Calculation Of Decay Rates Research Articles

Comparison of Ensemble vs One-Third Octave Band Averaging of Field Collected Decays

There are two allowable methods to calculate the average decay rate in ASTM E2235 - 20, "Standard Test Method for Determination of Decay Rates for Use in Sound Insulation Test Methods". The first averages the data that is presented by the sound level meter for each measurement. The second employs ensemble averaging to create one decay curve and then perform the decay rate calculation on that new curve. Historically, portable sound level meters exported a calculated reverberation time in each one-third octave band for each measurement due to lack of computing power. With the rapid increase in portable computing power, portable sound level meters can now easily perform ensemble averaging. These two methods will be compared. It will be shown that ensemble averaging will produce reliable results with far fewer decays than arithmetic averaging.

Precise estimate of charged Higgsino/Wino decay rate

Higgsinos and Winos in the supersymmetric Standard Model are prime candidates for dark matter due to their weakly interacting nature. The mass differences between their charged components (charginos) and neutral components (neutralinos) become degenerate when other superparticles are heavy, resulting in long-lived charginos. In the case of the Winos, the mass difference is approximately 160 MeV across a wide range of the parameter space. Consequently, the chargino decays into the lightest neutralino, emitting a single charged pion. For Higgsinos, however, mass differences ranging from O(0.1) GeV to O(1) GeV are possible, leading to a variety of decay channels. In this paper, we extend our previous analysis of Wino decay to the chargino with a larger mass difference. We emphasize characterizing its decay signatures through leptonic and hadronic modes. By utilizing the latest experimental data, we perform a comprehensive study of the decay rate calculations incorporating these hadronic modes to determine the impact on the predicted chargino lifetime. Additionally, we conduct next-to-leading order (NLO) calculations for the leptonic decay modes. Our NLO results can be applied to the case of more general fermionic electroweak multiplets, e.g., quintuplet dark matter.

Electroweak input schemes and universal corrections in SMEFT

The choice of an electroweak (EW) input scheme is an important component of perturbative calculations in Standard Model Effective Field Theory (SMEFT). In this paper we perform a systematic study of three different EW input schemes in SMEFT, in particular those using the parameter sets {MW, MZ, GF}, {MW, MZ, α}, or {α, MZ, GF}. We discuss general features and calculate decay rates of Z and W bosons to leptons and Higgs decays to bottom quarks in these three schemes up to next-to-leading order (NLO) in dimension-six SMEFT. We explore the sensitivity to Wilson coefficients and perturbative convergence in the different schemes, and show that while the latter point is more involved than in the Standard Model, the dominant scheme-dependent NLO corrections are universal and can be taken into account by a simple set of substitutions on the leading-order results. Residual NLO corrections are then of similar size between the different input schemes, and performing calculations in multiple schemes can give a useful handle on theory uncertainties in SMEFT predictions and fits to data.

A New Water Hammer Decay Model: Analyzing the Interference of Multiple Fractures and Perforations on Decay Rate

Summary Hydraulic fracturing technology is an important technique for developing tight oil and gas resources. Multicluster fracture diagnosis is significant for hydraulic fracture design and optimization. Water hammer fracturing diagnostic technology is an emerging diagnostic technology. Fracture network complexity can be assessed by the water hammer decay rate. In this paper, a new characteristic line coupling model for the fracture-wellbore system is proposed. This model calculates the number of fractures and perforations based on the water hammer signal. First, our paper defines a method for calculating the water hammer decay rate. Second, a characteristic line simulation method for water hammer coupled with fractures and perforations is proposed. Third, the effects of different fracture-wellbore systems on the water hammer decay rate are analyzed. The method is validated by laboratory experiments and numerical analysis. Finally, through a field case, the results of the number of fracture openings explained by the optical fiber and our model are compared to provide support for the field water hammer fracturing diagnosis. Our paper provides a new model for water hammer decay rate calculation and evaluation of fracture number.

The Boring Monopole

We study false vacuum decays catalysed by metastable magnetic monopoles which act as tunnelling sites with exponentially enhanced decay rates. Metastable monopoles are configurations where the monopole core is in the true vacuum of the scalar potential. The field profiles describing the decay do not have the typically assumed O(3)/O(4)O(3)/O(4) symmetry, thus requiring an extension of the usual decay rate calculation. To numerically determine the saddle point solutions which describe the tunnelling process we use a new algorithm based on the mountain pass theorem. This method can be applied more widely to phase transitions with reduced symmetry, such as decays away from the zero and infinite temperature limits. In our setup monopole-catalysed tunnelling can dominate over the homogeneous false vacuum decay for a wide range of parameters, significantly modify the gravitational wave signal or trigger phase transitions which would otherwise never complete. A single boring monopole in our Hubble patch may determine the lifetime of our current vacuum.

Influence of electron density, temperature and decay energy on β – decay rates in a stellar environment * *Supported by the National Natural Science Foundation of China (11822503) and the Fundamental Research Funds for the Central Universities (Nanjing University)

In this paper, the decay rates in the magnetic field of a neutron star are investigated under different conditions of electron density, temperature, and decay energy. By considering the influence of magnetic field on the electron spectrum, we improve the Takahashi–Yokoi model and perform the calculations of decay rates for the nickel (Ni) isotopes, which are the typical neutron-rich nuclei participating in the rapid neutron-capture process (r-process). It is found that the decay rates are increased significantly in the extremely strong magnetic field ( G). Furthermore, we find oscillation of decay rates with the increase of magnetic field strength, implying that the magnitude of decay rates is closely related to not only the decay energy but also the environmental electron density. In contrast, the impact of temperature on the decay rates is found to be negligible in the range of K K.

Laser spectroscopy of the yPJo7 states of Cr i

Here we report measured and calculated values of decay rates of the 3d$^4$($^5$D)4s4p($^3$P$^{\rm{o}}$)\ y$^7$P$^{\rm{o}}_{2,3,4}$ states of Cr I. The decay rates are measured using time-correlated single photon counting with roughly 1% total uncertainty. In addition, the isotope shifts for these transitions are measured by laser induced fluorescence to roughly 0.5% uncertainty. The decay rate calculations are carried out by a hybrid approach that combines configuration interaction and the linearized coupled cluster method (CI+all-order method). The measurements provide a much needed precision benchmark for testing the accuracy of the CI+all-order approach for such complicated systems with six valence electrons, allowing to significantly expand its applicability. These measurements also demonstrate operation of a cryogenic buffer gas beam source for future experiments with MgF molecules toward quantum blackbody thermometry.

UV Time-Resolved Laser-Induced Fluorescence Spectroscopy of Amino Acids Found in Meteorites: Implications for Space Science and Exploration.

Laser-induced fluorescence spectroscopy is a useful laboratory and in situ technique for planetary exploration, with applications in biosignature detection and the search for life on Mars. However, little work has been completed on the utility of fluorescence spectroscopy techniques on asteroid relevant material. In preparation for asteroid sample return missions such as NASA's OSIRIS-REx and JAXA's Hayabusa2, we conducted UV time resolved laser-induced fluorescence spectroscopy (TR-LIF) analysis of 10 amino acids, all of which have been found in the carbonaceous meteorites Murchison and Allende. We present the calculation of decay rates of each amino acid (1.55-3.56 ns) and compare with those of relevant homogeneous minerals (15-70 ns). Moreover, we demonstrate a linear relationship between calculated lifetimes and elemental abundance of nitrogen and carbon (p < 0.025). The quantitative and qualitative fluorescence analyses presented in this work will lead to more reliable identification of organic material within meteorites and asteroids in a time-efficient, minimally destructive way.

Migration and fate of characteristic pollutants migration from an abandoned tannery in soil and groundwater by experiment and numerical simulation

The tannery industry is an integral part of economic development in many developing countries, and the environmental pollution caused by the tannery industry cannot be ignored. In this study, soil and groundwater samples at different depths were collected from an abandoned tannery to investigate the temporal and spatial distribution of characteristic pollutants produced by tanning. The concentrations of Cr, Cl, F and NH4+–N in the soil from the sludge temporary storage area were higher than those from the liming and unhairing workshop, chrome tanning workshop, wastewater outlet, and around wastewater pond. The concentration of Cr(VI) in all sampling sites was below the detection limit. The main species of Cr in the groundwater were Cr(NH3)6Cl2+ and CrO42− based on the simulation of Visual MINTEQ. The saturation index was negative and changed with time indicating that Cr existed in the dissolved phase. The proportion of Cr(VI) to total Cr was negatively correlated with the saturation index in village 1 and village 3. The simulation results from Visual MODFLOW and MT3DMS showed that the migration of Cr, NH4+–N, Cl− and F− mainly occurred in the Quaternary system. The coverage of the pollution plume of pollutants in villages 1 and 3 was as follows: Cr > NH4+−N > Cl− > F−. Two decay rate calculation methods of pollutants with migration time and distance were put forward to provide a basis for the actual investigation of the pollution migration scope and time determination.

Algorithm for quantum computation of particle decays

A quantum algorithm is developed to calculate decay rates and cross sections using quantum resources that scale polynomially in the system size assuming similar scaling for state preparation and time evolution. This is done by computing finite-volume one- and two-particle Green's functions on the quantum hardware. Particle decay rates and two particle scattering cross sections are extracted from the imaginary parts of the Green's function. A $0+1$ dimensional implementation of this method is demonstrated on IBM's superconducting quantum hardware for the decay of a heavy scalar particle to a pair of light scalars.

Modeling of underexpanded hydrogen jets through square and rectangular slot nozzles

The development and revision of safety codes and standards for hydrogen infrastructure requires a solid scientific basis, including studies of unignited releases from high pressure systems for various scenarios. Most hydrogen releases are modeled as axisymmetric jets, but real leaks are more likely to be non-axisymmetric jets issuing from high aspect ratio cracks or slots. In the present study, underexpanded hydrogen jets from square and rectangular nozzles with aspect ratios of 1–16 were numerically modeled for stagnation pressures up to 20 MPa. The near and far flow fields were modeled separately using two sequential computational domains to accurately and efficiently capture the flow characteristics. The numerical models were first validated with experimental data from a previous experimental study and literature data. The mass fraction and velocity distributions show that the centerline decay rates increase as the nozzle aspect ratio increases, but this increase is dependent on the pressure. This means that the canonical decay law of round turbulent jets and plumes no longer applies to the slot nozzle jets for high pressures. The radial profiles collapse onto a Gaussian curve in the major axis plane, but neither collapse, nor are they Gaussian in the minor axis plane with peaks away from the jet centerline. Different shock patterns were identified along the major and minor axes and the axis switching phenomenon seen in the literature was also reproduced. The axis switching resulted in significantly wider flattened concentration distributions compared with the axisymmetric jet which may require consideration during safety analyses for non-circular nozzles. A scaling factor taking both the nozzle shape and pressure effects into account was then developed to better scale the centerline decay rates for jets from both the square and rectangular nozzles. The present study demonstrates that the nozzle shape effects on the jet spreading should not be overlooked and proper scaling factors are required to collapse the data and calculate decay rates.

Precision decay rate calculations in quantum field theory

Tunneling in quantum field theory is worth understanding properly, not least because it controls the long term fate of our universe. There are however, a number of features of tunneling rate calculations which lack a desirable transparency, such as the necessity of analytic continuation, the appropriateness of using an effective instead of classical potential, and the sensitivity to short-distance physics. This paper attempts to review in pedagogical detail the physical origin of tunneling and its connection to the path integral. Both the traditional potential-deformation method and a recent more direct propagator-based method are discussed. Some new insights from using approximate semi-classical solutions are presented. In addition, we explore the sensitivity of the lifetime of our universe to short distance physics, such as quantum gravity, emphasizing a number of important subtleties.

Transverse collisional instabilities of a Bose-Einstein condensate in a driven one-dimensional lattice

Motivated by recent experiments, we analyse the stability of a three-dimensional Bose-Einstein condensate (BEC) loaded in a periodically driven one-dimensional optical lattice. Such periodically driven systems do not have a thermodynamic ground state, but may have a long-lived steady state which is an eigenstate of a "Floquet Hamiltonian". We explore collisional instabilities of the Floquet ground state which transfer energy into the transverse modes. We calculate decay rates, finding that the lifetime scales as the inverse square of the scattering length and inverse of the peak three- dimensional density. These rates can be controlled by adding additional transverse potentials.

Continous rail absorber design using decay rate calculation in FEM

In recent years, many countries have added railway noise to the issues covered by noise regulations. It is known that the rail is the dominant source of rolling noise at frequency range of 500Hz-2000Hz for the conventional speeds (<160km/h). One of the effective ways to reduce noise from railway track is using a rail vibration absorber. To study the acoustic performance of rail absorber, the decay rates of vibration have long been used by researcher. In this paper, A FE model of a periodic supported rail with infinite element in ABAQUS is developed to study the acoustic performance of the rail absorber. To compute the decay rates, acceleration responses along the rail transferred to MATLAB to obtain response levels in frequency domain and then by processing the response levels, the decay rates obtained for each1/3octav band. Continous rail absorber is represented by a steel layer and an elastomer layer. The decay rates for conventional rail and rail with one-side absorber and also, the rail with two side absorber are obtained and compared. Then, to improve the system of rail absorber, a steel plate with elastomer layer is added to bottom of the rail foot. The vertical decay rate results show that the decay rate of rail vibration along the track is significantly increased around the tuned frequency of the absorber and thus the rail vibration energy is substantially reduced in the corresponding frequency region and also effective in rail noise reduction.

Closed system approach to open systems: tunnelling decay of interacting cold bosons in an optical lattice

A Bose–Hubbard Hamiltonian, modelling cold bosons in an optical lattice, is used to simulate the dynamics of interacting open quantum systems as subsystems of a larger, closed system, avoiding complications like the introduction of baths, complex absorbing potentials or absorbing boundaries. The numerically exact unitary dynamics is compared with the effective descriptions of the subsystems based on non-Hermitian Hamiltonians or Lindblad master equations. The validity of popular models with constant decay rates is explicitly analysed for decaying single and double wells. For simplicity, we concentrate on simulations with very small particle numbers (mostly N = 2, 3) and neglect the interaction in parts of the system where this is appropriate. We furthermore present a discrete lattice version of the Siegert approximation method for calculating decay rates.

Stability of excited dressed states with spin-orbit coupling

We study the decay behaviors of ultracold atoms in metastable states with spin-orbit coupling (SOC), and demonstrate that there are two SOC-induced decay mechanisms. One arises from the trapping potential and the other is due to interatomic collision. We present general schemes for calculating decay rates from these two mechanisms, and illustrate how the decay rates can be controlled by experimental parameters.We experimentally measure the decay rates over a broad parameter region, and the results agree well with theoretical calculations. This work provides an insight for both quantum simulation involving metastable dressed states and studies on few-body problems with SO coupling.

EXACT COLEMAN–DE LUCCIA INSTANTONS

We present exact Coleman–De Luccia (CDL) instantons, which describe vacuum decay from Anti-de Sitter (AdS) space, de Sitter (dS) space and Minkowski space to AdS space. We systematically obtain these exact solutions by considering deformation of Hawking-Moss (HM) instantons. We analytically calculate the action of instantons and discuss a subtlety in calculation of decay rates.

Decay rates for some quasi-birth-and-death processes with phase-dependent transition rates

Recently, there has been considerable interest in the calculation of decay rates for models that can be viewed as quasi-birth-and-death (QBD) processes with infinitely many phases. In this paper we make a contribution to this endeavour by considering some classes of models in which the transition function is not homogeneous in the phase direction. We characterize the range of decay rates that are compatible with the dynamics of the process away from the boundary. In many cases, these rates can be attained by changing the transition structure of the QBD process at level 0. Our approach, which relies on the use of orthogonal polynomials, is an extension of that in Motyer and Taylor (2006) for the case where the generator has homogeneous blocks.

Decay rates for some quasi-birth-and-death processes with phase-dependent transition rates

Recently, there has been considerable interest in the calculation of decay rates for models that can be viewed as quasi-birth-and-death (QBD) processes with infinitely many phases. In this paper we make a contribution to this endeavour by considering some classes of models in which the transition function is not homogeneous in the phase direction. We characterize the range of decay rates that are compatible with the dynamics of the process away from the boundary. In many cases, these rates can be attained by changing the transition structure of the QBD process at level 0. Our approach, which relies on the use of orthogonal polynomials, is an extension of that in Motyer and Taylor (2006) for the case where the generator has homogeneous blocks.

Decay Rate of an Excited Atom in Dispersive and Dissipative Plasma Media

Calculations of decay rates of an excited atom embedded in a dispersive and dissipative plasma medium are presented in this paper. The usual expression for decay rate of an initially excited atom in dipole approximation is given by Fermi’s golden rule. The electric field correlation function is related to the imaginary part of the potential Green’s function along with the fluctuation of dissipation theorem and Kubo’s formula. Using the Green’s function technique offers possibilities of closed function representations. It is applicable to evaluate the decay rate of an excited atom that allows us to understand the particular structure of the vacuum state of the electromagnetic field. In this paper, the decay rate of an excited atom in dispersive and dissipative media is estimated.