Induced Decay Rates Research Articles

Extension of Λ NN → NNN Weak Interactions and the Two-Nucleon Induced Hypernuclear Nonmesonic Decays: Roles of Strange-Meson and Δ 33-Induced (ρρ)-Pair Exchanges

Abstract In the preceding paper we introduced three-body $\Lambda NN \rightarrow NNN$ weak interactions and proposed a framework to deduce the effective two-body $\Lambda N \rightarrow NN$ potentials to be used for estimates of nonmesonic decay rates of hypernuclei. In order to complete the framework, here we extend the treatment to include new diagrams arising from strange-meson exchanges and the $\Delta _{33}$-isobar induced $(\rho \rho )$-pair exchange. Thus we present new forms of the $V^{(\text {eff.2B})}_{(K \pi )\kappa }$, $V^{(\text {eff.2B)}}_{(K \pi )K^{*}}$, and $V^{(\text {eff.2B})}_{D33(\rho \rho )}$ potentials. By adding these potentials to the previous ones, we investigate in full the roles of various types of effective $\Lambda N \rightarrow NN$ potentials in the estimates of two-nucleon induced nonmesonic decays. It is shown that the destructive interference of the tensor forces between the strange-meson-exchange potentials and the non-strange-meson-exchange ones is particularly important in reducing the theoretical two-nucleon induced nonmesonic decay rates. The potential $V^{(\text {eff.2B})}_{D33(\rho \rho )}$ is weak in comparison with $V^{(\text {eff.2B})}_{\rm FM(\pi \pi )}$. The full terms of the potentials have features of strong central, moderately strong, or weak tensors, and weak parity-violating vector forces. Erroneous overestimates of the decay rates reported in the previous paper are corrected, and new numbers calculated with the full terms are presented for the two-nucleon induced decay rates of the $^5_\Lambda {\rm He}$, $^{11}_\Lambda {\rm B}$, and $^{12}_\Lambda {\rm C}$ hypernuclei, which are comparable to the experimental data.

Optomechanical Heating and Cooling via Tip-Enhanced Raman Scattering in Epsilon-Near-Zero Medium

Media with the dielectric permittivityclose to zero (epsilon-near-zero or ENZ) maintain conditions for enhanced light-matter interactions. In this paper, we propose to use these media to enhance the optomechanical coupling of vibrational excitations of the medium with the optical near-field of the nanoantenna. It is shown that the ENZ medium significantly increases the optically induced decay rate of a vibration, which can be used for cooling (when the incident light frequency is less than the ENZ frequency) or heating (when the incident light frequency is greater than the ENZ frequency). Due to the proximity of the refractive index to zero as well, oscillations of the polarization of the medium are coherent, which further enhances the optomechanical effects. Analytical expressions are obtained for the optical shift of the resonance and the induced decay rate.

Experimental study of the disinfection performance of a 222-nm Far-UVC upper-room system on airborne microorganisms in a full-scale chamber

222-nm Far-UVC light is an emerging and promising tool for rapidly inactivating airborne pathogens. In this study, we experimentally evaluated the performance of a 222-nm Far-UVC upper-room disinfection system with a 15 W Far-UVC lamp in a full-scale chamber (11.9 m3). One gram-positive bacteria, namely Staphylococcus epidermidis and two gram-negative bacteria, namely Escherichia coli and Salmonella enterica were selected for the experiments. The aerosolized bacteria were injected into the chamber and exposed to 222-nm Far-UVC light. The first-order decay rates of indoor bioaerosols concentration with and without Far-UVC treatment were estimated. According to the results, the 222-nm Far-UVC induced decay rates of three bacteria were 0.0611 ± 0.003, 0.409 ± 0.048, and 0.474 ± 0.015 min−1, respectively. Besides, the UV susceptibility constants (Z-values) of these three bacteria were estimated as 0.157, 0.974, and 1.18 m2/J, respectively. The gram-positive bacteria, S. epidermidis, showed higher resistance to Far-UVC light as compared to the gram-negative bacteria, E. coli and S. enterica. In addition, a case study on airborne SARS-CoV-2 indoor transmission was simulated, and the infection risk of SARS-CoV-2 was compared using the Far-UVC and enhanced ventilation approaches. The results showed that both UV inactivation and ventilation approaches can significantly reduce the infection risk. More importantly, the Far-UVC may be a feasible and sustainable solution for reducing infection risk and improving indoor air quality.

Effective two-body ΛN → NN weak potentials deduced from three-body ΛNN → NNN interactions and hypernuclear non-mesonic weak decay rates

Abstract We intend to study the role of the three-body weak ΛNN → NNN interaction in two-nucleon induced hypernuclear non-mesonic weak decay. The three-body weak interactions are constructed on the basis of the meson-pair exchange (MPE) model and then we derive the effective two-body ΛN → NN weak potentials from the three-body interactions based on the Loiseau–Nogami–Ross approximation. The strong coupling constants of MPE are taken from the Nijmegen ESC and GESC models and the weak ones of MPE are evaluated in the weak Λ–n mixing model by Dalitz and Von Hippel [Phys. Lett. 10, 153 (1964)]. The effective two-body ΛN → NN weak potentials are applied to evaluate hypernuclear non-mesonic decay rates, which should give a certain additional contribution to the two-nucleon induced decay rate Γ2N. Calculations of $\Gamma ^{({\text{eff.2B}})}_{nm}$ are done for $^5_\Lambda {\rm He}$, $^{11}_\Lambda {\rm B}$, and $^{12}_\Lambda {\rm C}$ and the results are compared with experimental data $\Gamma ^\mathrm{exp}_{2N}$. We have demonstrated the possibility of accounting for the two-nucleon induced non-mesonic decays of light and p-shell hypernuclei by introducing the effective two-body potentials deduced from the three-body weak interactions, though the calculated $\Gamma ^{(\text{eff.2B})}_{nm}$ still includes uncertainties. Discussions and limitations of our “effective two-body ΛN → NN model” are given.

H-COUP: A program for one-loop corrected Higgs boson couplings in non-minimal Higgs sectors

We describe a numerical calculation tool H-COUP33The webpage of H-COUP is given in http://www-het.phys.sci.osaka-u.ac.jp/~kanemu/HCOUP_HP1013/HCOUP_HP.html, where one can download the set of source files of H-COUP_1.0. written in Fortran, which provides one-loop electroweak corrected vertices for the discovered Higgs boson h(125) in various Higgs sectors. The renormalization is based on the improved on-shell scheme without gauge dependence. In the first version H-COUP_1.0, the following models are included, namely, the Higgs singlet model, four types (Type-I, Type-II, Type-X, Type-Y) of two Higgs doublet models with a softly-broken Z2 symmetry and the inert doublet model. We first briefly introduce these models and then explain how to install and run this tool in an individual machine. A sample of numerical outputs is provided for user information. Program summaryProgram title: H-COUPProgram Files doi: http://dx.doi.org/10.17632/f88szmrj5x.1Licensing provisions: GPLv3Programming language: Fortran90Nature of problem: One-loop electroweak corrected vertices for the discovered Higgs boson h(125) are numerically calculated in the Higgs singlet model, four types (Type-I, Type-II, Type-X, Type-Y) of two Higgs doublet models with a softly-broken Z2 symmetry and the inert doublet model. The renormalization is based on the improved on-shell scheme without gauge dependence. Loop induced decay rates, i.e., h→γγ, h→Zγ and h→gg are also computed in these extended Higgs sectors at leading order.Solution method: All one-loop integrals for one-, two- and three-point functions are analytically expressed by using Passarino–Veltman functions in a systematic way, and their numerical values are calculated through the LoopTools. One-loop corrected h(125) vertices are then numerically provided in terms of form factors which are obtained by decomposing their Lorentz structure.Additional comments including restrictions and unusual features: In the version 1.0, QCD corrections are not included in the calculation of the h(125) vertices as well as the loop induced decay rates. In addition, the total width, decay branching ratios and cross sections are not outputted automatically. Details of these issues are described in Sec. VII of this manual.

Fluorescence characteristics of a molecule in the vicinity of a plasmonic nanomatryoska: Nonlocal optical effects

The fluorescence characteristics of a dipole molecule in the vicinity of a spherical multilayered metallic nanoshell (a plasmonic nanomatryoska) of ultra-small dimensions is studied via electrodynamic modeling, where we have computed the fluorescence decay rates, the shifts in emission frequency, and the overall fluorescence yields for molecular dipoles of both tangential and radial orientations. Our focus is on structures of ultra small dimensions in order to elucidate the possibly novel nonlocal optical effects in such a phenomenon. The results show that at very close distances between the molecule and the nanoshell, the nonlocal effects in general lead to smaller structure-induced effects with broadened and blue-shifted plasmonic resonances. These effects include overall smaller induced decay rates, smaller red-shifts in emission frequency, and somewhat larger fluorescence yields at low emission frequencies. Physical interpretation of our simulation results is provided.

Fecal coliform population dynamics associated with the thermophilic stabilization of treated sewage sludge

The inactivation of fecal coliforms in anaerobic batch reactors has been investigated at the thermophilic temperatures of 50, 55 and 60 °C. Throughout inactivation experiments at each temperature, individual colonies were isolated and identified by 16S rDNA gene sequencing to illustrate how the diversity of fecal coliforms is affected by thermophilic treatment. Results indicate that even though fecal coliforms in raw sewage sludge are comprised of several different bacterial species, each with variable temperature induced decay rates, the overall inactivation of fecal coliforms in raw sewage sludge was found to follow a first-order relationship. No tailing was observed across the range of fecal coliform concentrations measured. Fecal coliforms in raw sludge contained six different genera of bacteria and were 62% enriched in E. coli. Within 1.5 log removal of fecal coliform concentration by thermophilic treatment, the populations had shifted to, and remained at 100% E. coli. Subsequent inactivation rates measured in isolated fecal coliform strains confirmed that E. coli cells isolated post-treatment were more thermotolerant than E. coli and non-E coli bacteria isolated prior to thermal treatment. Overall, this study describes the potential enrichment of thermotolerant E. coli in biosolids fecal coliforms and demonstrates that while thermotolerant species are present at the end of treatment, pure first-order approximations are appropriate for estimating residence times to reduce fecal coliforms to levels promulgated in U.S. Class A biosolids standards.

Neutron–proton coincidences from Non-Mesonic Weak Decay of p-shell Λ-hypernuclei and determination of the two-nucleon induced process

The decay of Λ-hypernuclei without π emission, known as Non-Mesonic Weak Decay (NMWD), gives an effective tool to investigate ΔS=1 four-baryon interactions. It was theoretically suggested that the two-nucleon induced mechanism could play a substantial role in reproducing the observed NMWD decay rates and nucleon spectra, but at present no direct evidence of such a mechanism has been obtained. The FINUDA experiment, exploiting the possibility to detect both charged and neutral particles coming from the hypernucleus decay, has allowed us to deduce the relative weight of the two nucleon induced decay rate to the total NMWD rate. The value of Γ2N/ΓNMWD=0.21±0.07stat−0.02sys+0.03sys has been deduced, well consistent with the previous determinations.

Resolving intercontinental pollution plumes in global models of atmospheric transport

Synoptic‐scale pollution plumes in the free troposphere can preserve their identity as well‐defined structures for a week or more while traveling around the globe. Eulerian chemical transport models (CTMs) have difficulty reproducing these layered structures due to numerical plume dissipation. We show that this dissipation is much faster than would be expected from the order of the advection scheme because of interaction between numerical diffusion and the nonuniformity of the atmospheric flow. The nonuniform flow stretches out the plume, enhancing the effect of numerical diffusion. For sufficiently strong stretching, the numerical decay of the plume is independent of the model grid resolution and is set instead by the flow Lyapunov exponent λ. In this regime, conventional numerical methods are not convergent: upon increasing grid resolution, the plume still decays with the same decay rate. The critical plume size below which the numerical scheme does not converge is set by the geometric mean of the grid spacing and the characteristic length scale l = v/λ over which the flow varies, where v is the wind speed. Above this critical plume size the numerically induced decay rate of the plume scales like the square root of the grid spacing. Application to an intercontinental pollution plume in a global CTM with realistic atmospheric flow shows that proper simulation of such a plume would require an impractical increase in grid resolution. Novel methods such as adaptive grids or embedded Lagrangian plumes are needed.

Hyperfine induced ${\sf 1 s}{\sf 2 s}\ ^{\sf 1}$ S $_{\sf 0} \rightarrow {\sf 1 s}^{\sf 2}\ ^{\sf 1}$ S0 M1 transition of He-like ions

Hyperfine induced \(1s2s ^1\)S\(_0 \rightarrow 1s^2 ^1\)S0 M1 transition probabilities of He-like ions have been calculated from relativistic configuration interaction wavefunctions including the frequency independent Breit interaction and QED effects. Present results for 151Eu and 155Gd are in good agreement with previous calculations [L.N. Labzowsky et al., Phys. Rev. A 63, 054105 (2001)]. Electronic data are given in terms of a general scaling law in Z that, given isotopic nuclear spin and magnetic moment, allows hyperfine induced decay rates to be estimated for any isotope. The results should be helpful for future experimental investigations on QED and parity non-conservation effects.

Relativistic, QED and nuclear effects in highly charged ions revealed by resonant electron–ion recombination in storage rings

Dielectronic recombination (DR) of few-electron ions has evolved into a sensitive spectroscopic tool for highly charged ions. This is due to technological advances in electron-beam preparation and ion beam cooling techniques at heavy-ion storage rings. Recent experiments prove unambiguously that DR collision spectroscopy has become sensitive to 2nd order QED and to nuclear effects. This review discusses the most recent developments in high-resolution spectroscopy of low-energy DR resonances, experimental studies of KLL DR of very heavy hydrogen like ions, isotope shift measurements of DR resonances, and the experimental determination of hyperfine induced decay rates in divalent ions utilizing DR.

Ammonium ions induce inactivation of Kir2.1 potassium channels expressed in Xenopus oocytes.

1. The decay of inward currents was studied using the giant patch-clamp technique and a cloned inward rectifier K(+) channel, Kir2.1, expressed in Xenopus oocytes. 2. In inside-out patches, inward currents carried by NH4(+) or Tl(+) decayed over time. When the voltage was more negative, the degree and rate of decay were greater. The rate of NH4(+)-induced decay saturated at a symmetrical [NH4(+)] of approximately 100 mM. The decay rate was slow (2.6 x 10(3) M(-1) s(-1)) at -140 mV with 10 mM [NH4(+)]. 3. Upon a 10 degrees C increase in temperature, the single-channel NH4(+) current amplitude increased by a factor of 1.57, whereas the NH4(+)-induced decay rate increased by a factor of 2.76. In the R148Y Kir2.1 mutant (tyrosine 148 is at the external pore mouth), NH4(+)-induced inactivation was no longer observed. 4. NH4(+) single-channel currents revealed one open and one closed state. The entry rate into the closed state was voltage dependent whereas the exit rate from the closed state was not. An increase of internal [NH4(+)] not only decreased the entry rate into but also elevated the exit rate from the closed state, consistent with the occupancy model modified from the foot-in-the-door model of gating. 5. These results suggest that the decay of NH4(+) current is unlikely to be due to a simple bimolecular reaction leading to channel block. We propose that NH4(+) binding to Kir2.1 channels induces a conformational change followed by channel closure. 6. The decay induced by permeant ions other than K(+) may serve as a secondary selectivity filter, such that K(+) is the preferred permeant ion for Kir2.1 channels.

Induced transitions between Wannier ladders

We study the transitions between the ground and excited Wannier states induced by a weak ac field. Because the upper Wannier states are several orders of magnitude less stable than the ground states, these transitions decrease the global stability of the system characterized by the rate of probability leakage or decay rate. Using non-Hermitian resonant perturbation theory we obtain an analytical expression for this induced decay rate. The analytical results are compared with exact numerical calculations of the system decay rate.

Impossibility to Measure the Total Neutron- and Proton-Induced Nonmesonic Decays forHΛ3

Based on realistic calculations for the nonmesonic decay rate of Hypertriton we demonstrate, that in principle it is not possible to measure the total n- and p- induced decay rates and as a consequence $\Gamma_n /\Gamma_p$ for that lightest hypernucleus.For the nonmesonic decay process the calculations are performed with modern YN forces based on various meson exchanges and taking the final state interaction among the three nucleons fully into account. Our findings have consequences also for the interpretation of experimental $\Gamma_n/\Gamma_p$ ratios for heavier hypernuclei where severe discrepancies exist to theoretical $\Gamma_n/\Gamma_p$ ratios.

Hyperfine Induced Transitions as Diagnostics of Isotopic Composition and Densities of Low‐Density Plasmas

The J = 0 --> J' = 0 radiative transitions, usually viewed as allowed through two-photon decay, may also be induced by the hyperfine (HPF) interaction in atoms or ions having a nonzero nuclear spin. We compute new and review existing decay rates for the nsnp P-3(J)0 --> nS(2 1)S(J'= 0) transitions in ions of the Be (n = 2) and Mg (n = 3) isoelectronic sequences. The HPF induced decay rates for the J = 0 --> J' = 0 transitions are many orders of magnitude larger than those for the competing two-photon processes, and when present are typically 1 or 2 orders of magnitude smaller than the decay rates of the magnetic quadrupole (J = 2 --> J' = 0) transitions for these ions. Several HPF induced transitions are potentially of astrophysical interest in ions of C, N, Na, Mg, Al, Si, K, Cr, Fe, and Ni. We highlight those cases that may be of particular diagnostic value for determining isotopic abundance ratios and/or electron densities from UV or EUV emission-line data. We present our atomic data in the form of scaling laws so that, given the isotopic nuclear spin and magnetic moment, a simple expression yields estimates for HPF induced decay rates. We examine some UV and EUV solar and nebular data in light of these new results and suggest possible applications for future study. We could not find evidence for the existence of HPF induced lines in the spectra we examined, but we demonstrate that existing data have come close to providing interesting upper limits. For the planetary nebula SMC N2, we derive an upper limit of 0.1 for C-13/C-12 from Goddard High-Resolution Spectrograph data obtained by Clegg. It is likely that more stringent limits could be obtained using newer data with higher sensitivities in a variety of objects. (Less)

Constraints on supersymmetry due to b → sγ. An improved calculation

The calculation of the one-loop induced decay rate b → sγ is improved by including radiative corrections to the charged Higgs mass and to the charged-Higgs-fermion-fermion vertex. It is shown how the radiative corrections modify the excluded zone in the tan β − m A plane, imposed by the non-observation of this decay. In particular, a light C P-odd Higgs at large tan β becomes allowed.

Spin-Diffusion Limitations for High-Sensitivity NMR Techniques

The experimental sensitivity attainable in employing such high-sensitivity NMR techniques as double nuclear resonance and rotating-frame relaxation can be limited by spin-diffusion rates within the bulk detected spin system. We develop a diffusion kernel solution to the driven spin-diffusion equation and calculate the detected-system magnetization decay rate induced by a dilute concentration of pumping centers. Our results show that spin-diffusion suppression of the induced decay rate depends only upon local parameters, is independent of concentration of pumping centers, and, in all systems whose experimental study has thus far been reported, would produce at most a 10% effect. These particular conclusions apply only to the case of completely dispersed pumping centers, but the general approach can be extended to treat aggregated systems. Our description of the spin-diffusion behavior yields results in agreement with existing experimental data, but in disagreement with previous theoretical treatments.