α Decay Properties of Even-Even Nuclei~(296-308)120 Within the Two-Potential Approach

In the present work,we predict the α decay half-lives of unknown even-even nuclei ~(296-308)120 within the two-potential approach,whose α decay energy Qa is calculated using WS3+mass model.To reduce the deviations between the predictions and experimental data due to nuclear shell effect,the analytic formula of α decay hindrance factor is introduced to the two-potential approach,whose parameters had been extracted from even-even nuclei in the region of 82 Z 126 and 152 N 184 in our previous work [Deng et al.,Chin.Phys.C 42(2018) 044102].In addition,for comparing,we use a type of α decay general formula Universal Decay Law(UDL) and a semi-empirical formula in the superheavy nucleus(SEMFLS) to calculate the half-lives of even-even nuclei ~(296-308)120.The results indicate that our predicted values and the calculated values of the above two empirical formulas are mutually confirmed.Meanwhile,we systematically study α decay chains of ~(296-308)120 and predict the decay modes for superheavy nuclei to help to identify new superheavy isotopes.     

α-decay half-lives of superheavy nuclei and general predictions

The generalized liquid drop model （GLDM） and the cluster model have been employed to calculate the α-decay half-lives of superheavy nuclei （SHN） using the experimental α-decay Q values. The results of the cluster model are slightly poorer than those from the GLDM if experimental Q values are used. The prediction powers of these two models with theoretical Q values from Audi et al. （QAudi） and Muntian et al. （QM） have been tested to find that the cluster model with QAudi and QM could provide reliable results for Z 〉 112 but the GLDM with QAudi for Z 112. The half-lives of some still unknown nuclei are predicted by these two models and these results may be useful for future experimental assignment and identification.     

Competition between α-decay and β-decay for heavy and superheavy 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 Mo¨ller et al. The half-lives of the nuclei close to the β-stable region are calculated and the competition between α-decay andβ-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.     

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.     

Half-Lives of Superheavy Nuclei in Z=113 Alpha Decay Chain

The generalized liquid drop model （GLDM）, including the proximity effects and centrifugal potential, and the cluster model with Cosh potential are used to study the half-lives of some Z = 113 isotopes and their α-decay products. The experimental half-lives of 284^113, 283^113, 282^113 and their α-decay products are well reproduced by the two models when zero angular momenta transfer is assumed. For 278^113 and its α-decay products, both the GLDM and the duster model could provide satisfactory results if we assume the α particle carry five units of angular momenta, which indicates that possible nonzero angular momenta transfer and need further experimental measurements with high precision. Finally, we show that half-lives of α-decay are quite sensitive to the angular momentum transfers, and a formula could be used to describe the correlation between α-decay half-life and angular momentum transfer successfully.     

基于两势方法系统研究壳结构对原子核α衰变的影响

基于两势方法（two-potential-approach,TPA）系统研究了偶-偶核、奇-A核和奇-奇核α衰变半衰期。为了考虑原子核的壳结构的影响而导致的实验半衰期与计算结果之间的偏差,引入了与α结团形成概率相关的禁戒因子和预形成因子。结合前期相关工作[X.D.Sun et al.,Phys.Rev.C 93,034316（2016）;X.D.Sun et al.,Phys.Rev.C 95,014319（2017）;X.D.Sun et al.,Phys.Rev.C 95,044303（2017）],考虑到壳效应对α粒子预形成的影响,通过分析α衰变半衰期的实验数据,拟合得到了α粒子预形成因子/禁戒因子修正公式的参数,得到了α衰变预形成因子/禁戒因子的计算结果,证实了壳效应及质子-中子相互作用在α结团形成过程中起着重要的作用,离壳越近预形成概率越小离壳越远预形成概率越大。In the present work, the α decay half-lives are systematically studied within the two-potentialapproach for even-even nuclei, odd-A nuclei and odd-odd nuclei. To describe the deviations between experimental half-lives and calculated results due to the nuclear shell structure, α preformation factor and hindrance factor related with α cluster preformation probability are introduced. It is consistent with our previous works[X. D. Sun et al., Phys. Rev. C 93, 034316 (2016); X. D. Sun et al., Phys. Rev. C 95, 014319 (2017); X. D. Sun et al., Phys. Rev. C 95, 044303 (2017)]. Considering the shell effect on the preformation of α and by analyzing the experimental data of the α decay half-lives, the parameters of the α preformation factor/hindrance factor correction formula are obtained. we confirm that the shell effect and the proton-neutron correlation play key roles in the α preformation where the preformation probability near the shell is less than the preformation probability far from the shell.     

Exploring the uncertainties in theoretical predictions of nuclear β-decay half-lives

Nuclear β-decay half-lives are predicted based on an empirical formula and the mass predictions from various nuclear models.It is found that the empirical formula can reproduce the nuclearβ-decay half-lives well,especially for short-lived nuclei with T_1/2<1s.The theoretical half-life uncertainties fromβ-decay energies and the parameters of the empirical formula are further investigated.It is found that the uncertainties of the half-lives are relatively large for heavy nuclei and nuclei near the neutron-drip line.For nuclei on the r-process path,the uncertainties for those with N=126 are about one order of magnitude,which are much larger than the uncertainties for those with N=50 and 82.However,theoretical uncertainties from the parameters of the empirical formula are relatively small for the nuclei on the r-process path,which indicates that the empirical formula is very suitable for predicting theβ-decay half-lives in r-process simulations.     

Ground-State Bands of Fm and No Isotopes in Cluster Model

We investigate the ground-state rotational bands of nuclei with Z ≥ 100 using cluster model proposed by Buck et al. [Phys. Rev. Lett. 94 (2005) 202501]. The core-cluster decomposition of each nucleus is determined by the corresponding electric quadrupole transition strength B(E2 : 2 → 0 ). The theoretical spectra of fermium and nobelium isotopes are compared with available experimental data. Good agreement between model and data is obtained.     

α decay properties of ~(296)Og within the two-potential approach

The present work is a continuation of our previous paper [J.-G. Deng, et al., Chin. Phys. C, 41:124109(2017)]. In the present work, the α decay half-life of the unknown nucleus296 Og is predicted within the two-potential approach and the hindrance factors of all 20 even-even nuclei in the same region as296 Og, i.e. proton number 82Z 126 and neutron number 152N 184, from250 Cm to294 Og, are extracted. The prediction is 1.09 ms within a factor of 5.12. In addition, based on the latest experimental data, a new set of parameters of α decay hindrance factors for the even-even nuclei in this region, considering the shell effect and proton-neutron interaction,are obtained.     

Ground State Properties of New Element Z=113 and Its Alpha Decay Chain

We investigate the ground state properties of the new element ^278 113 and of the α-decay chain with different models, where the new element Z=113 has been produced at RIKEN in Japan by cold-fusion reaction [Morita et al. J. Phys. Soc. Jpn. 73 (2004) 2593]. The experimental decay energies are reproduced by the deformed relativistic mean-field model, by the Skyrme-Hartree-Fock (SHF) model, and by the macroscopic-microscopic model.Theoretical half-lives also reasonably agree with the data. Calculations further show that prolate deformation is important for the ground states of the nuclei in the α-decay chain of ^278 113. The common points and differences among different models are compared and discussed.     

New Geiger-Nuttall law for cluster radioactivity half-lives

In this study, derived from Balasubramaniam’s formula [Phys. Rev. C 70, 017301(2004)] and further considering the effect of the parent nucleus mass, blocking effect, and effect of reduced mass on cluster radioactivity half-lives, we propose a new Geiger-Nuttall law that is model-independent to systematically evaluate the halflives of this process for 16 even-even nuclei and 10 odd-A nuclei. For comparison, a single universal curve for cluster radioactivity and α decay proposed by Poenaru [Phys. ...     

Theoretical approaches to alpha decay half-lives of super-heavy nuclei

We consider the systematics of α-decay half-lives of super-heavy nuclei versus the decay energy and the total α-kinetic energy. We calculate the half-lives using the experimental Q_α values. The computed half-lives are compared with the experimental data and with existing empirical estimates and are found to be in good agreement.Also, we obtain α-preformation factors from the ratio between theoretical and experimental results for some superheavy nuclei and evaluate the standard deviation. The results indicate the acceptability of the approach.     

Simultaneous Space and Time Synchronization Using Shared Entangled Qubits

This paper generalizes the quantum clock synchronization protocol of Josza, et al., [Richard Jozsa, et al.,Phys. Rev. Lett. 85 (2000) 2010] to synchronize space and thne simultaneously.     

Half-lives of double β~+-decay with two neutrinos

Nuclear doubleβ--decays with two neutrinos were observed for many years and a systematic law describing the relation between their half-lives and decay energies was also proposed recently[Phys Rev C,2014,89:064603].However,doubleβ+-decay(β+β+)with emission of both two positrons and two neutrinos has not been observed up to date.In this article,we perform a systematic analysis on the candidates of doubleβ+-decay,based on the 2012 nuclear mass table.Eight nuclei are found to be the good candidates for doubleβ+-decay and their half-lives are predicted according to the generalization of the systematic law to doubleβ+-decay.As far as we know,there is no theoretical result on doubleβ+-decay of nucleus154Dy and our result is the first prediction on this nucleus.This is also the first complete research on eight doubleβ+-decay candidates based on the available data of nuclear masses.It is expected that the calculated half-lives of doubleβ+-decay in this article will be useful for future experimental search of doubleβ+-decay.     

α particle preformation and shell effect for heavy and superheavy nuclei

The α particle preformation factor is extracted within a generalized liquid drop model for Z = 84-92 isotopes and N = 126,128,152,162,176,184 isotones.The calculated results show clearly that the shell effects play a key role in α particle preformation.The closer the proton and neutron numbers are to the magic numbers,the more difficult the formation of the α cluster inside the mother nucleus is.The preformation factors of the isotopes reflect that N = 126 is a magic number for Po,Rn,Ra,and Th isotopes,but for U isotopes the weakening of the influence of the N =126 shell closure is evident.The trend of the factors for N = 126 and N = 128 isotones also support this conclusion.We extend the calculations for N = 152,162,176,184 isotones to explore the magic numbers for heavy and superheavy nuclei,which are probably present near Z = 108 to N = 152,162 isotones and Z = 116 to N = 176,184 isotones.The results also show that another subshell closure may exist after Z = 124 in the superheavy nuclei.This is useful for future experiments.     

Global α-decay study based on the mass table of the relativistic continuum Hartree-Bogoliubov theory

The α-decay energies(Qα) are systematically investigated with the nuclear masses for 10 Z 120 isotopes obtained by the relativistic continuum Hartree-Bogoliubov(RCHB) theory with the covariant density functional PC-PK1, and compared with available experimental values. It is found that the α-decay energies deduced from the RCHB results present a similar pattern to those from available experiments. Owing to the large predicted Qαvalues( 4 Me V), many undiscovered heavy nuclei in the proton-rich side and super-heavy nuclei may have large possibilities for α-decay. The influence of nuclear shell structure on α-decay energies is also analysed.     

Empirical formula for β~--decay half-lives of r-process nuclei

Experimental data ofβ--decay half-lives of nuclei with atomic number between 20 and 190 are investigated.A systematic formula has been proposed to calculateβ~--decay half-lives of neutron-rich nuclei,with a particular consideration on shell and pair effects,the decay energy Q as well as the nucleon numbers(Z,N).Although the formula has relatively few parameters,it reproduces the experimentalβ~--decay half-lives of neutron-rich nuclei very well.The predicted half-lives for the r-process relevant nuclei obtained with the current formula serve as reliable input in the r-process model calculations.     

Gound State Properties of Nuclei in ^295118 α-Decay Chain

The properties of nuclei belonging to the α-decay chain of superheavy element ^295118 have been studied in the framework of axially deformed relativistic mean field （RMF） theory with the parameter set of NL-Z2 in the blocked BCS approximation. Some ground state properties such as binding energies, deformations, and α-decay energies Qα have been obtained and agree well with those from finite-range droplet model （FRDM）. The single-particle spectra of nuclei in ^295118 α-decay chain show that the shell gaps present obviously nucleon number dependence. The root-mean-square （rms） radii of proton, neutron and matter distributions change slowly from ^283112 to ^295118 but dramatically from ^279110 to ^283112, which may be due to the subshell closure at Z = 110 in ^279110. The α-decay half-lives in 295118 decay chain are evaluated by employing the cluster model and the generalized liquid drop model （GLDM）, and the overall agreement is found when they are compared with the known experimental data. The α-decay lifetimes obtained from the cluster model are slightly larger than those of GLDM ones. Finally, we predict the α-decay half-lives of Z=118, 116, 114, 112 isotopes using the cluster model and GLDM, which also indicate these two models can corroborate each other in studies on superheavy nuclei. The results from GLDM are always lower than those obtained from the cluster model.     

Probing R-parity Violating Interactions via p

[1]Y. Fukuda, et al., Super-Kamiokande Collaboration,Phys. Lett. B 433 (1998) 9; Phys. Lett. B 436 (1998) 33; Phys. Rev. Lett. 81 (1998) 1562; M. Apollonio, et al.,Chooz Collaboration, Phys. Lett. B 420 (1998) 297. [2]H.P. Nilles, Phys. Rep. 1 (1984) 110; H.E. Haber and G.Kane, Phys. Rep. 117 (1985) 75. [3]P. Fayet, Phys. Lett. B 69 (1977) 489; G.R. Farrar and P. Fayet, Phys. Lett. B 76 (1978) 575. [4]S. Weinberg, Phys. Rev. D 26 (1982) 287; N. Sakai and T. Yanagida, Nucl. Phys. B 197 (1982) 533. [5]J.C. Romao, M.A. Diaz, M. Hirsch, W. Porod, and J.W.Valle, Phys. Rev. D 61 (2000) 071703; Phys. Rev. D 62 (2000) 113008. [6]G. Abbiendi, et al., Phys. Lett. B 519 (2001) 23. [7]Y.B. Sun, L. Han, W.G. Ma, T. Farshid, R.Y. Zhang, and Y.J. Zhou, JHEP 0409 (2004) 043. [8]R. Barbieri, et al., hep-ph/9810232; B. Allanach, et al.,hep-ph/9906224; F. Deliot, et al., Phys. Lett. B 475 (2000) 184; G. Moreau, et al., Nucl. Phys. B 604 (2001) 3; S. Bar-Shalom, et al., Phys. Rev. D 64 (2001) 095008. [9]T. Sj(o)strand, P. Eden, C. Friberg, L. L(o)nnblad, G. Miu,S. Mrenna, and E. Norrbin, Computer Phys. Commun.135 (2001) 238 (LU TP 00-30, [hep-ph/0010017]). [10]R. Barbieri, et al., [hep-ph/9810232]; B. Allanach, et al.,[hep-ph/9906224]. [11]The Dφ detector is described in detail elsewhere as T.LeCompte and H.T. Diehl, Ann. Rev. Nucl. Part. Sci. 50 (2000) 71; Dφ Collaboration, S. Abachi, et al., Nucl.Instrum. Methods Phys. Res. A 338 (1994) 185.     

Entanglement Purification with Higher Error Threshold for Imperfection of Local Operations and Bell State Measurements

We analyse further the entanglement purification protocol proposed by Feng et al. [Phys. Lett. A 271(2000)44] in the case of imperfect local operations and measurements. It is found that this protocol allows of higher error threshold. Compared with the standard entanglement purification proposed by Bennett et al. [Phys. Rev.Lett. 76 (1996) 722], it turns out that this protocol is remarkably robust against the influences of imperfect local operations and measurements.