Standard Model Equations Research Articles

Dimension-eight operator basis for universal standard model effective field theory

We present the basis of dimension-eight operators associated with universal theories. We first derive a complete list of independent dimension-eight operators formed with the Standard Model bosonic fields characteristic of such universal new physics scenarios. Without imposing C or P symmetries the basis contains 175 operators—that is, the assumption of universality reduces the number of independent Standard Model effective field theory (SMEFT) coefficients at dimension eight from 44807 to 175. 89 of the 175 universal operators are included in the general dimension-eight operator basis in the literature. The 86 additional operators involve higher derivatives of the Standard Model bosonic fields and can be rotated in favor of operators involving fermions using the Standard Model equations of motion for the bosonic fields. By doing so we obtain the allowed fermionic operators generated in this class of models which we map into the corresponding 86 independent combinations of operators in the dimension-eight basis of [C. W. Murphy, Dimension-8 operators in the standard model effective field theory, .]. Published by the American Physical Society 2024

Computational assessment of MHD Carreau tri-hybrid nano-liquid flow along an elongating surface with entropy generation : A comparative study

This research looks at the incompressible, viscous, steady-state laminar stagnation-point-flow of a Carreau ternary-hybrid nano-liquid towards a convectively heated expanding surface, taking into account first-order slippage and Ohmic dissipation. Viscous dissipation and the effects of Lorentz forces are also considered. It is discussed how thermal radiation and heat absorption/generation contribute to the heat transport process. Minimizing entropy during the transport of a Carreau ternary hybrid nano-liquid has also been studied. In addition, convective circumstances are used conceptually in the numerical solution of the current model. tiny-particles of silver (Ag), molybdenum disulfide (MoS2), and multi-wall carbon nanotubes (MWCNT) are analyzed in this work’s flow study. As a base fluid, carboxymethyl cellulose (CMC-water) is used. With the use of appropriate similarity trans-formations, the standard model equations are transformed into dimensionless form. Finding solutions for momentum and heat fields using the Runge–Kutta-Fehlberg technique and a shooting strategy. The figures depict a wide range of characteristics, including fluid flow velocity, temperature, skin friction, the Nusselt number, entropy minimization, and the Bejan number. Key results from the present model include the fact that the velocity curve flattens down as Weissenberg number increases.

Long term creep and shrinkage of nano silica modified high volume fly ash concrete

The long-term creep and shrinkage behaviour of two High-Volume Fly Ash (HVFA) concretes incorporating nano silica with 65% and 80% replacement of cement has been investigated. This comprised a detailed analysis of the microstructure, pore structure and chemistry of the two HVFA systems up to a period of 450 days. The compressive strength and modulus of elasticity of HVFA-65 concrete increased from 32 to 73 MPa and 30.3 to 40.5 GPa, respectively between 7 and 450 days. The HVFA-80 concrete achieved compressive strength values of 22 and 71 MPa and elastic modulus values of 28.9 and 37 GPa. After a total loading period of 450 days, HVFA-65 and HVFA-80 concretes displayed creep parameters, which were significantly below the values predicted by AS 3600, ACI 209 and CEB-FIP standard model equations. After a total drying period of 450 days 28-day cured specimens showed significantly reduced shrinkage compared to 7-day cured specimens. On the other hand, HVFA-80 concrete displayed higher shrinkage compared to the HVFA-65 specimens throughout the period. All specimens except for 7-day cured HVFA-80 concrete were within the maximum permissible shrinkage of 800 microns recommended for Australian construction practices. HVFA-65 concrete showed a denser microstructure and a stronger, better packed interfacial transition zone (ITZ) compared to HVFA-80 at all ages. The XRD and FTIR analysis data identified the formation of hydration products including C-S-H and C-A-S-H which contributed towards both the strength gain as well as the creep and shrinkage properties displayed by the HVFA concrete by minimizing the total porosity and pore size.

Renormalization group evolution of dimension-seven baryon- and lepton-number-violating operators

We study dimension-seven operators in standard model effective field theory. These operators are classified into two sets, one violating lepton number but preserving baryon number ($\Delta L=\pm 2$, $\Delta B=0$) and the other violating both but preserving their sum ($-\Delta L=\Delta B=\pm 1$). It has been found in the previous literature that there are respectively 13 and 7 such independent operators. We show that one operator is redundant in each set so that the complete list contains only 12 and 6 operators respectively. We accomplish this by using standard model equations of motion and various Fierz identities. We calculate the one-loop anomalous dimension matrix for the 6 operators in the second set, and illustrate its possible phenomenological implications by working out renormalization group running of the Wilson coefficients that could contribute to the type of proton decays with $-\Delta L=\Delta B=\pm 1$, such as $p\to\nu\pi^+$.

Potential of biosorbent developed from fruit peel of Trewia nudiflora for removal of hexavalent chromium from synthetic and industrial effluent: Analyzing phytotoxicity in germinating Vigna seeds

Chromium (VI) removal efficiency of a biosorbent prepared from fruit peel of Trewia nudiflora plant was studied. The effect of pH, sorbent dose, initial metal concentration and temperature was studied with synthetic Cr+6 solution in batch mode. About 278 mg/g of Cr+6 sorption was obtained at 293 K at an optimum pH of 2.0 and biosorbent dose of 0.75 g/L. Equilibrium sorption data with varying initial concentration of Cr+6 (22–248 mg/L) at three different temperatures (293–313 K) were analyzed by various isotherms. Biosorption kinetics and thermodynamics were described using standard model equations. Encouraging results were obtained by the application of the biosorptive treatment for removal of Cr+6 from wastewater collected from common effluent treatment plant of tannery industry. In addition, Cr+6 desorption behavior was studied on different systems. Biosorbent was characterized by FESEM, FT-IR and XRD, etc. Effect of the biosorptive treatement with respect to the phytotoxicity of Cr+6 was analyzed by studying the seed germination behavior and enzyme activity of a pulse seed (Vigna radiata L.). Different concentrations of Cr+6 solution in both synthetic medium, as well as, in tannery effluent was employed and the results were compared with that of biosorbent treated medium. The study showed that due to efficient removal of Cr+6 from aqueous phase, considerable enhancement of seed germination, as well as, increase in root length was obtained for the biosorbent treated solutions which were close to that of the control values. Significant decrease (P < 0.01) in POD activity was observed in seeds irrigated with biosorbent treated wastewater compared to untreated wastewater. The study showed that the novel biosorbent prepared might be utilized for abatement of heavy metal toxicity, i.e., Cr+6 from industrial effluent.

Excess risk estimates of hearing impairment of Indian professional drivers

Noise and vibration are occupational hazards that affect worker health and safety. Prolonged exposure to noisy environment results in hearing loss of the affected individuals. The objective of this study was to estimate an excess risk of hearing impairment of professional drivers in Kolkata city of India. In this study, 90 healthy male subjects of similar age, height and weight were equally sampled in three separate sub-samples of 30 subjects each viz. drivers with less than 10 years of occupational noise exposure, drivers with more than 10 years of occupational noise exposure and office workers as control. The audiometric testing of both ears of the selected subjects was conducted at frequencies of 0.125, 0.25, 0.5, 1, 1.5, 2, 3, 4, 6, 8 and 10 kHz. The average estimated excess risks of hearing impairment of the subjects were calculated from audiometric data using five standard model equations. The hearing threshold levels of office workers at audiometric test frequencies of 0.5, 1, 2 and 3 kHz did not exceed 25 dB (A) to cause hearing handicap. However, it exceeded 25 dB (A) for professional drivers (<10 years of noise exposure and >10 years of noise exposure). The values of estimated average excess risk indicated that hearing damage of professional drivers was expected to occur sooner at 3 and 4 kHz frequencies than losses at lower frequencies. It was concluded that the occupational hazards of professional driving significantly increased hearing threshold levels of drivers as compared to office workers. Relevance to industry This study emphasizes the need to periodically check professional driver's hearing to determine their auditory threshold shift or excess risk, especially those working in noisy environments. It highlights an urgent need to take up some interventions to reduce the harmful effect of loud traffic noise to drivers exposed to noisy environment in populated cities.

Atomic Mix Synthetic Acceleration of Dose Computations in Binary Statistical Media

An iterative solution of coupled standard model equations arising in electron transport in binary statistical mixtures is considered. Convergence degradation is observed in certain energy groups and is attributed to chunk sizes appearing optically thin in the higher energy groups. Fourier analysis shows that the spectral radius approaches unity for the zero wave-number error mode as the chunk sizes become vanishingly small. It is shown that the atomic mix model accurately approximates transport under these circumstances and moreover provides a suitable low-order approximation to the iteration error. Fourier analysis and numerical implementation confirm that atomic mix acceleration is unconditionally effective for the application considered here. Our computations also demonstrate the inaccuracy of the atomic mix model for electron dose, especially for materials with strongly contrasting physical properties.

New theoretical model based on the application of the energy conservation principle for erbium-doped silica fibre lasers

A new theoretical model based on the standard-model equations but ensuring conservation of energy by accounting for the optical powers stored in the laser cavity is presented. This model succeeds in grouping two sorts of previous models: those based on standard equations and those based on conservation of number of photons. Furthermore, it provides a more complete quantitative description of EDSFLs (erbium-doped silica fibre lasers) and also improves the qualitative description of these devices by including the spontaneous emission terms and by determining the optical powers involved as well as the oscillation wavelength. The possibility of solving the EDSFL system including the power modal distribution within the fibre is also considered. Finally, a detailed comparison between this model and the models proposed by other authors is shown, where it is proved that the new model describes much better the behaviour of EDSFLs.

The Use of Indoor Air Measurements To Evaluate Intrusion of Subsurface VOC Vapors into Buildings

ABSTRACT The implementation of a risk-based corrective action approach often requires consideration of soil vapor migration into buildings and potential inhalation exposure and risk to human health. Due to the uncertainty associated with models for this pathway, there may be a desire to analyze indoor air samples to validate model predictions, and this approach is followed on a somewhat frequent basis at sites where risks are considered potentially significant. Indoor air testing can be problematic for a number of reasons. Soil vapor intrusion into buildings is complex, highly dependent on site-specific conditions, and may vary over time, complicating the interpretation of indoor air measurements when the goal is to deduce the subsurface-derived component. An extensive survey of indoor air quality data sets highlights the variability in indoor volatile organic compound (VOC) concentrations and numerous sources that can lead to elevated VOC levels. The contribution from soil vapor is likely to be small relative to VOCs from other sources for most sites. In light of these challenges, we discuss how studies that use indoor air testing to assess subsurface risks could be improved. To provide added perspective, we conclude by comparing indoor air concentrations and risks arising from subsurface VOCs, predicted using standard model equations for soil vapor fate and intrusion into buildings, to those associated with indoor sources.

Spatial harmonics of photorefractive gratings in a barium titanate crystal

Calibrated optical Bragg-scattering measurements of the fundamental steady-state space-charge-field amplitude, and of two higher spatial harmonics, in photorefractive p-type barium titanate excited by a light intensity pattern that is a simple sine function of distance are reported. These measurements are performed over the entire range (0&amp;lt;m&amp;lt;1) of intensity modulation index m when the modulation period is both much larger than, and comparable to, the smallest characteristic (Debye screening) length involved in the photoconduction process. There is no externally applied electric field. The measurements are compared to numerical solutions of the standard single-carrier band-conduction model of photoconductivity, and good agreement is found except for large unexplained differences at high modulation index (∼0.8&amp;lt;m&amp;lt;1). Phenomenological analytic expressions are also given for the fundamental and two higher field-grating harmonics that are useful approximations to the numerical solutions of the standard model equations for all m and for (small, intermediate, and large) grating periods.

On the Stability and Uniqueness of Elastohydrodynamic Lubrication Solutions

It was suggested in [1] that solutions of the line contact problem of elastohydrodynamic lubrication (EHL) are unstable in a certain parameter regime, and that both stable and unstable solutions can coexist in another regime. The author also suggested that these regimes limit the applicability of the standard model equations. In this work, the present authors repeat this calculation using the highly accurate solutions described in our previous work [3]. In all cases we have considered, we find no evidence of instability or multiplicity of solutions. We conclude that the existence of regions of instability or multiplicity were based on numerical artifacts and that considerations of stability or multiplicity do not limit the applicability of the standard model equations of EHL.