α decay energies and half-lives from a macroscopic-microscopic model

α decay energies of 323 heavy nuclei with Z≥82 are evaluated with a macroscopic-microscopic model.In this model,the macroscopic part is treated by the continuous medium model and the microscopic part consists of shell and pairing corrections based on the Nilsson potential.α decay half-lives are calculated by Viola-Seaborg formula.The results of α decay energies and half-lives are compared with experimental values and satisfactory agreement is found.The recoiling effect of the daughter nucleus on α decay half-life is also discussed.     

Alpha decay half-lives of heavy nuclei within a generalized liquid drop model

Theoretical α-decay half-lives of the heaviest nuclei are calculated using the experimental Q_α value. The barriers in the quasi-molecular shape path is determined within a Generalized Liquid Drop Model (GLDM) and the WKB approximation is used. The results are compared with calculations using the Density-Dependent M3Y (DDM3Y) effective interaction and the Viola-Seaborg-Sobiczewski (VSS) formulae. The calculations provide consistent estimates for the half-lives of the α decay chains of these superheavy elements. The experimental data stand between the GLDM calculations and VSS ones in the most time.     

Half-life of bismuth isotopes predicted by the Coulomb and proximity potential model; a proposition for the spherical nuclei

We know that the ground state energy, half-life, spin and parity of the heavy nuclei can be determined via the study of alpha decay. Bearing this in mind, we have calculated the penetration probability in the barrier, the decay constant and thereby the half-lives of 21 isotopes of Bi by using the proximity potential model. The comparison with the existing data is motivating.     

Research on some superheavy nuclei

Studies on some superheavy nuclei are performed. The α decay energies are calculated by an improved local binding energy formula, and the α decay half-lives are calculated by the Viola-Seaborg formula. Good agreements between theoretical and experimental results are reached.     

Alpha decay half-lives of heavy nuclei within a generalized liquid drop model

Theoretical α-decay half-lives of the heaviest nuclei are calculated using the experimental Qα value. The barriers in the quasi-molecular shape path is determined within a Generalized Liquid Drop Model (GLDM) and the WKB approximation is used. The results are compared with calculations using the DensityDependent M3Y (DDM3Y) effective interaction and the Viola-Seaborg-Sobiczewski (VSS) formulae. The calculations provide consistent estimates for the half-lives of the α decay chains of these superheavy elements. The experimental data stand between the GLDM calculations and VSS ones in the most time.     

Scattering of scalar light wave from a Gaussian—Schell model medium

<正>The scattering of scalar light wave from a random medium with a correlation function of Gaussian-Schell model distribution is studied.It is shown that the properties of the scattered field,i.e.,the spectral density and the spectral degree of coherence of the scattered field,are closely related to the properties of the scattering medium,including the scaled effective radius and the scaled correlation length of the correlation function.     

Study of the η’→Ve~+e~- decay with hidden local symmetry model

Within the hidden local symmetry framework, the Dalitz decay η→Ve+e-is studied with the vector meson dominance model. It is found that the partial width Γ(η→ωe+e-)≈40 e V and branching ratio B(η→ωe+e-)≈2×10-4, and Γ(η→ρe+e-)≈10Γ(η→ωe+e-) and B(η→ρe+e-)≈10B(η→ωe+e-). The maximum position of the dilepton distribution is m e+e-≈1.33 Me V. These decays are measurable with the advent of high statistic ηexperiments.     

Half-lives and fine structure for the α decay of deformed even-even nuclei

The α-decay properties of well-deformed even-even nuclei are systematically calculated within the multichannel cluster model (MCCM). Instead of working in the WKB framework, the quasibound solution to the coupled Schro¨dinger equation is presented with outgoing wave boundary conditions, and the coupling potential is taken into full account in terms of the general quantum theories. The calculated α-decay half-lives are found to agree well with the experimental data with a mean factor of less than 2. The fine...     

Competition between α-decay and β-decay for heavy andsuperheavy nuclei

In this work, the β-stable region for Z≥90 is proposed based on a successful binding energy formula. The calculated β-stable nuclei in the β-stable region are in good agreement with the ones obtained by Möller et al. The half-lives of the nuclei close to the β-stable region are calculated and the competition between α-decay and β-decay is systematically investigated. The calculated half-lives and the suggested decay modes are well in line with the experimental results. The decay modes are mostly β^--decay above the β-stable region. Especially for Z≤111, all the decay modes are β^--decay. Regarding the nuclei above the β-stable region, α-decay and β^--decay (α+β^-) can occur simultaneously when Z≥112. This is a very interesting phenomenon. The competition between α-decay and β-decay is very complex and drastic below the β-stable region. The predictions for half-lives and decay modes of the nuclei with Z=107-110 are presented in detail.     

Partial entropy change and entanglement in the mixed state for a Jaynes－Cummings model with Kerr medium

By using the algebraic dynamical approach, an atom--field bipartite system in mixed state is employed to investigate the partial entropy change and the entanglement in a cavity filled with Kerr medium. The effects of different nonlinear intensities are studied. One can find that the Kerr nonlinearity can reduce the fluctuation amplitudes of the partial entropy changes and the entanglement of the two subsystems, and also influence their periodic evolution. Meanwhile, increasing the Kerr nonlinear strength can convert the anti-correlated behaviour of the partial entropy change to the positively correlated behaviour. Furthermore, the entanglement greatly depends on the temperature. When the temperature or the nonlinear intensity increases to a certain value, the entanglement can be suppressed greatly.     

B_(s,d)→μ~+μ_- decays in a flavor changing Z′ model

We study the pure leptonic decays Bs,d →μ+μ- in a Flavor Changing Z′ Model.From the recent measurements of the branching ratios B(Bs,d →μ+μ-),we have derived the bounds on the effective μ-μ-Z′ lepton coupling BμLμ.We find that,(i) if neglecting the contribution from the right-handed lepton coupling BμRμ,we obtain 1.32 < BμLμ < 3.32;(ii) if considering the contribution from the right-handed lepton coupling BμRμ and setting BμLμ =BμRμ,we obtain 0.99相似文献   

Entanglement dynamics of a double two-photon Jaynes-Cummings model with Kerr-like medium

In this paper, the entanglement dynamics of a double two-photon Jaynes--Cummings model with Kerr-like medium is investigated. It is shown that initial entanglement has an interesting subsequent time evolution, including the so-called entanglement sudden death effect. It is also shown analytically that the Kerr-like medium can repress entanglement sudden death and enhance the degree of atom--atom entanglement. A more interesting fact is that the Kerr effect is more obvious when each of the two cavities with have the Kerr-like medium than only one of them with the Kerr-like medium.     

Study of semileptonic decays Bs→Ds1(2536)lν and Bs→Ds2(2573) lν in the CQM model

Based on the assumption that D_s1(2536) and D_s2(2573) belong to T doublet (1⁺,2⁺), we calculate the semileptonic decays of B_s to D_s1(2536) and D_s2(2573) in terms of the Constituent Quark Meson (CQM) model. For B_s→D_s1(2536)+lν and B_s→D_s2(2573)+lν, the order of magnitude of the obtained branching ratios is 10^－3. Our numerical results of the semileptonic decays of B_s to D_s1(2536) and D_s2(2573) are large, which implies that two semileptonic decays should be seen     

An angle-dependent potential and alpha-decay half-lives ofdeformed nuclei for 67≤Z≤91

The half-lives of deformed nuclei are reported for 67≤Z≤91. We consider an angle-dependent potential which yields multiple approximations. The results are in better agreement with the experimental data when the multiple approximation is solely considered for the daughter nuclei.     

Rare Decay B_c → D_s *μ~+ μ~- in a Family Non-Universal Z′ Model

Using the form factors calculated in the three-point QCD sum rules, we calculate the new physics contributions to the physical observables of B c → Ds* μ+ μ decay in a family non-universal Z′ model. Under the consideration of three cases of the new physics parameters, we find that: (a) the Z′ boson can provide large contributions to the differential decay rates; (b) the forward-backward asymmetry (FBA) can be increased by about 47%, 38%, and 110% at most in S1, S2, and extreme limit values (ELV), respectively. In addition, the zero crossing can be shifted in all the cases; (c) when s 0.08, the value of P L can be changed from 1 in the Standard Model (SM) to 0.5 in S1, 0.6 in S2, and 0 in extreme limit values, respectively; (d) the new physics corrections to P T will decrease the SM prediction about 25% for the cases of S1     

Dynamics of Entropy and Nonclassicality Features of the Interaction between a ◇-type Four-Level Atom and a Single-Mode Field in the Presence of Intensity-Dependent Coupling and Kerr Nonlinearity

The interaction between a◇-type four-level atom and a single-mode field in the presence of Kerr medium with intensity-dependent coupling involving multi-photon processes has been studied. Using the generalized(nonlinear)Jaynes–Cummings model, the exact analytical solution of the wave function for the considered system under particular condition, has been obtained when the atom is initially excited to the topmost level and the field is in a coherent state. Some physical properties of the atom-field entangled state such as linear entropy showing the entanglement degree, Mandel parameter, mean photon number and normal squeezing of the resultant state have been calculated. The effects of Kerr medium, detuning and the intensity-dependent coupling on the temporal behavior of the latter mentioned nonclassical properties have been investigated. It is shown that by appropriately choosing the evolved parameters in the interaction process, each of the above nonclassicality features, which are of special interest in quantum optics as well as quantum information processing, can be revealed.     

Charmed andϕmeson decay constants from 2+1-flavor lattice QCD

On a lattice with 2+1-flavor dynamical domain-wall fermions at the physical pion mass,we calculate the decay constants of D_s^* , D^* ,and φ .The lattice size is 48^3×96 ,which corresponds to a spatial extension of -5.5 fm,with a lattice spacing of a\approx a≈0.114 fm.For the valence light,strange,and charm quarks,we use overlap fermions at several mass points close to their physical values.Our results at the physical point are f_D=213(5) MeV, f_Ds=249(7) MeV, f_D^*=234(6) MeV, f_Ds^*=274(7) MeV,and f_Ds=241(9) MeV.The couplings of D^* and D_s^* to the tensor current( f_V^T )can be derived from ratios f_D^*^T/f_D^*=0.91(4) and f_Ds^*^T/f_Ds^*=0.92(4) ,respectively,which are the first lattice quantum chromodynamics(QCD)results.We also obtain ratios f_D^*/f_D=1.10(3) and f_Ds^*/f_Ds=1.10(4) ,which reflect the size of heavy quark symmetry breaking in charmed mesons.Ratios f_Ds/f_D=1.16(3) and f_Ds^*/f_D^*=1.17(3) can be taken as a measure of SU(3)flavor symmetry breaking.     

Four-level model of ion-ion laser-induced collisional energy transfer and numerical calculations for Ca~+-Sr~+ system

The four-level model of laser-induced collisional energy transfer(LICET) for the ion-ion collision system is established based on the time-dependent Schro¨dinger equation for the electron dynamics,through which the equations of motion of the probability amplitudes and cross section of the collision system are obtained.Numerical calculations are performed for the Ca+-Sr+ system,with the results showing that the peak of the LICET spectrum appears at a resonant frequency of the transfer laser.The magnitude of the obtained collision cross section is in the order of 10 16 cm2,and is comparable to that obtained in atomic systems,which indicates the validity of the established four-level model.     

Evaluation of the 1077 keV γ-ray emission probability from ~(68)Ga decay

68Ga decays to the excited states of68Zn through the electron capture decay mode. New recommended values for the emission probability of 1077 keV γ-ray given by the ENSDF and DDEP databases all use data from absolute measurements. In 2011, JIANG Li-Yang deduced a new value for 1077 keV γ-ray emission probability by measuring the69Ga(n,2n)68Ga reaction cross section. The new value is about 20% lower than values obtained from previous absolute measurements and evaluations. In this paper, the discrepancies among the measurements and evaluations are analyzed carefully and the new values are re-recommended. Our recommended value for the emission probability of 1077 keV γ-ray is(2.72±0.16)%.