Dynamically induced scalar quark confinement

We employ a functional approach to investigate the confinement problem in quenched Landau gauge QCD. We demonstrate analytically that a linear rising potential between massive quarks is generated by infrared singularities in the dressed quark-gluon vertex. The selfconsistent mechanism that generates these singularities is driven by the scalar Dirac amplitudes of the full vertex and the quark propagator. These can only be present when chiral symmetry is broken. We have thus uncovered a novel mechanism that directly links chiral symmetry breaking with confinement.Comment: 12 pages, 2 figures; v2: clarifications added and typos corrected, version to be published by MPL

Signatures of the impact of flare ejected plasma on the photosphere of a sunspot light-bridge

We investigate the properties of a sunspot light-bridge, focusing on the changes produced by the impact of a plasma blob ejected from a C-class flare. We observed a sunspot in active region NOAA 12544 using spectropolarimetric raster maps of the four Fe I lines around 15655 \AA\ with the GREGOR Infrared Spectrograph (GRIS), narrow-band intensity images sampling the Fe I 6173 \AA\ line with the GREGOR Fabry-P\'erot Interferometer (GFPI), and intensity broad band images in G-band and Ca II H band with the High-resolution Fast Imager (HiFI). All these instruments are located at the GREGOR telescope at the Observatorio del Teide, Tenerife, Spain. The data cover the time before, during, and after the flare event. The analysis is complemented with Atmospheric Imaging Assembly (AIA) and Helioseismic and Magnetic Imager (HMI) data from the Solar Dynamics Observatory (SDO). The physical parameters of the atmosphere at differents heights were inferred using spectral-line inversion techniques. We identify photospheric and chromospheric brightenings, heating events, and changes in the Stokes profiles associated to the flare eruption and the subsequent arrival of the plasma blob to the light bridge, after traveling along an active region loop. The measurements suggest that these phenomena are the result of reconnection events driven by the interaction of the plasma blob with the magnetic field topology of the light bridge.Comment: Accepted for publication in A&

Avaliação fisiológica de sementes de mogno brasileiro (Swietenia macrophylla King.) em diferentes temperaturas e substratos.

Este trabalho teve como objetivo determinar as características biométricas de frutos e sementes, e o efeito da temperatura e substrato na germinação de sementes de mogno brasileiro. A mensuração foi realizada com auxilio de paquímetro digital, e para o teste de germinação foi utilizado germinador com temperaturas constantes de 25°C e 30°C, e como substratos o papel toalha, a vermiculita, areia e areia+serragem. O delineamento experimental utilizado foi inteiramente casualizado com esquema fatorial 2x4 (temperaturas x substratos, respectivamente), com 4 repetições e 25 sementes por parcela. Os resultados absolutos de contagem de germinação foram transformados em percentagem, logo após, transformados em arco seno (x/100)1/2 para normalização da distribuição. No tratamento areia+serragem, nas condições de temperaturas constantes iguais a 25º e 30º C os percentuais de germinação foram superiores

Roles for Personal Informatics in Chronic Pain

Self-management of chronic pain is a complex and demanding activity. Multidisciplinary pain management programs are designed to provide patients with the skills to improve, maintain functioning and self-manage their pain but gains diminish in the long-term due to lack of support from clinicians. Sensing technology can be a cost-effective way to extend support for self-management outside clinical settings but they are currently under-explored. In this paper, we report studies carried out to investigate how Personal Informatics Systems (PIS) based on wearable body sensing technology could facilitate pain self-management and functioning. Five roles for PIS emerged from a qualitative study with people with chronic pain and physiotherapists: (i) assessment, planning and prevention (ii) a direct supervisory and co-management role, (iii) facilitating deeper understanding, (iv) managing emotional states, and (v) sharing for social acceptability. A web-based survey was conducted to understand the parameters that should be tracked to support self-management and what tracked information should be shared with others. Finally, we suggest an extension to previous PIS models and propose design implications to address immediate, short-term and long-term information needs for personal use of people with chronic pain and for sharing with others. / Note: As originally published there is an error in the document. The following information was omitted by the authors: "The project was funded by the EPSRC grant Emotion & Pain Project EP/H017178/1 rather than the EPSRC grant EP/G043507/1: Pain rehabilitation: E/Motion-based automated coaching.." The article PDF remains unchanged

Derivative expansion and large gauge invariance at finite temperature

We study the 0+1 dimensional Chern-Simons theory at finite temperature within the framework of derivative expansion. We obtain various interesting relations, solve the theory within this framework and argue that the derivative expansion is not a suitable formalism for a study of the question of large gauge invariance.Comment: 12 pages, Late

Three- and Four-Point Functions in CPT-Even Lorentz-Violating Scalar QED

The renormalization of quantum field theories usually assumes Lorentz and gauge symmetries, besides the general restrictions imposed by unitarity and causality. However, the set of renormalizable theories can be enlarged by relaxing some of these assumptions. In this work, we consider the particular case of a CPT-preserving but Lorentz-breaking extension of scalar QED. For this theory, we calculate the one-loop radiative corrections to the three- and four-point scalar-vector vertex functions, at the lowest order in the Lorentz violation parameters; and we explicitly verify that the resulting low-energy effective action is compatible with the usual gauge invariance requirements. With these results, we complete the one-loop renormalization of the model at the leading order in the Lorentz-violating parameters.Comment: 18 pages, minor corrections in metadat

Perturbative Aspects of CPT-Even Lorentz-Violating Scalar Chromodynamics

In this work, we formulate the theory of Lorentz-violating scalar Quantum Chromodynamics with an arbitrary non-Abelian gauge group. This theory belongs to the class of models encompassed by the standard model extension framework. At the lowest order in the theory's Lorentz violation parameters, we calculate the divergent quantum corrections, including the renormalization group $\beta$-functions of the theory. The Lorentz-violating sector is shown to be scale invariant if there is a particular relation between the couplings.Comment: 18 pages, matches published versio

Derivative Expansion and the Effective Action for the Abelian Chern-Simons Theory at Higher Orders

We study systematically the higher order corrections to the parity violating part of the effective action for the Abelian Chern-Simons theory in 2+1 dimensions, using the method of derivative expansion. We explicitly calculate the parity violating parts of the quadratic, cubic and the quartic terms (in fields) of the effective action. We show that each of these actions can be summed, in principle, to all orders in the derivatives. However, such a structure is complicated and not very useful. On the other hand, at every order in the powers of the derivatives, we show that the effective action can also be summed to all orders in the fields. The resulting actions can be expressed in terms of the leading order effective action in the static limit. We prove gauge invariance, both large and small of the resulting effective actions. Various other features of the theory are also brought out.Comment: 36 page