory of Skyrmions in Quantum Hall Ferromagnets

We present a microscopic theory of skyrmions in the monolayer quantum Hall ferromagnet. It is a peculiar feature of the system that the number density and the spin density are entangled intrinsically as dictated by the W$$ algebra. The skyrmion and antiskyrmion states are constructed as W$_{\infty }$-rotated states of the hole-excited and electron-excited states, respectively. They are spin textures accompanied with density modulation that decreases the Coulomb energy. We calculate their excitation energy as a function of the Zeeman gap and compared the result with experimental data.Comment: 15 pages (to be published in PRB

Hawking Fluxes, Back reaction and Covariant Anomalies

Starting from the chiral covariant effective action approach of Banerjee and Kulkarni [Phys. Lett. B 659, 827(2008)], we provide a derivation of the Hawking radiation from a charged black hole in the presence of gravitational back reaction. The modified expressions for charge and energy flux, due to effect of one loop back reaction are obtained.Comment: 6 pages, no figures, minor changes and references added, to appear in Classical and Quantum Gravit

Black Hole Entropy: From Shannon to Bekenstein

In this note we have applied directly the Shannon formula for information theory entropy to derive the Black Hole (Bekenstein-Hawking) entropy. Our analysis is semi-classical in nature since we use the (recently proposed [8]) quantum mechanical near horizon mode functions to compute the tunneling probability that goes in to the Shannon formula, following the general idea of [5]. Our framework conforms to the information theoretic origin of Black Hole entropy, as originally proposed by Bekenstein.Comment: 9 pages Latex, Comments are welcome; Thoroughly revised version, reference and acknowledgements sections enlarged, numerical error in final result corrected, no major changes, to appear in IJT

Collection of anthropometry from older and physically impaired persons: traditional methods versus TC2 3-D body scanner

With advances in technology it is now possible to collect a wide range of anthropometric data, to a high degree of accuracy, using 3D light-based body scanners. This gives the potential to speed up the collection of anthropometric data for design purposes, to decrease processing time and data input required, and to reduce error due to inaccuracy of measurements taken using more traditional methods and equipment (anthropometer, stadiometer and sitting height table). However, when the data collection concerns older and/or physically impaired people there are serious issues for consideration when deciding on the best method to collect anthropometry. This paper discusses the issues arising when collecting data using both traditional methods of data collection and a first use by the experimental team of the TC2 3D body scanner, when faced with a ‘non-standard’ sample, during an EPSRC funded research project into issues surrounding transport usage by older and physically impaired people. Relevance to industry: Designing products, environments and services so that the increasing ageing population, as well as the physically impaired, can use them increases the potential market. To do this, up-to-date and relevant anthropometry is often needed. 3D light-based bodyscanners offer a potential fast way of obtaining this data, and this paper discusses some of the issues with using one scanner with older and disabled people