Level scheme in 160Tm towards complete high-spin structure

High-spin states of ¹⁶⁰Tm have been studied through the ¹⁴⁶Nd(¹⁹F, 5n) reaction at a beam energy of 102 MeV. The previously known πh_11/2⊙νi_13/2 yrast band and πh_11/2⊙νh_9/2 side band are confirmed, and several low-lying levels are observed. A 4-quasiparticle band feeding into the yrast band based on the πg_7/2⊙νh_9/2⊙νi_13/2² is suggested. Other two bands are observed and assigned to be based on the πd_3/2⊙νi_13/2 and πg_7/2⊙νi_13/2 configurations, respectively.     

SEVERAL PROBABLE QUESTIONS ON "A STUDY OF A SEMICLASSICAL APPROXIMATIONS FOR HEAVY ION TRANSFER REACTIONS"

The identity G(S,θ,π,0)=(－1)^{λ₁－λ₂}G(S,θ,0,0) is proved thus the transition amplitude's formula ((33), H-B,see[1]) stands good under the nonforward angular scattering conditions. The equation (ε₁-Δε₁-h²k₁²/2m_x⁾=(ε₂-Δε₂- h²k₂²/2m_x⁾ in Ref[1] may be questionable. The transfer amplitude's formula ((48), H-B) may be suitable only in post representation. The choice of different representations probablely influences the calculation results. The two symmetry properties of the transfer amplitude can simplify the numerical calculation.     

πg9/2⊙νh11/2 doublet bands in A~100 mass region

Using the model with one particle and one hole coupled with a triaxial rotor, the πg^－1_9/2⊙νh_11/2 doublet bands in the A~100 mass region are studied, and compared with the πh_11/2⊙νh^－1_11/2 doublet bands. It is found that the calculated results for the configuration of πg^－1_9/2⊙νh_11/2 are very similar the results for a pure h_11/2 proton particle and a neutron quasiparticle with λ_n=ε₅. After including the pair correlation, the model describes the candidate chiral doublet bands in ¹⁰⁶Rh successfully, which supports the interpretation of chirality geometry.     

PROTON-NUCLEUS SCATTERING IN A THERMODYNAMICAL FIREBALL MODEL

We attempt use a simple fireball model to explain the slow rise of the ratio R_A≡〈N_A〉/〈N_N〉 of the charged multiplicity for proton-nucleus scattering to that for proton-proton scattering verses the apparent nuclear thickness <span style="border-top: 1px solid; padding-top: 0px;"><em>v</em></span>. The pseudo-rapidity distribution dN_A/d_η is also discussed. In this model, the pi mesons are emitted by fireballs created during nucleon-nucleon scattering. When the incident energy E_lab Z 50 GeV/c², these fire-balls take so long a time to expend to thermal equilibrium that the fireballs have passed through the nucleus completely before pions are emitted. As a result, the charged multiplicity is greatly reduced.This model gives excellent fittings to pp charged mutiplicity, R_A verses <span style="border-top: 1px solid; padding-top: 0px;"><em>v</em></span> as well as R_emalsion verses E_lab without any free theoretical parameter. By choosing only one parameter for the equilibrium of angular momentum, dN_A/d_η can be fitted satisfactorily except for the large pseudo-rapidity region.     

DEEP INELASTIC SCATTERING PROCESSES OF THE ELECTRONS ON POLARIZED NUCLEONS AND POLARIZATION EFFECTS IN THE PROCESSES OF HEAVY LEPTONS PAIR PRODUCTION

By using the distribution functions of the valence stratons with definite helici-ties, the differential cross sections and asymmetries of 1. the deep inelastic scatteringprocesses of electrons on polarized protons, polarized neutrons and polarized nucleons,and 2. the process p+N→μ⁺μ^-+X (where the p and N are polarized) are comput-ed. From the kinematics, it is shown that no polarization effects exist in the process π(K) +N→μ⁺μ^- + X (where N is polarized). Also from the parton model it isshown that no polarized effects exist in the process P + N→μ⁺μ^- + X (where P and N are polarized).     

THE NEGATIVE-POSITIVE RATIO OF CHARGED COSMIC RAY HADRONS AT THE 3220 m ABOVE SEA-LEVEL

Single tracks of unaccompanÏed charged hadrons, within a horigontal area of 0.23m² have been measured with a magnetic spectrometer, a pre-selector of momentum in combination with a multiplate cloud chamber in a laboratory at 3220m above sea level. Taking various possible corrections into account, the negative-positive ratio of charged hadrons was obtained as N^-/N⁺=0.53±0.05 in the momentum range of 10-20 GeV/c. If we considered N⁺ contained only P and π⁺, N^-were π^-and that N_π+/N_π-=1, we deduced the result N_π-/N_p=0.9±0.1. Taking the form of the π^-integral spectrum as j（>p）=Kp^-γ, it was estimated that γ（?）2.3 in the momentum range 5—20 GeV/c. In this paper the integral verticel flux intensity of all charged hadrons was also estimated roughly, the result is:j_⊥^p+π（>12 GeV/c）=（7.4±0.7）×10^-5/cm²·sг·s_^.     

THE GENERATOR COORDINATE METHOD AND NUCLEAR COLLECTIVE MOTIONS (Ⅳ) TDGCM VERSUS ATDHF

Considering the time-dependent generator coordinate method, the time-dependent Schrodinger equation for nuclear collective motions is obtained. It is then possible to obtain through Wigner matrix a variational expression for mean collective properties q(t) and p(t) in classical limits. Under adiabatic approximation this is just the expression by which Villars has obtained the ATDHF results.     

High-spin states and signature inversion studies in 110Ag

The high-spin states of ¹¹⁰Ag were populated via fusion evaporation reaction ¹¹⁰Pd(⁷Li, 2p2n)¹¹⁰Ag and a new level scheme has been presented. The systematics of signature splitting and signature inversion of the πg_9/2⊙νh_11/2 configuration band in Ag isotopes are studied. The spin of inversion point decreases with increasing neutron number and this feature is explained as due to the competition between the p-n residual interaction and the Coriolis force.     

Rotational properties in even-even superheavy 254-258Rf nuclei based on total-Routhian-surface calculations

High-spin yrast structures of even-even superheavy nuclei ^254-258Rf are investigated by means of total-Routhian-surface approach in three-dimensional (β₂, γ, β₄) space. The behavior in the moments of inertia of ²⁵⁶Rf is well reproduced by our calculations, which is attributed to the j_15/2 neutron rotation-alignment. The competition between the rotationally aligned i_13/2 proton and j_15/2 neutron may occur to a large extent in ²⁵⁶Rf. High-spin predictions are also made for its neighboring isotopes ^254,258Rf, showing that the alignment of the j_15/2 neutron pair is more favored than that of the i_13/2 proton pair.     

关于Pt偶同位素的h9/2质子对

本文对于Pt偶同位素中的h_9/2质子对的排列现象作了比较系统的计算和讨论.结果表明,如用改善的Nilsson参数κ、μ,给出的h_9/2的排列频率与νi_13/2排列频率的差值Δhω_c=hω_c(πh_9/2)－hω_c(νi_13/2)对于78¹⁸⁴Pt106核具有最小值,约为75keV.这和最近实验上确定的¹⁸⁴Pt核转晕带上出现的大的上弯现象,是由于νi_13/2和πh_9/2两个排列频率非常靠近的结果一致.而运用Nilsson的标准κ、μ则不能给出这一结果.这两个排列的先后次序仍是值得深入研究的问题.对于相邻Pt偶同位素的πh_9/2排列频率的理论预言,期待着实验数据的检验.     

Description of the candidate chiral doublet bands in 98Tc

The candidate chiral doublet bands in ⁹⁸Tc with configuration πg_9/2 × νh_11/2 are studied theoretically for the first time via the triaxial particle rotor model. The main properties of the doublet bands including the energy spectra and electromagnetic transitions are calculated for different triaxiality parameter γ, and the data in ⁹⁸Tc can be well described by the calculations with γ=38°. Based on the analysis of angular momentum components, it is found that the chiral rotational geometry in ⁹⁸Tc deviates from the ideal chiral picture.     

Properties of the ν7/2-[503]（f7/2） band in 185Pt

High-spin states in ¹⁸⁵Pt have been reinvestigated via the reaction ¹⁷³Yb(¹⁶O, 4n) at a beam energy of 90 MeV. The previously known band based on the ν7/2^-[503](f_7/2) Nilsson orbital has been extended to higher spin states. Properties of the ν7/2^-[503](f_7/2) band have been discussed with an emphasis on the evolution of configuration while increasing the spin.     

Semileptonic decays Bc→(ηc,J/Ψ)lv in the perturbative QCD approach

In this paper we study the semileptonic decays of B_c^-→(η_c,J/Ψ)l^-v_l. We first evaluate the B_c→(η_c,J/Ψ) transition form factors F₀(q²), F₊(q²), V(q²) and A_0,1,2(q²) by employing the pQCD factorization approach, and then we calculate the branching ratios for all considered semileptonic decays. Based on the numerical results and the phenomenological analysis, we find that: (a) the pQCD predictions for the values of the B_c→η_c and B_c→J/Ψ transition form factors agree well with those obtained by using other methods; (b) the pQCD predictions for the branching ratios of the considered decays are Br(B_c^-→η_c e^-v_e(μ^-v_μ)=(4.41_-1.09^+1.22)×10^-3, Br(B_c^-→η_cτ^-v_τ) =(1.37_-0.34^+0.37)×10^-3, Br(B_c^-→J/Ψ e^-v_e(μ^-v_μ)) =(10.03_-1.18^+1.33)×10^-3, and Br(B_c^-→J/Ψτ^-v_τ) =(2.92_-0.34^+0.40)×10^-3; and (c) we also define and calculate two ratios of the branching ratios R_ηc and R_J/Ψ, which will be tested by LHCb and the forthcoming Super-B experiments.     

Shears mechanism in two-dimensional cranking relativistic mean field approach

Using the new two-dimensional cranking relativistic mean field (RMF) approach, the shears mechanism of magnetic rotation based on configuration πh²_11/2⊙νh^－2_11/2 in ¹⁴²Gd is microscopically and self-consistently examined by investigating the aligning angular momenta of the valence nucleons.     

双奇核中πi13/2 νi13/22－准粒子转动带旋称反转研究

利用重离子熔合蒸发反应和在束γ谱学实验方法研究了双奇核^176,178Ir和¹⁸²Au的高自旋态结构,在这3个双奇核中观测到了基于πi_13/2 νi_13/2准粒子组态下的转动带.以能级间隔系统学为判据,对¹⁸⁴Au核中πi_13/2 νi_13/2转动带能级自旋进行了指定.指出^176,178Ir和^182,184Au 4个双奇核的πi_13/2 νi_13/2转动带在低自旋区均出现旋称反转.对πi_13/2 νi_13/2转动带旋称反转现象进行了定性的讨论.用推转壳模型对πh_9/2 νi_13/2带和πi_13/2 νi_13/2带能级结构进行了理论研究,发现当采用形变和对力自洽计算后,从理论上可以定性地解释两个半退耦带出现的旋称反转现象.     

Study of diphoton decays of the lightest scalar Higgs boson in the Next-to-Minimal Supersymmetric Standard Model

The CMS and ATLAS experiments at the LHC have announced the discovery of a Higgs boson with mass at approximately 125 GeV/c² in the search for the Standard Model Higgs boson via, notably, the γγ and ZZ to four leptons final states. Considering the recent results of the Higgs boson searches from the LHC, we study the lightest scalar Higgs boson h₁ in the Next-to-Minimal Supersymmetric Standard Model by restricting the next-to-lightest scalar Higgs boson h₂ to be the observed to the 125 GeV/c² state. We perform a scan over the relevant NMSSM parameter space that is favoured by low fine-tuning considerations. Moreover, we also take the experimental constraints from direct searches, B-physics observables, relic density, and anomalous magnetic moment of the muon measurements, as well as the theoretical considerations, into account in our specific scan. We find that the signal rate in the two-photon final state for the NMSSM Higgs boson h₁ with the mass range from about 80 GeV/c² to about 122 GeV/c² can be enhanced by a factor of up to 3.5 when the Higgs boson h₂ is required to be compatible with the excess from latest LHC results. This motivates the extension of the search at the LHC for the Higgs boson h₁ in the diphoton final state down to masses of 80 GeV/c², particularly with the upcoming proton-proton collision data to be taken at center-of-mass energies of 13-14 TeV.     

关于Pt偶同位素的i13/2中子对

本文对偶Pt同位素i13/2中子对作了一个较细致的系统的分析. 实验数据和用不同κ、μ参数所得到的Nillson推转模型结果间的比较, 给出如下重要性质: 1) 改善的κ、μ参数能够很好符合¹⁸⁵Au数据, 对Pt同位素一般地似乎也是合适的, 但尚需更多的实验与理论数据检验. 2)仅仅有νi_13/2排列不能解释¹⁸⁴Pt中大的上弯现象, 而πh_9/2排列应该同样也起作用. 3)实验数据与理论计算之间的偏离表明, 一种包括ε₂, ε₄及γ三维势能面的计算是必需的.     

Prolate and Oblate Shape Coexistence in 188Pt

A standard in-beam γ-spectroscopy experiment for ¹⁸⁸Pt is performed via the¹⁷⁶Yb(¹⁸O, 6n) reaction at beam energies of 88 and 95MeV, and the level scheme for ¹⁸⁸Pt is established. Prolate and oblate shape coexistence has been demonstrated to occur in ¹⁸⁸Pt by applying the projected shell model. The rotation alignment of i_13/2 neutrons drives the yrast sequence changingsuddenly from prolate to oblate shape at angular momentum 10h, indicating likely a new type of shape phase transition along the yrast line in ¹⁸⁸Pt.     

关于162,164Er,164,166Yb,168Hf诸核的回弯机制

通过对相邻奇A核转动带的回弯行为的分析,无法肯定^162,164Er,^164,166Yb,¹⁶⁸Hf诸核的回弯机制。本文利用HFB推转模型,计算了这些核的排列角动量i（ω）和回弯的临界角频率ω_c,探讨了阻塞效应的影响,通过和实验值的比较,确定了它们出现回弯均是由于一对i_13/2中子转动排列的结果。     

Magnetic rotation in 106Ag

The high spin states of ¹⁰⁶Ag were populated via the fusion-evaporation reaction ¹⁰⁰Mo(¹¹B,5n)¹⁰⁶Ag at a beam energy of 60 MeV. A new level scheme of ¹⁰⁶Ag is presented. The positive parity band based on the configuration of πg_9/2⊙ν[h²_11/2(g_7/2/d_5/2)] is assigned to magnetic rotation band of shears mechanism. Theoretical calculation of the effective interaction on the basis of TAC mode were also performed, the calculated results agrees well with the value extracted from the experiment.