Decay Distributions Research Articles

Probing new physics with B¯→ρ(770)ℓ−ν¯ℓ and B¯→a1(1260)ℓ−ν¯ℓ

The $B$ meson semileptonic modes to $\rho(770)$ and $a_1 (1260)$ are useful to pin down possible non Standard Model effects. The 4d differential $\bar B \to \rho(\pi \pi) \ell^- \bar \nu_\ell$ and $ \bar B \to a_1 (\rho \pi) \ell^- \bar \nu_\ell$ decay distributions are computed in SM and in extensions involving new Lepton Flavour Universality violating semileptonic $b \to u$ operators. The Large Energy limit for the light meson is also considered for both modes. The new effective couplings are constrained using the available data, and several observables in $\bar B \to \rho(\pi\pi) \ell^- \bar \nu_\ell$ in which NP effects can be better identified are selected, using the angular coefficient functions. The complementary role of $\bar B \to \rho(\pi \pi) \ell^- \bar \nu_\ell$ and $\bar B \to a_1 (\rho \pi) \ell^- \bar \nu_\ell$ is discussed.

Quantifying effects of root systems of planted and natural vegetation on rill detachment and erodibility of a loessial soil

The objectives of this study were to evaluate different root parameters for estimating rill detachment, and to compare and quantify the effectiveness of planted and natural vegetation on soil physical characteristics and in reducing rill detachment and erodibility. Laboratory-concentrated-flow flume tests were performed under a flow discharge of 3 L min−1 and a slope of 15° with intact soil samples. A silt loam soil (Calcic Cambisol, in Loess Plateau in China) was sampled in 2015 from laboratory with planted ryegrass (Lolium perenne L.) and in 2014 from natural vegetation fields under 12 to 36-a restoration. The results indicated that root length density was the best parameter for estimating the effects of roots on rill detachment and erodibility for both planted ryegrass and natural vegetation, with exponential reduction equations. The exponents were more negative for natural vegetation (−0.411) than for planted species (−0.217) because of the existence of more complex root networks under more diverse natural vegetation. Rill erodibility of soil samples with roots decreased exponentially from the baseline erodibility of the root-free soil as RLD increased. Root systems of the restored natural vegetation ameliorated soil characteristics (bulk density, aggregate stability and organic matter content) more profoundly than those of the laboratory tests due to stronger bonding and binding effects, resulting in a lower absolute soil detachment rate for a given root density. There existed a vertical decay distribution pattern of root densities with soil depth for natural vegetation and planted ryegrass, and this distribution of root systems reached a steady state after 12 years natural vegetation restoration. More vegetation types under more different hydraulic conditions should be evaluated in future studies to provide better scientific bases for modelling their impacts on rill detachment and erodibility.

Exponential tooth decay curve.

A review of the distribution of d₃mft scores for Wales was undertaken to inform decisions on future reporting of decay experience. Visual examination of data from one survey suggested that caries in Wales is distributed along an exponential decay curve. Weighted d₃mft data from 2007/8, 2011/12 and 2014/15 was utilised. The data was compared with a pragmatically chosen exponential decay model. Distribution curves for d₃mft were plotted for each data set, correlation coefficients calculated and residuals plotted. The three surveys demonstrate similar exponential decay distributions across the range of d₃mft scores. Plots of each curve against the exponential decay model demonstrated close correlation (0.9826 - 0.9871). The progressive shift of these similarly shaped curves suggest similar levels of caries reduction across the spectrum of caries experience and thus improved oral health without widening of health inequality. The close fit with this simple mathematical model suggests that caries prevalence could be used to generate a theoretical distribution and thereby and estimate of mean d₃mft score. Such an approach could facilitate simplified oral health surveillance in areas where caries distributions are known from previous surveys. Within Wales caries does seem to be distributed in line with an exponential decay curve. As a result decay prevalence and mean d₃mft are mathematically related. This finding may have potential to support simplified local oral health surveillance. The data provides evidence suggesting improvements in caries experience in Wales are not at the expense of increased inequality.

Angular and CP-Violation Analyses of B-→D⁎+l-ν-l Decays at Hadron Collider Experiments

The B-→D⁎+l-ν-l branching fractions ratio between muon and tau lepton decay modes R(D⁎) has shown intriguing discrepancies between the Standard Model prediction and measurements performed at BaBar, Belle, and LHCb experiments, a possible sign of beyond the Standard Model physics. Theoretical studies show how observables related to the B-→D⁎+l-ν-l differential decay distribution can be used to further constrain New Physics contributions, but their experimental measurements are lacking to date. This article proposes the measurement of B-→D⁎+l-ν-l angular and CP-violating observables at hadron collider experiments, by exploiting approximate reconstruction algorithms using information from detectable final-state particles only. The resolution on the phase space variables is studied using B-→D⁎+l-ν-l decays simulated in a forward detector geometry like LHCb. A method to correct the observable values for the reconstruction inaccuracies based on detector simulation is successfully tested on simulated data and the decrease in precision with respect to a perfect reconstruction is evaluated. The D⁎+ longitudinal polarization fraction and the AT(2)CP-violating observable can be measured losing a factor of 2 and 5 in precision, respectively. The extraction of angular distributions from the template fit selecting B-→D⁎+l-ν-l decays and associated systematic uncertainties are also discussed.

Radiative b-baryon decays to measure the photon and b-baryon polarization

The radiative decays of b-baryons facilitate the direct measurement of photon helicity in brightarrow sgamma transitions thus serving as an important test of physics beyond the Standard Model. In this paper we analyze the complete angular distribution of ground state b-baryon radiative decays to multibody final states assuming an initially polarized b-baryon sample. Our sensitivity study suggests that the photon polarization asymmetry can be extracted to a good accuracy along with a simultaneous measurement of the initial b-baryon polarization. With higher yields of b-baryons, achievable in subsequent runs of the Large Hadron Collider (LHC), we find that the photon polarization measurement can play a pivotal role in constraining different new physics scenarios.

Types and rates of decomposition of Larix sibirica trees and logs in a mixed European boreal old-growth forest

Information on pathways and rates of decomposition of coarse woody debris (CWD) from one of the dominant boreal tree species – Siberian larch (Larix sibirica Ledeb.) – is scarce. We examined presence and distribution of internal decay in its living trees and decomposition rates in an 88-year chronosequence of logs in an old-growth mesic mixed European boreal forest. Fifty-two percent of the trees started decaying prior to death. Butt or stem rot was caused by white- and brown-rot biotrophic fungi in almost equal proportions. Those trees lost on average 29% of their initial wood mass. The mean decomposition rate of wood as related to initial conditions was 0.007 yr−1 for wood with initial biotrophic decay and 0.010 yr−1 for wood with saprotrophic decay. Bark lost its mass and volume faster – at a rate of 0.056 yr−1. The rate of carbon (C) loss for the whole stem was 0.024 yr−1 in wood affected by saprotrophic fungi and 0.007 yr−1 when the tree was affected by biotrophic fungi. When calculating C losses due to decomposition, separating bark and wood with different C concentrations and decomposition patterns as well as the rate of biotrophic and saprotrophic decay enables us to refine estimates of the role of Siberian larch CWD in C cycling. Further research is still needed to resolve uncertainties around the role of fungal communities and the origins and decomposition rates of butt rots and stem rots in living trees of Siberian larch, as well as the distribution patterns of these fungi and decomposition processes in individual trees and at the ecosystem level.

Study of Bs→ℓ+ℓ−γ decays in covariant quark model

We study the rare radiative leptonic decays ${B}_{s}\ensuremath{\rightarrow}{\ensuremath{\ell}}^{+}{\ensuremath{\ell}}^{\ensuremath{-}}\ensuremath{\gamma}$ ($\ensuremath{\ell}=e$, $\ensuremath{\mu}$, $\ensuremath{\tau}$) within the Standard Model, considering both the structure-dependent amplitude and bremsstrahlung. In the framework of the covariant confined quark model developed by us, we calculate the form factors characterizing the ${B}_{s}\ensuremath{\rightarrow}\ensuremath{\gamma}$ transition in the full kinematical region of the dilepton momentum squared and discuss their behavior. We provide the analytic formula for the differential decay distribution and give predictions for the branching fractions in both cases: with and without long-distance contributions. Finally, we compare our results with those obtained in other approaches.

A Look at Retirement Funds in the Iranian Legal System

Pension funds are an important pillar of the social security system of the country. Historically, retirement funds in the Iranian legal system have been a source of many problems, most notably financial deficits. The lack of prospects for the future and the uncertain program and unprofessional management, as a result of the lack of transparency and ineffective and sometimes contradictory laws, have all worked together to make retirement funds a problem in the country; this turmoil and turmoil situation And the inadequacies of funds in all respects have caused worries about the future. Reasons for the aging of the population and the decline in employment and ... have increased the seriousness of the crisis. The implementation of early-retirement laws in different periods, macroeconomic fluctuations, and neglect of misguided and non-normative outlooks and government roles, and largely one-way interactions with funds, are one of the most important reasons for the existence of a crisis in retirement funds In recent years. In Iran, the increase in the number of retirement funds has been caused by various programs and systems (various regulations); in the absence of comprehensive welfare and social security systems in the country, the stratification and distribution of decay and support Boxes will also be added. In this context, it is necessary to gain a comprehensive understanding of the status and legal system of the pension funds, with the study of how the administration and the status of the cost are spent, the inputs of these funds and the amount and group covered. In other words, the multiplicity of pension funds and the lack of coordination between these institutions and the lack of a single standard in them and the lack of respect for the fairness of the income received by retirees has caused dissatisfaction with this important group of society, because the type of services and range of support, also from the fund to the fund The difference is different, and this creates discrimination and increases the gap between the strata; it should be noted that the function and function of pension funds is international and the lack of attention to these funds can have serious consequences in the community. Currently, reforms to the rules and regulations of the pension funds and the management and management of these funds are important and important priorities, and the planned measures should be directed towards changing the situation and improving the efficiency and funds and optimal and wise use. Resources are maintained, with no loss or damage to retirement benefits.

W boson polarization as a measure of gauge-Higgs anomalous couplings at the LHC

We show how the W boson polarization in the process of associated W±H production at the Large Hadron Collider (LHC) can be used to constrain anomalous WWH couplings. We first calculate the spin density matrix for the W to linear order in the anomalous couplings, which are assumed to be small. We then evaluate angular asymmetries in the decay distributions of leptons produced in the decay of the W and show how they can be used to measure the individual elements of the polarization tensor. We estimate the limits that can be placed on the anomalous WWH couplings at a future run of the LHC.

Dose reconstruction from PET images in carbon ion therapy: a deconvolution approach

Dose and range verification have become important tools to bring carbon ion therapy to a higher level of confidence in clinical applications. Positron emission tomography is among the most commonly used approaches for this purpose and relies on the creation of positron emitting nuclei in nuclear interactions of the primary ions with tissue. Predictions of these positron emitter distributions are usually obtained from time-consuming Monte Carlo simulations or measurements from previous treatment fractions, and their comparison to the current, measured image allows for treatment verification. Still, a direct comparison of planned and delivered dose would be highly desirable, since the dose is the quantity of interest in radiation therapy and its confirmation improves quality assurance in carbon ion therapy.In this work, we present a deconvolution approach to predict dose distributions from PET images in carbon ion therapy. Under the assumption that the one-dimensional PET distribution is described by a convolution of the depth dose distribution and a filter kernel, an evolutionary algorithm is introduced to perform the reverse step and predict the depth dose distribution from a measured PET distribution. Filter kernels are obtained from either a library or are created for any given situation on-the-fly, using predictions of the -decay and depth dose distributions, and the very same evolutionary algorithm.The applicability of this approach is demonstrated for monoenergetic and polyenergetic carbon ion irradiation of homogeneous and heterogeneous solid phantoms as well as a patient computed tomography image, using Monte Carlo simulated distributions and measured in-beam PET data. Carbon ion ranges are predicted within less than 0.5 mm and 1 mm deviation for simulated and measured distributions, respectively.

Angular analysis of the decay B+→K+μ+μ− in proton-proton collisions at s=8 TeV

The angular distribution of the flavor-changing neutral current decay B$^+$ $\to$ K$^+\mu^+\mu^-$ is studied in proton-proton collisions at a center-of-mass energy of 8 TeV. The analysis is based on data collected with the CMS detector at the LHC, corresponding to an integrated luminosity of 20.5 fb$^{-1}$. The forward-backward asymmetry $A_{\mathrm{FB}}$ of the dimuon system and the contribution $F_{\mathrm{H}}$ from the pseudoscalar, scalar, and tensor amplitudes to the decay width are measured as a function of the dimuon mass squared. The measurements are consistent with the standard model expectations.

Constraining P and CP violation in the main decay of the neutral Sigma hyperon

On general grounds based on quantum field theory the decay amplitude for Σ0→Λγ consists of a parity conserving magnetic and a parity violating electric dipole transition moment. Because of the subsequent self-analyzing weak decay of the Λ hyperon the interference between magnetic and electric dipole transition moment leads to an asymmetry in the angular distribution. Comparing the decay distributions for the Σ0 hyperon and its antiparticle gives access to possible C and CP violation. Based on flavor SU(3) symmetry the present upper limit on the neutron electric dipole moment can be translated to an upper limit for the angular asymmetry. It turns out to be far below any experimental resolution that one can expect in the foreseeable future. Thus any true observation of a CP violating angular asymmetry would constitute physics beyond the standard model, even if extended by a CP violating QCD theta-vacuum-angle term.

Novel |V_{us}| Determination Using Inclusive Strange τ Decay and Lattice Hadronic Vacuum Polarization Functions.

We propose and apply a new approach to determining |V_{us}| using dispersion relations with weight functions having poles at Euclidean (spacelike) momentum which relate strange hadronic τ decay distributions to hadronic vacuum polarization (HVP) functions obtained from lattice quantum chromodynamics. We show examples where spectral integral contributions from the region where experimental data have large errors or do not exist are strongly suppressed but accurate determinations of the relevant lattice HVP combinations remain possible. The resulting |V_{us}| agrees well with determinations from K physics and three-family Cabibbo-Kobayashi-Maskawa unitarity. Advantages of this new approach over the conventional hadronic τ decay determination employing flavor-breaking sum rules are also discussed.

Nonleptonic two-body decays of single heavy baryons ΛQ , ΞQ , and ΩQ ( Q=b , c ) induced by W emission in the covariant confined quark model

We have made a survey of heavy-to-heavy and heavy-to-light nonleptonic heavy baryon two-body decays and have identified those decays that proceed solely via $W$-boson emission, i.e. via the tree graph contribution. Some sample decays are $\Omega_{b}^{-}\to\Omega_{c}^{(*)0}\rho^{-}(\pi^{-}),\, \Omega_{b}^{-}\to\Omega^{-}J/\psi(\eta_{c}),\, \Xi_{b}^{0,-}\to\Xi^{0,-}J/\psi(\eta_{c}),\, \Lambda_{b}\to \Lambda J/\psi(\eta_{c}),\, \Lambda_{b}\to \Lambda_{c} D_{s}^{(\ast)},\, \Omega_{c}^{0}\to\Omega^{-}\rho^{+}(\pi^{+})$, and $\Lambda_c \to p \phi$. We make use of the covariant confined quark model previously developed by us to calculate the tree graph contributions to these decays. We calculate rates, branching fractions and, for some of these decays, decay asymmetry parameters. We compare our results to experimental findings and the results of other theoretical approaches when they are available. Our main focus is on decays to final states with a lepton pair because of their clean experimental signature. For these decays we discuss two-fold polar angle decay distributions such as in the cascade decay $\Omega_{b}^{-}\to\Omega^{-}(\to \Xi\pi,\Lambda K^{-})+J/\psi(\to \ell^{+}\ell^{-})$. Lepton mass effects are always included in our analysis.

Tests of the standard model in neutron β decay with a polarized neutron and electron and an unpolarized proton

We analyse the electron--energy and angular distribution of the neutron beta decay with polarized neutron and electron and unpolarized proton, calculated in Phys. Rev. C 95, 055502 (2017) within the Standard Model (SM), by taking into account the contributions of interactions beyond the SM. After the absorption of vector and axial vector contributions by the axial coupling constant and Cabibbo-Kobayashi-Maskawa (CKM) matrix element (Bhattacharya et al., Phys. Rev. D 85, 054512 (2012) and so on) these are the contributions of scalar and tensor interactions only. The neutron lifetime, correlation coefficients and their averaged values, and asymmetries of the neutron beta decay with polarized neutron and electron are adapted to the analysis of experimental data on searches of contributions of interactions beyond the SM. Using the obtained results we propose some estimates of the values of the scalar and tensor coupling constants of interactions beyond the SM. We use the estimate of the Fierz interference term "b_F = - 0.0028 +/- 0.0026" by Hardy and Towner (Phys. Rev. C 91, 025501 (2015)), the neutron lifetime "tau_n = 880.2(1.0)s"(Particle Data Group, Chin. Phys. C 40, 100001 (2016)) and the experimental data "N_{\exp} = 0.067 +/- 0.011_{\rm stat.} +/- 0.004_{\rm syst.}" for the averaged value of the correlation coefficient of the neutron-electron spin-spin correlations, measured by Kozela et al. (Phys. Ref. C 85, 045501 (2012)). The contributions of G-odd correlations are calculated and found at the level of 10^{-5} in agreement with the results obtained by Gardner and Plaster (Phys. Rev. C 87, 065504 (2013)).

Inlet flow disturbance effects on direct numerical simulation of incompressible round jet at Reynolds number 2500

This letter reports inlet flow disturbance effects on direct numerical simulation of incompressible round jet at Reynolds number 2500. The simulation employs an accurate projection method in which a sixth order biased upwind difference scheme is used for spatial discretization of nonlinear convective terms, with a fourth order central difference scheme used in the discretization of the divergence of intermediate velocity. Carefully identifying reveals that the inlet flow disturbance has some influences on the distribution pattern of mean factor of swirling strength intermittency. With the increase of inlet disturbance magnitude jet core cone slightly shortens, observable differences occur in the centerline velocity and its fluctuations, despite the negligible impacts on the least square fitted centerline velocity decay constant (Bu) and distribution parameter (Ku) for velocity profile in self-similar region.

Decay Angular Distributions of K* and D* Mesons as a Tool for the Dynamics of Open Strange and Charm Production

We analyze decay spin-density matrix elements of $K^*$ and $D^*$ vector mesons and find that the corresponding vector meson decay distributions are sensitive to the production mechanisms. This suggests that the measurement of these quantities can be used to unravel the production mechanisms.

Resonance dynamics of DCO (X̃ 2A') simulated with the dynamically pruned discrete variable representation (DP-DVR).

Selected resonance states of the deuterated formyl radical in the electronic ground state X̃ 2A' are computed using our recently introduced dynamically pruned discrete variable representation [H. R. Larsson, B. Hartke, and D. J. Tannor, J. Chem. Phys. 145, 204108 (2016)]. Their decay and asymptotic distributions are analyzed and, for selected resonances, compared to experimental results obtained by a combination of stimulated emission pumping and velocity-map imaging of the product D atoms. The theoretical results show good agreement with the experimental kinetic energy distributions. The intramolecular vibrational energy redistribution is analyzed and compared with previous results from an effective polyad Hamiltonian. Specifically, we analyzed the part of the wavefunction that remains in the interaction region during the decay. The results from the polyad Hamiltonian could mainly be confirmed. The C=O stretch quantum number is typically conserved, while the D-C=O bend quantum number decreases. Differences are due to strong anharmonic coupling such that all resonances have major contributions from several zero-order states. For some of the resonances, the coupling is so strong that no further zero-order states appear during the dynamics in the interaction region, even after propagating for 300 ps.

Four-Leptonic Decays of Charged and Neutral B Mesons within the Standard Model

The branching ratios and differential distributions for the four-leptonic decays \({B^ - } \to {\mu ^ + }{\mu ^ - }{\bar v_e}{e^ - }\), \({B^ - } \to {e^ + }{e^ - }{\bar v_\mu }{\mu ^ - }\), and \({B^ - } \to {\mu ^ + }{\bar v_\mu }{\mu ^ - }{\mu ^ - }\) are calculated within the Standard Model. The branching ratios for the rare decays Bd,s → e+e−μ+μ− and Bd,s → μ+μ−μ+μ− are estimated. Methods for testing the lepton universality in rare multileptonic decays of charged and neutral B mesons are proposed.

Distribution of stem decay in the beech trees of the Azerbaijan and its impact on the output of commercial wood

To determine the distribution of stem decay in the beech stands of Azerbaijan, we sought to identify the species, number, and height of attachment of fruiting bodies; the extent of decay in tree trunks growing under different conditions; and its influence on the trees’ commercial wood. The research was conducted on three farms representing the most common forest types of the Greater Caucasus within Azerbaijan. Examination of the presence of fruiting bodies in the tree trunk revealed that stem decay is the most common infection in beech (Fagus orientalis) stands, especially in fresh, moist areas, with less infection under dry growing conditions. In this work, the length, diameter, and volume of decay were studied by infecting the trunks of 93 model trees affected with mushrooms in 1–4 m cuttings. Our results showed that as the age of the stand increased, extent, diameter, and volume of decay increased significantly: the extent of decay from 1.47 to 6.43 m; the diameter of the decay from 8.15 to 32.7 cm; and the volume of decay from 2.5 to 13.2%. The relationship between age and the specified indicators is presented graphically. Using data obtained from the same sample of trees, we determined the expected and actual yield of commercial wood by age class. We determined that stem decay in beech stands leads to a decrease in the yield of commercial wood on average from 25.1% in the middle-aged to 14.8% in overmature plantations, respectively, with an estimated yield of 40.8–62.7%. Here we present mathematical models of the output of commercial wood from the infected part of the stands by age classes with the use of average data on the extent of decay in model trees.