Search

Half-lives and branching ratios for the two mirror $ \beta$ decays of Mg and Si have been measured at the University of Jyväskylä with the IGISOL facility. The results obtained, $ T_{1/2}=11.303(3)$ s and $ T_{1/2}= 4.112(2)$ s for the half-lives of Mg and Si , respectively, are 7 and 8 times more precise than the averages of previous measurements. The values obtained for the super-allowed branching ratios of Mg and Si are $ B.R.=92.18(8)\%$ and $ B.R.=99.74(2)\%$ , respectively. The result for Mg is three times more precise than the average of the previous measurements, while for Si the precision has not been improved, the average of the previous measurements being already very precise. Isospin-symmetry-breaking corrections have been calculated for the two nuclei to determine the corrected $ {F}t$ value. [ABSTRACT FROM AUTHOR]

Motivated by the rapid development of heavy-flavor experiments, phenomenological studies of nonleptonic $$\bar{B}_{d,s} \rightarrow D^{*}_{d,s} V$$ and $$\bar{B}_{d,s}^* \rightarrow D_{d,s} V$$ ( $$V=\rho \,,K^*$$ ) decays are performed within the framework of QCD factorization. Relative to the previous work, the QCD corrections to the transverse amplitudes are evaluated at next-to-leading order. The theoretical predictions of the observables are updated. For the measured $$\bar{B}_{d,s} \rightarrow D^{*}_{d,s} V$$ decays, the tensions between theoretical results and experimental measurements, i.e. the ' $$R_{ds}^{V}$$ puzzle' and ' $$D^{*} V$$ (or $$R_{V/\ell \bar{\nu }_\ell }$$ ) puzzle', are presented after detailed analyses. For the $$\bar{B}_{d,s}^* \rightarrow D_{d,s} V$$ decays, they have relatively large branching fractions of the order $$\gtrsim \mathcal{O}(10^{-9})$$ and are in the scope of Belle-II and LHCb experiments. Moreover, they also provide a way to crosscheck the possible puzzles mentioned above through the similar ratios $$R_{ds}^{\prime V}$$ and $$R_{V/\ell \bar{\nu }_\ell }^{\prime }$$ . More refined experimental measurements and theoretical efforts are required to confirm or refute such two anomalies. [ABSTRACT FROM AUTHOR]

Regularities in fragmentation of adduct ions [M + NH] and [M + Na] of N-trifluoroacetyl neuraminic acid phenyl thioglycosides under collisionally-induced decay (CID) activation are studied. For [M + Na] ions, elimination of the CHOS fragment (along with thiophenol molecule) proceeds both in the presence or the absence of an acetyl group, whereas for the [M + NH] ion, elimination of thiophenol C6H6S is observed. Similar elimination of the CHOS fragment has been observed previously only for cationized molecules of phenylthioglycoside acetates of hexoses. [ABSTRACT FROM AUTHOR]

Many extensions of the standard model of particle physics suggest that neutrinos should be Majorana-type fermions-that is, that neutrinos are their own anti-particles-but this assumption is difficult to confirm. Observation of neutrinoless double-β decay (0νββ), a spontaneous transition that may occur in several candidate nuclei, would verify the Majorana nature of the neutrino and constrain the absolute scale of the neutrino mass spectrum. Recent searches carried out with 76Ge (the GERDA experiment) and 136Xe (the KamLAND-Zen and EXO (Enriched Xenon Observatory)-200 experiments) have established the lifetime of this decay to be longer than 1025 years, corresponding to a limit on the neutrino mass of 0.2-0.4 electronvolts. Here we report new results from EXO-200 based on a large 136Xe exposure that represents an almost fourfold increase from our earlier published data sets. We have improved the detector resolution and revised the data analysis. The half-life sensitivity we obtain is 1.9 × 1025 years, an improvement by a factor of 2.7 on previous EXO-200 results. We find no statistically significant evidence for 0νββ decay and set a half-life limit of 1.1 × 1025 years at the 90 per cent confidence level. The high sensitivity holds promise for further running of the EXO-200 detector and future 0νββ decay searches with an improved Xe-based experiment, nEXO. [ABSTRACT FROM AUTHOR]

A general decay formula for the emission of charged particles from metastable nuclei is developed based on the basic phenomenon of resonances occurring in quantum scattering process under Coulomb-nuclear potential. It relates the half-lives of radioactive decays with the Q values of the outgoing elements with masses and charges of the nuclei involved in the decay. The relation is found to be a generalization of the Geiger-Nuttall law in α radioactivity and explains well all the known emissions of charged particles including clusters, alpha and proton. [ABSTRACT FROM AUTHOR]

Evaluations of the characteristics of the radionuclides Cm, Cm, Cm, and Cm obtained from data published up to 2013 are presented. A computer program is developed for constructing and visualizing the decay schemes of radionuclides and is used to determine the decay schemes for these curium isotopes. [ABSTRACT FROM AUTHOR]

The decay scheme of Br is established by the Br( T = 16.2 h) β/EC study. The 1791.31 keV level, which was identified initially by Müller et al with Se( p, p) reaction more than three decades ago, is reconfirmed. However, the spin and parity have not been assigned by Müller et al. Now we consider it reasonable to assign the 1791.31 keV level as a new candidate of the three-phonon multiplet in Se. In addition, in order to study the deformation of Se which lies in transitional region between strongly deformed and spherical nuclei, we calculate the total Routhian surfaces (TRS) of positive-parity states by cranking shell model formalism. [ABSTRACT FROM AUTHOR]

We have investigated the effects of the family of a non-universal Z′ model on the Λ→ Λρ, pK and pρ decays. This model includes the interactions between fermions and the Z′ boson, with the contributions of flavor-changing neutral currents (FCNCs) mediated by the Z′ boson, and we find that the branching ratio for Λ→ Λρ decay is significantly enhanced from its corresponding standard model (SM) value. It reaches up to the $\mathcal{O}(10^{-7})$ level; the currently running experiments could make observations of this decay process. For the Λ→ pK and Λ→ pρ decays, their branching ratios are also sensitive to the new physics (NP) weak phases. [ABSTRACT FROM AUTHOR]

We study effects of direct interatomic interaction on cooperative processes in atom-photon dynamics. Using a model of two-level atoms with Ising-type interaction as an example, it is demonstrated that interparticle interaction can promote cooperative radiative relaxation. For small number of atoms this results in inhibition of incoherent spontaneous decay leading to the regime of collective pulse relaxation. Above superradiance threshold increase in delay time and enhancement of superradiance is occurred. In the case of strong interaction (as compared to excitation energy of an atom) transition to the regime of multiphoton relaxation occurs, which we discuss using a simple model of two atoms in a high-Q single mode cavity. It is shown that such transition is accompanied by Rabi oscillations involving many-atom multiphoton states. Dephasing effect of dipole-dipole interaction and solitonic mechanism of relaxation are discussed as well. [ABSTRACT FROM AUTHOR]

We studied the annihilation kinetics for triplet excitations in isolated pairs of organic molecules and their delayed fluorescence decay using a new mathematical model for the process. According to this model, the intensity of delayed annihilation fluorescence (DAF) for isolated pairs is directly proportional to the number of pairs in which both molecules are found in the excited triplet state. We show that the decrease in such pairs and the decay of their delayed annihilation fluorescence occur according to an exponential law in the absence of random scatter in the deactivation rate constants for the triplet excitations. The results of an experimental study of the DAF decay kinetics for 1,12-benzoperylene in n-hexane at 77 K, where triplet-triplet annihilation occurs in isolated pairs, confirm the validity of the theoretical conclusions. [ABSTRACT FROM AUTHOR]

Branching ratios and half-lives of $ \alpha$ -decay to the ground-state rotational bands as well as the high-lying excited states of even-even nuclei have been calculated in the framework of the generalized liquid drop model (GLDM) and Royer’s formula that we improved very recently. The calculation covers the isotopic chains from Ra to No in the mass regions 222 $ \leq$ A $ \leq$ 252 and 88 $ \leq$ Z $ \leq$ 102 . The agreement between the calculated results and the experimental data indicates the reliability of investigating the properties of the unfavored $ \alpha$ -decay with our method, especially the improved Royer’s formula, which is very valuable for the analysis of experimental data. In addition, the dependence of half-lives on excitation energies of daughter nuclei has been investigated. It is shown that the influence on half-lives becomes stronger and stronger with the increase of the excitation energies. [ABSTRACT FROM AUTHOR]

We search for ψ(3770)→ π+ π− η, K+ K− η, $p\bar{p}\eta$ , ρ0 π+ π− η, K+ K− π+ π− η, $p\bar{p}\pi^{+}\pi^{-}\eta$ , $p\bar{p}K^{+}K^{-}\eta$ and $p\bar{p}K^{+}K^{-}\pi^{0}$ using data samples of 17.3 and 6.5 pb−1 integrated luminosities recorded at the center-of-mass energies of 3.773 and 3.65 GeV, respectively, by the BES-II detector operating at the BEPC collider. We obtain cross section measurements at both energies and upper limits on ψ(3770) decay branching fractions to the final states studied. [ABSTRACT FROM AUTHOR]

The exclusive weak decay of Λ b→ Λ γ and Λ b→ Λ l+ l− are investigated in the Appelquist–Cheng–Dobrescu model, which is an extension of the standard model in the presence of universal extra dimensions. Employing the transition form factors obtained in the light-cone sum rules, we analyze how the invariant-mass distribution, the forward–backward asymmetry and the polarization asymmetry of the Λ baryon of these decay modes can be used to constrain the only additional free parameter with respect to the standard model, namely, the radius, R, of the extra dimension. Our results indicate that the Kaluza–Klein modes can lead to approximately 25% suppression of the branching ratio of Λ b→ Λ γ; however, their contributions can bring about 10% enhancement to the decay rate of Λ b→ Λ l+ l−. It is shown that in the present scenario the zero position of the forward–backward asymmetry of Λ b→ Λ μ+ μ− is sensitive to the compactification parameter R, while the measurement of polarizations of Λ baryon in the Λ b decays are not a useful tool to provide any valuable information for the universal extra-dimension model. [ABSTRACT FROM AUTHOR]

To test the validity of perturbative QCD (pQCD) and investigate its range of application, one should look for a suitable process. B→ J/ ψ D is a promising candidate. The linear momentum of the products is relatively small, so that there may exist a region where exchanged gluons are soft and the perturbative treatment may fail, so that the non-perturbative effect would be significant. We attribute such non-perturbative QCD effects to the long-distance final-state interaction (FSI) which is estimated in this work. We find that the contribution from the FSI to the branching ratio is indeed sizable and may span the rather wide range of 10−6∼10−5 and cover a region where the pQCD prediction is of the same order. A more accurate measurement of its branching ratio may provide important information about the application region of pQCD and help to clarify the picture of inelastic rescattering (i.e. FSI), which is generally believed to play an important role in B decays. [ABSTRACT FROM AUTHOR]

Recently, Liu et al. [Phys. Rev. B 74, 075314 (2006)] pointed out that the atomic instant decay rate in one dimensional photonic crystal (1DPC) showed a series of pulse-like peaks with time. In this paper, we continue their work, and adopt a special 1DPC, in which the refractive indexes of both constitution layers in a period are the same, to perform the analysis in detail. Our results show that the pulse-like peak of instant decay rate originates from the interaction between the atom and the sub-reservoir, the latter of which corresponds to the group of reflected fields having the same optical distance. The atom interacts with such a sub-reservoir mainly after the time needed for propagation. However, near the arrival time of the reflected field, the atomic level is broadened and couples to all frequency components of the sub-reservoir, and the pulse-like peak of instant decay rate appears. Although our conclusion is deduced with the special 1DPC, it is also valid for more general cases and might be useful to measure the quantum Zeno and anti-Zeno effect, since the interval of repeated measurements may be expanded to several optical cycles in 1DPC, which will facilitate the observation of the quantum Zeno or anti-Zeno effect. [ABSTRACT FROM AUTHOR]

In grand-unified theories (GUT), non-universal boundary conditions for the gaugino masses may arise at the unification scale and may affect the observability of the neutral MSSM Higgs bosons ( h/ H/ A) at the LHC. The implications of such non-universal gaugino masses are investigated for Higgs boson production in the SUSY cascade decay chain $\tilde{g}\rightarrow \tilde{q}q$ , $\tilde{q}\rightarrow \tilde{\chi_{2}}q$ , $\tilde{\chi_{2}}\rightarrow \tilde{\chi_{1}}h/H/A$ , $h/H/A\rightarrow b\bar{b}$ produced in pp interactions. In the singlet representation with universal gaugino masses only the light Higgs boson can be produced in this cascade with the parameter region of interest for us, while with non-universal gaugino masses heavy neutral MSSM Higgs boson production may dominate. The allowed parameter space in the light of the WMAP constraints on the cold dark-matter relic density is investigated in the above scenarios for gaugino mass parameters. We also demonstrate that combination of representations can give the required amount of dark matter in any point of the parameter space. In the non-universal case we show that heavy Higgs bosons can be detected in the cascade studied in parameter regions with the WMAP preferred neutralino relic density. [ABSTRACT FROM AUTHOR]

The e+ e− → π+ π− π+ π− cross section is calculated for energies of 0.65 ≤ √ s ≤ 1 GeV in the framework of the generalized hidden local symmetry model. The calculations are compared with the data of CMD-2 and BaBaR. It is shown that the inclusion of heavy isovector resonances ρ(1450) and ρ(1700) is necessary for reconciling calculations with the data. It is found that, at √ s ≈ 1 GeV, the contributions of the above resonances are much larger, by a factor of 30, than the ρ(770) one, and amount to a considerable fraction ∼0.3–0.6 of the latter at √ s ∼ mρ. [ABSTRACT FROM AUTHOR]

We examine daily records of sunspot group areas (measured in millionths of a solar hemisphere or μHem) for the last 130 years to determine the rate of decay of sunspot group areas. We exclude observations of groups when they are more than 60° in longitude from the central meridian and only include data when at least three days of observations are available following the date of maximum area for a group’s disk passage. This leaves data for over 18 000 measurements of sunspot group decay. We find that the decay rate increases linearly from 28 μHem day−1 to about 140 μHem day−1 for groups with areas increasing from 35 μHem to 1000 μHem. The decay rate tends to level off for groups with areas larger than 1000 μHem. This behavior is very similar to the increase in the number of sunspots per group as the area of the group increases. Calculating the decay rate per individual sunspot gives a decay rate of about 3.65 μHem day−1 with little dependence upon the area of the group. This suggests that sunspots decay by a Fickian diffusion process with a diffusion coefficient of about 10 km2 s−1. Although the 18 000 decay rate measurements are lognormally distributed, this can be attributed to the lognormal distribution of sunspot group areas and the linear relationship between area and decay rate for the vast majority of groups. We find weak evidence for variations in decay rates from one solar cycle to another and for different phases of each sunspot cycle. However, the strongest evidence for variations is with latitude and the variations with cycle and phase of each cycle can be attributed to this variation. High latitude spots tend to decay faster than low latitude spots. [ABSTRACT FROM AUTHOR]

We revisit the determination of α S ( m ) using a fit to inclusive τ hadronic spectral moments in light of (1) the recent calculation of the fourth-order perturbative coefficient K 4 in the expansion of the Adler function, (2) new precision measurements from BABAR of e+e− annihilation cross sections, which decrease the uncertainty in the separation of vector and axial-vector spectral functions, and (3) improved results from BABAR and Belle on τ branching fractions involving kaons. We estimate that the fourth-order perturbative prediction reduces the theoretical uncertainty, introduced by the truncation of the series, by 20% with respect to earlier determinations. We discuss to some detail the perturbative prediction of two different methods: fixed-order perturbation theory (FOPT) and contour-improved perturbative theory (CIPT). The corresponding theoretical uncertainties are studied at the τ and Z mass scales. The CIPT method is found to be more stable with respect to the missing higher order contributions and to renormalization scale variations. It is also shown that FOPT suffers from convergence problems along the complex integration contour. Nonperturbative contributions extracted from the most inclusive fit are small, in agreement with earlier determinations. Systematic effects from quark-hadron duality violation are estimated with simple models and found to be within the quoted systematic errors. The fit based on CIPT gives α S ( m )=0.344±0.005±0.007, where the first error is experimental and the second theoretical. After evolution to M Z we obtain α S ( M )=0.1212±0.0005±0.0008±0.0005, where the errors are respectively experimental, theoretical and due to the evolution. The result is in agreement with the corresponding N3LO value derived from essentially the Z width in the global electroweak fit. The α S ( M ) determination from τ decays is the most precise one to date. [ABSTRACT FROM AUTHOR]

Taking into account the gluon correction contributions to the correlation function, the form factors relevant to the rare $B_{c}\rightarrow X\nu\bar{\nu}$ decays are calculated in the framework of the three-point QCD sum rules, where X stands for axial vector particle, AV( D s1), and vector particles, V( D *, D ). The total decay width as well as the branching ratio of these decays are evaluated using the q 2 dependent expressions of the form factors. A comparison of our results with the predictions of the relativistic constituent quark model is presented. [ABSTRACT FROM AUTHOR]

The aim of this paper is to apply direct methods to the study of integrals that appear naturally in Statistical Mechanics and Euclidean Field Theory. We provide weighted estimates leading to the exponential decay of the two-point correlation functions for certain classical convex unbounded models. The methods involve the study of the solutions of the Witten Laplacian equations associated with the Hamiltonian of the system. [ABSTRACT FROM AUTHOR]

The implications of the model with a SU(2)-singlet up-type quark, heavy enough not to be produced at the LHC, namely, the contribution of the new quark to the branching ratios of the K → πν $$ \bar \nu $$ , B → πν $$ \bar \nu $$ , and B → Kν $$ \bar \nu $$ decays are investigated. It is shown that the deviation from the Standard Model can be up to 10% in the case of a 5-TeV quark. Precise measurements of these branching ratios in future experiments will allow for the observation of the contributions of the new quark or to impose stronger constraints on its mass. [ABSTRACT FROM AUTHOR]

An experimental setup for highly reproducible generation of artificial ball lightnings is implemented. Thousands of floating glowing plasmoids 12–20 cm in diameter are produced. Research facilities for studying the plasmoids are developed. It is found that short-lived ball lightnings live for about 1 s and carry an electric charge. The lightnings are shown to have a complex structure: a central kernel containing a rich variety of hydrated ions and aerosol of decay products is surrounded by a thin negatively charged shell. [ABSTRACT FROM AUTHOR]

This paper describes the preparation of samples for an experiment to measure the cross-section for 235U(n,n′)235mU in a fast fission spectrum of neutrons provided by a fast pulsed reactor/critical assembly. Samples of 235mU have been prepared for the calibration of the internal conversion electron detector that is used for the 235mU measurement. Two methods are described for the preparation of 235mU. The first method used a U-Pu chemical separation based on anion-exchange chromatography and the second method used an alpha recoil collection method. Thin, uniform samples of 235mU+235U were prepared for the experiment using electrodeposition. [ABSTRACT FROM AUTHOR]

Bianchi Type-I cosmological models containing perfect fluid with time varying G and Λ have been presented. The solutions obtained represent an expansion scalar θ bearing a constant ratio to the anisotropy in the direction of space-like unit vector λi. Of the two models obtained, one has negative vacuum energy density, which decays numerically. In this model, we obtain Λ ∼ H², Λ ∼ R44=R and Λ ∼ T-2 (T is the cosmic time) which is in accordance with the main dynamical laws for the decay of Λ. The second model reduces to a static solution with repulsive gravity. [ABSTRACT FROM AUTHOR]

Based on the concept of cold valley in cold fission and fusion, we have investigated the cluster decay process in 248-254 Cf isotopes. In addition to alpha particle minima, other deep minima occur for S, Ar and Ca clusters. It is found that inclusion of proximity potential does not change the position of minima but minima become deeper. Taking Coulomb and proximity potential as interacting barrier for post-scission region, we computed half-lives and other characteristics for various clusters from these parents. Our study reveals that these parents are stable against light clusters and unstable against heavy clusters. Computed half-lives for alpha decay agree with experimental values within two orders of magnitude. The most probable clusters from these parents are predicted to be 46Ar, 48;50Ca which indicate the role of doubly or near doubly magic clusters in cluster radioactivity. Odd A clusters are found to be favorable for emission from odd A parents. Cluster decay model is extended to symmetric region and it is found that symmetric fission is also probable which stresses the role of doubly or near doubly magic 132Sn nuclei. Geiger-Nuttal plots were studied for various clusters and are found to be linear with varying slopes and intercepts. [ABSTRACT FROM AUTHOR]

Considering two assumptions on the molecular state, i.e. the S-wave Λ̄–K- and S-wave Σ̄0–K- molecular states, we study the possible decays of N̄X(1625) that include N̄X(1625)→K-Λ̄,π0p̄,ηp̄,π-n̄. Our results indicate that (1) if N̄X(1625) is the Λ̄–K- molecular state, K-Λ̄ is the main decay mode of N̄X(1625), and the branching ratios of the rest decay modes are tiny; (2) if N̄X(1625) is the Σ̄0–K- molecular state, the branching ratio of N̄X(1625)→K-Λ̄ is one or two orders smaller than that of N̄X(1625)→π0p̄,ηp̄,π-n̄. Thus the search for N̄X(1625)→π0p̄,ηp̄,π-n̄ will be helpful to shed light on the nature of N̄X(1625). [ABSTRACT FROM AUTHOR]

With usage of the Low theorem, the general expression for the amplitude of radiative kaon decay K + → π + π 0 γ is determined. The possible reason of suppression for the branching ratio of kaon decay K + → π + π 0 is considered. [ABSTRACT FROM AUTHOR]

We are interested in stability/instability of the zero steady state of the superlinear parabolic equation u t + Δ2 u = | u| p-1 u in $${\mathbb{R}^n\times[0,\infty)}$$ , where the exponent is considered in the “super-Fujita” range p > 1 + 4/ n. We determine the corresponding limiting growth at infinity for the initial data giving rise to global bounded solutions. In the supercritical case p > ( n + 4)/( n−4) this is related to the asymptotic behaviour of positive steady states, which the authors have recently studied. Moreover, it is shown that the solutions found for the parabolic problem decay to 0 at rate t −1/( p-1). [ABSTRACT FROM AUTHOR]

A new procedure was suggested for asymmetric synthesis of of 6-[18F]fluoro-3,4- L-dihydroxyphenylalanine (6-18F- L-FDOPA), an important radiotracer for studies of the dopaminergic system by positron emission tomography (PET). The key step of the synthesis is stochiometric asymmetric alkylation of chiral Ni(II) complexes using 3,4-methylenedioxy-6-[18F]fluorobenzyl bromide as alkylating agent. A series of Ni(II) complexes containing various substituents in the benzyl group were tested. The highest enantiomeric purity of 6-18F- L-FDOPA was attained with the complex derived from ( S)- N-(2-benzoylphenyl)-1-(3,4-dichlorobenzyl)-pyrrolidine-2-carboxamide, Ni-DCBPB-Gly, under mild alkylation conditions (CH2Cl2, 40°C, potassium tert-butylate as base). Such conditions are favorable from the viewpoint of synthesis automation. The radiochemical yield of 6-18F- L-FDOPA corrected for the radioactive decay was 10–15% at a synthesis time of 120 min, including purification by semipreparative HPLC. The radiochemical and chemical purity of the product exceeded 99%, and the enantiomeric purity was as high as 95%, meeting the requirements for using 6-18F- L-FDOPA in PET practice. [ABSTRACT FROM AUTHOR]

The beam asymmetry, Σ , was measured at ELSA in the reaction $ \boldsymbol\gamma$ p → η p using linearly polarised tagged photon beams, produced by coherent bremsstrahlung off a diamond. The crystal was oriented to provide polarised photons in the energy range E γ = 800 to 1400MeV with the maximum polarisation of P γ = 49 % obtained at 1305MeV. Both dominant decay modes of the η into two photons and 3π0 were used to extract the beam asymmetry from the azimuthal modulation of the cross-section. The measurements cover the angular range Θcm ≃ 50 -150 degrees. Large asymmetries up to 80% are observed, in agreement with a previous measurement. The eta-MAID model and the Bonn-Gatchina partial wave analysis describe the measurements, but the required partial waves differ significantly. [ABSTRACT FROM AUTHOR]

Low-spin states of 182Ir were populated through the β+ /EC decay of 182Pt . Two strong E2 transitions were observed for the first time: a 25.7keV transition in 182Ir and a 34.0keV transition in Re of probable mass A = 178 . Spin and parity, I π = 3+ , are firmly assigned to the 182Ir ground state (g.s.). For the excited states, the parity is established and the spin determined or restricted. These assignments support most of the interpretations of the level structure previously suggested. The systematics for the known 5+ → 3+ transitions in π h 9/2 ⊗ ν 1/2-[521] bands is presented. Using a semi-microscopic two-quasiparticle axial-rotor coupling model, particle configurations have been attributed or suggested for most of the coupled states lying at low energy in 182Ir . [ABSTRACT FROM AUTHOR]

It is reported that the width of the first excited state ( $ {\frac{{7^+}}{{2}}}$ , 37.133keV) of 121 51Sb embedded in a ZnSb alloy can be modified by reabsorption of γ -rays scattered backward on the platinum (gold) reflector. Its dependence on the reflector shape is also investigated. The decay rate is reduced about 4.5% at a temperature of 4.2K by a platinum spherical reflector of 5mm radius. [ABSTRACT FROM AUTHOR]

Photoproduction of η -mesons was studied with the Crystal-Barrel detector at ELSA for photon energies in the range from 0.75 to 3GeV. Total and differential cross-sections are presented. The η mesons are detected in two decay modes, in η → 2γ and in η → 3π0 → 6γ . The cross-sections vary slowly as functions of energy and η production angle suggesting that only few resonances make significant contributions to the cross-section. For photon energies above 1.5GeV, the differential cross-sections show a strong forward peak due to meson exchanges in the t channel. A comparison of the η -photoproduction cross-sections with SAID and MAID as well as with a partial-wave analysis performed on our data in combination with other data sets shows good agreement. The Bonn-Gatchina partial-wave analysis suggests that the largest contribution to η photoproduction for energies below 3GeV proceeds via three resonances, the well-known N(1535) S 11 , via N(1720) P 13 , and a newly suggested N(2070) D 15 . [ABSTRACT FROM AUTHOR]

Contributions to the B s( d) → γγ decay amplitude beyond the Standard Model are estimated within a model featuring one universal extra dimension. It is found that these additional contributions may amount to 6 or 7% of the branching ratios evaluated within the Standard Model. [ABSTRACT FROM AUTHOR]

We define a general procedure, based on analyticity and dispersion relations, to estimate low-energy amplitudes for processes like: φ→ e + e - M and φ→ γM, starting from cross-section data on e + e -→ φM, where M is a generic light scalar or pseudoscalar meson. In particular this procedure is constructed to obtain predictions on the radiative decay rate which are crucially linked on the assumed quark structure for the meson M under consideration. Three cases are analyzed: M = η, M = f 0( q¯) and M = f 0( qq¯). While in the η case the estimate of the branching fraction for the radiative decay φ→ ηγ is in agreement with the data, in the case of f 0, such agreement is obtained only under the hypothesis of a tetraquark scalar meson. [ABSTRACT FROM AUTHOR]

The vacuum decay in a de Sitter universe is studied for the class of effective inflaton potentials that curvature at the top is less than as well as greater than a critical value determined previously. By comparing the actions of the Hawking - Moss instanton and the Coleman - de Luccia instanton(s) the mode of vacuum decay is determined in this critical situation. [ABSTRACT FROM AUTHOR]

We study the decay dynamics of an interacting Bose–Einstein condensate in the presence of a metastable trapping potential from which the condensate can escape via tunneling through finite barriers. The time-dependent decay process is reproduced by means of the instantaneous decay rates of the condensate at a given population of the quasi-bound state, which are calculated with the method of complex scaling. Both for the case of a double-barrier potential as well as for the case of a tilted periodic potential, we find pronounced deviations from a monoexponential decay behavior, which would generally be expected in the absence of the atom–atom interaction. [ABSTRACT FROM AUTHOR]

We have performed a series of experiments examining the properties of high Mach number blast waves. Experiments were conducted on the Z-Beamlet laser at Sandia National Laboratories. We created blast waves in the laboratory by using ∼1000 J laser pulses to illuminate millimeter scale solid targets immersed in gas. Our experiments studied the validity of theories forwarded by Ryu and Vishniac (1987, 1991) and Vishniac (1983) to explain the dynamics of perturbations on astrophysical blast waves. These experiments consisted of a systematic scan of the decay rates of perturbations of known primary mode number induced on the surface of blast waves by means of a regularly spaced wire array. The amplitude of the induced perturbations relative to the radius of the blast wave was tracked and fit to a power law in time. Measurements were taken for a number of different mode numbers in a mixed gas consisting of 7.5 Torr xenon and 2.5 Torr nitrogen and the results are compared to theoretical predictions. It is found that two of the three mode numbers imply one polytropic index while the third case, which is the most complicated for several reasons, implies a higher polytropic index. [ABSTRACT FROM AUTHOR]

Decays of thermally fixed holograms in LiNbO3 crystals doped with 5.5 mol. % of Mg and 0.1 mol. % of Fe were measured at different temperatures. The analysis showed that the time decay is a thermally activated single process. The thermal activation energy depends on the Mg impurity and hydrogen concentration. Samples with moderate hydrogen concentration show an activation energy of 1.16 eV. Extrapolated room temperature hologram lifetimes as long as 540 years were determined. Samples with large amount of hydrogen impurity showed a lower activation energy and also lower room temperature lifetime. [ABSTRACT FROM AUTHOR]

The decay of 213, 214Ra was studied by α-γ and γ-γ coincidence measurements. The nuclei were produced in the reactions 170Er(48Ca, xn)218- x Ra and 170Er(50Ti, 3n)217Th and subsequent α decay of 217Th to 213Ra. Evaporation residues recoiling out of the target were separated in-flight by the velocity filter SHIP and implanted into a position-sensitive 16-strip PIPS detector in order to study their subsequent decays. Associated γ-rays were detected by a four-fold Ge-Clover detector. In the present work we extracted new and improved data for 213, 214Ra including isomeric transitions. The results are discussed and compared with previously published data. [ABSTRACT FROM AUTHOR]

A brief summary of the status of neutrino masses, mixing, and oscillations is presented. Neutrinoless double β decay is considered. Predictions for the effective Majorana mass are reviewed. A possible test of the calculations of nuclear matrix elements of the 0 νββ decay is proposed. [ABSTRACT FROM AUTHOR]

We consider infinite order chains whose transition probabilities depend on a finite suffix of the past. These suffixes are of variable length and the set of the lengths of all suffix is unbounded. We assume that the probability transitions for each of these suffixes are continuous with exponential decay rate. For these chains, we prove the weak consistency of a modification of Rissanen's algorithm Context which estimates the length of the suffix needed to predict the next symbol, given a finite sample. This generalizes to the unbounded case the original result proved for variable length Markov chains in the seminal paper Rissanen (1983). Our basic tool is the canonical Markov approximation which enables to approximate the chain of infinite order by a sequence of variable length Markov chains of increasing order. Our proof is constructive and we present an explicit decreasing upper bound for the probability of wrong estimation of the length of the current suffix. [ABSTRACT FROM AUTHOR]

We provide a uniform decay estimate for the local energy of general solutions to the inhomogeneous wave equation on a Schwarzschild background. Our estimate implies that such solutions have asymptotic behavior $$|\phi| = O\left(r^{-1}\big|t-|r^*|\big|^{-\frac{1}{2}}\right)$$ as long as the source term is bounded in the norm $$(1-\frac{2M}{r})^{-1}\cdot(1 + t + |r^*|)^{-1}L^1\big(H^3_\Omega(r^2dr^* d\omega)\big)$$ . In particular this gives scattering at small amplitudes for non-linear scalar fields of the form $$\square_{g}\varphi = \lambda |\varphi |^{p}\varphi $$ for all 2 < p. [ABSTRACT FROM AUTHOR]

The energy and the decay width of the πK atom are evaluated in the framework of the quasipotential-constraint theory approach. The main electromagnetic and isospin symmetry breaking corrections to the lowest-order formulas for the energy shift from the Coulomb binding energy and for the decay width are calculated. They are estimated to be of the order of a few per cent. We display formulas to extract the strong interaction S-wave πK scattering lengths from future experimental data concerning the πK atom. [ABSTRACT FROM AUTHOR]

The mass of the W boson is determined from the direct reconstruction of W decays in WW→qq̄qq̄ and WW→ℓνqq̄ events in e+e- collisions at LEP. The data sample corresponds to an integrated luminosity of 683 pb-1 collected with the ALEPH detector at centre-of-mass energies up to 209 GeV. To minimise any effect from colour reconnection a new procedure is adopted in which low energy particles are not considered in the mass determination from the qq̄qq̄ channel. The combined result from all channels is $m_{\text{W}}=80.440 \pm0.043{\text{(stat.)}} \pm0.024{\text{(syst.)}} \pm0.009{\text{(FSI)}} \pm0.009{\text{(LEP)}} \text{GeV/}c^2, $ where FSI represents the possible effects of final state interactions in the qq̄qq̄ channel and LEP indicates the uncertainty in the beam energy. From two-parameter fits to the W mass and width, the W width is found to be $\Gamma_{\text{W}} = 2.14 \pm0.09{\text{(stat.)}} \pm0.04{\text{(syst.)}} \pm0.05{\text{(FSI)}} \pm0.01{\text{(LEP)}} \text{GeV}. $ [ABSTRACT FROM AUTHOR]

We analyze the semileptonic Bc→Bu *ℓ+ℓ- decay in the framework of the Standard Model. We calculate the Bc to Bu * transition form factors in QCD sum rules. Analytical expressions for the spectral densities and gluon condensates are presented. The branching ratio of the Bc→Bu *ℓ+ℓ- decay is calculated, and it is obtained that this decay can be detectable at forthcoming LHC machines. [ABSTRACT FROM AUTHOR]

In this paper, we present results of a feasibility study of a model-independent way to measure the angle φ3 of the unitarity triangle. The method involves B±→DK± decays where the neutral D decays to the K0 Sπ+π- final state, together with the sample of decays of CP-tagged D mesons (produced, e.g. in ψ(3770)→DD̄ process) to the same final state. We consider different approaches to the extraction of φ3 and obtain the expected statistical accuracy of the φ3 measurement as a function of B and DCP statistics. [ABSTRACT FROM AUTHOR]

In this paper we study the lepton polarization asymmetry for the semileptonic OZI-forbidden annihilation decay B- c→η’ℓ-ν̄, where ℓ=μ,τ. Our results show that the branching ratios turn out to be of order 10-4. Besides, we find that longitudinal, transversal and normal components of lepton polarizations can be measured for both μ and τ decay modes in the future experiments at the LHC. [ABSTRACT FROM AUTHOR]

X(1835) has been treated as a baryonium with sizable gluon content, and to be almost flavor singlet. This picture allows us to rationally understand X(1835) production in J/ψ radiative decays, and its large couplings with p¯, η′ππ. The processes ϒ(1 S) → γ X(1835) and J/ψ → ω X(1835) have been examined. It has been found that Br(ϒ(1 S) → γ X(1835)) Br( X(1835) → p¯) < 6.45×10-7, which is compatible with CLEO's recent experimental result (Phys. Rev. D 73, 032001 (2006) hep-ex/0510015). The branching fractions Br( J/ψ → ω X(1835)), Br( J/ψ → ρ X(1835)) with X(1835) → p¯ and X(1835) → η′π+π- have been estimated by the quark-pair creation model. We show that they are heavily suppressed, so the signal of X(1835) is very difficult, if not impossible, to be observed in these processes. The experimental checks for these estimations are expected. The existence of the baryonium nonet is conjectured, and a model-independent derivation of their production branching fractions is presented. [ABSTRACT FROM AUTHOR]