LHC signatures of sterile neutrinos in a minimal radiative extended seesaw framework

The presence of small neutrino masses and flavour mixings can be accounted for naturally in various models about extensions of the standard model, particularly in the seesaw mechanism models. In this work, we present a minimally extended seesaw framework with two right-handed neutrinos, where the active neutrino masses are derived in the radiative regime. Using the framework it can be shown that within certain mass limits, the light neutrino mass term can approach a form that is similar to its form under type-I seesaw mechanism. Apart from this, we show that the decay width of right-handed neutrinos (produced through the decay of [Formula: see text] boson in a particle collider) is short enough to cause a sufficiently long lifetime for the particles, thus ensuring an observable displacement in the LHC between the production and decay vertices. We comment on the fact that these displaced vertex signatures thus can serve as a means to verify the existence of these right-handed neutrinos in future experiments. Lastly, we line up the possibility of our future work where the vertex signatures of particles greater than the mass of [Formula: see text] boson can be worked upon.

Near-inertial dissipation due to stratified flow over abyssal topography

Linear theory for steady stratified flow over topography sets the range for topographic wavenumbers over which freely propagating internal waves are generated, and the radiation and breaking of these waves contribute to energy dissipation away from the ocean bottom. However, previous numerical work demonstrated that dissipation rates can be enhanced by flow over large scale topographies with wavenumbers outside of the lee wave radiative range. We conduct idealized 3D numerical simulations of steady stratified flow over 1D topography in a rotating domain and quantify vertical distribution of kinetic energy dissipation. We vary two parameters: the first determines whether the topographic obstacle is within the lee wave radiative range and the second, proportional to the topographic height, measures the degree of flow non-linearity. For certain combinations of topographic width and height, breaking occurs in pulses every inertial period, such that kinetic energy dissipation develops inertial periodicity. In these simulations, kinetic energy dissipation rates are also enhanced in the interior of the domain. In the radiative regime the inertial motions arise due to resonant wave-wave interactions. In the small wavenumber non-radiative regime, instabilities downstream of the obstacle can facilitate the generation and propagation of non-linearly forced inertial motions, especially as topographic height increase. In our simulations, dissipation rates for tall and wide non-radiative topography are comparable to those of radiative topography, even away from the bottom, which is relevant to the ocean where the topographic spectrum is such that wider abyssal hills also tend to be taller.

Missing red supergiants and carbon burning

ABSTRACT Recent studies on direct imaging of Type II core-collapse supernova progenitors indicate a possible threshold around MZAMS ∼ 16–20 M⊙, where red supergiants (RSG) with larger birth masses do not appear to result in supernova explosions and instead implode directly into a black hole. In this study, we argue that it is not a coincidence that this threshold closely matches the critical transition of central carbon burning in massive stars from the convective to radiative regime. In lighter stars, carbon burns convectively in the centre and result in compact final pre-supernova cores that are likely to result in explosions, while in heavier stars after the transition, it burns as a radiative flame and the stellar cores become significantly harder to explode. Using the $\rm {\small {kepler}}$ code we demonstrate the sensitivity of this transition to the rate of 12C(α, γ)16O reaction and the overshoot mixing efficiency, and we argue that the upper mass limit of exploding RSG could be employed to constrain uncertain input physics of massive stellar evolution calculations. The initial mass corresponding to the central carbon burning transition range from 14 to 26 M⊙ in recently published models from various groups and codes, and only a few are in agreement with the estimates inferred from direct imaging studies.

Main Characteristics of Dust Storm sand Their Radiative Impacts: With a Focuson Tajikistan

Dust storms are commonly occurring phenomena in Tajikistan. The known aridity of the region is a major factor in promoting numerous dust storms. They have many diverse impacts on the environment and the climate of the region. The classification of dust storms and synoptic conditions related to their formation in Central Asia are discussed in the content of their diverse impact. We address dust optical properties that are representative of the region. Dust storms significantly reduce visibly and pose a human health threads. They also cause a significant impact on the radiative regime. As a result, dust storms may cause a decrease in temperature during daytime of up to 16 о С and an increase in temperature during night time from up to 7 о С compared to a clear day.

The stability of the radiative regime in Bucharest during 2017-2018

The paper presents an analysis of the solar irradiation and the stability of the solar radiative regime, available for Bucharest and the southern area of Romania. The study is based on meteorological data measured at 3.6 seconds, on several consecutive days of each season, in the years 2017 and 2018. Data acquisition was performed at Technical University of Civil Engineering Bucharest. The daily mean values for sunshine number and sunshine stability number are computed and analysed. The analyses carried out in this research are useful for applications of solar energy and conversion to thermal energy in hot air solar collectors to estimate the temperature variation at the collector air outlet as well as for photovoltaic panels to estimate the resulting electrical energy.

Influence of Leaf Specular Reflection on Canopy Radiative Regime Using an Improved Version of the Stochastic Radiative Transfer Model

Interpreting remotely-sensed data requires realistic, but simple, models of radiative transfer that occurs within a vegetation canopy. In this paper, an improved version of the stochastic radiative transfer model (SRTM) is proposed by assuming that all photons that have not been specularly reflected enter the leaf interior. The contribution of leaf specular reflection is considered by modifying leaf scattering phase function using Fresnel reflectance. The canopy bidirectional reflectance factor (BRF) estimated from this model is evaluated through comparisons with field-measured maize BRF. The result shows that accounting for leaf specular reflection can provide better performance than that when leaf specular reflection is neglected over a wide range of view zenith angles. The improved version of the SRTM is further adopted to investigate the influence of leaf specular reflection on the canopy radiative regime, with emphases on vertical profiles of mean radiation flux density, canopy absorptance, BRF, and normalized difference vegetation index (NDVI). It is demonstrated that accounting for leaf specular reflection can increase leaf albedo, which consequently increases canopy mean upward/downward mean radiation flux density and canopy nadir BRF and decreases canopy absorptance and canopy nadir NDVI when leaf angles are spherically distributed. The influence is greater for downward/upward radiation flux densities and canopy nadir BRF than that for canopy absorptance and NDVI. The results provide knowledge of leaf specular reflection and canopy radiative regime, and are helpful for forward reflectance simulations and backward inversions. Moreover, polarization measurements are suggested for studies of leaf specular reflection, as leaf specular reflection is closely related to the canopy polarization.

Quantification of the Solar Radiative Regime Variability Based on the Clearness Index

The fluctuation of solar radiation at ground level represents a challenge in modeling the time series of solar irradiance. A procedure for the quantification of the instability of the solar radiative regime is reported. This procedure is based on the clearness index, as the ratio of the horizontal solar irradiance measured at ground level and the estimated one at extraterrestrial level. New quantities for classifying the days from the radiative stability point of view are being introduced. A procedure for classifying days according to their stability regime as stable, variable and unstable is presented.