Z0→2γZ^0 \rightarrow 2 \gamma decay from Infrared Lorentz Symmetry Violation

Lorentz symmetry forbids decays of massive spin-1 particle like the $Z^0$ into two massless photons, a result known as the Landau-Yang theorem. But it is known that infrared effects can break Lorentz invariance. Employing the construction of Mund et. al. \cite{MRS} which incorporated this Lorentz violation, we propose an interaction leading to the decay $Z^0 \rightarrow 2 \gamma$ and study the dependence of the decay on the parameter of this Lorentz violation.Comment: 12 pages, 2 figure

Violation of the Landau-Yang theorem from infrared Lorentz symmetry breaking

Lorentz symmetry forbids decays of massive spin-1 particle like the Z0 into two massless photons, a result known as the Landau-Yang theorem. But it is known that infrared effects can break Lorentz invariance. Employing the construction of Mund et al. [1] which incorporated this Lorentz violation, we propose an interaction leading to the decay Z0→ 2γ and study the dependence of the decay on the parameter of this Lorentz violation

On a class of 2-surface observables in general relativity

The boundary conditions for canonical vacuum general relativity is investigated at the quasi-local level. It is shown that fixing the area element on the 2- surface S (rather than the induced 2-metric) is enough to have a well defined constraint algebra, and a well defined Poisson algebra of basic Hamiltonians parameterized by shifts that are tangent to and divergence-free on $. The evolution equations preserve these boundary conditions and the value of the basic Hamiltonian gives 2+2 covariant, gauge-invariant 2-surface observables. The meaning of these observables is also discussed.Comment: 11 pages, a discussion of the observables in stationary spacetimes is included, new references are added, typos correcte

Morphological Classification of Radio Galaxies using Semi-Supervised Group Equivariant CNNs

Out of the estimated few trillion galaxies, only around a million have been detected through radio frequencies, and only a tiny fraction, approximately a thousand, have been manually classified. We have addressed this disparity between labeled and unlabeled images of radio galaxies by employing a semi-supervised learning approach to classify them into the known Fanaroff-Riley Type I (FRI) and Type II (FRII) categories. A Group Equivariant Convolutional Neural Network (G-CNN) was used as an encoder of the state-of-the-art self-supervised methods SimCLR (A Simple Framework for Contrastive Learning of Visual Representations) and BYOL (Bootstrap Your Own Latent). The G-CNN preserves the equivariance for the Euclidean Group E(2), enabling it to effectively learn the representation of globally oriented feature maps. After representation learning, we trained a fully-connected classifier and fine-tuned the trained encoder with labeled data. Our findings demonstrate that our semi-supervised approach outperforms existing state-of-the-art methods across several metrics, including cluster quality, convergence rate, accuracy, precision, recall, and the F1-score. Moreover, statistical significance testing via a t-test revealed that our method surpasses the performance of a fully supervised G-CNN. This study emphasizes the importance of semi-supervised learning in radio galaxy classification, where labeled data are still scarce, but the prospects for discovery are immense.Comment: 9 pages, 6 figures, accepted in INNS Deep Learning Innovations and Applications (INNS DLIA 2023) workshop, IJCNN 2023, to be published in Procedia Computer Scienc

Photosynthetic and Growth Response of Sugar Maple (Acer saccharum Marsh.) Mature Trees and Seedlings to Calcium, Magnesium, and Nitrogen Additions in the Catskill Mountains, NY, USA

Funding for Open Access provided by the UMD Libraries Open Access Publishing Fund.Decline of sugar maple in North American forests has been attributed to changes in soil calcium (Ca) and nitrogen (N) by acidic precipitation. Although N is an essential and usually a limiting factor in forests, atmospheric N deposition may cause N-saturation leading to loss of soil Ca. Such changes can affect carbon gain and growth of sugar maple trees and seedlings. We applied a 2^2 factorial arrangement of N and dolomitic limestone containing Ca and Magnesium (Mg) to 12 forest plots in the Catskill Mountain region of NY, USA. To quantify the short-term effects, we measured photosynthetic-light responses of sugar maple mature trees and seedlings two or three times during two summers. We estimated maximum net photosynthesis (An-max) and its related light intensity (PAR at An-max), apparent quantum efficiency (Aqe), and light compensation point (LCP). To quantify the long-term effects, we measured basal area of living mature trees before and 4 and 8 years after treatment applications. Soil and foliar chemistry variables were also measured. Dolomitic limestone increased Ca, Mg, and pH in the soil Oe horizon. Mg was increased in the B horizon when comparing the plots receiving N with those receiving CaMg. In mature trees, foliar Ca and Mg concentrations were higher in the CaMg and N+CaMg plots than in the reference or N plots; foliar Ca concentration was higher in the N+CaMg plots compared with the CaMg plots, foliar Mg was higher in the CaMg plots than the N+CaMg plots; An-max was maximized due to N+CaMg treatment; Aqe decreased by N addition; and PAR at An-max increased by N or CaMg treatments alone, but the increase was maximized by their combination. No treatment effect was detected on basal areas of living mature trees four or eight years after treatment applications. In seedlings, An-max was increased by N+CaMg addition. The reference plots had an open herbaceous layer, but the plots receiving N had a dense monoculture of common woodfern in the forest floor, which can impede seedling survival

Domain Formation in Finite-Time Quenches

We study the formation of domains in a continuous phase transition with a finite-temperature quench. The model treated is the $\Phi^4$ theory in two spatial dimensions with global O(2) symmetry. We investigate this using real-time thermal field theory, following Boyanovsky and collaborators, and find that domain sizes appear to be smaller than those produced in an instantaneous quench in the tree-level approximation. We also propose that a more physical picture emerges by examining the two-point functions which do not involve any cutoff on the short wavelength Goldstone modes.Comment: Revtex, 16 pages, 5 figures, Minor change

Energy levels of the soliton--heavy-meson bound states

We investigate the bound states of heavy mesons with finite masses to a classical soliton solution in the Skyrme model. For a given model Lagrangian we solve the equations of motion exactly so that the heavy vector mesons are treated on the same footing as the heavy pseudoscalar mesons. All the energy levels of higher grand spin states as well as the ground state are given over a wide range of the heavy meson masses. We also examine the validity of the approximations used in the literatures. The recoil effect of finite mass soliton is naively estimated.Comment: 24 pages, REVTeX v3.0, 6 figures are available upon request

An Insight into the Sex Differences in COVID-19 Patients: What are the Possible Causes?

Studies have reported a sex bias in case fatalities of COVID-19 patients. Moreover, it is observed that men have a higher risk of developing a severe form of the disease compared to women, highlighting the importance of disaggregated data of male and female COVID-19 patients. On the other hand, other factors (eg, hormonal levels and immune functions) also need to be addressed due to the effects of sex differences on the outcomes of COVID-19 patients. An insight into the underlying causes of sex differences in COVID-19 patients may provide an opportunity for better care of the patients or prevention of the disease. The current study reviews the reports concerning with the sex differences in COVID-19 patients. It is explained how sex can affect angiotensin converting enzyme-2 (ACE2), that is a key component for the pathogenesis of COVID-19, and summarized the gender differences in immune responses and how sex hormones are involved in immune processes. Furthermore, the available data about the impact of sex hormones on the immune functions of COVID-19 cases are looked into

Heavy Quark Solitons

We investigate the heavy baryons which arise as solitonic excitations in a ``heavy meson" chiral Lagrangian which includes the light vector particles. It is found that the effect of the light vectors may be substantial. We also present a simple derivation which clearly shows the connection to the Callan-Klebanov approach.Comment: 13 pages; LaTex; SU-4240-532; UR 1306/ER-40685-755 (Minor typos corrected