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The a decay rate of 210Po was measured in a film sample (210Po @Bi2O3) and a slice sample (210Po @Bi metal), respectively. The former was used as a reference sample. The half-lives of 210Po @Bi2O3 and 210Po @Bi metal environments were observed to be (138.40 ± 0.21 d) and (138.87 ± 0.87 d) at room temperature, respectively. It was found that the half-life of 210Po is consistent with international recommendations within the uncertainty 0Po between film sample (210Po ©Bi2O3) and limits, and we did not find any deviation of the a decay rate of slice sample (210Po @Bi metal). [ABSTRACT FROM AUTHOR]

We report new data on the 136Sb 6- yrast isomer with T1/2 = 489(40) ns and πg17/2 × νf37/2 configuration, populated in the projectile fission of 238U on a 9Be target. The analysis confirms the lifetime, providing a good accuracy measurement. In addition, the decay of the isomer to the ground state is newly suggested. Our result for the isomeric decay scheme is in a good agreement with shell-model calculations. [ABSTRACT FROM AUTHOR]

Background: Until now the knowledge about nucleon resonances with a mass higher than 2 GeV has been scarce. Huge amounts of experimental data of the multipion photoproduction have been accumulated, and more can be expected in the future in facilities such as JLab 12 GeV. It makes it possible to investigate the decay of a nucléon resonance into another nucleon resonance. Purpose: The possibility to research the decay of the N(2120) to nucleon resonances near 1.7 GeV in the three-pion photoproduction will be explored to provide useful information for future experimental study. Method: The pion and radiative decay amplitudes of nucleon resonances are studied within the constituent quark model, which is used to calculate the couplings constants, especially for the decay of a nucleon resonance near 2.1 GeV to another nucleon resonance near 1.7 GeV. The three-pion photoproduction off the neutron target, i.e., γn n→ π-π- Δ++ → π-π-π+ p, is investigated based on the effective Lagrangian method with the coupling constant obtained form the decay amplitudes. Results: The resonance contribution with a state N(²PM)3/2 near 2.1 GeV decaying to a state N(4PM)5/2 near 1.7 GeV, i.e., N(2120) → N(1675)π, is dominant in the process considered. The total cross section from the resonance contribution is at the order of 1 μb and can be easily distinguished from the background. Conclusions: Our results suggest it is practicable to research the decay of the N(2120) to the N(1675) in experiment. [ABSTRACT FROM AUTHOR]

The structure and decay dynamics for 0+ and 2+ continuum excitations of 26O are investigated in a three-body 24O + n + n model. The validity of a simple approximation for the cross section profile for long-lived 2n emission is demonstrated. A sequence of three 0+ monopole ("breathing mode" type) excited states is predicted. These states could probably be interpreted as analogs of Efimov states pushed in the continuum due to insufficient binding. The calculated energies of the 2+ states are related to the excitation spectrum of 25O. We discuss the correlation between the predicted 26O spectrum and experimental observations. [ABSTRACT FROM AUTHOR]

Recent measurements of α-particle induced reactions on the 64Zn nucleus, below and around the Coulomb barrier, are analyzed simultaneously with α-particle emission at similar energies in proton-induced reactions on Zn isotopes. All open reaction channels, particularly the γ decay, are calculated using consistent input parameters. Additionally, we check a previous optical-model potential for α particles on nuclei within the mass number range 45≤A≤209 [Avrigeanu et al., Phys. Rev. C 90, 044612 (2014)] and prove its correctness in the outgoing channel at least for the present case involving 64Zn and nearby nuclei. The reliability of this potential for incident as well as emitted low-energy α particles is supported by the successful reproduction of high-precision measured data, using no empirical rescaling factor of the γ and/or particle widths. [ABSTRACT FROM AUTHOR]

The two-neutrino double-β Gamow-Teller and Fermi transitions are studied within an exactly solvable model, which allows a violation of both spin-isospin SU(4) and isospin SU(2) symmetries, and is expressed with generators of the SO(8) group. It is found that this model reproduces the main features of realistic calculation within the quasiparticle random-phase approximation with isospin symmetry restoration concerning the dependence of the two-neutrino double-β decay matrix elements on isovector and isoscalar particle-particle interactions. By using perturbation theory an explicit dependence of the two-neutrino double-β decay matrix elements on the like-nucleon pairing, particle-particle T=0 and T=1, and particle-hole proton-neutron interactions is obtained. It is found that double-β decay matrix elements do not depend on the mean field part of Hamiltonian and that they are governed by a weak violation of both SU(2) and SU(4) symmetries by the particle-particle interaction of Hamiltonian. It is pointed out that there is a dominance of two-neutrino double-β decay transition through a single state of intermediate nucleus. The energy position of this state relative to energies of initial and final ground states is given by a combination of strengths of residual interactions. Further, energy-weighted Fermi and Gamow-Teller sum rules connecting ΔZ=2 nuclei are discussed. It is proposed that these sum rules can be used to study the residual interactions of the nuclear Hamiltonian, which are relevant for charge-changing nuclear transitions. [ABSTRACT FROM AUTHOR]

A complete calculation of phase space factors (PSFs) for Majoron-emitting 0νβ-β- decay modes is presented. The calculation makes use of exact Dirac wave functions with finite nuclear size and electron screening and includes lifetimes, single-electron spectra, summed electron spectra, and angular electron correlations. Combining these results with recent microscopic interacting boson model nuclear matrix elements (NMEs) we make half-life predictions for the ordinary Majoron decay (spectral index n=1). Furthermore, comparing theoretical predictions with the obtained experimental lower bounds for this decay mode we are able to set limits on the effective Majoron-neutrino coupling constant 〈gMee〉. [ABSTRACT FROM AUTHOR]

We present the first model-independent measurement of the absolute branching fraction of the Λ+c→pK-π+ decay using a data sample of 978 fb-1 collected with the Belle detector at the KEKB asymmetric-energy e+e- collider. The number of Λ+c baryons is determined by reconstructing the recoiling D(*)-̄pπ+ system in events of the type e+e-→D(*)−̄pπ+Λ+c. The branching fraction is measured to be B(Λ+c→pK-π+)=(6.84±0.24+0.21-0.27)%, where the first and second uncertainties are statistical and systematic, respectively. [ABSTRACT FROM AUTHOR]

A determination of the spin and parity of the Λ(1405) is presented using photoproduction data from the CLAS detector at Jefferson Lab. The reaction γ+p→K++Λ(1405) is analyzed in the decay channel Λ(1405)→Σ++π-, where the decay distribution to Σ+π- and the variation of the Σ+ polarization with respect to the Λ(1405) polarization direction determines the parity. The Λ(1405) is produced, in the energy range 2.55

A search for the lepton-flavor-violating decays B0s → e± μ± and B0 → e± μ± is performed with a data sample, corresponding to an integrated luminosity of 1.0 fb-1 of pp collisions at √s = 7 TeV, collected by the LHCb experiment. The observed number of B0s → e± μ± and B0 → e± μ± candidates is consistent with background expectations. Upper limits on the branching fractions of both decays are determined to be B(B0s → e± μ±) < 1.1(1.4) x 10-8 and B(B0 → e± μ± ) <2.8(3.7) X 10-9 at 90% (95%) confidence level (C.L.). These limits are a factor of 20 lower than those set by previous experiments. Lower bounds on the Pati-Salam leptoquark masses are also calculated, MLQ(B0s → e± μ±)> 101 TeV/c2 and MLQ(B0s → e± μ±)> 126 TeV/c2 at 95% C.L., and are a factor of 2 higher than the previous bounds. [ABSTRACT FROM AUTHOR]

We report the results of a high-statistics search for H dibaryon production in inclusive ϒ(15) and Y(25) decays. No indication of an H dibaryon with a mass near the MH = 2mΛ threshold is seen in either the H → Λpπ- or ΛΛ decay channels and 90% confidence level branching-fraction upper limits are set that are between one and two orders of magnitude below the measured branching fractions for inclusive ϒ(1S) and ϒ(2S) decays to antideuterons. Since ϒ(1S, 2S) decays produce flavor-SU(3)-symmetric final states, these results put stringent constraints on H dibaryon properties. The results are based on analyses of 102 million ϒ(1S) and 158 million ϒ(2S) events collected with the Belle detector at the KEKB e+e- collider. [ABSTRACT FROM AUTHOR]

The decays of two long-lived low-lying isomeric states of 80Ga were studied at the PARRNe mass separator of the ALTO ISOL facility. Over the 75 γ rays previously attributed to the 80Ga decay, the decay time of 67 individual β-delayed γ activities were measured. This allowed the determination of the decay time of these two recently reported long-lived--actually β-decaying--states as well as to partially disentangle the two decay schemes. Thanks to the relatively high spin difference between these two 80Ga isomers spin assignments of the daughter 80Ge states could be further constrained rendering the comparison with calculations easier. From this comparison it appears that the suspected maximum of collectivity at Z = 32 along the N = 50 line should express itself through the coexistence of spherical and collective β-soft structures. [ABSTRACT FROM AUTHOR]

Self-consistent proton-neutron quasiparticle random phase approximation based on the spherical nonlinear point-coupling relativistic Hartree-Bogoliubov theory is established and used to investigate the β+/electron-capture (EC)-decay half-lives of neutron-deficient Ar, Ca, Ti, Fe, Ni, Zn, Cd, and Sn isotopes. The isoscalar proton-neutron pairing is found to play an important role in reducing the decay half-lives, which is consistent with the same mechanism in the β decays of neutron-rich nuclei. The experimental β+/EC-decay half-lives can be well reproduced by a universal isoscalar proton-neutron pairing strength. [ABSTRACT FROM AUTHOR]

We present the formation and decay dynamics of a trion (charged exciton) and exciton system in chemically p-doped single-walled carbon nanotubes (SWNTs) investigated by time-resolved photoluminescence measurements at 300 K. In (6,5) SWNTs with hole densities in the range of 0.27-1.05 nm-1, a trion is formed from the coalescence of an exciton and a free hole, with a rate of 1.7 × 1013 nm s-1. The linear dependence of the trion decay rate on the hole density allows us to find that the trion decay is governed by both a trion-hole Auger recombination process and an internal Auger recombination process. The observed high efficiencies of Auger processes dominate over the radiative recombination rate of trions, which demonstrates dynamic properties of excitonic complexes in the presence of enhanced Coulomb interactions in one-dimensional systems. [ABSTRACT FROM AUTHOR]

Both isoscalar and isovector spin-dipole excitations of 4He are studied using realistic nuclear forces in the complex scaling method. The ground state of 4He and discretized continuum states with Jπ=0-, 1-, 2- for A=4 nuclei are described in explicitly correlated Gaussians reinforced with global vectors for angular motion. Two- and three-body decay channels are specifically treated to take into account final state interactions. The observed resonance energies and widths of the negative-parity levels are all in fair agreement with those calculated from both the spin-dipole and electric-dipole strength functions as well as the energy eigenvalues of the complex scaled Hamiltonian. Spin-dipole sum rules, both non-energy-weighted and energy-weighted, are discussed in relation to tensor correlations in the ground state of 4He. [ABSTRACT FROM AUTHOR]

The form factors in the radiative decay of J/ψ to a scalar glueball are studied within quenched lattice QCD on anisotropic lattices. The continuum extrapolation is carried out by using two different lattice spacings. With the results of these form factors, the partial width of J/ψ radiatively decaying into the pure gauge scalar glueball is predicted to be 0.35(8) keV, which corresponds to a branching ratio of 3.8(9) X 10-3. By comparing with experiments, out results indicate that f0 (1710) has a larger overlap with the pure gauge glueball than other related scalar mesons. [ABSTRACT FROM AUTHOR]

The article considers the transverse mass observable, originally used in the discovery of the W boson. It also defines an observable generalizing the transverse mass that takes into account the fact that one of the intermediate W bosons is likely to be on shell. A new variable is compared with existing ones and argues that it gives a significant improvement for discovery in the region mh 2mW.

We present a new method using Dalitz plots and Bose symmetry of pions that allows the complete determination of the magnitudes and phases of weak decay amplitudes. We apply the method to processes such as B → K* π, with the subsequent decay of K* → Kπ. Our approach enables the additional measurement of an isospin amplitude without any theoretical assumption. This advance will help in measuring the weak phase and probing for new physics beyond the standard model with fewer assumptions. [ABSTRACT FROM AUTHOR]

The superluminal neutrinos detected by OPERA indicate Lorentz invariance violation (LIV) of the neutrino sector at the order of 10-5. We study the implications of the result in this work. We find that such a large LIV implied by OPERA data will make the neutrino production process π → μ + vμ kinematically forbidden for a neutrino energy greater than about 5 GeV. The OPERA detection of neutrinos at 40 GeV can constrain the LIV parameter to be smaller than 3 x 10-7. Furthermore, the neutrino decay in the LIV framework will modify the neutrino spectrum greatly. The atmospheric neutrino spectrum measured by the IceCube Collaboration can constrain the LIV parameter to the level of 10-12. The future detection of astrophysical neutrinos of galactic sources is expected to be able to give an even stronger constraint on the LIV parameter of neutrinos. [ABSTRACT FROM AUTHOR]

We search for hadronic decays of a light Higgs boson (A0) produced in radiative decays of an Y(2S) or Y(3S) meson, Y → γA0. The data have been recorded by the BABAR experiment at the Y(3S) and Y(2S) center-of-mass energies and include (121.3 ± 1.2) x 106 Y(3S) and (98.3 ± 0.9) x 106 Y(2S) mesons. No significant signal is observed. We set 90% confidence level upper limits on the product branching fractions B(Y(nS) → γA0)B(A0 → hadrons) (n = 2 or 3) that range from 1 x 10-6 for an A0 mass of 0.3 GeV/c⊃2 to 8 x 10-5 at 7 GeV/c⊃2. [ABSTRACT FROM AUTHOR]

We report the first observation of the doubly Cabibbo-suppressed decays D+ → K+ η(') using a 791 fb-1 data sample collected with the Belle detector at the KEKB asymmetric-energy e+e- collider. The ratio of the branching fractions of doubly Cabibbo-suppressed relative to singly Cabibbo-suppressed D+ → π+η(') decays are B(D+ → K+η)/B(D+ → π+η) = (3.06 ± 0.43 ± 0.14)% and B(D+ → K+ η')/B(D+ → π+η') = (3.77 ± 0.39 + 0.10)%. From these, we find that the relative final-state phase difference between the tree and annihilation amplitudes in D+ decays, δTA, is (72 ± 9)° or (288 ± 9)°. We also report the most precise measurements of CP asymmetries to date: Due to image rights restrictions, multiple line equation(s) cannot be graphically displayed. (+ 1.74 ± 1.13 ± 0.19)% and Due to image rights restrictions, multiple line equation(s) cannot be graphically displayed. [ABSTRACT FROM AUTHOR]

The spin-bath induced decay of a quantum system out of a metastable state, which can tunnel and undergo thermal activation, is considered. The treatment is based on the c-number description of bath degrees of freedom and a canonical thermal distribution of the associated c-number variables. We show that, apart from the usual frequency prefactor and its dynamical modification in the spatial diffusion-limited regime, i.e., the Grote-Hynes factor, the rate coefficient contains two other factors. One is a quantum correction to the dynamical factor resulting from quantum transmission and reflection of the particle at the finite barrier. This term exhibits exponential rate enhancement at low temperature. The other one is a quantum corrected Arrhenius factor, which incorporates the effect of thermal saturation. At 0 K, dissipation due to tunneling multiplies the tunneling probability by a factor that gets exponentially damped by friction, implying that, at this temperature, the behavior of spin bath is almost identical to that of a harmonic bath. [ABSTRACT FROM AUTHOR]

The two protons emitted in the decay of 54Zn have been individually observed for the first time in a time projection chamber. The total decay energy and the half-life measured in this work agree with the results obtained in a previous experiment. Angular and energy correlations between the two protons are determined and compared to theoretical distributions of a three-body model. Within the shell model framework, the relative decay probabilities show a strong contribution of the p2 configuration for the two- proton emission. After 45Fe, the present result on 54Zn constitutes only the second case of a direct observation of the ground state two-proton decay of a long-lived isotope. [ABSTRACT FROM AUTHOR]

Extensive calculations on isoscaling behavior with the sequential-decay model gemini are performed for the medium-to-heavy nuclei in the mass range A = 60-120 at excitation energies up to 3 MeV/nucleon. The comparison between the products after the first-step decay and the ones after the entire-steps decay demonstrates that there exists a strong sequential decay effect on the final isoscaling parameters and the apparent temperature. Results show that the apparent symmetry energy coefficient γapp does not reflect the initial symmetry energy coefficient Csym embedded in the mass calculation in the present GEMINI model. [ABSTRACT FROM AUTHOR]

A detailed description, at the atomistic scale, of the dynamics of excess electrons and holes is fundamental in order to improve the performance of many optoelectronic devices. Among all recombination processes, nonradiative decay paths play a fundamental role in most semiconductor devices, such as optoelectronic devices and solar cells, limiting their efficiency. In this work, a precise ab initio analysis of the direct Auger recombination processes in both n- and p-type Si and GaAs crystals is presented. Our simulations of minority carrier Auger lifetimes rely on an accurate electronic band structure, calculated using density functional theory with the inclusion of quasiparticle corrections. The results obtained are in good agreement with experimental data for both n-Si and p-GaAs, proving the importance of the direct Auger recombination mechanism in such systems. On the contrary, we show that different nonradiative recombination paths are necessary to explain the experimental results for both p-Si and n-GaAs. [ABSTRACT FROM AUTHOR]

We introduce a general methodology of update rules accounting for arbitrary interevent time (IET) distributions in simulations of interacting agents. We consider in particular update rules that depend on the state of the agent, so that the update becomes part of the dynamical model. As an illustration we consider the voter model in fully connected, random, and scale-free networks with an activation probability inversely proportional to the time since the last action, where an action can be an update attempt (an exogenous update) or a change of state (an endogenous update). We find that in the thermodynamic limit, at variance with standard updates and the exogenous update, the system orders slowly for the endogenous update. The approach to the absorbing state is characterized by a power-law decay of the density of interfaces, observing that the mean time to reach the absorbing state might be not well defined. The IET distributions resulting from both update schemes show power-law tails. [ABSTRACT FROM AUTHOR]

We study the short-time stability of quantum dynamics in quasi-one-dimensional systems with respect to small localized perturbations of the potential. To this end, we analytically and numerically address the decay of the Loschmidt echo (LE) during times that are short compared to the Ehrenfest time. We find that the LE is generally a nonmonotonic function of time and exhibits strongly pronounced minima and maxima at the instants when the corresponding classical particle traverses the perturbation region. We also show that, under general conditions, the envelope decay of the LE is well approximated by a Gaussian, and we derive explicit analytical formulas for the corresponding decay time. Finally, we demonstrate that the observed nonmonotonic nature of the LE decay is only pertinent to one-dimensional (and, more generally, quasi-one-dimensional) systems. and that the short-time decay of the LE can be monotonic in a higher number of dimensions. [ABSTRACT FROM AUTHOR]

The level structure of 114Ru has been investigated via the β decay of very neutron-rich 114Tc by means of Penning-trap-assisted γ spectroscopy. The deduced β-decay scheme suggests the existence of two β-decaying states in 114Tc with Iπ=1+ and I⩾ 4, with half-lives of t1/2(1+)=90(20) ms and t1/2(I⩾4)=100(20) ms, respectively. The Qβ value, which covers a possible mixture of two states, has been determined to be Qβ=11 785(12) keV. The level energies in 114Ru are compared with theory by using a microscopic Bohr Hamiltonian approach with the Sly4 version of the Skyrme interaction. [ABSTRACT FROM AUTHOR]